JP2002064790A - Image processor, its method program code and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To encode an area with high image quality more than other areas by focusing on the area, when a user designates the area to be compressed with high image quality and to encode an automatic exposure evaluation value capturing area more than other areas, without the need for troublesome operations. SOLUTION: When a ROI(region of interest) is set in advance, an AE evaluation value capturing area is set to be a high image quality area (S1704), and when it is not set, the AE evaluation value capturing area is set in the middle of an image (S1703). Then an AE evaluation value is obtained from the captured AE evaluation value capturing area (S1705). When the AE evaluation value is greater than a prescribed reference value (S1706), an aperture diameter is selected small (S1707), and when the AE evaluation value is smaller than the prescribed reference value, the aperture diameter is selected larger (S1708). Then a display signal is generated (S1709) and displayed on a monitor 18 (S1710).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing apparatus for encoding image data, a program code for the method, and a storage medium.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram of a conventional video camera.

A zoom lens 11 enlarges or reduces an image.
12 is a focus lens for focusing an image, 13 is a CCD for photoelectrically converting the image, 14 is an A / D converter for changing an analog signal from the CCD 13 to a digital signal, and 15 is a camera signal processing circuit for adjusting a captured image. , 16 a buffer memory for temporarily storing image data, 17 a D / A converter for converting a digital signal into an analog signal, 1
Reference numeral 8 denotes a monitor that displays a captured image, 19a denotes a focus motor that moves the focus lens 12, 19b denotes a focus motor driver that drives the focus motor 19a, 20a denotes a zoom motor that moves the zoom lens 11, and 20b denotes a zoom motor 20a. A zoom motor driver to be driven; 22, a system controller for controlling each circuit; 23, a compression circuit for compressing image data;
24, a recording circuit for recording the compressed image data;
Is an AF evaluation value generation circuit that generates an AF evaluation value described later;
Reference numeral 26 denotes an AF evaluation value capturing area control circuit that performs processing described later based on the AF evaluation value.

Light from a subject passes through a zoom lens 11 and a focus lens 12 and forms an image on an imaging surface of a CCD 13. The image on the imaging surface is photoelectrically converted by the CCD 13 and converted into a digital signal by the A / D converter 14.
The image quality is adjusted by the camera signal processing circuit 15. The adjusted image data is stored in the buffer memory 16.

[0005] The system controller 22 also performs an auto focus (hereinafter, AF) control operation. In today's video cameras, so-called TV-AF AF is generally used. This utilizes the fact that the high-frequency component of the video signal increases as the focus becomes higher. Note that the AF evaluation value is an evaluation value calculated so as to increase as this focus comes into focus.

A predetermined area (AF evaluation value capture area) is extracted from the video signal obtained by the camera signal processing circuit 15 by an AF evaluation value capture area control circuit 26, and the extracted area is extracted. The image signal is input to the AF evaluation value generation circuit 25.

The AF evaluation value generation circuit 25 extracts a predetermined high frequency component from the input image signal. Then, the system controller 2 adjusts the high-frequency component to a maximum.
2 sends a signal to the focus motor driver 19b. In response to this signal, the focus motor driver 19b moves the focus lens 12 via the focus motor 19a to perform focus adjustment. Further, since the photographer often places the subject in the center of the screen, the AF evaluation value capturing area is set in the center of the normal screen.

The image data stored in the buffer memory 16 is converted into an analog signal by a D / A converter 17 and displayed on a monitor 18 such as a liquid crystal display (LCD).

On the other hand, the image signal stored in the buffer memory 16 is compressed by being subjected to a high-efficiency encoding process by a compression circuit 23, and the compressed image signal is stored in the recording circuit 2.
In step 4, it is recorded on a recording medium.

Next, a high-efficiency encoding process based on DCT (discrete cosine transform) used in a conventional digital video camera will be described with reference to a block diagram of FIG. 110, a block processing circuit for forming a DCT block; 111, a shuffling circuit for rearranging the blocked images; 112, a DCT processing circuit for performing orthogonal transformation; 113, a quantization processing circuit for quantizing image data; 114 is an encoding circuit using a Huffman code or the like;
Reference numeral 5 denotes a deshuffling circuit that restores the image data rearranged by the shuffling circuit 111, and reference numeral 116 denotes a coefficient setting circuit that determines a quantization coefficient.

The image signal output from the buffer memory 16 is divided by a block processing circuit 110 into blocks each consisting of 8 × 8 pixels. And the luminance signal is 4
And one color difference signal, each of which constitutes one macroblock from a total of six DCT blocks.
Shuffles in macroblock units. Then, after leveling the information amount, the information is output to a DCT (discrete cosine transform) processing circuit 112. The DCT processing circuit 112 performs orthogonal transform on the block and outputs frequency coefficient data. The frequency coefficient data output from the DCT processing circuit 112 is input to the quantization processing circuit 113. Then, the set of data coefficients for each frequency component is divided by an appropriate numerical value generated by the coefficient setting circuit 116. Then, the encoding circuit 114 performs Huffman encoding to make the length variable, and the deshuffling circuit 115 restores the original image arrangement to output to the recording circuit 24. In this way, the data amount is compressed to about one fifth.

FIG. 15 shows a functional configuration of a conventional video camera which performs AE (automatic exposure adjustment). The same parts as those in FIG. 10 are denoted by the same reference numerals, and description thereof will be omitted. 1
Reference numeral 501 denotes an aperture, 1502 denotes an AE evaluation value generation circuit including an integration circuit for obtaining an average value of the luminance level of the imaging signal in the side light region, and 1503 denotes an AE evaluation value for sampling the imaging signal in the side light region. This is a capture area control circuit. Reference numeral 1504a denotes an IG meter for controlling the aperture amount by driving the aperture 1501, and 1504b denotes an IG meter 150.
4a is an IG driver that drives 4a.

In the camera shown in FIG. 1, light from a subject passes through a zoom lens 11 and a focus lens 12, the exposure is adjusted by an aperture 1501, and an image is formed on an imaging surface of a CCD 13. A / A, like the camera shown in FIG.
The image data is stored in the buffer memory 16 via the D converter 14 and the camera signal processing circuit 15.

On the other hand, the system controller 22 of the camera shown in FIG. 15 performs an AE control operation. The system controller 22 controls the IG meter 1504a so that the output of the AE evaluation value generation circuit 1502 is constant, and performs the AE operation by moving the aperture 1501. The AE is a mechanism in which an imaging device such as a camera determines a shooting state “arbitrarily” and adjusts the aperture to a state that is suitable for the situation, so that the photographing intention of the photographer may not be reflected in the image. appear. For example, when the main subject is photographed with a bright sky as the background, if the AE operation is performed with the information of the entire screen, the aperture is adjusted according to the brightness of the sky, resulting in the main subject being blackened. In order to avoid such a situation as much as possible, it is general to employ a method of performing AE with emphasis on a subject located at the center of the imaging screen. This is based on the fact that the photographer often places the main subject at the center of the screen when shooting. This method has a disadvantage that when the main subject is placed at a place other than the center of the screen, the exposure may not be properly adjusted for the main subject.

The image data stored in the buffer memory 16 is displayed on the monitor 18 in the same manner as the camera shown in FIG.

On the other hand, the image signal stored in the buffer memory 16 is recorded on a recording medium in a recording circuit 24 in the same manner as in the camera shown in FIG.

[0017]

However, in the conventional video camera, since the image is leveled and compressed as a whole, if the encoding is performed with higher efficiency, the overall image quality may be reduced. .

In order to solve such a problem, even if the image quality of the background of the image is slightly lower than that of the others, the encoding can be more efficiently performed by processing only the main specific portion with high image quality.

In a video camera having an AF function, when a specific portion is designated and encoded as a high image quality area as shown in FIG. 8A, the AF evaluation value capturing area differs from the high image quality area. There is fear.

In a video camera having an AE function, a region to be encoded with high image quality and a region to be subjected to automatic exposure adjustment are not associated with each other. Capture area)
Is not optimal, the image quality may be degraded.

The present invention has been made in view of the above problems, and when a user designates an area to be compressed with high image quality, the area is focused on, and this area has a higher image quality than other areas. Is provided.

Further, the present invention provides a configuration for encoding an automatic exposure evaluation value capturing area with higher image quality than other areas without performing a troublesome operation.

[0023]

In order to achieve the object of the present invention, for example, an image processing apparatus of the present invention has the following arrangement.

That is, an image processing apparatus for encoding image data, comprising: first designating means for designating a predetermined area in the image data;
A second designating means for the user to designate a desired area, wherein when the desired area is designated by the second designating means, the desired area is designated; If not, the predetermined area specified by the first specifying means is encoded as a high-quality area which is an area to be encoded with higher image quality than other areas.

In the case where a desired area is specified by the second specifying means, the desired area is
If the desired area is not specified, the first
And focus control means for focusing on the predetermined area designated by the designation means.

The focus control means realizes the focus control by an autofocus function.

If a desired area is specified by the second specifying means, the desired area is
If the desired area is not specified, the first
And an exposure adjusting means for adjusting the exposure of the predetermined area designated by the designation means.

The exposure adjusting means realizes the control of the exposure adjustment by controlling the aperture.

[0029]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an image processing apparatus according to a preferred embodiment of the present invention;

[First Embodiment] The imaging apparatus according to the present embodiment has an AE (Automatic Exposure Adjustment) function, and executes the AE function on a designated area. Hereinafter, the imaging device according to the present embodiment will be described.

FIG. 1 is a schematic block diagram of the image pickup apparatus according to the present embodiment, which will be described.

Pixel signals constituting an image to be encoded are input to an image input unit 1 in a raster scan order, and the output is input to a discrete wavelet transform unit 2. In the following description, the image signal represents a monochrome multi-valued image. However, if a plurality of color components such as a color image are encoded, each of RGB color components or luminance, RY, BY, etc. The chromaticity components may be independently compressed as described above.

The discrete wavelet transform unit 2 performs a two-dimensional discrete wavelet transform process on the input image signal, and calculates and outputs a transform coefficient. FIG. 2A shows a basic configuration of the discrete wavelet transform unit 2.
The input image signal X is stored in the processing buffer memory 2a, and is sequentially read out by the processing unit 2b to perform a conversion process. Then, it is written into the processing buffer memory 2a again. Here, the configuration of the processing in the processing unit 2b will be described. When an instruction to read the image signal X is issued by the sequence control circuit 2e in the processing unit 2b, the image signal X is read into the processing unit 2b and separated into signals of even addresses and odd addresses by a combination of a delay element and a downsampler. , Two filters p and u
Performs a filtering process. FIGS. S and d show low-pass coefficients and high-pass coefficients when one-dimensional decomposition is performed on the one-dimensional image signal X, and are calculated by the following equations.

D (n) = x (2n + 1) -floor ((x (2n) + x (2n + 2)) / 2) (Equation 1) s (n) = x (2n) + floor (( d (n-1) + d (n)) / 4) (Equation 2) where X (n) is an image signal to be converted, and
or (x) is a function that returns the largest integer value that does not exceed x.

When a write instruction is issued by the sequence control circuit 2e, the low-pass coefficient s and the high-pass coefficient d that have undergone one-level decomposition are stored again in the processing buffer memory 2a. With the above processing, one-dimensional discrete wavelet transform processing is performed on the image signal.

FIG. 2B is a diagram showing a configuration of a two-dimensional discrete wavelet transform. In FIG. 2B, a two-dimensional discrete wavelet transform is performed by converting a one-dimensional transform into a horizontal
This is performed sequentially in the vertical direction. First, the input image data is subjected to wavelet transform processing in the horizontal direction, and is decomposed into low-pass coefficients and high-pass coefficients. The data is then decimated in half by downsizing (down arrow). Then, similar processing is performed in the vertical direction. FIG. 2C shows 2
This is a configuration example of a two-level transform coefficient group obtained by a two-dimensional discrete wavelet transform process, and an image signal includes coefficient sequences HH1, HL1, LH1, HH2, and H in different frequency bands.
It is decomposed into L2, LH2 and LL. In the following description, these coefficient sequences are called subbands. The coefficients of each subband are output to the subsequent quantization unit 3.

In FIG. 1, the region designating section 6 determines a region (ROI: region of interesting) to be coded with higher image quality than the surrounding portion in the image to be coded. Then, it generates mask information indicating which coefficients belong to the designated area when the target image is subjected to the discrete wavelet transform. FIG. 3A shows an example when generating mask information. As shown on the left side of the figure, a star-shaped region (ROI) is designated in the image by a predetermined instruction input, and when the image including the designated region is subjected to the discrete wavelet transform, the region designation unit 6 designates the designated region. Calculate the portion occupied by the sub-band in each sub-band.

An example of the mask information calculated in this way is shown on the right side of FIG. In this example, mask information when a two-level discrete wavelet transform is performed on the image on the left side of the figure is calculated as shown in the figure. In the figure, the stitch portion of the star shape is a designated area, and the bit of the mask information in this area is 1 and the bits of the other mask information are 0. Since the entire mask information is the same as the configuration of the transform coefficient by the two-dimensional discrete wavelet transform, it is possible to identify whether or not the coefficient at the corresponding position belongs to the designated area by inspecting the bits in the mask information. it can. The mask information generated in this way is output to the quantization unit 3.

Further, the area designating section 6 calculates the bit shift amount B for the coefficient in the designated area based on the parameter for designating the image quality for the designated area inputted by the input device (not shown), together with the above-mentioned mask information. Output to the quantization unit 3. This parameter may be a numerical value representing the compression ratio assigned to the designated area, or a numerical value representing the image quality.

The quantization unit 3 quantizes the coefficient input from the discrete wavelet transform unit 2 at a predetermined quantization step, and outputs an index for the quantized value. Here, the quantization is performed by the following equation.

Q = sign (c) floor (abs (c) / Δ) (Expression 3) sign (c) = 1; c> = 0 (Expression 4) sign (c) = − 1; c <0 (Expression 3) 5) Here, c is a coefficient to be quantized. In this embodiment, it is assumed that the value of Δ includes 1. In this case, no quantization is actually performed.

Next, the quantization section 3 changes the quantization index by the following equation based on the mask information and the shift amount B input from the area specifying section 6. Here, b of a
The power is expressed as a ＾ b.

Q = q * 2 ＾ B; m = 1 (Equation 6) q = q; m = 0 (Equation 7) Here, m is a value of a bit in the mask information corresponding to the position of the quantization index. is there. By the above processing, only the quantization index belonging to the area (ROI) specified by the area specifying unit 6 is shifted up by B bits.

FIGS. 3B and 3C show the change of the quantization index due to the shift up.
FIG. 3B shows a quantization index group of a certain subband. When the value of the mask in the shaded quantization index is 1 and the number of shifts B is 2, the quantization index after the shift is as shown in FIG. It should be noted that, as shown in FIG.
Is complemented. The quantization index group after the change is output to the entropy encoding unit 4 that follows.

The mask in the present embodiment should be used not only for the above-mentioned shift-up processing but also for accurately restoring the original image from the data obtained after the encoding by the entropy encoding unit 4. Plays a role, but is not limited to this. For example, assuming that the number B of upshifts is the same as the number of bits of each quantization index to be subjected to the bit shift processing (4 bits in FIG. 3),
Even if the mask information is not sent to the decoding side, the decoding side can easily determine the ROI and the rest, so that the original image can be accurately restored.

The entropy coding unit 4 decomposes the input quantization index into bit planes, performs binary arithmetic coding on a bit plane basis, and outputs a code stream. FIG. 4 is a diagram for explaining the operation of the entropy encoding unit 4. In this example, a non-zero quantization index is 3 in a region within a subband having a size of 4 × 4.
And has values of +13, -6, and +3, respectively. The entropy encoding unit 4 scans this area to find the maximum value M, and calculates the number of bits S required to represent the quantization index of the maximum value M by the following equation.

S = ceil (log2 (abs (M))) (Equation 8) Here, ceil (x) represents the smallest integer value of x or more. In the example shown in FIG. 4, since the maximum coefficient value is 13, the number of bits S is 4 from (Equation 8). Therefore, the 16 quantization indices in the sequence are processed in units of four bit planes as shown in FIG. First, the entropy coding unit 4 performs binary arithmetic coding on each bit of the most significant bit plane (represented by the MSB in the figure) and outputs it as a bit stream. Next, the bit plane is lowered by one level, and each bit in the bit plane is encoded in the same manner as described above until the target bit plane reaches the least significant bit plane (represented by LSB in the figure) and output to the code output unit 5. At this time, the code of each quantization index is entropy-encoded immediately after the first non-zero bit is detected in the bit plane scanning.

Note that the compression ratio of the entire image to be encoded can be controlled by changing the quantization step Δ. In the present embodiment, the lower bits of the bit plane to be encoded by the entropy encoding unit 4 are restricted (discarded) in accordance with a necessary compression rate. That is, not all the bit planes are coded, and the bits from the upper bit plane to the number of bit planes corresponding to the desired compression ratio are coded. When this function of limiting the lower bit plane is used, only bits corresponding to the designated area shown in FIG. 3 are included in the code string, that is, only the designated area is encoded at a low compression rate, It is possible to compress the image as a high quality image.

Next, a description will be given of a video camera as an image pickup apparatus using the above-mentioned encoding processing.

FIG. 5A is an external view of the video camera. FIG. 16 is a block diagram showing a functional configuration of the video camera, and FIG. 12B is a diagram showing a display example displayed on the monitor 18. As shown in FIG. Note that this video camera can capture a moving image and / or a still image. In FIG. 16, the same parts as those shown in FIG. 15 (circuits, etc.) are assigned the same numbers.

In FIG. 16, reference numeral 32 denotes an image (for example, an image of a frame surrounding the specified area, an image of a frame surrounding the specified area,
A display control circuit for generating an image of a cursor) and multiplexing it with the image data to generate a display signal; 33, an area detector for generating area information for an area specified by an area specifying lever 34; Area designation lever 38 for designating an arbitrary area (designated area) from the displayed image
Is an area designating lever detection circuit for detecting the pressed state of the area designating lever 34.

An image is captured using the video camera having the above configuration, and the captured result is displayed as image data.
Alternatively, processing until storage is described.

The light from the subject is scaled by the zoom lens 11, the scaled light is focused by the focus lens 12, and the focused light is photoelectrically converted by the CCD 13. The image data converted into the electric signal is output to the A / D converter 14 and converted into a digital signal. The image data converted into the digital signal is formed as a color image by the camera signal processing circuit 15, and the image quality such as gain and white balance is adjusted. Camera signal processing circuit 15
Is output to the buffer memory 16. The display control circuit 32 controls the buffer memory 1
A signal for display is generated using the image data stored in 6. Then, the display signal is output to the D / A converter 17, converted into an analog signal, and displayed on the monitor 18. Although the output of the buffer memory 16 has a sufficiently short delay time, data may be supplied to the display control circuit 32 before or during the buffer memory 16 in the case of trouble in shooting.

On the other hand, the image data stored in the buffer memory 16 is subjected to an encoding process by a compression circuit 23 to be compressed, and the compressed image data is recorded in a recording circuit 24 using a magnetic tape, an optical disk, a semiconductor memory or the like. .

Here, when an area (ROI) desired to be encoded with high image quality is designated (using the area designation lever 34) for the image displayed on the monitor 18, the area detection circuit 3
In 3, information on the designated area (area information)
Generate The area information includes, for example, a coordinate value and a size of the designated area with respect to the monitor 18. This area information is stored in the buffer memory 16. The image data and the area information stored in the buffer memory 16 are sent to the display control circuit 32, and a frame (or a cursor) indicating a designated area based on the area information is multiplexed with the image data.
Generate a display signal. The display signal in which the designated area is multiplexed with the image data is converted into an analog signal by the D / A converter 17 and displayed on the monitor 18.

FIG. 12B shows an image displayed on the monitor 18 as a result of the above processing. Reference numeral 1201 denotes a frame indicating a designated area based on the above-described area information. The image shown in FIG. 12B is an example of a display image after the high image quality area is specified by the area specifying lever 34, and is displayed so that the specified area and the non-designated area can be distinguished by the frame 1201.

On the other hand, the image data and the area information stored in the buffer memory 16 are sent to the compression circuit 23, and the image data is coded separately into a part to be compressed with high image quality and a part to be compressed normally based on the area information. It is processed and compressed, and recorded on a recording medium.

FIG. 6 shows a schematic configuration of the compression circuit 23.

Reference numeral 40 denotes a wavelet transform circuit for decomposing the input image data into sub-bands, and 41 generates mask information indicating which coefficient of each decomposed sub-band belongs to a designated area. An occupancy calculation circuit for calculating the ratio of the mask information, 42 is a bit shift amount calculation circuit for calculating the bit shift amount of the image data in the mask information, 43 is a quantization processing circuit for performing quantization, and 48 is a compression parameter. And a coefficient setting circuit for setting a coefficient for quantization; 44, an index changing circuit for changing a quantization index in accordance with the bit shift amount;
Is a bit plane decomposition circuit for decomposing a quantization index into bit planes, 46 is an encoding control circuit for controlling the number of bit planes recorded in the recording circuit 24, and 47 is a binary arithmetic coding for each bit plane. This is a binary arithmetic coding circuit for performing.

The compression and encoding processing performed in the compression circuit 23 having the above configuration will be described.

The image data stored in the buffer memory 16 is divided by the wavelet transform circuit 40 into each sub-band. The data of each divided sub-band is input to the occupancy calculating circuit 41, and mask information is generated.
Further, the occupancy of the mask information in each subband is calculated.

The bit shift amount calculation circuit 42 acquires a parameter for specifying the image quality for the specified area from the coefficient setting circuit 48. The parameter may be a numerical value representing a compression ratio to be assigned to the designated area or a numerical value representing image quality. From this parameter, the bit shift amount for the coefficient in the designated area is calculated and output to the quantization processing circuit 43 together with the mask information.

The quantization processing circuit 43 quantizes the coefficient based on a predetermined numerical value (for example, a quantization step) input from the coefficient setting circuit 48, and outputs an index for the quantized value. It also outputs the mask information and the bit shift amount described above.

The index change circuit 44 bit-shifts only the quantization index belonging to the specified area to the information by the above-mentioned bit shift amount based on the above-mentioned mask information. The quantization index thus changed is output to the subsequent bit plane decomposition circuit 45.

The bit plane decomposition circuit 45 decomposes the input quantization index into bit planes.

The encoding control circuit 46 calculates the number of bit planes for determining the data size of the entire compressed frame. That is, the lower bit plane to be discarded is determined.

The binary arithmetic coding circuit 47 performs binary arithmetic coding in order from the most significant bit plane and outputs it as a bit stream. Then, the data is output up to the bit plane calculated by the encoding control circuit 46.

Next, a method of designating a designated area as a high image quality area will be described with reference to FIGS. 5A, 5B and 7. FIG. 5A is a detailed view of the area designation lever 34, FIG. 5B is a detailed view of the area designation lever detection circuit 38, and FIG.
3 is an example of a display image. In FIG. 5A, 34a is an upper designation lever for giving an instruction to move the cursor upward, 34b is a right designation lever for giving an instruction to move the cursor rightward, and 34c is a lower designation lever for giving an instruction to move the cursor downward. The designated lever 34d is a left designated lever 34 for giving an instruction to move the cursor to the left.
"e" is a confirmation button for issuing an instruction for fixing the cursor position.

In FIG. 5B, Y + indicates the upper designated lever 3.
4a, an upper detection switch that receives the instruction of 4a and sends an instruction to move the cursor upward to the system controller 22;
Similarly, X + is a right detection switch that receives an instruction from the right instruction lever 34b and sends an instruction to move the cursor to the right to the system controller 22, and Y− is a downward instruction lever 3
4c, a down detection switch for receiving an instruction of 4c and sending an instruction to move a cursor downward to the system controller 22;
X- is a left detection switch that receives an instruction from the left designation lever 34d and sends an instruction to move the cursor to the left to the system controller 22;
This is a selection switch that receives the instruction of e and sends a determination instruction to the system controller 22. 3 of area designation lever 34
By operating the levers 4a, 34b, 34c and 34d and the confirmation button 34e, the cursor can be moved and the above-mentioned designated area can be designated.

A method of actually specifying the above-mentioned specified area will be described. Here, as an example, by specifying four vertices, an area surrounded by the vertices is set as a high-quality area (ROI).

When the selection switch 34e at the center of the area designation lever 34 is pressed, a cursor P0 for designating an area is displayed superimposed on the center of the monitor 18 as shown in FIG. The operator operates the area designation lever 34 in the direction in which the cursor P0 is to be moved while looking at the cursor P0 displayed on the monitor 18. The area designation lever detection circuit 38 detects the pressed state of the area designation lever 34, and the system controller 22 calculates the amount of movement of the cursor based on the detection result by the area designation lever detection circuit 38. Then, the cursor P0 is moved to the calculated position. Here, when the selection button 34e of the area designation lever 34 is pressed, one of the vertices forming the high image quality area is determined. Similarly, to determine the next vertex, the user moves the cursor by operating the area designation lever 34. By repeating this operation, four vertices can be selected as shown in FIG. Then, by pressing the confirm button 34e, the four vertices 1, P2, and P4 selected as shown in FIG.
The area connected by P3 and P4 is designated as a high image quality area.

FIG. 14 is a flowchart of the above process. The program code according to this flowchart is stored in the system controller 22 or R (not shown).
It is stored in a memory such as an OM, and is read and executed by a CPU (not shown).

In step S1401, in accordance with a cursor movement instruction from the area designation lever 34, an operation relating to cursor movement (as described above, the cursor movement amount, etc.)
Is performed, and as a result of this calculation, the cursor is moved.

In step S1402, the enter button 34
It is determined whether or not e is pressed. That is, it is determined whether or not a vertex is set at the position of the cursor at this point.
If the confirm button 34e is pressed (in the case of confirmation), the process proceeds to step S1403, and one vertex is set at the cursor position at this point as described above. On the other hand, if the confirm button 34e has not been pressed (if not confirmed), the process shifts to step S1401 to perform cursor movement processing.

Next, in step S1404, it is determined whether the number of set vertices is four. Then, if four vertices are set at this point, the processing according to this flowchart ends. After that, an area surrounded by these four vertices is set as a high image quality area. On the other hand, if the set number of vertices is less than 4, step S1401
Then, the process of setting vertices is performed again.

Here, the number of vertices to be determined in step S1404 is set to 4 because the high image quality area is square, but the number of vertices to be determined in step S1404 is set when the high image quality area is hexagonal, for example. Is 6
Becomes The image included in the high image quality area may be visually recognized by changing the color and brightness.

As described above, the high image quality area is designated by selecting the four vertices. In addition to this, the motion information, edge components, It is also possible to specify a specific object or person using the color component. As a method of specifying a more detailed high image quality area, a touch panel may be overlaid on the monitor 18 and the touch panel may be specified by pointing with a finger or the like.

Next, the AE evaluation value generation circuit 1502 will be described. Among the video signals generated by the camera signal processing circuit 15, the AE evaluation value capturing area control circuit 1503
As a result, only the video signal in a predetermined area in the screen enters the AE evaluation value generation circuit 1502. The AE evaluation value capturing area is set by the system controller 22, but since the photographer often places the subject to be photographed in the center of the screen,
Initially, it is set in the center of the screen. However, when the photographer subsequently specifies the high image quality area, the system controller 22 controls the AE evaluation value acquisition area control circuit 1503 so that the high image quality area becomes the AE evaluation value acquisition area. The AE evaluation value generation circuit 1502 is configured by an integrator for calculating an average value of the luminance level of the video signal (this average value is used as the AE evaluation value in the present embodiment). The system controller 22 changes the aperture diameter of the diaphragm 19 while monitoring the increase or decrease of the AE evaluation value so as to keep the generated AE evaluation value at a predetermined reference value.

Next, the AE operation of the imaging apparatus according to the present embodiment will be described with reference to the flowchart of the same processing shown in FIG. The program code according to the flowchart is stored in a memory such as a ROM (not shown) stored in the system controller 22, and is read and executed by a CPU (not shown). These processes are performed in the system controller 22.

First, it is determined whether or not a high image quality area (ROI) has been set (step S1702). If it has been set, the process moves to step S1703,
The AE evaluation value capturing area is set as a high image quality area (step S1704). On the other hand, if it is not set, the process moves to step S1702, and the AE evaluation value capturing area is set at the center of the screen (step S1703).

Then, the above average value is obtained from the AE evaluation value fetched area, and fetched as the AE evaluation value (step S1705).

Next, the acquired AE evaluation value is compared with, for example, a predetermined reference value stored in a memory in the system controller 22 (step S1706). In this step, the magnitude relationship between the fetched AE evaluation value and a predetermined reference value is compared. In this step, if the AE evaluation value is larger than the predetermined reference value, the luminance level in the AE evaluation value capturing area is higher than the predetermined reference value (too bright), and thus the aperture 1501 is controlled via the IG driver 1504b. To reduce the opening diameter (step S170).
7). On the other hand, when the AE evaluation value is smaller than the predetermined reference value, the luminance level in the AE evaluation value capturing area is smaller than the predetermined reference value (too dark), so that the aperture 1501 is set to I
Control is performed via the G driver 1504b to increase the aperture diameter (step S1708).

Then, a display signal in which the high image quality area and the non-high image quality area are multiplexed is generated (step S1709), and the generated display signal is displayed on the monitor 18 (step S1710).

On the other hand, the compression circuit 23 is controlled so as to perform different encoding on the high-quality area and the non-high-quality area, respectively, and a recording signal is generated (step S1711). Then, the recording signal is recorded in the recording circuit 24 (step S1712).

As described above, even when the background of an image has a slightly lower image quality than others, only a main specific portion is processed with high image quality and encoding is performed more efficiently. In a video camera having an automatic exposure function, There is a possibility that the high image quality area differs from the automatic exposure evaluation value capturing area. Therefore, in particular, for a product such as a digital video camera for home use that regularly uses the automatic exposure function, a specific portion is set to be the same as the automatic exposure evaluation value capturing area. In the present embodiment, the automatic exposure evaluation value capturing area and the high image quality area are the same. However, the automatic exposure evaluation value capturing area may be included in the high image quality area, or the high image quality area and the automatic exposure evaluation value capturing area may be included. It is clear that improvement can be expected even with the same center.

As described above, according to the imaging apparatus of the present embodiment, a specific portion can be compressed with higher image quality than other regions.
By setting the automatic exposure evaluation value capturing area to be the same as the specific area, it is possible to encode a specific part with higher exposure and higher quality than other parts without performing a troublesome operation.

[Second Embodiment] The imaging apparatus according to the present embodiment has an AF (autofocus) function.
Execute the AF function for the specified area. Hereinafter, the imaging device according to the present embodiment will be described.

Note that the schematic configuration of the image pickup apparatus according to the present embodiment is the same as that described in the first embodiment (FIG. 1). The encoding process performed by the imaging apparatus according to the present embodiment is the same as the encoding process described in the first embodiment.

Next, a video camera as an image pickup device according to the present embodiment will be described. FIG. 12A is a block diagram illustrating a functional configuration of the video camera according to the present embodiment. The same parts as those shown in FIG. 16 (circuits and the like) are assigned the same numbers.

The difference between the video camera of the present embodiment and the video camera of the first embodiment shown in FIG. 16 is that the AE evaluation value generation circuit 1502 and the AE evaluation value taking-in area control circuit 1503 each have an AF evaluation value. A point of change to the generation circuit 25 and the AF evaluation value capturing area control circuit 26 and a mechanism (19a, 19b, 20a) for controlling the zoom lens 11 and the focus 12 instead of the mechanism (1504a, 1504b) for controlling the aperture 1501 , 20b). In this embodiment, the aperture 1501 and the function of controlling the aperture 1501 (19a, 19b, 20a, 20b) are also provided.
May be newly added, or a mechanism (19a, 19b, 20a, 20b) for controlling the zoom lens 11 and the focus 12 may be added to the video camera of the first embodiment.

In the image pickup apparatus according to the present embodiment, a method for specifying a high image quality area is performed using the area specifying lever 34 as in the first embodiment.

Next, the AF evaluation value generation circuit 25 will be described. Of the video signals generated by the camera signal processing circuit 15, only the video signal of a predetermined area (AF evaluation value capture area) in the screen is input to the AF evaluation value generation circuit 25 by the AF evaluation value capture area control circuit 26. . The AF evaluation value capturing area is set by the system controller 22, but the subject that the photographer wants to photograph is often set at the center of the screen, so that it is generally set at the center of the screen. The AF evaluation value generation circuit 25 is configured by a band-pass filter that extracts a predetermined high-frequency component. The AF evaluation value generated in this way is shown in FIG.
As shown in the graph shown in FIG. 3, the focus becomes larger as the focus becomes higher, and the focus (focus lens position) at which the AF evaluation value becomes the maximum is the focal point. The system controller 22 moves the focus lens 12, monitors the increase or decrease of the AF evaluation value, and controls the focus motor driver 19b so that the AF evaluation value increases. Finally, the focus lens 1 is set so that the AF evaluation value takes a peak value.
Move 2 It is assumed that the data of the graph shown in FIG. 13 (for example, a data structure in a table format listing the correspondence between the AF evaluation value and the focus lens position) is stored in a memory (not shown).

FIG. 9 shows a flowchart of the various control processes described above by the system controller 22. Note that the program code according to this flowchart is stored in the R (not shown) stored in the system controller 22.
It is stored in a memory such as an OM, and is read and executed by a CPU (not shown).

In step S102, it is determined whether or not a high quality area (ROI) has been set in advance for the captured image. If not set, the process proceeds to step S103, and the AF evaluation value capturing area is set at the center of the screen. On the other hand, if it is set, step S1
The process shifts to 04, and the AF evaluation value capturing area is set at the same position as the ROI as shown in FIG. This determination process (the process in step S102) is performed by the system controller 22. Then, the AF evaluation value capturing area determined by the above processing is set in the AF evaluation value capturing area control circuit 26. Thereafter, the AF evaluation value capturing area control circuit 2 is controlled so that only the video signal included in the set area is processed by the AF evaluation value generation circuit 25.

Next, in step S105, the AF evaluation value is fetched from the AF evaluation value generation circuit 25.

In step S106, the past A stored in the RAM (not shown) in the system controller 22 is stored.
The F evaluation value is compared with the AF evaluation value captured in step S105. If the AF evaluation value captured in step S105 is larger than the past AF evaluation value, the focus lens 12 currently moved
Is the correct direction (the direction of the focal point), the process directly proceeds to step S108.

On the other hand, step S is larger than the past AF evaluation value.
If the acquired AF evaluation value is decreased in 105, the direction of the focus lens 12 currently being moved is wrong (away from the focal point), so the processing shifts to step S107 and the focus lens 12 Reverse the direction of movement.

In step S108, step S
As used in step 106, the current AF evaluation value is stored in the system controller 22 in the R (not shown) in preparation for the next processing.
Save to AM.

The processing from step S109 to step S112 is performed from step S1709 to step S171.
Since the processing is the same as the processing up to 2, the description is omitted here.

By executing the above processing, it is possible to encode only a specified area (for example, the background of an image) with higher image quality than an unspecified area. As a result, the size of the encoded data can be reduced as compared with encoding the entire image with high image quality.

In a video camera having an AF function, when a specific portion is designated as a high-quality area and coding is performed, there is a possibility that the AF evaluation value capturing area and the high-quality area may be different. Therefore, in the video camera according to the present embodiment, the specific portion as the high image quality region is set to be the same as the AF evaluation value capturing region. However, besides, it is obvious that the improvement can be expected also by including the AF evaluation value capturing area in the high image quality area or making the center of the high image quality area and the AF evaluation value capturing area the same.

Also, an area compressed with higher image quality than other areas has a low compression ratio and therefore contains many high-frequency components.
Becomes sensitive to movement of focus. For this reason, it is necessary to make the above-described specific portion the same as the AF evaluation value capturing area.

As described above, according to the imaging apparatus of the present embodiment, the specific portion can be compressed with higher image quality than the other regions, and the AF evaluation value capturing region is made the same as the specific region, so that the specific portion can be compared with the other portions. Encoding can be performed with high image quality in a focused state.

[Other Embodiments] Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus (one device) For example, the present invention may be applied to a copying machine, a facsimile machine, and the like.

Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and a computer (a computer) of the system or the apparatus. Or a CPU or MPU) reads out and executes the program code stored in the storage medium,
Needless to say, this is achieved. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.
In addition, by the computer executing the readout program code, not only the functions of the above-described embodiments are realized, but also based on the instructions of the program code,
The operating system (OS) running on the computer performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
It goes without saying that a case where the function of the above-described embodiment is realized by the processing is also included.

When the present invention is applied to the storage medium, the storage medium has the contents described above (FIG. 9 and / or FIG. 1).
4, and / or the program code corresponding to the flowchart (shown in FIG. 17).

[0108]

As described above, according to the present invention, when the user specifies an area to be compressed with high image quality, the area is focused and this area is coded with higher image quality than the other areas. It can be performed. Further, the automatic exposure evaluation value capturing area can be encoded more effectively than other areas without performing a troublesome operation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an imaging device according to first and second embodiments of the present invention.

FIG. 2A is a diagram showing a basic configuration of a discrete wavelet transform unit 2;

FIG. 2B is a diagram showing a configuration of a two-dimensional discrete wavelet transform.

FIG. 2C is a diagram showing a configuration example of a two-level transform coefficient group obtained by a two-dimensional discrete wavelet transform process.

FIG. 3 is a diagram illustrating an example when mask information is generated and a change in a quantization index.

FIG. 4 is a diagram illustrating an operation of an entropy encoding unit 4.

FIG. 5A is a diagram illustrating the appearance of a video camera and details of an area designation lever according to the first and second embodiments of the present invention.

FIG. 5B is a detailed diagram of an area designation lever detection circuit 38;

FIG. 6 is a diagram showing a schematic configuration diagram of a compression circuit 23;

FIG. 7 is a diagram illustrating an example of an image displayed on a monitor 18 when a designated area is designated.

FIG. 8 is a diagram illustrating setting of a high image quality area.

FIG. 9 is a flowchart of a process performed by the system controller 22.

FIG. 10 is a configuration diagram of a conventional video camera.

FIG. 11 is a block diagram showing a high-efficiency encoding process based on DCT (Discrete Cosine Transform) used in a conventional digital video camera.

FIG. 12A is a block diagram illustrating a functional configuration of a video camera according to a second embodiment of the present invention.

FIG. 12B is a diagram showing a display example displayed on the monitor 18.

FIG. 13 is a diagram illustrating a relationship between a focus lens position and an AF evaluation value.

FIG. 14 is a flowchart of a process for specifying a specified area.

FIG. 15 is a diagram showing a functional configuration of a conventional video camera that performs AE.

FIG. 16 is a diagram illustrating a functional configuration of an imaging device according to the first embodiment of the present invention.

FIG. 17 is a flowchart of a process of an AE operation in the first embodiment of the present invention.

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Claims (16)

[Claims] 1. An image processing apparatus for encoding image data, comprising: a first designation unit for designating a predetermined region in the image data; and a user designating a desired region in the image data. And a second specifying unit for specifying the desired region when the desired region is specified by the second specifying unit, and the second unit when the desired region is not specified. The image processing apparatus according to claim 1, wherein the predetermined area specified by the first specifying unit is encoded as a high image quality area which is an area to be encoded with higher image quality than other areas. 2. The image processing apparatus according to claim 1, wherein the first specifying unit specifies the predetermined area near a center of an image. 3. The image processing apparatus according to claim 1, wherein the second specifying unit specifies each vertex constituting the desired area when specifying the desired area. 4. When the desired area is specified by the second specifying means, the first specifying means is used for the desired area when the desired area is not specified. The image processing apparatus according to any one of claims 1 to 3, further comprising a focus control unit that focuses on the predetermined area specified in (1). 5. The image processing apparatus according to claim 4, wherein said focus control means realizes control of said focus by an autofocus function. 6. When the desired area is specified by the second specifying means, the first specifying means is used for the desired area when the desired area is not specified. The image processing apparatus according to any one of claims 1 to 3, further comprising an exposure adjusting unit configured to adjust exposure of the predetermined area specified by (1). 7. The image processing apparatus according to claim 6, wherein the exposure adjustment unit realizes the control of the exposure adjustment by controlling an aperture. 8. An image processing method for encoding image data, comprising: a first designation step of designating a predetermined area in the image data; and a user designating a desired area in the image data. And a second specifying step for performing the setting. If the desired area is specified in the second specifying step, the desired area is specified. If the desired area is not specified, the An image processing method, wherein the predetermined area specified in the first specifying step is coded as a high-quality area which is a region to be coded with higher image quality than other areas. 9. The image processing method according to claim 8, wherein in the first specifying step, the predetermined area is specified near a center of an image. 10. The image processing method according to claim 8, wherein in the second specifying step, when the desired area is specified, each vertex constituting the desired area is specified. 11. When the desired area is specified in the second specifying step, the first specifying step is performed for the desired area when the desired area is not specified. The image processing method according to any one of claims 8 to 10, further comprising a focus control step of focusing on the predetermined area designated by (1). 12. The image processing method according to claim 11, wherein in the focus control step, the focus control is realized by an autofocus function. 13. When the desired area is specified in the second specifying step, the first specifying step is performed for the desired area when the desired area is not specified. 9. The method according to claim 8, further comprising an exposure adjusting step of adjusting an exposure of the predetermined area specified by the following.
11. The image processing method according to any one of claims 10 to 10. 14. The image processing method according to claim 13, wherein, in the exposure adjusting step, the control of the exposure adjustment is realized by controlling an aperture. 15. A program code for executing the image processing method according to claim 8 on a computer. 16. A computer-readable storage medium storing the program code according to claim 15.