US20120262598A1 - Image signal processing apparatus - Google Patents
Image signal processing apparatus Download PDFInfo
- Publication number
- US20120262598A1 US20120262598A1 US13/531,234 US201213531234A US2012262598A1 US 20120262598 A1 US20120262598 A1 US 20120262598A1 US 201213531234 A US201213531234 A US 201213531234A US 2012262598 A1 US2012262598 A1 US 2012262598A1
- Authority
- US
- United States
- Prior art keywords
- image signal
- picture
- smoothing
- encoded
- setting value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000012545 processing Methods 0.000 title claims abstract description 120
- 238000009499 grossing Methods 0.000 claims abstract description 192
- 238000007906 compression Methods 0.000 claims abstract description 45
- 230000006835 compression Effects 0.000 claims abstract description 45
- 230000008859 change Effects 0.000 claims abstract description 40
- 238000013139 quantization Methods 0.000 claims description 110
- 230000002123 temporal effect Effects 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 16
- 230000007423 decrease Effects 0.000 abstract description 35
- 230000000694 effects Effects 0.000 abstract description 23
- 206010047571 Visual impairment Diseases 0.000 abstract description 10
- 230000002411 adverse Effects 0.000 abstract description 7
- 230000015654 memory Effects 0.000 description 20
- 238000006243 chemical reaction Methods 0.000 description 16
- 230000006870 function Effects 0.000 description 14
- 230000001629 suppression Effects 0.000 description 13
- 238000010586 diagram Methods 0.000 description 9
- 230000002457 bidirectional effect Effects 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 6
- 230000005540 biological transmission Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 4
- 238000004891 communication Methods 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 230000003252 repetitive effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000013144 data compression Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
- H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
- H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/80—Camera processing pipelines; Components thereof
- H04N23/81—Camera processing pipelines; Components thereof for suppressing or minimising disturbance in the image signal generation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
- H04N19/115—Selection of the code volume for a coding unit prior to coding
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
- H04N19/117—Filters, e.g. for pre-processing or post-processing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
- H04N19/124—Quantisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
- H04N19/136—Incoming video signal characteristics or properties
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
- H04N19/146—Data rate or code amount at the encoder output
- H04N19/152—Data rate or code amount at the encoder output by measuring the fullness of the transmission buffer
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
- H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
- H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
- H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
- H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
- H04N19/85—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using pre-processing or post-processing specially adapted for video compression
Definitions
- the present invention relates to an image signal processing apparatus for processing a photographed image signal and, more particularly, to suppression processing of a flicker that occurs upon increasing the camera gain in a compression scheme using intra-picture and inter-picture prediction.
- Efficient moving image encoding as represented by MPEG2 generally executes compression encoding by using a plurality of different picture types including intra-frame and inter-frame prediction. More specifically, only frames at a predetermined interval use a picture type for intra-frame encoding. Frames between them use a picture type for inter-frame prediction due to the fact that successive frames have high image data correlation, thereby increasing the moving image data compression efficiency.
- FIG. 17 is a block diagram showing a conventional image signal processing apparatus.
- Reference numeral 1702 denotes a camera unit; and 1701 , a camera including a optical lens system and a photo-electric conversion unit such as a CCD (Charge Coupled Device).
- An analog moving image signal photographed by the camera 1701 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and ⁇ -conversion by a photographed image signal processing circuit 1703 .
- a camera control circuit 1725 executes processing such as exposure control of the camera 1701 on the basis of, for example, the brightness of the photographed image.
- the camera control circuit 1725 raises the amplifier gain of the photographed image signal processing circuit 1703 in order to not reduce the shutter speed, thereby preventing any afterimage.
- the photographed image signal processing circuit 1703 supplies its output to a frame rearranging circuit 1709 as image data to be encoded.
- the frame rearranging circuit 1709 rearranges frames in encoding order.
- the frames are rearranged in an order suitable for encoding.
- a B-picture serving as a bidirectional prediction frame should be encoded after the encoding of the preceding and succeeding frames and therefore it is moved backward.
- a difference circuit 1710 outputs the image data itself to a DCT circuit 1711 .
- the difference circuit 1710 calculates the difference value between the image data and a predicted image and outputs the difference value to the DOT circuit 1711 according to a selection by a switch 1723 .
- the DCT circuit 1711 converts the image data into a DCT coefficient.
- a quantization circuit 1712 quantizes the DCT coefficient using a predetermined quantization scale Q. When the Q value changes, the coefficient value after quantization changes greatly. Hence, the generated code amount changes.
- a variable-length coding circuit 1713 for example, entropy-encodes the quantization coefficient output from the quantization circuit 1712 and outputs it as encoded data.
- a buffer 1714 temporarily saves the generated encoded data to control the encoding rate.
- the encoded data stored in the buffer 1714 is read out at a predetermined rate and output from a terminal 1715 as compression-encoded data.
- the coefficient data quantized by the quantization circuit 1712 undergoes inverse quantization by an inverse quantization circuit 1717 and inverse DCT by an inverse DCT circuit 1718 to obtain predicted image data.
- an adding circuit 1719 saves data after inverse DCT directly in a video memory 1720 .
- the adding circuit 1719 adds the predicted image to the P- and B-pictures and saves it in the video memory 1720 as locally decoded image data.
- a motion compensation predicting circuit 1721 compares the locally decoded image data saved in the video memory 1720 with the input image data.
- predicted image data with motion compensation in the forward direction is generated and supplied to the above-described difference circuit 1710 .
- predicted image data with bidirectional motion compensation is generated and supplied to the above-described difference circuit 1710 .
- the motion compensation predicting circuit 1721 also supplies the generated image data to the adding circuit 1719 as a predicted image for next local decoding.
- a rate control circuit 1727 executes code amount assignment control of a picture to be encoded for a target encoding rate using information such as a past generated code amount and buffer fill factor obtained from the buffer 1714 .
- the rate control circuit 1727 controls the quantization circuit 1712 by deciding the quantization scale Q based on a code amount assigned to each picture type.
- the generated code amount after quantization changes between the I-, P-, and B-pictures.
- the quantization scale Q is therefore generally changed in accordance with the picture type. For example, an encoding scheme known as MPEG2-TM (Test Model) sets the quantization scale corresponding to each picture type.
- Conventional video cameras execute exposure control of the camera 1701 in accordance with the brightness of a photographed image, as in the above-described camera unit 1702 .
- the video camera In a normal brightness range, the video camera generally maintains adequate exposure mainly by combining the F-number and shutter speed.
- a video camera may increase the gain in a dark scene with a full aperture.
- an image photographed at the increased gain has a low S/N ratio because of a random noise component mixed into the image.
- an encoding such as the above-described MPEG2 using a plurality of different picture types is used, the luminance peak generated by the noise component after encoding varies depending on the picture type. The variation is observed as a luminance flicker in the reproduced moving image, resulting in a visual disturbance, as is known.
- FIG. 16 shows graphs a through c for explaining the cause of a luminance flicker in the reproduction mode which is generated when increasing the gain of the camera used in the conventional arrangement described above.
- the graph a of FIG. 16 shows a reproduction signal from I-pictures.
- the luminance peak of the noise component superimposed on a flat image signal is maintained to some extent by intra-frame encoding. This is also because the assigned code amount of I-pictures is generally larger than that of the other picture types.
- the graph b of FIG. 16 shows a reproduction signal from P- and B-pictures.
- the correlation between frames is low because of the random noise component.
- the encoded image signal degrades because of the increase in inter-frame difference information of P- and B-pictures.
- the noise peak decreases so that a luminance peak difference is generated, unlike the I-pictures in the graph a of FIG. 16 .
- a luminance flicker derived from noise is generated in reproducing a moving image, as shown in the graph c of FIG. 16 .
- the conventional technique to remove random noise derived when increasing the gain i.e., the method of changing the filter characteristic as in WO97/05745 is one of general encoding distortion reducing methods in the case of a low S/N ratio and can expect a partial effect.
- the filter intensity must be sufficiently high.
- a TV program image can sometimes contain intentionally added noise intended to produce a film-like effect based on the granularity of noise. In this situation, it is impossible to uniformly remove noise using a filter. Removal of the noise component itself must be suppressed as much as possible. That is, to effectively reduce the above-described luminance flicker while maintaining image quality, the invention of WO97/05745 does not suffice.
- the present invention has been made to solve the above-described unsolved problems of the prior art, and has as its object to effectively reduce a luminance flicker caused by noise while suppressing adverse effects such as afterimages and decreases in resolution due to smoothing as much as possible even when the S/N ratio of an image photographed at an increased gain is low. It has, as another object, the reduction of a luminance flicker while making the most of the effect of noise even when photographing an image containing noise that is intentionally added to obtain an effect in the image.
- One aspect of the present invention relates to an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, characterized by comprising, acquisition unit adapted to acquire a gain setting value for the image signal;
- compression encoding adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit; and control adapted to control to change, in accordance with the gain setting value acquired by the acquisition unit, an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising, acquisition unit adapted to acquire a gain setting value for the image signal, smoothing unit adapted to execute smoothing processing of the image signal, compression encoding unit, provided on a subsequent stage of the smoothing unit, adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit, and control unit adapted to control to change, in accordance with the gain setting value acquired by the acquisition unit, an intensity of smoothing processing by the smoothing unit and an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising, acquisition adapted to acquire a gain setting value of gain adjustment for the image signal and a sharpness setting value of sharpness adjustment, smoothing unit adapted to execute smoothing processing of the image signal, compression encoding unit, provided on a subsequent stage of the smoothing unit, adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit, and control unit adapted to control to change, in accordance with the gain setting value and the sharpness setting value acquired by the acquisition unit, an intensity of smoothing processing by the smoothing unit and an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising, acquisition unit adapted to acquire a gain setting value for the image signal, smoothing unit adapted to execute smoothing processing of the image signal, compression encoding unit, provided on a subsequent stage of the smoothing unit, adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit, and designation unit adapted to designate a target bit rate of compression encoding of the compression encoding unit, and control unit adapted to control to change, in accordance with the gain setting value acquired by the acquisition unit and the target bit rate designated by the designation unit, an intensity of smoothing processing by the smoothing unit and an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- FIG. 1 is a block diagram of a digital video camera according to the first embodiment
- FIG. 2 shows graphs showing an example of assigned code amount control according to the first embodiment
- FIG. 3 shows graphs showing another example of assigned code amount control according to the first embodiment
- FIG. 4 shows graphs showing an example of smoothing intensity control according to the first embodiment
- FIG. 5 shows graphs showing another example of smoothing intensity control according to the first embodiment
- FIG. 6 shows block diagrams showing structural examples of a smoothing circuit
- FIG. 7 is a block diagram of a digital video camera according to the second embodiment.
- FIG. 8 shows graphs showing an example of assigned code amount control according to the second embodiment
- FIG. 9 shows graphs showing another example of assigned code amount control according to the second embodiment.
- FIG. 10 shows graphs showing an example of smoothing intensity control according to the second embodiment
- FIG. 11 shows graphs showing another example of smoothing intensity control according to the second embodiment
- FIG. 12 is a block diagram of a digital video camera according to the third embodiment.
- FIG. 13 shows graphs showing an example of assigned code amount control according to the third embodiment
- FIG. 14 shows graphs showing another example of assigned code amount control according to the third embodiment
- FIG. 15 shows graphs for explaining a luminance flicker reduction effect according to the present invention.
- FIG. 16 shows graphs for explaining a cause of a luminance flicker
- FIG. 17 is a block diagram showing the arrangement of a conventional image signal processing apparatus.
- An embodiment of an image signal processing apparatus of the present invention will be described by exemplifying a digital video camera capable of encoding an image signal photographed with a camera by a compression scheme using intra-picture prediction and inter-picture prediction and outputting the encoded data.
- Pictures include a field image and a frame image. In the following description, a picture indicates a frame image.
- FIG. 1 is a block diagram showing, as the first embodiment, a digital video camera according to an embodiment of an image signal processing apparatus of the present invention.
- Reference numeral 102 denotes a camera unit; and 101 , a camera including a lens optical system and a photo-electric conversion unit such as a CCD.
- An analog moving image signal photographed by the camera 101 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and ⁇ -conversion by a photographed image signal processing circuit 103 .
- a camera control circuit 125 executes processing such as exposure control of the camera 101 on the basis of, for example, the brightness of the photographed image. If a dark image will be photographed at a the shutter speed less than a predetermined value in the moving image photographing mode of the camera unit 102 , as described above, the camera control circuit 125 controls to raise the amplifier gain of the photographed image signal processing circuit 103 not to reduce the shutter speed, thereby preventing any afterimage.
- a camera apparatus for business use generally has a function of causing a user to arbitrarily switch the camera gain. When the camera unit 102 has this function, the camera control circuit 125 controls to make the photographed image signal processing circuit 103 have a fixed amplifier gain corresponding to a user setting value input from an operation unit (not shown).
- the photographed image signal processing circuit 103 supplies its output to a smoothing circuit 124 as an image signal from the camera unit 102 .
- the smoothing circuit 124 includes a variable-band special filter that limits the spatial band of an image signal, a variable temporal filter that executes temporal smoothing of each pixel, or a combination thereof.
- the smoothing circuit 124 will be described later in detail.
- the output from the smoothing circuit 124 is supplied to a frame rearranging circuit 109 as image data to be encoded.
- the frame rearranging circuit 109 rearranges frames in an encoding order.
- the frames are rearranged in an order suitable for encoding.
- a B-picture serving as a bidirectional prediction frame should be encoded after encoding of the preceding and succeeding frames and therefore is moved backward.
- a difference circuit 110 For I-pictures, a difference circuit 110 outputs the image data itself to a DCT circuit 111 .
- the difference circuit 110 calculates the difference value between the image data and a predicted image and outputs the difference value to the DCT circuit 111 by selecting a switch 123 .
- the DCT circuit 111 converts the image data into a DCT coefficient.
- a quantization circuit 112 quantizes the DCT coefficient by using a predetermined quantization scale Q. When the Q value changes, the coefficient value after quantization largely changes. Hence, the generated code amount changes.
- a variable-length coding circuit 113 for example, entropy-encodes the quantization coefficient output from the quantization circuit 112 and outputs it as encoded data.
- a buffer 114 temporarily saves the generated encoded data to control the encoding rate.
- the encoded data stored in the buffer 114 is read out at a predetermined rate and output from a terminal 115 as compression-encoded data. It is possible to efficiently record the output compression-encoded data on a recording medium such as a tape, disc, or semiconductor memory or efficiently transmit the compression-encoded data by using a network or commutation channel.
- the coefficient data quantized by the quantization circuit 112 undergoes inverse quantization by an inverse quantization circuit 111 and inverse DCT by an inverse DCT circuit 118 to obtain predicted image data.
- an adding circuit 119 saves data after inverse DCT directly in a video memory 120 .
- the adding circuit 119 adds the predicted image to the P- and B-pictures and saves it in the video memory 120 as locally decoded image data.
- a motion compensation predicting circuit 121 compares the locally decoded image data saved in the video memory 120 with the input image data.
- predicted image data with motion compensation in the forward direction is generated and supplied to the above-described difference circuit 110 .
- predicted image data with bidirectional motion compensation is generated and supplied to the above-described difference circuit 110 .
- the motion compensation predicting circuit 121 also supplies the generated image data to the adding circuit 119 as a predicted image for next local decoding.
- a rate control circuit 127 executes code amount assignment control of a picture to be encoded for a target encoding rate in accordance with information such as a past generated code amount and buffer fill factor obtained from the buffer 114 and the setting value of a code amount ratio setting circuit 126 (to be described later). At this time, the rate control circuit 127 controls the quantization circuit 112 by deciding the quantization scale Q based on a code amount assigned to each picture type. The generated code amount after quantization changes between the I-, P-, and B-pictures. The quantization scale Q is therefore changed in accordance with the picture type. For example, in calculating of code amount assignment, the ratio of the quantization scale Q of P- and B-pictures to the quantization scale Q of I-pictures is set, thereby setting the quantization scale Q corresponding to each picture type.
- a flicker suppression control circuit 116 controls smoothing processing of the smoothing circuit 124 and the code amount ratio setting circuit 126 in accordance with a camera gain setting value supplied from the camera control circuit 125 .
- the flicker suppression control circuit 116 controls the code amount ratio setting circuit 126 to change the code amount ratio to be assigned to each picture type, thereby suppressing a luminance flicker upon increasing the gain.
- FIG. 2 shows graphs a and b showing control of assignment ratio of code amount by the camera gain.
- a graph a of FIG. 2 shows quantization scale ratio control for control of assignment ratio of code amount.
- the ratio of the quantization scale of P- and B-pictures to the quantization scale Q of I-pictures is set by code amount assignment control by the rate control circuit 127 , thereby controlling the code amount ratio to be assigned to each picture type.
- L 201 indicates a change in the quantization scale ratio of B-pictures according to the camera gain. When the camera gain exceeds +6 dB, the quantization scale ratio of B-pictures decreases. As a result, the generated code amount ratio of B-pictures increases.
- L 202 indicates a change in the quantization scale ratio of P-pictures according to the camera gain.
- the quantization scale ratio of P-pictures decreases.
- the generated code amount ratio of P-pictures increases.
- a graph b of FIG. 2 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain in the graph a of FIG. 2 .
- L 203 indicates an assigned code amount ratio of B-pictures.
- L 204 indicates an assigned code amount ratio of P-pictures.
- the assigned code amount ratio increases in accordance with the change L 202 in the quantization scale ratio in the graph a of FIG. 2 .
- FIG. 2 shows examples of control of assignment ratio of code amount proportional to the camera gain.
- a graph a of FIG. 3 shows quantization scale ratio control for control of assignment ratio of code amount.
- L 301 indicates a change in the quantization scale ratio of B-pictures according to the camera gain.
- the quantization scale ratio of B-pictures decreases in accordance with the camera gain.
- the generated code amount ratio of B-pictures increases.
- L 302 indicates a change in the quantization scale ratio of P-pictures according to the camera gain.
- the quantization scale ratio of P-pictures decreases in accordance with the camera gain.
- the generated code amount ratio of P-pictures increases.
- a graph b of FIG. 3 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain in the graph a of FIG. 3 .
- L 303 indicates an assigned code amount ratio of B-pictures. When the camera gain exceeds +6 dB, the assigned code amount ratio increases in accordance with the change L 301 in the quantization scale ratio in the graph a of FIG. 3 .
- L 304 indicates an assigned code amount ratio of P-pictures. When the camera gain exceeds +6 dB, the assigned code amount ratio increases in accordance with the change L 302 in the quantization scale ratio in the graph a of FIG. 3 .
- the assigned code amount ratio of P- and B-pictures increases as the camera gain increases. This allows to suppress loss of the peak of the noise component upon increasing the gain when P- and B-pictures are encoded. This arrangement can reduce a luminance flicker in reproducing encoded image data.
- the flicker suppression control circuit 116 controls spatial or temporal smoothing or spatial and temporal smoothing of the above-described smoothing circuit 124 .
- the arrangement to control the smoothing processing combines with the above-described arrangement to control code amount assignment, a synergy effect can be expected.
- the smoothing circuit 124 executes smoothing at an intensity corresponding to the camera gain to suppress the peak of the noise component itself and decrease the luminance peak due to the noise component of I-pictures. This allows to reduce the difference from the decrease in the luminance peak of noise upon encoding P- and B-pictures. As a result, a luminance flicker between the pictures can be suppressed. Additionally, this smoothing processing also suppresses the noise component input to the P- and B-pictures. This further suppresses the decrease in the luminance peak of noise dependent on encoding by an increase in the code amount assignment ratio.
- a circuit a of FIG. 6 shows a detailed example of the smoothing circuit 124 , which implements a smoothing circuit by a variable-band spatial filter that limits the spatial band.
- a one- or two-dimensional spatial filter (SPF) circuit 602 spatially smoothes an image signal supplied to a terminal 601 .
- the smoothing intensity of a spatial filter indicates the passband characteristic of the spatial filter.
- the variable-band spatial filter shown in the circuit a of FIG. 6 causes a coefficient setting circuit 604 to set the weighting coefficient of the filter to a reference pixel to obtain a predetermined passband characteristic, thereby changing the passband characteristic, i.e., the smoothing intensity.
- a terminal 603 is a smoothing intensity control input terminal.
- a terminal 605 outputs the image signal that has undergone the smoothing processing.
- a graph a of FIG. 4 shows an example of smoothing intensity control according to the camera gain.
- smoothing processing is executed.
- a graph b of FIG. 4 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a of FIG. 4 .
- L 401 indicates a band characteristic obtained when no smoothing processing is executed. This characteristic corresponds to the region less than +6 dB in the graph a of FIG. 4 .
- L 402 indicates a band characteristic obtained when smoothing processing is executed. This characteristic corresponds to the region equal to or more than +6 dB in the graph a of FIG. 4 .
- smoothing is executed by limiting the high frequency side of the passband. The band narrows, and the smoothing intensity increases.
- the camera gain has a predetermined threshold value so that the smoothing characteristic is changed in two steps (whole band is passed in one mode). It is also possible to change the smoothing intensity in proportion to the camera gain.
- a graph a of FIG. 5 shows an example of smoothing intensity control proportional to the camera gain. When the camera gain exceeds +6 dB, the smoothing intensity increases up to a predetermined upper limit in accordance with the camera gain.
- a graph b of FIG. 5 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a of FIG. 5 .
- the passband of the spatial filter narrows stepwise in accordance with the camera gain.
- variable temporal filter that executes temporal smoothing of each pixel is independently applicable to the smoothing processing of this embodiment. It is possible to use the above-described spatial filter together.
- a circuit b of FIG. 6 shows a detailed example of the smoothing circuit 124 , which implements a smoothing circuit by a variable temporal filter that executes temporal smoothing of each pixel.
- This circuit is known as a recursive filter.
- a subtracting circuit 607 calculates the difference between each pixel of an image signal supplied to a terminal 606 and a corresponding pixel of the preceding frame.
- a coefficient multiplying circuit 610 multiplies the difference value by a predetermined coefficient.
- An adding circuit 611 adds the result to the pixel of the preceding frame. If the coefficient is 1, an output terminal 623 outputs the same value as the input, and the smoothing intensity is 0. If the coefficient is smaller than 1, smoothing by an IIR filter is executed between the current frame and the preceding frame. The smoothing intensity changes depending on the coefficient.
- a terminal 608 is a smoothing intensity control input terminal.
- a coefficient setting circuit 609 sets a coefficient corresponding to the input smoothing intensity.
- a frame memory 612 holds
- FIG. 15 shows graphs a through c showing the luminance flicker reduction effect upon increasing the camera gain when encoded data generated in this embodiment is reproduced.
- the graph a of FIG. 15 shows the reproduction signal from I-pictures.
- the smoothing circuit suppresses the luminance peak of the noise component superimposed on a flat image signal so that the peak is lower than in the graph a of FIG. 16 . It is also possible to suppress the luminance peak of the noise component in I-pictures by assigning a smaller code amount to I-pictures when a larger code amount is assigned to the P- and B-pictures.
- the graph b of FIG. 15 shows the reproduction signal from P- and B-pictures. Smoothing suppresses the noise peak.
- the assigned code amount ratio increases, the luminance peak of noise is reproduced without excessively decreasing upon encoding. Hence, the luminance peak difference between the graphs a and b of FIG. 15 decreases. Even in reproducing a moving image, the luminance peak flicker caused by noise decreases, as is apparent from the graph c of FIG. 15 .
- the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain. This allows to effectively reduce the noise flicker while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing. Even when a camera apparatus for business use is used for photographing containing noise as a photographic effect, the flicker can be reduced while making the most of the effect of noise.
- FIG. 7 is a block diagram showing, as the second embodiment, a digital video camera according to another embodiment of an image signal processing apparatus of the present invention.
- Reference numeral 702 denotes a camera unit; and 701 , a camera including a lens optical system and a photo-electric conversion unit such as a CCD.
- An analog moving image signal photographed by the camera 701 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and ⁇ -conversion by a photographed image signal processing circuit 703 .
- the photographed image signal processing circuit 703 also executes sharpness control processing of controlling the resolution by adding, to the original image signal, an aperture correction signal generated from the high frequency component of the image signal.
- a camera control circuit 725 executes processing such as exposure control of the camera 701 on the basis of, for example, the brightness of the photographed image.
- the camera control circuit 725 controls the amplifier gain of the photographed image signal processing circuit 703 as needed, as in the first embodiment.
- the camera control circuit 725 also controls the sharpness control processing of the photographed image signal processing circuit 703 to adjust the resolution of the image signal. The sharpness can be either set within a predetermined range by the user or automatically controlled by the camera control circuit 725 in accordance with the photographing situation.
- the photographed image signal processing circuit 703 supplies its output to a smoothing circuit 724 as an image signal from the camera unit 702 .
- the smoothing circuit 724 includes a variable-band special filter that limits the spatial band of an image signal, a variable temporal filter that executes temporal smoothing of each pixel, or a combination thereof.
- the smoothing circuit 724 has already been described in detail in the first embodiment, and a repetitive description will be omitted here.
- the output from the smoothing circuit 724 is supplied to a frame rearranging circuit 709 as image data to be encoded.
- the frame rearranging circuit 709 rearranges frames in an encoding order.
- a difference circuit 710 For I-pictures, a difference circuit 710 outputs the image data itself to a DCT circuit 711 .
- the difference circuit 710 calculates the difference value between the image data and a predicted image and outputs the difference value to the DCT circuit 711 by selecting a switch 723 .
- the DCT circuit 711 converts the image data into a DCT coefficient.
- a quantization circuit 712 quantizes the DCT coefficient by using a predetermined quantization scale Q.
- a variable-length coding circuit 713 for example, entropy-encodes the quantization coefficient output from the quantization circuit 712 and outputs it as encoded data.
- a buffer 714 temporarily saves the generated encoded data to control the encoding rate.
- the encoded data stored in the buffer 714 is read out at a predetermined rate and output from a terminal 715 as compression-encoded data. It is possible to efficiently record the output compression-encoded data on a recording medium such as a tape, disc, or semiconductor memory or efficiently transmit the compression-encoded data by using a network or commutation channel.
- the coefficient data quantized by the quantization circuit 712 undergoes inverse quantization by an inverse quantization circuit 711 and inverse DOT by an inverse DCT circuit 718 to obtain predicted image data.
- an adding circuit 719 saves data after inverse DCT directly in a video memory 720 .
- the adding circuit 719 adds the predicted image to the P- and B-pictures and saves it in the video memory 720 as locally decoded image data.
- a motion compensation predicting circuit 721 compares the locally decoded image data saved in the video memory 720 with the input image data.
- predicted image data with motion compensation in the forward direction is generated and supplied to the above-described difference circuit 710 .
- predicted image data with bidirectional motion compensation is generated and supplied to the above-described difference circuit 710 .
- the motion compensation predicting circuit 721 also supplies the generated image data to the adding circuit 719 as a predicted image for next local decoding.
- a rate control circuit 727 executes code amount assignment control of a picture to be encoded for a target encoding rate in accordance with information such as a past generated code amount and buffer fill factor obtained from the buffer 714 and the setting value of a code amount ratio setting circuit 726 (to be described later). At this time, the rate control circuit 727 controls the quantization circuit 712 by deciding the quantization scale Q based on a code amount assigned to each picture type. The generated code amount after quantization changes between the I-, P-, and B-pictures. The quantization scale Q is therefore changed in accordance with the picture type.
- a flicker suppression control circuit 716 as a characteristic feature of this embodiment controls smoothing processing of the smoothing circuit 724 and the code amount ratio setting circuit 726 in accordance with a camera gain setting value and sharpness setting value supplied from the camera control circuit 725 .
- the flicker suppression control circuit 716 controls the code amount ratio setting circuit 726 to change the code amount ratio to be assigned to each picture type, thereby suppressing a luminance flicker upon increasing the gain.
- FIG. 8 shows graphs a and b showing control of assignment ratio of code amount by the camera gain and sharpness setting.
- the graph a of FIG. 8 shows quantization scale ratio control for control of assignment ratio of code amount.
- the graph a of FIG. 8 shows only the control characteristic of B-pictures.
- Symbols a , b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low).
- the threshold value of the change in the quantization scale changes between a , b, and c. When the camera gain exceeds +3, +6, and +9 dB, the quantization scale ratio of B-pictures decreases.
- the generated code amount ratio of B-pictures increases.
- the peak of the noise component is also enhanced as a high frequency component so that the luminance peak generated by noise increases.
- the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the sharpness intensity. If the sharpness is high, the quantization scale ratio decreases from a low camera gain.
- the graph b of FIG. 8 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain and sharpness setting in the graph a of FIG. 8 .
- a, b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low).
- the camera gain has a predetermined threshold value so that the quantization scale ratio is controlled in two steps. It is also possible to change the quantization scale ratio in proportion to the camera gain.
- FIG. 9 shows examples of control of assignment ratio of code amount proportional to the camera gain in accordance with sharpness setting.
- a graph a of FIG. 9 shows quantization scale ratio control for control of assignment ratio of code amount.
- the graph a of FIG. 9 shows only the control characteristic of B-pictures.
- Symbols a , b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low).
- the threshold value of the change in the quantization scale changes between a , b, and c.
- the quantization scale ratio of B-pictures decreases in accordance with the camera gain.
- the generated code amount ratio of B-pictures increases.
- the tilt of the change in the quantization scale changes between a , b, and c.
- the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the sharpness intensity.
- the quantization scale ratio decrease rate is also changed in accordance with the sharpness intensity. If the sharpness is high, the quantization scale ratio decreases from a low camera gain.
- a graph b of FIG. 9 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control proportional to the camera gain in accordance with the sharpness setting in the graph a of FIG. 9 .
- symbols a , b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low).
- the assigned code amount ratio of P- and B-pictures increases in accordance with the camera gain and sharpness setting. This allows to suppress loss of the peak of the noise component upon increasing the gain when P- and B-pictures are encoded. This arrangement can reduce a luminance flicker in reproducing encoded image data.
- the flicker suppression control circuit 716 controls spatial or temporal smoothing or spatial and temporal smoothing of the above-described smoothing circuit 724 .
- the arrangement to control the smoothing processing combines with the above-described arrangement to control code amount assignment, a synergy effect can be expected.
- the smoothing circuit 724 executes smoothing at an intensity corresponding to the camera gain and sharpness setting to suppress the peak of the noise component itself and decrease the luminance peak due to the noise component of I-pictures. This allows to reduce the difference from the decrease in the luminance peak of noise upon encoding P- and B-pictures. As a result, a luminance flicker between the pictures can be suppressed. Additionally, this smoothing processing also suppresses the noise component input to the P- and B-pictures. This further suppresses the decrease in the luminance peak of noise dependent on encoding by an increase in the code amount assignment ratio.
- a graph a of FIG. 10 shows an example of smoothing intensity control according to the camera gain and sharpness setting.
- Symbols a , b, and c indicate smoothing intensities according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low).
- the threshold value of the change in the smoothing intensity changes between a , b, and c.
- a graph b of FIG. 10 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a of FIG. 10 .
- L 1001 indicates a band characteristic obtained when no smoothing processing is executed. This characteristic corresponds to the region without smoothing processing (smoothing intensity: 0) in the graph a of FIG. 10 .
- L 1002 indicates a band characteristic obtained when smoothing processing is executed. This characteristic corresponds to the region where the smoothing processing is effective in the graph a of FIG. 10 .
- the camera gain has a predetermined threshold value so that the smoothing characteristic is changed in two steps (whole band is passed in one mode). It is also possible to change the smoothing intensity in proportion to the camera gain.
- a graph a of FIG. 11 shows smoothing intensity control proportional to the camera gain in accordance with sharpness setting. Symbols a , b, and c indicate smoothing intensities according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low).
- the threshold value of the change in the smoothing intensity changes between a , b, and c.
- the smoothing intensity increases up to a predetermined upper limit in accordance with the camera gain.
- a graph b of FIG. 11 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a of FIG. 11 .
- the passband of the spatial filter narrows stepwise in accordance with the camera gain.
- the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain and sharpness setting. This allows to effectively reduce the noise flicker while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing. Even when a camera apparatus for business use is used for photographing containing noise as a photographic effect, the flicker can be reduced while making the most of the effect of noise.
- FIG. 12 is a block diagram showing, as the third embodiment, a digital video camera according to still another embodiment of an image signal processing apparatus of the present invention.
- Reference numeral 1202 denotes a camera unit; and 1201 , a camera including a lens optical system and a photo-electric conversion unit such as a CCD.
- An analog moving image signal photographed by the camera 1201 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and ⁇ -conversion by a photographed image signal processing circuit 1203 .
- a camera control circuit 1225 executes processing such as exposure control of the camera 1201 on the basis of, for example, the brightness of the photographed image.
- the camera control circuit 1225 controls the amplifier gain of the photographed image signal processing circuit 1203 as needed, as in the first embodiment.
- the photographed image signal processing circuit 1203 supplies its output to a smoothing circuit 1224 as an image signal from the camera unit 1202 .
- the smoothing circuit 1224 includes a variable-band special filter that limits the spatial band of an image signal, a variable temporal filter that executes temporal smoothing of each pixel, or a combination thereof.
- the smoothing circuit 1224 has already been described in detail in the first embodiment, and a repetitive description will be omitted here.
- the output from the smoothing circuit 1224 is supplied to a frame rearranging circuit 1209 as image data to be encoded.
- the frame rearranging circuit 1209 rearranges frames in an encoding order.
- a difference circuit 1210 For I-pictures, a difference circuit 1210 outputs the image data itself to a DCT circuit 1211 .
- the difference circuit 1210 calculates the difference value between the image data and a predicted image and outputs the difference value to the DCT circuit 1211 by selecting a switch 1223 .
- the DCT circuit 1211 converts the image data into a DCT coefficient.
- a quantization circuit 1212 quantizes the DOT coefficient by using a predetermined quantization scale Q.
- a variable-length coding circuit 1213 for example, entropy-encodes the quantization coefficient output from the quantization circuit 1212 and outputs it as encoded data.
- a buffer 1214 temporarily saves the generated encoded data to control the encoding rate.
- the encoded data stored in the buffer 1214 is read out at a predetermined rate and output from a terminal 1215 as compression-encoded data. It is possible to efficiently record the output compression-encoded data on a recording medium such as a tape, disc, or semiconductor memory or efficiently transmit the compression-encoded data by using a network or commutation channel.
- the coefficient data quantized by the quantization circuit 1212 undergoes inverse quantization by an inverse quantization circuit 1211 and inverse DCT by an inverse DCT circuit 1218 to obtain predicted image data.
- an adding circuit 1219 saves data after inverse DCT directly in a video memory 1220 .
- the adding circuit 1219 adds the predicted image to the P- and B-pictures and saves it in the video memory 1220 as locally decoded image data.
- a motion compensation predicting circuit 1221 compares the locally decoded image data saved in the video memory 1220 with the input image data.
- predicted image data with motion compensation in the forward direction is generated and supplied to the above-described difference circuit 1210 .
- predicted image data with bidirectional motion compensation is generated and supplied to the above-described difference circuit 1210 .
- the motion compensation predicting circuit 1221 also supplies the generated image data to the adding circuit 1219 as a predicted image for next local decoding.
- a target bit rate setting circuit 1228 calculates a target bit rate in accordance with, for example, a user's encoding mode selection instruction and supplies the information to a rate control circuit 1227 and flicker suppression control circuit 1216 .
- the rate control circuit 1227 executes code amount assignment control of a picture to be encoded for a target encoding rate in accordance with information such as a past generated code amount and buffer fill factor obtained from the buffer 1214 , the information from the above-described target bit rate setting circuit 1228 , and the setting value of a code amount ratio setting circuit 1226 (to be described later).
- the rate control circuit 1227 controls the quantization circuit 1212 by deciding the quantization scale Q based on a code amount assigned to each picture type.
- the generated code amount after quantization changes between the I-, P-, and B-pictures.
- the quantization scale Q is therefore changed in accordance with the picture type.
- the flicker suppression control circuit 1216 controls smoothing processing of the smoothing circuit 1224 and the code amount ratio setting circuit 1226 in accordance with a camera gain setting value supplied from the camera control circuit 1225 and the target bit rate value supplied from the above-described target bit rate setting circuit 1228 .
- the flicker suppression control circuit 1216 controls the code amount ratio setting circuit 1226 to change the code amount ratio to be assigned to each picture type, thereby suppressing a luminance flicker upon increasing the gain.
- FIG. 13 shows graphs a and b showing control of assignment ratio of code amount by the camera gain and target bit rate value.
- the graph a of FIG. 13 shows quantization scale ratio control for control of assignment ratio of code amount.
- the graph a of FIG. 13 shows only the control characteristic of B-pictures.
- Symbols a , b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high).
- the threshold value of the change in the quantization scale changes between a , b, and c. When the camera gain exceeds +3, +6, and +9 dB, the quantization scale ratio of B-pictures decreases.
- the generated code amount ratio of B-pictures increases.
- the lower the target bit rate is the larger the decrease in the luminance peak caused by the noise component upon encoding of P- and B-pictures is.
- the luminance flicker readily becomes noticeable.
- the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the target bit rate. If the target bit rate is low, the quantization scale ratio decreases from a low camera gain.
- the graph b of FIG. 13 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain and target bit rate value in the graph a of FIG. 13 .
- symbols a , b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high).
- the camera gain has a predetermined threshold value so that the quantization scale ratio is controlled in two steps. It is also possible to change the quantization scale ratio in proportion to the camera gain.
- FIG. 14 shows examples of control of assignment ratio of code amount proportional to the camera gain in accordance with the target bit rate value.
- a graph a of FIG. 14 shows quantization scale ratio control for control of assignment ratio of code amount.
- the graph a of FIG. 14 shows only the control characteristic of B-pictures.
- Symbols a , b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high).
- the threshold value of the change in the quantization scale changes between a , b, and c.
- the quantization scale ratio of B-pictures decreases in accordance with the camera gain.
- the generated code amount ratio of B-pictures increases.
- the tilt of the change in the quantization scale changes between a , b, and c.
- the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the target bit rate.
- the quantization scale ratio decrease rate is also changed in accordance with the target bit rate. If the target bit rate is low, the quantization scale ratio decreases from a low camera gain.
- the assigned code amount ratio of P- and B-pictures increases as the camera gain increases. This allows to suppress loss of the peak of the noise component upon increasing the gain when P- and B-pictures are encoded. This arrangement can reduce a luminance flicker in reproducing encoded image data.
- the flicker suppression control circuit 1216 controls spatial or temporal smoothing or spatial and temporal smoothing of the above-described smoothing circuit 1224 .
- the arrangement to control the smoothing processing combines with the above-described arrangement to control code amount assignment, a synergy effect can be expected.
- the smoothing circuit 1224 executes smoothing at an intensity corresponding to the camera gain and target bit rate value to suppress the peak of the noise component itself and decrease the luminance peak due to the noise component of I-pictures. This allows to reduce the difference from the decrease in the luminance peak of noise upon encoding P- and B-pictures. As a result, a luminance flicker between the pictures can be suppressed. Additionally, this smoothing processing also suppresses the noise component input to the P- and B-pictures. This further suppresses the decrease in the luminance peak of noise dependent on encoding by an increase in the code amount assignment ratio.
- the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain and target bit rate value. This allows to effectively reduce the noise flicker while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing. Even when a camera apparatus for business use is used for photographing containing noise as a photographic effect, the flicker can be reduced while making the most of the effect of noise.
- the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain. This allows to effectively reduce the luminance flicker by noise while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing even when the S/N ratio of an image photographed at an increased gain is low. Additionally, it is possible to reduce the luminance flicker while making the most of the effect of noise even in photographing an image containing noise that is intentionally added to obtain a photographic effect.
- the functions of the processes of the camera control circuit, flicker suppression control circuit, code amount ratio setting circuit, and rate control circuit of the above-described embodiments may be implemented by causing the CPU (Central Processing Unit) of a computer to read out a program to implement the function of each process from a memory and execute the program.
- CPU Central Processing Unit
- Examples of the memory the CPU accesses are nonvolatile memories such as an HDD, optical disc, and flash memory, read-only recording media such as a CD-ROM, volatile memories except a RAM, and computer-readable/writable recording media by combinations thereof.
- the program to implement the functions of the processes of the camera control circuit, flicker suppression control circuit, code amount ratio setting circuit, and rate control circuit of the above-described embodiments may be recorded on a computer-readable recording medium such that a computer system can load and execute the program recorded on the recording medium to do the processes.
- the “computer system” includes an OS and hardware such as peripheral devices. More specifically, the functions of the above-described embodiments may be implemented when the program read out from a storage medium is written in the memory of a function expansion board inserted into a computer or a function expansion unit connected to a computer, and the CPU of the function expansion board or function expansion unit partially or wholly performs actual processing on the basis of the instructions of the program.
- the “computer-readable recording medium” indicates a portable medium including an optical disc such as a CD-ROM or DVD and a semiconductor memory card, or a storage device such as a hard disc incorporated in a computer system.
- the “computer-readable recording medium” also includes a device that holds a program for a predetermined time, like a volatile memory (RAM) in a compute system serving as a server or client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line.
- RAM volatile memory
- the program may be transmitted from a computer system that stores it in a storage device to another computer system through a transmission medium or transmission wave in a transmission medium.
- the “transmission medium” to transmit the program indicates a medium having a function of transmitting information, like a network (communication network) such as the Internet or a communication line such as a telephone line.
- the program may implement some of the above-described functions.
- the program may be a so-called differential file (differential program) implemented by combining the above-described functions with an already recorded program.
- a program product such as a computer-readable recording medium that records the program is also applicable as an embodiment of the present invention.
- the present invention incorporates the program, recording medium, transmission medium, and program product.
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Compression Or Coding Systems Of Tv Signals (AREA)
- Studio Devices (AREA)
Abstract
An object of this invention is to effectively reduce a luminance flicker caused by noise while suppressing an adverse effect such as an afterimage and a decrease in the resolution upon smoothing as much as possible even when the S/N ratio of an image photographed at an increased gain is low. An image signal processing apparatus includes a smoothing circuit (124) to execute smoothing processing of an image signal, a compression encoding circuit (112, 113) to compression-encode the image signal, a setting circuit (126) capable of setting, for the compression encoding circuit, the code amount for each picture type, and a control circuit (116) that controls in accordance with a gain setting value acquired from a camera (102) to change the intensity of smoothing processing and the assignment ratio of code amount for each picture type.
Description
- The present invention relates to an image signal processing apparatus for processing a photographed image signal and, more particularly, to suppression processing of a flicker that occurs upon increasing the camera gain in a compression scheme using intra-picture and inter-picture prediction.
- Recently, recorders capable of recording moving image data in a hard disc or a DVD (Digital Versatile Disc) are coming along and replacing conventional VCRs for recording TV programs. These recorders can record enormous amounts of moving image data on a single disc by compressing the data using efficient encodings such as MPEG (Moving Picture Experts Group) 2.
- Efficient moving image encoding as represented by MPEG2 generally executes compression encoding by using a plurality of different picture types including intra-frame and inter-frame prediction. More specifically, only frames at a predetermined interval use a picture type for intra-frame encoding. Frames between them use a picture type for inter-frame prediction due to the fact that successive frames have high image data correlation, thereby increasing the moving image data compression efficiency.
-
FIG. 17 is a block diagram showing a conventional image signal processing apparatus. -
Reference numeral 1702 denotes a camera unit; and 1701, a camera including a optical lens system and a photo-electric conversion unit such as a CCD (Charge Coupled Device). An analog moving image signal photographed by thecamera 1701 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and γ-conversion by a photographed imagesignal processing circuit 1703. Acamera control circuit 1725 executes processing such as exposure control of thecamera 1701 on the basis of, for example, the brightness of the photographed image. If a dark image will be photographed at a the shutter speed less than a predetermined value in the moving image photographing mode of thecamera unit 1702, thecamera control circuit 1725 raises the amplifier gain of the photographed imagesignal processing circuit 1703 in order to not reduce the shutter speed, thereby preventing any afterimage. - The photographed image
signal processing circuit 1703 supplies its output to a frame rearrangingcircuit 1709 as image data to be encoded. The frame rearrangingcircuit 1709 rearranges frames in encoding order. As an example of this, in an MPEG2 encoding, the frames are rearranged in an order suitable for encoding. For example, a B-picture serving as a bidirectional prediction frame should be encoded after the encoding of the preceding and succeeding frames and therefore it is moved backward. - For I-pictures, a
difference circuit 1710 outputs the image data itself to aDCT circuit 1711. For P- and B-pictures, thedifference circuit 1710 calculates the difference value between the image data and a predicted image and outputs the difference value to theDOT circuit 1711 according to a selection by aswitch 1723. TheDCT circuit 1711 converts the image data into a DCT coefficient. Aquantization circuit 1712 quantizes the DCT coefficient using a predetermined quantization scale Q. When the Q value changes, the coefficient value after quantization changes greatly. Hence, the generated code amount changes. - A variable-
length coding circuit 1713, for example, entropy-encodes the quantization coefficient output from thequantization circuit 1712 and outputs it as encoded data. Abuffer 1714 temporarily saves the generated encoded data to control the encoding rate. The encoded data stored in thebuffer 1714 is read out at a predetermined rate and output from aterminal 1715 as compression-encoded data. - Meanwhile, the coefficient data quantized by the
quantization circuit 1712 undergoes inverse quantization by aninverse quantization circuit 1717 and inverse DCT by aninverse DCT circuit 1718 to obtain predicted image data. For I-pictures, an addingcircuit 1719 saves data after inverse DCT directly in avideo memory 1720. For P- and B-pictures, the addingcircuit 1719 adds the predicted image to the P- and B-pictures and saves it in thevideo memory 1720 as locally decoded image data. A motioncompensation predicting circuit 1721 compares the locally decoded image data saved in thevideo memory 1720 with the input image data. For P-pictures, predicted image data with motion compensation in the forward direction is generated and supplied to the above-describeddifference circuit 1710. For B-pictures, predicted image data with bidirectional motion compensation is generated and supplied to the above-describeddifference circuit 1710. The motioncompensation predicting circuit 1721 also supplies the generated image data to the addingcircuit 1719 as a predicted image for next local decoding. - A
rate control circuit 1727 executes code amount assignment control of a picture to be encoded for a target encoding rate using information such as a past generated code amount and buffer fill factor obtained from thebuffer 1714. At this time, therate control circuit 1727 controls thequantization circuit 1712 by deciding the quantization scale Q based on a code amount assigned to each picture type. The generated code amount after quantization changes between the I-, P-, and B-pictures. The quantization scale Q is therefore generally changed in accordance with the picture type. For example, an encoding scheme known as MPEG2-TM (Test Model) sets the quantization scale corresponding to each picture type. - Conventional video cameras execute exposure control of the
camera 1701 in accordance with the brightness of a photographed image, as in the above-describedcamera unit 1702. In a normal brightness range, the video camera generally maintains adequate exposure mainly by combining the F-number and shutter speed. However, a video camera may increase the gain in a dark scene with a full aperture. Generally, an image photographed at the increased gain has a low S/N ratio because of a random noise component mixed into the image. In this case, if an encoding such as the above-described MPEG2 using a plurality of different picture types is used, the luminance peak generated by the noise component after encoding varies depending on the picture type. The variation is observed as a luminance flicker in the reproduced moving image, resulting in a visual disturbance, as is known. - Under these circumstances, a patent proposal has been made to remove random noise generated when increasing the gain by improving the characteristic of a filter circuit synchronized with increases in the gain (for example, WO97/05745).
-
FIG. 16 shows graphs a through c for explaining the cause of a luminance flicker in the reproduction mode which is generated when increasing the gain of the camera used in the conventional arrangement described above. The graph a ofFIG. 16 shows a reproduction signal from I-pictures. The luminance peak of the noise component superimposed on a flat image signal is maintained to some extent by intra-frame encoding. This is also because the assigned code amount of I-pictures is generally larger than that of the other picture types. - The graph b of
FIG. 16 shows a reproduction signal from P- and B-pictures. In an image photographed at an increased gain, the correlation between frames is low because of the random noise component. In normal encoding, therefore, the encoded image signal degrades because of the increase in inter-frame difference information of P- and B-pictures. The noise peak decreases so that a luminance peak difference is generated, unlike the I-pictures in the graph a ofFIG. 16 . Hence, a luminance flicker derived from noise is generated in reproducing a moving image, as shown in the graph c ofFIG. 16 . - The conventional technique to remove random noise derived when increasing the gain, i.e., the method of changing the filter characteristic as in WO97/05745 is one of general encoding distortion reducing methods in the case of a low S/N ratio and can expect a partial effect. However, in order to completely remove the above-described luminance flicker using a filter alone, the filter intensity must be sufficiently high. However this considerably degrades the resolution and causes serious, adverse effects such as an afterimage in the original image. A TV program image can sometimes contain intentionally added noise intended to produce a film-like effect based on the granularity of noise. In this situation, it is impossible to uniformly remove noise using a filter. Removal of the noise component itself must be suppressed as much as possible. That is, to effectively reduce the above-described luminance flicker while maintaining image quality, the invention of WO97/05745 does not suffice.
- The present invention has been made to solve the above-described unsolved problems of the prior art, and has as its object to effectively reduce a luminance flicker caused by noise while suppressing adverse effects such as afterimages and decreases in resolution due to smoothing as much as possible even when the S/N ratio of an image photographed at an increased gain is low. It has, as another object, the reduction of a luminance flicker while making the most of the effect of noise even when photographing an image containing noise that is intentionally added to obtain an effect in the image.
- One aspect of the present invention according to one of embodiments relates to an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, characterized by comprising, acquisition unit adapted to acquire a gain setting value for the image signal;
- compression encoding adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit; and control adapted to control to change, in accordance with the gain setting value acquired by the acquisition unit, an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- Another aspect of the present invention according to one of embodiments relates to an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising, acquisition unit adapted to acquire a gain setting value for the image signal, smoothing unit adapted to execute smoothing processing of the image signal, compression encoding unit, provided on a subsequent stage of the smoothing unit, adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit, and control unit adapted to control to change, in accordance with the gain setting value acquired by the acquisition unit, an intensity of smoothing processing by the smoothing unit and an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- Further aspect of the present invention according to one of embodiments relates an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising, acquisition adapted to acquire a gain setting value of gain adjustment for the image signal and a sharpness setting value of sharpness adjustment, smoothing unit adapted to execute smoothing processing of the image signal, compression encoding unit, provided on a subsequent stage of the smoothing unit, adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit, and control unit adapted to control to change, in accordance with the gain setting value and the sharpness setting value acquired by the acquisition unit, an intensity of smoothing processing by the smoothing unit and an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- Further aspect of the present invention according to one of embodiments relates to an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising, acquisition unit adapted to acquire a gain setting value for the image signal, smoothing unit adapted to execute smoothing processing of the image signal, compression encoding unit, provided on a subsequent stage of the smoothing unit, adapted to execute compression-encoding the image signal, adjustment unit capable of adjusting a code amount to be assigned to each picture type in the compression encoding unit, and designation unit adapted to designate a target bit rate of compression encoding of the compression encoding unit, and control unit adapted to control to change, in accordance with the gain setting value acquired by the acquisition unit and the target bit rate designated by the designation unit, an intensity of smoothing processing by the smoothing unit and an assignment ratio of code amount for each picture type which is adjusted by the adjustment unit.
- Further aspect of the present invention according to one of embodiments relates to a control method of an image signal processing apparatus for classifying pictures contained in an image signal into a plurality of picture types and compression-encoding the image signal, comprising steps of, acquiring a gain setting value for the image signal, setting an assignment ratio of code amount for each picture type, compression-encoding the image signal in accordance with the set ratio, changing, in accordance with the acquired gain setting value, an assignment ratio of code amount for each picture type.
- Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
-
FIG. 1 is a block diagram of a digital video camera according to the first embodiment; -
FIG. 2 shows graphs showing an example of assigned code amount control according to the first embodiment; -
FIG. 3 shows graphs showing another example of assigned code amount control according to the first embodiment; -
FIG. 4 shows graphs showing an example of smoothing intensity control according to the first embodiment; -
FIG. 5 shows graphs showing another example of smoothing intensity control according to the first embodiment; -
FIG. 6 shows block diagrams showing structural examples of a smoothing circuit; -
FIG. 7 is a block diagram of a digital video camera according to the second embodiment; -
FIG. 8 shows graphs showing an example of assigned code amount control according to the second embodiment; -
FIG. 9 shows graphs showing another example of assigned code amount control according to the second embodiment; -
FIG. 10 shows graphs showing an example of smoothing intensity control according to the second embodiment; -
FIG. 11 shows graphs showing another example of smoothing intensity control according to the second embodiment; -
FIG. 12 is a block diagram of a digital video camera according to the third embodiment; -
FIG. 13 shows graphs showing an example of assigned code amount control according to the third embodiment; -
FIG. 14 shows graphs showing another example of assigned code amount control according to the third embodiment; -
FIG. 15 shows graphs for explaining a luminance flicker reduction effect according to the present invention; -
FIG. 16 shows graphs for explaining a cause of a luminance flicker; and -
FIG. 17 is a block diagram showing the arrangement of a conventional image signal processing apparatus. - The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided show that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
- The embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
- An embodiment of an image signal processing apparatus of the present invention will be described by exemplifying a digital video camera capable of encoding an image signal photographed with a camera by a compression scheme using intra-picture prediction and inter-picture prediction and outputting the encoded data. Pictures include a field image and a frame image. In the following description, a picture indicates a frame image.
-
FIG. 1 is a block diagram showing, as the first embodiment, a digital video camera according to an embodiment of an image signal processing apparatus of the present invention.Reference numeral 102 denotes a camera unit; and 101, a camera including a lens optical system and a photo-electric conversion unit such as a CCD. An analog moving image signal photographed by thecamera 101 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and γ-conversion by a photographed imagesignal processing circuit 103. - A
camera control circuit 125 executes processing such as exposure control of thecamera 101 on the basis of, for example, the brightness of the photographed image. If a dark image will be photographed at a the shutter speed less than a predetermined value in the moving image photographing mode of thecamera unit 102, as described above, thecamera control circuit 125 controls to raise the amplifier gain of the photographed imagesignal processing circuit 103 not to reduce the shutter speed, thereby preventing any afterimage. A camera apparatus for business use generally has a function of causing a user to arbitrarily switch the camera gain. When thecamera unit 102 has this function, thecamera control circuit 125 controls to make the photographed imagesignal processing circuit 103 have a fixed amplifier gain corresponding to a user setting value input from an operation unit (not shown). - The photographed image
signal processing circuit 103 supplies its output to asmoothing circuit 124 as an image signal from thecamera unit 102. The smoothingcircuit 124 includes a variable-band special filter that limits the spatial band of an image signal, a variable temporal filter that executes temporal smoothing of each pixel, or a combination thereof. The smoothingcircuit 124 will be described later in detail. - The output from the smoothing
circuit 124 is supplied to aframe rearranging circuit 109 as image data to be encoded. Theframe rearranging circuit 109 rearranges frames in an encoding order. In, for example, MPEG2 encoding, the frames are rearranged in an order suitable for encoding. For example, a B-picture serving as a bidirectional prediction frame should be encoded after encoding of the preceding and succeeding frames and therefore is moved backward. - For I-pictures, a
difference circuit 110 outputs the image data itself to aDCT circuit 111. For P- and B-pictures, thedifference circuit 110 calculates the difference value between the image data and a predicted image and outputs the difference value to theDCT circuit 111 by selecting aswitch 123. TheDCT circuit 111 converts the image data into a DCT coefficient. Aquantization circuit 112 quantizes the DCT coefficient by using a predetermined quantization scale Q. When the Q value changes, the coefficient value after quantization largely changes. Hence, the generated code amount changes. - A variable-
length coding circuit 113, for example, entropy-encodes the quantization coefficient output from thequantization circuit 112 and outputs it as encoded data. Abuffer 114 temporarily saves the generated encoded data to control the encoding rate. The encoded data stored in thebuffer 114 is read out at a predetermined rate and output from a terminal 115 as compression-encoded data. It is possible to efficiently record the output compression-encoded data on a recording medium such as a tape, disc, or semiconductor memory or efficiently transmit the compression-encoded data by using a network or commutation channel. - On the other hand, the coefficient data quantized by the
quantization circuit 112 undergoes inverse quantization by aninverse quantization circuit 111 and inverse DCT by aninverse DCT circuit 118 to obtain predicted image data. For I-pictures, an addingcircuit 119 saves data after inverse DCT directly in avideo memory 120. For P- and B-pictures, the addingcircuit 119 adds the predicted image to the P- and B-pictures and saves it in thevideo memory 120 as locally decoded image data. A motioncompensation predicting circuit 121 compares the locally decoded image data saved in thevideo memory 120 with the input image data. For P-pictures, predicted image data with motion compensation in the forward direction is generated and supplied to the above-describeddifference circuit 110. For B-pictures, predicted image data with bidirectional motion compensation is generated and supplied to the above-describeddifference circuit 110. The motioncompensation predicting circuit 121 also supplies the generated image data to the addingcircuit 119 as a predicted image for next local decoding. - A
rate control circuit 127 executes code amount assignment control of a picture to be encoded for a target encoding rate in accordance with information such as a past generated code amount and buffer fill factor obtained from thebuffer 114 and the setting value of a code amount ratio setting circuit 126 (to be described later). At this time, therate control circuit 127 controls thequantization circuit 112 by deciding the quantization scale Q based on a code amount assigned to each picture type. The generated code amount after quantization changes between the I-, P-, and B-pictures. The quantization scale Q is therefore changed in accordance with the picture type. For example, in calculating of code amount assignment, the ratio of the quantization scale Q of P- and B-pictures to the quantization scale Q of I-pictures is set, thereby setting the quantization scale Q corresponding to each picture type. - A flicker
suppression control circuit 116 as a characteristic feature of this embodiment controls smoothing processing of the smoothingcircuit 124 and the code amountratio setting circuit 126 in accordance with a camera gain setting value supplied from thecamera control circuit 125. The flickersuppression control circuit 116 controls the code amountratio setting circuit 126 to change the code amount ratio to be assigned to each picture type, thereby suppressing a luminance flicker upon increasing the gain. -
FIG. 2 shows graphs a and b showing control of assignment ratio of code amount by the camera gain. A graph a ofFIG. 2 shows quantization scale ratio control for control of assignment ratio of code amount. As described above, the ratio of the quantization scale of P- and B-pictures to the quantization scale Q of I-pictures is set by code amount assignment control by therate control circuit 127, thereby controlling the code amount ratio to be assigned to each picture type. L201 indicates a change in the quantization scale ratio of B-pictures according to the camera gain. When the camera gain exceeds +6 dB, the quantization scale ratio of B-pictures decreases. As a result, the generated code amount ratio of B-pictures increases. L202 indicates a change in the quantization scale ratio of P-pictures according to the camera gain. When the camera gain exceeds +6 dB, the quantization scale ratio of P-pictures decreases. As a result, the generated code amount ratio of P-pictures increases. - A graph b of
FIG. 2 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain in the graph a ofFIG. 2 . L203 indicates an assigned code amount ratio of B-pictures. When the camera gain exceeds +6 dB, the assigned code amount ratio increases in accordance with the change L201 in the quantization scale ratio in the graph a ofFIG. 2 . L204 indicates an assigned code amount ratio of P-pictures. When the camera gain exceeds +6 dB, the assigned code amount ratio increases in accordance with the change L202 in the quantization scale ratio in the graph a ofFIG. 2 . To make the whole code generation amount as equal as possible before and after the camera gain exceeds +6 dB, a smaller code amount may be assigned to I-pictures when the code amount to be assigned to the P- and B-pictures increases. - In the examples shown in
FIG. 2 , the camera gain has a predetermined threshold value so that the quantization scale ratio is controlled in two steps. It is also possible to change the quantization scale ratio in proportion to the camera gain.FIG. 3 shows examples of control of assignment ratio of code amount proportional to the camera gain. A graph a ofFIG. 3 shows quantization scale ratio control for control of assignment ratio of code amount. L301 indicates a change in the quantization scale ratio of B-pictures according to the camera gain. When the camera gain exceeds +6 dB, the quantization scale ratio of B-pictures decreases in accordance with the camera gain. As a result, the generated code amount ratio of B-pictures increases. L302 indicates a change in the quantization scale ratio of P-pictures according to the camera gain. When the camera gain exceeds +6 dB, the quantization scale ratio of P-pictures decreases in accordance with the camera gain. As a result, the generated code amount ratio of P-pictures increases. - A graph b of
FIG. 3 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain in the graph a ofFIG. 3 . L303 indicates an assigned code amount ratio of B-pictures. When the camera gain exceeds +6 dB, the assigned code amount ratio increases in accordance with the change L301 in the quantization scale ratio in the graph a ofFIG. 3 . L304 indicates an assigned code amount ratio of P-pictures. When the camera gain exceeds +6 dB, the assigned code amount ratio increases in accordance with the change L302 in the quantization scale ratio in the graph a ofFIG. 3 . - As described above, in this embodiment, the assigned code amount ratio of P- and B-pictures increases as the camera gain increases. This allows to suppress loss of the peak of the noise component upon increasing the gain when P- and B-pictures are encoded. This arrangement can reduce a luminance flicker in reproducing encoded image data.
- In this embodiment, the flicker
suppression control circuit 116 controls spatial or temporal smoothing or spatial and temporal smoothing of the above-describedsmoothing circuit 124. When the arrangement to control the smoothing processing combines with the above-described arrangement to control code amount assignment, a synergy effect can be expected. - In a detailed arrangement of smoothing control, the smoothing
circuit 124 executes smoothing at an intensity corresponding to the camera gain to suppress the peak of the noise component itself and decrease the luminance peak due to the noise component of I-pictures. This allows to reduce the difference from the decrease in the luminance peak of noise upon encoding P- and B-pictures. As a result, a luminance flicker between the pictures can be suppressed. Additionally, this smoothing processing also suppresses the noise component input to the P- and B-pictures. This further suppresses the decrease in the luminance peak of noise dependent on encoding by an increase in the code amount assignment ratio. - A circuit a of
FIG. 6 shows a detailed example of the smoothingcircuit 124, which implements a smoothing circuit by a variable-band spatial filter that limits the spatial band. A one- or two-dimensional spatial filter (SPF)circuit 602 spatially smoothes an image signal supplied to a terminal 601. The smoothing intensity of a spatial filter indicates the passband characteristic of the spatial filter. The variable-band spatial filter shown in the circuit a ofFIG. 6 causes acoefficient setting circuit 604 to set the weighting coefficient of the filter to a reference pixel to obtain a predetermined passband characteristic, thereby changing the passband characteristic, i.e., the smoothing intensity. A terminal 603 is a smoothing intensity control input terminal. A terminal 605 outputs the image signal that has undergone the smoothing processing. - A graph a of
FIG. 4 shows an example of smoothing intensity control according to the camera gain. When the camera gain exceeds +6 dB, smoothing processing is executed. A graph b ofFIG. 4 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a ofFIG. 4 . L401 indicates a band characteristic obtained when no smoothing processing is executed. This characteristic corresponds to the region less than +6 dB in the graph a ofFIG. 4 . L402 indicates a band characteristic obtained when smoothing processing is executed. This characteristic corresponds to the region equal to or more than +6 dB in the graph a ofFIG. 4 . In spatial smoothing processing, smoothing is executed by limiting the high frequency side of the passband. The band narrows, and the smoothing intensity increases. - In the examples shown in
FIG. 4 , the camera gain has a predetermined threshold value so that the smoothing characteristic is changed in two steps (whole band is passed in one mode). It is also possible to change the smoothing intensity in proportion to the camera gain. A graph a ofFIG. 5 shows an example of smoothing intensity control proportional to the camera gain. When the camera gain exceeds +6 dB, the smoothing intensity increases up to a predetermined upper limit in accordance with the camera gain. A graph b ofFIG. 5 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a ofFIG. 5 . When the camera gain is +6 dB to +12 dB, the passband of the spatial filter narrows stepwise in accordance with the camera gain. - A variable temporal filter that executes temporal smoothing of each pixel is independently applicable to the smoothing processing of this embodiment. It is possible to use the above-described spatial filter together.
- A circuit b of
FIG. 6 shows a detailed example of the smoothingcircuit 124, which implements a smoothing circuit by a variable temporal filter that executes temporal smoothing of each pixel. This circuit is known as a recursive filter. A subtractingcircuit 607 calculates the difference between each pixel of an image signal supplied to a terminal 606 and a corresponding pixel of the preceding frame. Acoefficient multiplying circuit 610 multiplies the difference value by a predetermined coefficient. An addingcircuit 611 adds the result to the pixel of the preceding frame. If the coefficient is 1, anoutput terminal 623 outputs the same value as the input, and the smoothing intensity is 0. If the coefficient is smaller than 1, smoothing by an IIR filter is executed between the current frame and the preceding frame. The smoothing intensity changes depending on the coefficient. A terminal 608 is a smoothing intensity control input terminal. Acoefficient setting circuit 609 sets a coefficient corresponding to the input smoothing intensity. Aframe memory 612 holds the processed image signal to be used to process the succeeding frame. -
FIG. 15 shows graphs a through c showing the luminance flicker reduction effect upon increasing the camera gain when encoded data generated in this embodiment is reproduced. The graph a ofFIG. 15 shows the reproduction signal from I-pictures. The smoothing circuit suppresses the luminance peak of the noise component superimposed on a flat image signal so that the peak is lower than in the graph a ofFIG. 16 . It is also possible to suppress the luminance peak of the noise component in I-pictures by assigning a smaller code amount to I-pictures when a larger code amount is assigned to the P- and B-pictures. The graph b ofFIG. 15 shows the reproduction signal from P- and B-pictures. Smoothing suppresses the noise peak. In addition, since the assigned code amount ratio increases, the luminance peak of noise is reproduced without excessively decreasing upon encoding. Hence, the luminance peak difference between the graphs a and b ofFIG. 15 decreases. Even in reproducing a moving image, the luminance peak flicker caused by noise decreases, as is apparent from the graph c ofFIG. 15 . - As described above, in this embodiment, the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain. This allows to effectively reduce the noise flicker while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing. Even when a camera apparatus for business use is used for photographing containing noise as a photographic effect, the flicker can be reduced while making the most of the effect of noise.
-
FIG. 7 is a block diagram showing, as the second embodiment, a digital video camera according to another embodiment of an image signal processing apparatus of the present invention.Reference numeral 702 denotes a camera unit; and 701, a camera including a lens optical system and a photo-electric conversion unit such as a CCD. An analog moving image signal photographed by thecamera 701 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and γ-conversion by a photographed imagesignal processing circuit 703. The photographed imagesignal processing circuit 703 also executes sharpness control processing of controlling the resolution by adding, to the original image signal, an aperture correction signal generated from the high frequency component of the image signal. - A
camera control circuit 725 executes processing such as exposure control of thecamera 701 on the basis of, for example, the brightness of the photographed image. Thecamera control circuit 725 controls the amplifier gain of the photographed imagesignal processing circuit 703 as needed, as in the first embodiment. Thecamera control circuit 725 also controls the sharpness control processing of the photographed imagesignal processing circuit 703 to adjust the resolution of the image signal. The sharpness can be either set within a predetermined range by the user or automatically controlled by thecamera control circuit 725 in accordance with the photographing situation. - The photographed image
signal processing circuit 703 supplies its output to asmoothing circuit 724 as an image signal from thecamera unit 702. The smoothingcircuit 724 includes a variable-band special filter that limits the spatial band of an image signal, a variable temporal filter that executes temporal smoothing of each pixel, or a combination thereof. The smoothingcircuit 724 has already been described in detail in the first embodiment, and a repetitive description will be omitted here. - The output from the smoothing
circuit 724 is supplied to aframe rearranging circuit 709 as image data to be encoded. Theframe rearranging circuit 709 rearranges frames in an encoding order. - For I-pictures, a
difference circuit 710 outputs the image data itself to aDCT circuit 711. For P- and B-pictures, thedifference circuit 710 calculates the difference value between the image data and a predicted image and outputs the difference value to theDCT circuit 711 by selecting aswitch 723. TheDCT circuit 711 converts the image data into a DCT coefficient. Aquantization circuit 712 quantizes the DCT coefficient by using a predetermined quantization scale Q. - A variable-
length coding circuit 713, for example, entropy-encodes the quantization coefficient output from thequantization circuit 712 and outputs it as encoded data. Abuffer 714 temporarily saves the generated encoded data to control the encoding rate. The encoded data stored in thebuffer 714 is read out at a predetermined rate and output from a terminal 715 as compression-encoded data. It is possible to efficiently record the output compression-encoded data on a recording medium such as a tape, disc, or semiconductor memory or efficiently transmit the compression-encoded data by using a network or commutation channel. - On the other hand, the coefficient data quantized by the
quantization circuit 712 undergoes inverse quantization by aninverse quantization circuit 711 and inverse DOT by aninverse DCT circuit 718 to obtain predicted image data. For I-pictures, an addingcircuit 719 saves data after inverse DCT directly in avideo memory 720. For P- and B-pictures, the addingcircuit 719 adds the predicted image to the P- and B-pictures and saves it in thevideo memory 720 as locally decoded image data. A motioncompensation predicting circuit 721 compares the locally decoded image data saved in thevideo memory 720 with the input image data. For P-pictures, predicted image data with motion compensation in the forward direction is generated and supplied to the above-describeddifference circuit 710. For B-pictures, predicted image data with bidirectional motion compensation is generated and supplied to the above-describeddifference circuit 710. The motioncompensation predicting circuit 721 also supplies the generated image data to the addingcircuit 719 as a predicted image for next local decoding. - A
rate control circuit 727 executes code amount assignment control of a picture to be encoded for a target encoding rate in accordance with information such as a past generated code amount and buffer fill factor obtained from thebuffer 714 and the setting value of a code amount ratio setting circuit 726 (to be described later). At this time, therate control circuit 727 controls thequantization circuit 712 by deciding the quantization scale Q based on a code amount assigned to each picture type. The generated code amount after quantization changes between the I-, P-, and B-pictures. The quantization scale Q is therefore changed in accordance with the picture type. - A flicker
suppression control circuit 716 as a characteristic feature of this embodiment controls smoothing processing of the smoothingcircuit 724 and the code amountratio setting circuit 726 in accordance with a camera gain setting value and sharpness setting value supplied from thecamera control circuit 725. The flickersuppression control circuit 716 controls the code amountratio setting circuit 726 to change the code amount ratio to be assigned to each picture type, thereby suppressing a luminance flicker upon increasing the gain. -
FIG. 8 shows graphs a and b showing control of assignment ratio of code amount by the camera gain and sharpness setting. The graph a ofFIG. 8 shows quantization scale ratio control for control of assignment ratio of code amount. For the illustrative convenience, the graph a ofFIG. 8 shows only the control characteristic of B-pictures. Symbols a, b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low). The threshold value of the change in the quantization scale changes between a, b, and c. When the camera gain exceeds +3, +6, and +9 dB, the quantization scale ratio of B-pictures decreases. As a result, the generated code amount ratio of B-pictures increases. Generally, when the sharpness setting is high, the peak of the noise component is also enhanced as a high frequency component so that the luminance peak generated by noise increases. Hence, in this embodiment, the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the sharpness intensity. If the sharpness is high, the quantization scale ratio decreases from a low camera gain. - The graph b of
FIG. 8 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain and sharpness setting in the graph a ofFIG. 8 . As in the graph a ofFIG. 8 , a, b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low). - In the examples shown in
FIG. 8 , the camera gain has a predetermined threshold value so that the quantization scale ratio is controlled in two steps. It is also possible to change the quantization scale ratio in proportion to the camera gain. -
FIG. 9 shows examples of control of assignment ratio of code amount proportional to the camera gain in accordance with sharpness setting. A graph a ofFIG. 9 shows quantization scale ratio control for control of assignment ratio of code amount. For the illustrative convenience, the graph a ofFIG. 9 shows only the control characteristic of B-pictures. Symbols a, b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low). The threshold value of the change in the quantization scale changes between a, b, and c. When the camera gain exceeds +3, +6, and +9 dB, the quantization scale ratio of B-pictures decreases in accordance with the camera gain. As a result, the generated code amount ratio of B-pictures increases. Additionally, the tilt of the change in the quantization scale changes between a, b, and c. The higher the sharpness is, the more rapidly the quantization scale ratio decreases upon increasing the gain. In this embodiment, the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the sharpness intensity. In addition, the quantization scale ratio decrease rate is also changed in accordance with the sharpness intensity. If the sharpness is high, the quantization scale ratio decreases from a low camera gain. - A graph b of
FIG. 9 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control proportional to the camera gain in accordance with the sharpness setting in the graph a ofFIG. 9 . As in the graph a ofFIG. 9 , symbols a, b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low). - As described above, in this embodiment, the assigned code amount ratio of P- and B-pictures increases in accordance with the camera gain and sharpness setting. This allows to suppress loss of the peak of the noise component upon increasing the gain when P- and B-pictures are encoded. This arrangement can reduce a luminance flicker in reproducing encoded image data.
- In this embodiment, the flicker
suppression control circuit 716 controls spatial or temporal smoothing or spatial and temporal smoothing of the above-describedsmoothing circuit 724. When the arrangement to control the smoothing processing combines with the above-described arrangement to control code amount assignment, a synergy effect can be expected. - In a detailed arrangement of smoothing control, the smoothing
circuit 724 executes smoothing at an intensity corresponding to the camera gain and sharpness setting to suppress the peak of the noise component itself and decrease the luminance peak due to the noise component of I-pictures. This allows to reduce the difference from the decrease in the luminance peak of noise upon encoding P- and B-pictures. As a result, a luminance flicker between the pictures can be suppressed. Additionally, this smoothing processing also suppresses the noise component input to the P- and B-pictures. This further suppresses the decrease in the luminance peak of noise dependent on encoding by an increase in the code amount assignment ratio. - A graph a of
FIG. 10 shows an example of smoothing intensity control according to the camera gain and sharpness setting. Symbols a, b, and c indicate smoothing intensities according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low). The threshold value of the change in the smoothing intensity changes between a, b, and c. When the camera gain exceeds +3, +6, and +9 dB, the smoothing processing is executed. - A graph b of
FIG. 10 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a ofFIG. 10 . L1001 indicates a band characteristic obtained when no smoothing processing is executed. This characteristic corresponds to the region without smoothing processing (smoothing intensity: 0) in the graph a ofFIG. 10 . L1002 indicates a band characteristic obtained when smoothing processing is executed. This characteristic corresponds to the region where the smoothing processing is effective in the graph a ofFIG. 10 . - In the examples shown in
FIG. 10 , the camera gain has a predetermined threshold value so that the smoothing characteristic is changed in two steps (whole band is passed in one mode). It is also possible to change the smoothing intensity in proportion to the camera gain. A graph a ofFIG. 11 shows smoothing intensity control proportional to the camera gain in accordance with sharpness setting. Symbols a, b, and c indicate smoothing intensities according to the camera gain in correspondence with the sharpness setting intensities (high, medium, and low). The threshold value of the change in the smoothing intensity changes between a, b, and c. When the camera gain exceeds +3, +6, and +9 dB, the smoothing intensity increases up to a predetermined upper limit in accordance with the camera gain. The tilt of the increases changes depending on the sharpness setting. If the sharpness setting is high, the smoothing intensity is high even at a low camera gain. A graph b ofFIG. 11 shows the band characteristic of the spatial filter corresponding to the change in the smoothing intensity in the graph a ofFIG. 11 . When the camera gain is +6 dB to +12 dB, the passband of the spatial filter narrows stepwise in accordance with the camera gain. - As described above, in this embodiment, the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain and sharpness setting. This allows to effectively reduce the noise flicker while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing. Even when a camera apparatus for business use is used for photographing containing noise as a photographic effect, the flicker can be reduced while making the most of the effect of noise.
-
FIG. 12 is a block diagram showing, as the third embodiment, a digital video camera according to still another embodiment of an image signal processing apparatus of the present invention.Reference numeral 1202 denotes a camera unit; and 1201, a camera including a lens optical system and a photo-electric conversion unit such as a CCD. An analog moving image signal photographed by thecamera 1201 undergoes processing such as A/D-conversion, pixel interpolation, color conversion, and γ-conversion by a photographed imagesignal processing circuit 1203. - A camera control circuit 1225 executes processing such as exposure control of the
camera 1201 on the basis of, for example, the brightness of the photographed image. The camera control circuit 1225 controls the amplifier gain of the photographed imagesignal processing circuit 1203 as needed, as in the first embodiment. - The photographed image
signal processing circuit 1203 supplies its output to asmoothing circuit 1224 as an image signal from thecamera unit 1202. Thesmoothing circuit 1224 includes a variable-band special filter that limits the spatial band of an image signal, a variable temporal filter that executes temporal smoothing of each pixel, or a combination thereof. Thesmoothing circuit 1224 has already been described in detail in the first embodiment, and a repetitive description will be omitted here. - The output from the
smoothing circuit 1224 is supplied to aframe rearranging circuit 1209 as image data to be encoded. Theframe rearranging circuit 1209 rearranges frames in an encoding order. - For I-pictures, a
difference circuit 1210 outputs the image data itself to aDCT circuit 1211. For P- and B-pictures, thedifference circuit 1210 calculates the difference value between the image data and a predicted image and outputs the difference value to theDCT circuit 1211 by selecting aswitch 1223. TheDCT circuit 1211 converts the image data into a DCT coefficient. Aquantization circuit 1212 quantizes the DOT coefficient by using a predetermined quantization scale Q. - A variable-
length coding circuit 1213, for example, entropy-encodes the quantization coefficient output from thequantization circuit 1212 and outputs it as encoded data. Abuffer 1214 temporarily saves the generated encoded data to control the encoding rate. The encoded data stored in thebuffer 1214 is read out at a predetermined rate and output from a terminal 1215 as compression-encoded data. It is possible to efficiently record the output compression-encoded data on a recording medium such as a tape, disc, or semiconductor memory or efficiently transmit the compression-encoded data by using a network or commutation channel. - On the other hand, the coefficient data quantized by the
quantization circuit 1212 undergoes inverse quantization by aninverse quantization circuit 1211 and inverse DCT by aninverse DCT circuit 1218 to obtain predicted image data. For I-pictures, an addingcircuit 1219 saves data after inverse DCT directly in avideo memory 1220. For P- and B-pictures, the addingcircuit 1219 adds the predicted image to the P- and B-pictures and saves it in thevideo memory 1220 as locally decoded image data. A motioncompensation predicting circuit 1221 compares the locally decoded image data saved in thevideo memory 1220 with the input image data. For P-pictures, predicted image data with motion compensation in the forward direction is generated and supplied to the above-describeddifference circuit 1210. For B-pictures, predicted image data with bidirectional motion compensation is generated and supplied to the above-describeddifference circuit 1210. The motioncompensation predicting circuit 1221 also supplies the generated image data to the addingcircuit 1219 as a predicted image for next local decoding. - A target bit
rate setting circuit 1228 calculates a target bit rate in accordance with, for example, a user's encoding mode selection instruction and supplies the information to arate control circuit 1227 and flickersuppression control circuit 1216. - The
rate control circuit 1227 executes code amount assignment control of a picture to be encoded for a target encoding rate in accordance with information such as a past generated code amount and buffer fill factor obtained from thebuffer 1214, the information from the above-described target bitrate setting circuit 1228, and the setting value of a code amount ratio setting circuit 1226 (to be described later). At this time, therate control circuit 1227 controls thequantization circuit 1212 by deciding the quantization scale Q based on a code amount assigned to each picture type. The generated code amount after quantization changes between the I-, P-, and B-pictures. The quantization scale Q is therefore changed in accordance with the picture type. - The flicker
suppression control circuit 1216 as a characteristic feature of this embodiment controls smoothing processing of thesmoothing circuit 1224 and the code amountratio setting circuit 1226 in accordance with a camera gain setting value supplied from the camera control circuit 1225 and the target bit rate value supplied from the above-described target bitrate setting circuit 1228. The flickersuppression control circuit 1216 controls the code amountratio setting circuit 1226 to change the code amount ratio to be assigned to each picture type, thereby suppressing a luminance flicker upon increasing the gain. -
FIG. 13 shows graphs a and b showing control of assignment ratio of code amount by the camera gain and target bit rate value. The graph a ofFIG. 13 shows quantization scale ratio control for control of assignment ratio of code amount. For the illustrative convenience, the graph a ofFIG. 13 shows only the control characteristic of B-pictures. Symbols a, b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high). The threshold value of the change in the quantization scale changes between a, b, and c. When the camera gain exceeds +3, +6, and +9 dB, the quantization scale ratio of B-pictures decreases. As a result, the generated code amount ratio of B-pictures increases. Generally, the lower the target bit rate is, the larger the decrease in the luminance peak caused by the noise component upon encoding of P- and B-pictures is. Hence, the luminance flicker readily becomes noticeable. Hence, in this embodiment, the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the target bit rate. If the target bit rate is low, the quantization scale ratio decreases from a low camera gain. - The graph b of
FIG. 13 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control according to the camera gain and target bit rate value in the graph a ofFIG. 13 . As in the graph a ofFIG. 13 , symbols a, b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high). - In the examples shown in
FIG. 13 , the camera gain has a predetermined threshold value so that the quantization scale ratio is controlled in two steps. It is also possible to change the quantization scale ratio in proportion to the camera gain. -
FIG. 14 shows examples of control of assignment ratio of code amount proportional to the camera gain in accordance with the target bit rate value. A graph a ofFIG. 14 shows quantization scale ratio control for control of assignment ratio of code amount. For the illustrative convenience, the graph a ofFIG. 14 shows only the control characteristic of B-pictures. Symbols a, b, and c indicate changes in the quantization scale ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high). The threshold value of the change in the quantization scale changes between a, b, and c. When the camera gain exceeds +3, +6, and +9 dB, the quantization scale ratio of B-pictures decreases in accordance with the camera gain. As a result, the generated code amount ratio of B-pictures increases. - Additionally, the tilt of the change in the quantization scale changes between a, b, and c. The lower the target bit rate is, the more rapidly the quantization scale ratio decreases upon increasing the gain. In this embodiment, the threshold value of quantization scale ratio change corresponding to the camera gain is changed in accordance with the target bit rate. In addition, the quantization scale ratio decrease rate is also changed in accordance with the target bit rate. If the target bit rate is low, the quantization scale ratio decreases from a low camera gain.
- A graph b of
FIG. 14 shows a state wherein the assigned code amount ratio changes upon quantization scale ratio control proportional to the camera gain in accordance with the target bit rate value in the graph a ofFIG. 14 . As in the graph a ofFIG. 14 , symbols a, b, and c indicate changes in the assigned code amount ratio of B-pictures according to the camera gain in correspondence with the target bit rates (low, medium, and high). - As described above, in this embodiment, the assigned code amount ratio of P- and B-pictures increases as the camera gain increases. This allows to suppress loss of the peak of the noise component upon increasing the gain when P- and B-pictures are encoded. This arrangement can reduce a luminance flicker in reproducing encoded image data.
- In this embodiment, the flicker
suppression control circuit 1216 controls spatial or temporal smoothing or spatial and temporal smoothing of the above-describedsmoothing circuit 1224. When the arrangement to control the smoothing processing combines with the above-described arrangement to control code amount assignment, a synergy effect can be expected. - In a detailed arrangement of smoothing control, the
smoothing circuit 1224 executes smoothing at an intensity corresponding to the camera gain and target bit rate value to suppress the peak of the noise component itself and decrease the luminance peak due to the noise component of I-pictures. This allows to reduce the difference from the decrease in the luminance peak of noise upon encoding P- and B-pictures. As a result, a luminance flicker between the pictures can be suppressed. Additionally, this smoothing processing also suppresses the noise component input to the P- and B-pictures. This further suppresses the decrease in the luminance peak of noise dependent on encoding by an increase in the code amount assignment ratio. - The contents of smoothing intensity control according to the camera gain and target bit rate value is the same as those of smoothing control according to the camera gain and sharpness setting described with reference to
FIGS. 10 and 11 , and a description thereof will be omitted. - As described above, in this embodiment, the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain and target bit rate value. This allows to effectively reduce the noise flicker while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing. Even when a camera apparatus for business use is used for photographing containing noise as a photographic effect, the flicker can be reduced while making the most of the effect of noise.
- According to the present invention described above, the assigned code amount ratio of each picture type and the image signal smoothing intensity are controlled collectively in accordance with the camera gain. This allows to effectively reduce the luminance flicker by noise while minimizing an adverse effect such as a decrease in the resolution or an afterimage due to smoothing even when the S/N ratio of an image photographed at an increased gain is low. Additionally, it is possible to reduce the luminance flicker while making the most of the effect of noise even in photographing an image containing noise that is intentionally added to obtain a photographic effect.
- The functions of the processes of the camera control circuit, flicker suppression control circuit, code amount ratio setting circuit, and rate control circuit of the above-described embodiments may be implemented by causing the CPU (Central Processing Unit) of a computer to read out a program to implement the function of each process from a memory and execute the program.
- Examples of the memory the CPU accesses are nonvolatile memories such as an HDD, optical disc, and flash memory, read-only recording media such as a CD-ROM, volatile memories except a RAM, and computer-readable/writable recording media by combinations thereof.
- The program to implement the functions of the processes of the camera control circuit, flicker suppression control circuit, code amount ratio setting circuit, and rate control circuit of the above-described embodiments may be recorded on a computer-readable recording medium such that a computer system can load and execute the program recorded on the recording medium to do the processes. The “computer system” includes an OS and hardware such as peripheral devices. More specifically, the functions of the above-described embodiments may be implemented when the program read out from a storage medium is written in the memory of a function expansion board inserted into a computer or a function expansion unit connected to a computer, and the CPU of the function expansion board or function expansion unit partially or wholly performs actual processing on the basis of the instructions of the program.
- The “computer-readable recording medium” indicates a portable medium including an optical disc such as a CD-ROM or DVD and a semiconductor memory card, or a storage device such as a hard disc incorporated in a computer system. The “computer-readable recording medium” also includes a device that holds a program for a predetermined time, like a volatile memory (RAM) in a compute system serving as a server or client when a program is transmitted through a network such as the Internet or a communication line such as a telephone line.
- The program may be transmitted from a computer system that stores it in a storage device to another computer system through a transmission medium or transmission wave in a transmission medium. The “transmission medium” to transmit the program indicates a medium having a function of transmitting information, like a network (communication network) such as the Internet or a communication line such as a telephone line.
- The program may implement some of the above-described functions. The program may be a so-called differential file (differential program) implemented by combining the above-described functions with an already recorded program.
- A program product such as a computer-readable recording medium that records the program is also applicable as an embodiment of the present invention. The present invention incorporates the program, recording medium, transmission medium, and program product.
- The embodiments of the present invention have been described above in detail with reference to the accompanying drawings. Detailed arrangements are not limited to the embodiments and also include a design without departing from the spirit and scope of the present invention.
- While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
- This application claims the benefit of Japanese Patent Application No. 2005-324784, filed Nov. 9, 2005 which is hereby incorporated by reference herein in its entirety.
Claims (21)
1.-21. (canceled)
22. An image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, comprising:
an acquisition unit configured to acquire a gain setting value for the image signal;
a smoothing unit configured to execute smoothing processing of the image signal;
a compression encoding unit, provided on a subsequent stage of said smoothing unit, configured to execute compression-encoding of the image signal;
a setting unit configured to set code amounts to be respectively assigned to each picture type to said compression encoding unit; and
a control unit configured to change an intensity of the smoothing processing by said smoothing unit and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value acquired by said acquisition unit,
wherein said control unit increases the intensity of the smoothing processing by said smoothing unit, and the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, when the gain setting value is larger than a predetermined value.
23. The image signal processing apparatus according to claim 22 , wherein the assignment ratio is changed by changing a ratio of a quantization scale representation value for the picture to be intra-encoded to a quantization scale representation value for the picture to be encoded by inter-picture prediction.
24. The image signal processing apparatus according to claim 22 , wherein said smoothing unit executes spatial smoothing processing, temporal smoothing processing, or smoothing processing of both types.
25. The image signal processing apparatus according to claim 22 , further comprising a camera unit configured to generate the image signal by photographing, said camera unit having an arrangement to execute gain adjustment of the generated image signal and output the gain setting value, wherein said acquisition unit acquires the gain setting value output from said camera unit.
26. An image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, comprising:
an acquisition unit configured to acquire a gain setting value for the image signal and a sharpness setting value for the image signal;
a smoothing unit configured to execute smoothing processing of the image signal;
a compression encoding unit, provided on a subsequent stage of said smoothing unit, configured to execute compression-encoding of the image signal;
an setting unit configured to set code amounts to be respectively assigned to each picture type to said compression encoding unit; and
a control unit configured to control an intensity of the smoothing processing by said smoothing unit and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value and the sharpness setting value acquired by said acquisition unit.
27. The image signal processing apparatus according to claims 26 , wherein said control unit increases the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction, when the gain setting value is larger than a predetermined value defined by the sharpness setting value.
28. The image signal processing apparatus according to claims 26 , wherein said control unit changes the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, in proportion to the gain setting value at a rate defined by the sharpness setting value.
29. The image signal processing apparatus according to claim 26 , wherein said control unit executes the smoothing processing of the image signal when the gain setting value is larger than a predetermined value defined by the sharpness setting value.
30. The image signal processing apparatus according to claim 26 , wherein said control unit changes an intensity of the smoothing processing in proportion to the gain setting value at a rate defined by the sharpness setting value.
31. The image signal processing apparatus according to claim 26 , further comprising a camera unit configured to generate the image signal by photographing, said camera unit having an arrangement to execute gain adjustment and sharpness adjustment of the generated image signal and output the gain setting value and the sharpness setting value,
wherein said acquisition unit acquires the gain setting value and the sharpness setting value output from said camera unit.
32. An image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, comprising:
an acquisition unit configured to acquire a gain setting value for the image signal;
a smoothing unit configured to execute smoothing processing of the image signal;
a compression encoding unit, provided on a subsequent stage of said smoothing unit, configured to execute compression-encoding of the image signal;
a setting unit configured to set code amounts to be respectively assigned to each picture type to said compression encoding unit;
a designation unit configured to designate a target bit rate of compression encoding of said compression encoding unit; and
a control unit configured to change an intensity of the smoothing processing by said smoothing unit and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value acquired by said acquisition unit and the target bit rage designated by said designation unit,
wherein said control unit increases the intensity of the smoothing processing by said smoothing unit, and the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded and changes a degree of increase of the assignment ratio in accordance with the target bit rate designated by said designation unit, when the gain setting value is larger than a predetermined value.
33. An image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, comprising:
an acquisition unit configured to acquire a gain setting value for the image signal;
a compression encoding unit configured to execute compression-encoding the image signal;
a setting unit configured to set code amounts to be respectively assigned to each picture type to said compression encoding unit; and
a control unit configured to change an assignment ratio between the code amounts to be assigned to each picture types, in accordance with the gain setting value acquired by said acquisition unit,
wherein said control unit increases the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, when the gain setting value is larger than a predetermined value.
34. A method executed by an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, the method comprising:
an acquisition step of acquiring a gain setting value for the image signal;
a smoothing step of executing smoothing processing of the image signal;
a compression encoding step, provided on a subsequent stage of said smoothing step, of executing compression-encoding of the image signal;
a setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step; and
a control step of changing an intensity of the smoothing processing by said smoothing step and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value acquired by said acquisition step,
wherein said control step increases the intensity of the smoothing processing by said smoothing step, and the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, when the gain setting value is larger than a predetermined value.
35. A method executed by an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, the method comprising:
an acquisition step of acquiring a gain setting value for the image signal and a sharpness setting value for the image signal;
a smoothing step of executing smoothing processing of the image signal;
a compression encoding step, provided on a subsequent stage of said smoothing step, of executing compression-encoding of the image signal;
an setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step; and
a control step of controlling an intensity of the smoothing processing by said smoothing step and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value and the sharpness setting value acquired by said acquisition step.
36. A method executed by an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, the method comprising:
an acquisition step of acquiring a gain setting value for the image signal;
a smoothing step of executing smoothing processing of the image signal;
a compression encoding step, provided on a subsequent stage of said smoothing step, of executing compression-encoding of the image signal;
a setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step;
a designation step of designating a target bit rate of compression encoding of said compression encoding step; and
a control step of changing an intensity of the smoothing processing by said smoothing step and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value acquired by said acquisition step and the target bit rage designated by said designation step,
wherein said control step increases the intensity of the smoothing processing by said smoothing step, and the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded and changes a degree of increase of the assignment ratio in accordance with the target bit rate designated by said designation step, when the gain setting value is larger than a predetermined value.
37. A method executed by an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, the method comprising:
an acquisition step of acquiring a gain setting value for the image signal;
a compression encoding step of executing compression-encoding the image signal;
a setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step; and
a control step of changing an assignment ratio between the code amounts to be assigned to each picture types, in accordance with the gain setting value acquired by said acquisition step,
wherein said control step increases the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, when the gain setting value is larger than a predetermined value.
38. A computer-readable storage medium on which is stored code of a computer-executable program for causing an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, to execute:
an acquisition step of acquiring a gain setting value for the image signal;
a smoothing step of executing smoothing processing of the image signal;
a compression encoding step, provided on a subsequent stage of said smoothing step, of executing compression-encoding of the image signal;
a setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step; and
a control step of changing an intensity of the smoothing processing by said smoothing step and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value acquired by said acquisition step,
wherein said control step increases the intensity of the smoothing processing by said smoothing step, and the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, when the gain setting value is larger than a predetermined value.
39. A computer-readable storage medium on which is stored code of a computer-executable program for causing an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, to execute:
an acquisition step of acquiring a gain setting value for the image signal and a sharpness setting value for the image signal;
a smoothing step of executing smoothing processing of the image signal;
a compression encoding step, provided on a subsequent stage of said smoothing step, of executing compression-encoding of the image signal;
an setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step; and
a control step of controlling an intensity of the smoothing processing by said smoothing step and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value and the sharpness setting value acquired by said acquisition step.
40. A computer-readable storage medium on which is stored code of a computer-executable program for causing an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, to execute:
an acquisition step of acquiring a gain setting value for the image signal;
a smoothing step of executing smoothing processing of the image signal;
a compression encoding step, provided on a subsequent stage of said smoothing step, of executing compression-encoding of the image signal;
a setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step;
a designation step of designating a target bit rate of compression encoding of said compression encoding step; and
a control step of changing an intensity of the smoothing processing by said smoothing step and an assignment ratio between the code amounts to be assigned to each picture type, in accordance with the gain setting value acquired by said acquisition step and the target bit rage designated by said designation step,
wherein said control step increases the intensity of the smoothing processing by said smoothing step, and the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded and changes a degree of increase of the assignment ratio in accordance with the target bit rate designated by said designation step, when the gain setting value is larger than a predetermined value.
41. A computer-readable storage medium on which is stored code of a computer-executable program for causing an image signal processing apparatus for classifying an image signal according to a plurality of different picture types including a picture to be intra-encoded and a picture to be encoded by inter-picture prediction and compression-encoding the image signal, to execute:
an acquisition step of acquiring a gain setting value for the image signal;
a compression encoding step of executing compression-encoding of the image signal;
a setting step of setting code amounts to be respectively assigned to each picture type to said compression encoding step; and
a control step of changing an assignment ratio between the code amounts to be assigned to each picture types, in accordance with the gain setting value acquired by said acquisition step,
wherein said control step increases the assignment ratio of the code amount to be assigned to the picture to be encoded by inter-picture prediction with respect to the code amount to be assigned to the picture to be intra-encoded, when the gain setting value is larger than a predetermined value.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/531,234 US20120262598A1 (en) | 2005-11-09 | 2012-06-22 | Image signal processing apparatus |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2005324784A JP4794987B2 (en) | 2005-11-09 | 2005-11-09 | Video signal processing device |
JP2005-324784 | 2005-11-09 | ||
PCT/JP2006/322690 WO2007055389A2 (en) | 2005-11-09 | 2006-11-08 | Image signal processing apparatus |
US9312608A | 2008-05-08 | 2008-05-08 | |
US13/531,234 US20120262598A1 (en) | 2005-11-09 | 2012-06-22 | Image signal processing apparatus |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2006/322690 Continuation WO2007055389A2 (en) | 2005-11-09 | 2006-11-08 | Image signal processing apparatus |
US9312608A Continuation | 2005-11-09 | 2008-05-08 |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120262598A1 true US20120262598A1 (en) | 2012-10-18 |
Family
ID=37906920
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/093,126 Expired - Fee Related US8229004B2 (en) | 2005-11-09 | 2006-11-08 | Image signal processing apparatus with code amount control for inter-frame and intra-frame encoding |
US13/531,234 Abandoned US20120262598A1 (en) | 2005-11-09 | 2012-06-22 | Image signal processing apparatus |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/093,126 Expired - Fee Related US8229004B2 (en) | 2005-11-09 | 2006-11-08 | Image signal processing apparatus with code amount control for inter-frame and intra-frame encoding |
Country Status (5)
Country | Link |
---|---|
US (2) | US8229004B2 (en) |
EP (1) | EP1949705B1 (en) |
JP (1) | JP4794987B2 (en) |
CN (1) | CN101305617B (en) |
WO (1) | WO2007055389A2 (en) |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4794987B2 (en) | 2005-11-09 | 2011-10-19 | キヤノン株式会社 | Video signal processing device |
JP4936557B2 (en) * | 2008-01-24 | 2012-05-23 | キヤノン株式会社 | Encoder |
JP5081729B2 (en) * | 2008-06-03 | 2012-11-28 | 株式会社日立国際電気 | Image encoding device |
JP5136470B2 (en) * | 2009-03-06 | 2013-02-06 | 富士通株式会社 | Moving picture coding apparatus and moving picture coding method |
JP2011029954A (en) * | 2009-07-27 | 2011-02-10 | Sony Corp | Image encoding device and image encoding method |
JP5762026B2 (en) * | 2011-02-01 | 2015-08-12 | キヤノン株式会社 | Image processing device |
JP2012227955A (en) * | 2012-07-12 | 2012-11-15 | Hitachi Kokusai Electric Inc | Image encoder |
US9215411B2 (en) * | 2014-02-03 | 2015-12-15 | Google Inc. | Enhancing video conferences |
US9635212B2 (en) * | 2014-05-30 | 2017-04-25 | Apple Inc. | Dynamic compression ratio selection |
JP6381380B2 (en) * | 2014-09-08 | 2018-08-29 | キヤノン株式会社 | Imaging apparatus, control method and program thereof |
EP3300363B1 (en) * | 2015-12-15 | 2018-08-29 | Axis AB | A bit rate controller and a method for limiting output bit rate |
EP3379830B1 (en) * | 2017-03-24 | 2020-05-13 | Axis AB | A method, a video encoder, and a video camera for encoding a video stream |
EP3557872A1 (en) * | 2018-04-16 | 2019-10-23 | InterDigital VC Holdings, Inc. | Method and device for encoding an image or video with optimized compression efficiency preserving image or video fidelity |
CN111200734B (en) | 2018-11-19 | 2022-03-11 | 浙江宇视科技有限公司 | Video coding method and device |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003219366A (en) * | 2002-01-18 | 2003-07-31 | Canon Inc | Image processing apparatus, image processings system, compression processing method, storage medium, and program |
US20040008772A1 (en) * | 2001-06-07 | 2004-01-15 | Masaaki Kojima | Camera-integrated video recording and reproducing apparatus, and record control method thereof |
US20040135883A1 (en) * | 1999-06-09 | 2004-07-15 | Olympus Corporation | Image processing unit whose ability to process endoscopic image signal can be expanded, and endoscopic imaging system |
US20050175096A1 (en) * | 2001-04-19 | 2005-08-11 | Jungwoo Lee | Apparatus and method for allocating bits temporaly between frames in a coding system |
US20050226526A1 (en) * | 2003-01-09 | 2005-10-13 | Sony Corporation | Image processing device and method |
Family Cites Families (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0402058B1 (en) * | 1989-06-07 | 1996-03-27 | Canon Kabushiki Kaisha | Predictive decoding device correcting code errors |
DE69032737T2 (en) * | 1989-07-13 | 1999-04-29 | Canon K.K., Tokio/Tokyo | Encoding and decoding device suitable for copying data |
US6718122B1 (en) * | 1991-01-18 | 2004-04-06 | Canon Kabushiki Kaisha | Image processing apparatus |
US6219157B1 (en) * | 1992-06-18 | 2001-04-17 | Canon Kabushiki Kaisha | Image coding apparatus |
DE69323855T2 (en) * | 1992-12-24 | 1999-09-16 | Canon K.K., Tokio/Tokyo | Device for reproducing an image signal |
JPH08181987A (en) * | 1994-12-22 | 1996-07-12 | Canon Inc | Coder |
WO1997005745A1 (en) * | 1995-07-31 | 1997-02-13 | Sony Corporation | Image pickup system, picture processor, encoder, encoding method, and random noise removing method |
KR100188934B1 (en) * | 1995-08-28 | 1999-06-01 | 윤종용 | Apparatus and method of encoding image signal |
JP3767007B2 (en) * | 1996-03-27 | 2006-04-19 | ソニー株式会社 | Encoding apparatus and encoding method |
KR100610520B1 (en) * | 1997-07-08 | 2006-08-09 | 소니 가부시끼 가이샤 | Video data encoder, video data encoding method, video data transmitter, and video data recording medium |
JP4208342B2 (en) * | 1999-05-14 | 2009-01-14 | キヤノン株式会社 | Image recording apparatus, method, and computer-readable storage medium |
JP4362795B2 (en) * | 1999-07-13 | 2009-11-11 | 日本ビクター株式会社 | Video encoding apparatus and method |
JP2001313906A (en) * | 2000-04-27 | 2001-11-09 | Hitachi Ltd | Digital camera |
JP3641214B2 (en) * | 2001-02-28 | 2005-04-20 | 株式会社東芝 | Moving picture coding apparatus and moving picture coding method |
JP2003023637A (en) * | 2001-07-06 | 2003-01-24 | Sony Corp | Image coding method and image coding device |
JP4423214B2 (en) * | 2005-02-23 | 2010-03-03 | キヤノン株式会社 | Image processing device |
JP4759360B2 (en) * | 2005-10-07 | 2011-08-31 | キヤノン株式会社 | Image processing device |
WO2006090755A1 (en) | 2005-02-23 | 2006-08-31 | Canon Kabushiki Kaisha | Image processing apparatus |
JP4794987B2 (en) | 2005-11-09 | 2011-10-19 | キヤノン株式会社 | Video signal processing device |
-
2005
- 2005-11-09 JP JP2005324784A patent/JP4794987B2/en not_active Expired - Fee Related
-
2006
- 2006-11-08 CN CN2006800419714A patent/CN101305617B/en not_active Expired - Fee Related
- 2006-11-08 WO PCT/JP2006/322690 patent/WO2007055389A2/en active Application Filing
- 2006-11-08 EP EP20060823392 patent/EP1949705B1/en not_active Not-in-force
- 2006-11-08 US US12/093,126 patent/US8229004B2/en not_active Expired - Fee Related
-
2012
- 2012-06-22 US US13/531,234 patent/US20120262598A1/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040135883A1 (en) * | 1999-06-09 | 2004-07-15 | Olympus Corporation | Image processing unit whose ability to process endoscopic image signal can be expanded, and endoscopic imaging system |
US20050175096A1 (en) * | 2001-04-19 | 2005-08-11 | Jungwoo Lee | Apparatus and method for allocating bits temporaly between frames in a coding system |
US20040008772A1 (en) * | 2001-06-07 | 2004-01-15 | Masaaki Kojima | Camera-integrated video recording and reproducing apparatus, and record control method thereof |
JP2003219366A (en) * | 2002-01-18 | 2003-07-31 | Canon Inc | Image processing apparatus, image processings system, compression processing method, storage medium, and program |
US20050226526A1 (en) * | 2003-01-09 | 2005-10-13 | Sony Corporation | Image processing device and method |
Also Published As
Publication number | Publication date |
---|---|
WO2007055389A2 (en) | 2007-05-18 |
JP4794987B2 (en) | 2011-10-19 |
CN101305617B (en) | 2013-02-20 |
JP2007134880A (en) | 2007-05-31 |
US8229004B2 (en) | 2012-07-24 |
WO2007055389B1 (en) | 2008-02-07 |
CN101305617A (en) | 2008-11-12 |
EP1949705B1 (en) | 2014-06-04 |
EP1949705A2 (en) | 2008-07-30 |
US20090096883A1 (en) | 2009-04-16 |
WO2007055389A3 (en) | 2007-12-06 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8229004B2 (en) | Image signal processing apparatus with code amount control for inter-frame and intra-frame encoding | |
US8634458B2 (en) | Image processing apparatus | |
US7903733B2 (en) | Adaptive filtering to enhance video encoder performance | |
US8903222B2 (en) | Image reproducing apparatus, image reproducing method, image capturing apparatus, and control method therefor | |
US7023914B2 (en) | Video encoding apparatus and method | |
US8009963B2 (en) | Adaptive filtering to enhance video bit-rate control performance | |
US8611426B2 (en) | Image-sensing apparatus | |
US8102436B2 (en) | Image-capturing apparatus and method, recording apparatus and method, and reproducing apparatus and method | |
US20080317377A1 (en) | Image coding apparatus and image coding method | |
US8488681B2 (en) | Image capturing apparatus, control method therefor, program, and storage medium | |
JPH03267877A (en) | Picture coding method | |
KR20050074906A (en) | Method and apparatus for loop filtering | |
JPWO2009093472A1 (en) | Video compression device | |
US7606433B2 (en) | Encoding apparatus, encoding method, and storage medium | |
US20080187052A1 (en) | Video coding device, video recording device, video coding method, and video coding program | |
JP4643437B2 (en) | Information processing device | |
JP2007028598A (en) | Compression coding apparatus and compression coding method | |
JP2005295215A (en) | Moving image encoding device | |
JP2005175974A (en) | Imaging device | |
JP3202270B2 (en) | Video encoding device | |
JP4185413B2 (en) | Flicker reduction quantizer, flicker reduction quantization method, and program thereof | |
JP2001313906A (en) | Digital camera | |
US8340174B2 (en) | Image processing device and image processing method | |
KR0157467B1 (en) | Moving image encoding method and device | |
JP4612897B2 (en) | Image processing device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |