JP2002077798A - Apparatus and method for processing moving image as well as recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the calculating amount required to correct a moving image. SOLUTION: An apparatus for processing the moving image comprises an encoding unit 100 for encoding the moving image including a correcting unit 122 between an arithmetic unit 102 and a DCT unit 103, and a deciding unit 123 and a correcting data generator 124 provided between a movement compensating unit 116 and the unit 122. The image of a frame is divided into a plurality of blocks by a dividing unit 101, and a differential block between the block of the image and a predicting block is obtained by a subtractor 102. The unit 123 confirms whether a mean value of pixel values of the differential block falls within a predetermined range or not, and decides that correction of the differential block is needed if it is out of the range. In this case, the generator 124 generates correction data based on the predicted block from the unit 116, and the unit 122 corrects the differential block. Thus, only if the correction is needed, the correction data is generated and the correction is conducted. Reduction is a calculating amount required for the correction is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for correcting various image characteristics such as gradation, hue, and saturation of a moving image acquired as digital data.

[0002]

2. Description of the Related Art As one method of correcting a moving image, a method of correcting the image by treating each frame image of the moving image as a still image is considered. For example, an ideal correction is realized by applying a known correction method such as an adaptive histogram equalization method to an image of each frame constituting a moving image.

[0003] Also, Japanese Patent Application Laid-Open No. 9-65252 discloses that
Divide the image of each frame of the moving image into multiple blocks,
A technique is described in which a correction curve is selected based on the average luminance level of each block, and a moving image is corrected using the selected correction curve.

[0004]

When the image of each frame of a moving image is treated as a still image and a known correction method is applied to the still image, the amount of calculation for each image increases. Therefore, in order to correct a moving image in real time, it is necessary to develop an expensive device, which is hardly practical.

Further, in the apparatus described in Japanese Patent Application Laid-Open No. 9-65252, it is necessary to select a correction curve and perform correction processing on all blocks even when there is almost no difference between frames. In order to correct a moving image in real time, an expensive device needs to be developed.

In order to realize the correction of a moving image at low cost without using an expensive device, it is essential to reduce the amount of calculation required for the correction as much as possible. of course,
Even when a moving image is temporarily recorded in a recording device and the moving image is corrected without obtaining real-time properties, a reduction in the amount of calculation required for the correction is required to perform the correction as quickly as possible.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the amount of calculation required for correcting a moving image.

[0008]

According to a first aspect of the present invention, there is provided a moving image processing apparatus, wherein a difference between a predicted image derived from an image of a frame preceding a current frame and an image corresponding to the current frame is provided. Means for acquiring an image; and means for determining whether correction of the difference image is necessary based on the difference image.

According to a second aspect of the present invention, there is provided the moving image processing apparatus according to the first aspect, wherein the moving image processing apparatus is used for correcting the difference image when the determination unit determines that correction is necessary. Means for generating correction data.

According to a third aspect of the present invention, in the moving image processing apparatus according to the second aspect, the means for generating the correction data generates the correction data based on the predicted image.

According to a fourth aspect of the present invention, there is provided the moving image processing apparatus according to the third aspect, wherein: a means for storing a plurality of correction tables used for generating the correction data; Means for selecting one correction table from the plurality of correction tables, and the means for generating the correction data generates the correction data with reference to the selected correction table.

According to a fifth aspect of the present invention, there is provided the moving image processing apparatus according to any one of the first to fourth aspects, further comprising a means for correcting the difference image in accordance with a result of the determination by the determining means.

According to a sixth aspect of the present invention, in the moving picture processing apparatus according to any one of the first to fifth aspects, the predicted image is obtained by performing motion compensation on an image corresponding to a previous frame. It is an image.

According to a seventh aspect of the present invention, in the moving image processing apparatus according to any one of the first to sixth aspects, the apparatus further comprises means for dividing an image of each frame into a plurality of partial images, Means for determining whether correction is necessary for each difference image corresponding to each of the plurality of partial images.

The invention according to claim 8 is a moving image processing apparatus, comprising: means for acquiring a difference image between a predicted image derived from an image of a frame preceding the current frame and an image corresponding to the current frame. Means for determining whether or not it is necessary to update correction data used for correcting a moving image based on the difference image.

According to a ninth aspect of the present invention, there is provided the moving image processing apparatus according to the eighth aspect, further comprising means for correcting a moving image according to the correction data.

According to a tenth aspect of the present invention, in the moving image processing apparatus according to any one of the first to ninth aspects, the difference image is obtained when encoding or decoding a moving image. .

According to an eleventh aspect of the present invention, there is provided a moving image processing method, comprising: obtaining a difference image between a predicted image derived from an image of a frame preceding the current frame and an image corresponding to the current frame. Determining the necessity of correction of the difference image based on the difference image.

According to a twelfth aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a program for causing a computer to execute moving image correction, wherein the computer executes the program by causing the computer to execute a current frame. Executing a step of obtaining a difference image between a predicted image derived from an image of a previous frame and an image corresponding to the current frame, and a step of determining whether correction of the difference image is necessary based on the difference image Let it.

According to a thirteenth aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a program for causing a computer to execute a moving image correction, wherein the execution of the program by the computer causes the computer to execute a current frame. Obtaining a difference image between a predicted image derived from an image of a previous frame and an image corresponding to the current frame, and determining whether to update correction data used for correcting a moving image based on the difference image. And a determining step.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <1. First Embodiment> FIG.
1 is a diagram illustrating a configuration of an image processing system 1 that acquires, corrects, and reproduces a moving image. An image processing system 1 includes a video camera 1 that acquires a moving image as digital data.
0, a reproducing apparatus 20 that receives a moving image acquired by the video camera 10 via a recording medium 91 such as a magnetic tape and reproduces the moving image, and a display 30 that displays the reproduced moving image.

FIG. 2 is a block diagram showing a main configuration relating to processing of a moving image in the image processing system 1. As shown in FIG. The image processing system 1 includes an encoding unit 100 and a decoding unit 200. A moving image acquired by the video camera 10 is input to the encoding unit 100 as input image data 8.
Entered as 1. The input image data 81 is encoded (that is, compressed) in the encoding unit 100, and encoded data 82 is output. Encoded data 82
Are input to the decoding unit 200 at the time of reproduction, decoded (that is, decompressed), and output as output image data 83.

Although the encoding unit 100 and the decoding unit 200 may be provided only in either the video camera 10 or the playback device 20 as described later, in the following description, the video camera 10
In the following description, the playback device 20 includes the decoding unit 200.

FIG. 3 is a block diagram showing the configuration of the encoding unit 100. Hereinafter, each configuration of the encoding unit 100 will be described.

The dividing section 101 divides an image of each frame of a moving image input as the input image data 81 into a plurality of partial images (hereinafter, referred to as “blocks”). For example, a raster scan image is converted into a block scan image in units of 8 × 8 pixel blocks.

The subtraction unit 102 generates a difference image (hereinafter, referred to as a “difference block”) between a block of the image from the division unit 101 and a block of a prediction image (hereinafter, referred to as a “prediction block”) from the motion compensation unit 116 described later. ").

The difference block output from the subtraction unit 102 is corrected via a delay unit 121 and a correction unit 122 (the details of which will be described later), and the DCT unit 10
3 is input. The DCT unit 103 performs DCT (Discrete Cosine Transform) on the corrected difference block, and converts a signal in the time domain into a DCT coefficient in the frequency domain.

The quantizing section 104 quantizes the DCT coefficient from the DCT section 103, and the encoding section 105 performs variable-length encoding on the quantized DCT coefficient, and sequentially outputs the encoded data as encoded data 82.

The DCT coefficient from the quantization unit 104 is also input to the inverse quantization unit 111, and the inverse quantization unit 111
The DCT coefficient is restored. The inverse DCT unit 112
Generate a difference block from the coefficients.

The restored difference block and the prediction block from the motion compensator 116 are input to the adder 113, and the adder 113 adds these blocks. Thereby, a block of the image (that is, decoded data) on which the correction by the correction unit 122 is reflected is generated. Thereafter, the blocks of the generated image are stored in the frame memory 114.

The frame memory 114 functions as a delay unit for one frame, and sequentially outputs the corrected block of the previous frame image while sequentially storing the corrected block of the current frame image.

The motion vector detecting section 115 includes the dividing section 1
The block of the image of the current frame from 01 and the block of the image after the correction of the previous frame from the frame memory 114 are input. The motion vector detection unit 115 detects a motion vector 85 indicating the motion of the subject from these blocks. Although not shown in FIG. 2, the motion vector 8
5 (data thereof) is the recording medium 9 together with the encoded data 82.
1 to the decoding unit 200.

The motion compensator 116 predicts a block of an image of the current frame using the motion vector 85 from the motion vector detector 115 and a block of an image after correction of the previous frame from the frame memory 114. Accordingly, the motion compensation unit 116 generates a prediction block. Then, the prediction block includes the subtraction unit 102 and the addition unit 1
13 and the correction data generation unit 124.

The configuration described above is almost the same as the configuration in normal moving image compression. Next, the delay unit 1 which is a configuration related to moving image correction in the encoding unit 100
21, the correction unit 122, the determination unit 123, and the correction data generation unit 124 will be described.

The delay section 121 is a section for storing and delaying data for one block. Thus, when correction data to be described later is input to the correction unit 122, a difference block to be corrected can be input to the correction unit 122.

The correction unit 122 performs correction on the difference block, thereby substantially performing tone correction on the decoded image.

The determination unit 123 determines whether or not the difference block needs correction based on the difference block and the correction parameter 84 input separately. Note that the correction parameter 84 is stored in a memory in advance, for example, set by an operator using the operation unit of the video camera 10.

The correction data generation unit 124 includes a judgment unit 123
The correction data for correction is generated in accordance with the result of the determination. The correction data is generated based on the prediction block from the motion compensation unit 116. Note that, as described later, the determination unit 1
When it is determined that the correction is unnecessary in 23, the generation of the correction data in the correction data generation unit 124 and the correction by the correction unit 122 are not substantially performed.

As described above, the encoding unit 100
As in the case of a moving image encoding method such as PEG, a motion vector for each block is detected, and a difference block from a motion-compensated adjacent frame is obtained, and then variable-length encoding such as Huffman encoding is performed. ing. Then, the encoding unit 100 determines whether correction is necessary for the difference block based on the difference block. In general, both corresponding blocks of adjacent frames have high correlation, and the input image block and the block after motion compensation have higher correlation, so that the encoding unit 100 performs correction based on the difference block. By determining the necessity, the amount of calculation required for correction is reduced.

FIG. 4 is a block diagram showing a configuration of a decoding unit 200 for decoding the encoded data 82 and generating the output image data 83. The decoding unit 200
It has the same configuration as a normal decoding device.

The decoding section 201 performs variable-length decoding on the input coded data 82 to obtain quantized DCT coefficients. The inverse quantization unit 202 obtains an original DCT coefficient from the quantized DCT coefficient. And the inverse DCT section 203
As a result, a difference block is obtained from the DCT coefficients.

The adder 204 receives the difference block and the prediction block of the current frame from the motion compensator 207, and adds these blocks to generate an image block of the current frame.

The generated blocks are sequentially input to the synthesizing unit 205 and synthesized, and a block scan image in units of blocks is converted into a raster scan corrected image. Then, the generated corrected image is output as output image data 83.

On the other hand, the block generated by the adder 204 is also stored in the frame memory 206, and is used by the motion compensator 207 to generate a prediction block when generating an image of the next frame. As described above, the motion vector 85 is input to the decoding unit 200 together with the encoded data 82, and is used when the motion compensation unit 207 performs motion compensation.

Next, the flow of processing related to correction in the encoding unit 100 will be described.

FIG. 5 is a diagram showing the flow of processing in the judgment section 123. In the determination unit 123, first, the subtraction unit 102
(Step S11). Note that the processing for the pixel value is, to be precise, a value derived from the pixel value (gradation in this embodiment)
However, in the following description, the process will be described simply as a process for a pixel value.

Subsequently, the average value is compared with a range indicated by a preset correction parameter 84 (step S1).
2). If the average value is within the range indicated by the correction parameter 84, the determination unit 123 outputs “0” as the determination value to the correction data generation unit 124 (step S13). Is output (step S1
4).

FIG. 6 is a block diagram showing the configuration of the correction data generator 124 to which the judgment value is input, and FIG. 7 is a diagram showing the flow of processing in the correction data generator 124.

The correction data generation unit 124 includes the motion compensation unit 1
16 (predicted image data 84
2) an average value calculation unit 1241 for calculating an average value of pixel values;
A table selector 1242 for selecting a correction table, and a memory 124 for storing a plurality of representative correction tables 844
3, a coefficient generation unit 1244 for obtaining a correction coefficient which is an element of the correction data 843, and a delay unit 1245 for delaying one block. The correction coefficient is a value used for pixel value conversion for the difference block. Note that memory 1
243 may be provided outside the correction data generation unit 124.

The judgment value, which is the judgment result 841 from the judgment unit 123, is input to the average value calculation unit 1241, and it is first checked whether the judgment value is "1" (step S2).
1) If the judgment value is “1”, the average value calculation unit 1
241 calculates the average value of the pixel values in the prediction block (step S22).

Next, based on the average value, the table selection unit 1
Reference numeral 242 denotes a plurality of correction tables 84 in the memory 1243.
4 is selected (step S23).

FIG. 8 is a diagram for explaining the operation of selecting a correction table. A curve denoted by reference numeral 51 in FIG. 8 indicates the characteristics of the correction table. The horizontal axis corresponds to the pixel value in the prediction block, and the slope K of the curve (= ΔY / ΔX)
Corresponds to a correction coefficient for converting the pixel value of the difference block. That is, the correspondence between the pixel value of the prediction block and the correction coefficient is stored in the correction table.

The point indicated by the reference numeral 51a indicates the center of a portion having a large slope in each curve. Then, the table selection unit 1242 specifies the point 51a having the horizontal axis coordinate value closest to the value of the average value A of the prediction block obtained by the average value calculation unit 1241, and generates a curve 51 having the specified point 51a. The corresponding correction table is selected.

The selected correction table is stored in the coefficient generator 12.
The prediction block input to the coefficient generation unit 1244 is also input to the coefficient generation unit 1244 at an appropriate timing. Note that only information that specifies the selected correction table may be input to the coefficient generation unit 1244. The coefficient generation unit 1244 obtains a correction coefficient corresponding to each pixel of the prediction block with reference to the selected correction table (Step S24). The obtained correction coefficient group is output as correction data 843. In addition, by using the average value A of the prediction block, appropriate correction data corresponding to the difference block is generated, and generation of correction data is easily realized by preparing a plurality of correction tables and performing selection. You.

When the judgment value from the judgment unit 123 is “0”, the average value calculation unit 1241 and the table selection unit 1242
Does not operate, and the coefficient generator 1244 outputs “1” as all correction coefficients (step S25). As described later, the operation of outputting all the correction coefficients as “1” is as follows.
This is substantially equivalent to not generating correction data for correcting the difference block.

FIG. 9 is a diagram showing the flow of processing in the correction unit 122. The correction unit 122 first specifies a pixel to be corrected in the difference block as a target pixel (step S31). Then, it is determined whether or not the correction coefficient is "1" (step S32), and the correction coefficient is set to "1".
If it is not 1 ", the pixel value of the target pixel is multiplied by a correction coefficient (step S33). That is, if the pixel value before correction is X1 and the correction coefficient corresponding to this pixel is K, the pixel after correction is The value X2 is obtained as X2 = K × X1.

On the other hand, when the correction coefficient is "1", no multiplication is performed, and the pixel value of the target pixel is not corrected. That is, X2 = X1. Then, by confirming the correction coefficient and performing necessary multiplication for each pixel, the block for the difference image is corrected as needed (step S34).

As described above, when "0" is output from the determination unit 123 as the determination value, the correction data generation unit 124
Are all "1". Therefore, in this case, the correction by the correction unit 122 is not performed. That is, when the determination unit 123 determines that the correction is unnecessary, the correction processing is not performed. Note that the correction processing may be deactivated by directly inputting the determination result to the correction unit 122.

When the processing relating to the correction of one difference block is completed, the upper limit and the lower limit of the pixel value are limited so that the pixel value falls within a range that can be processed by the subsequent calculations (steps S35 and S36). After that, the corrected difference block is output from the correction unit 122.

As described above, the encoding unit 100 determines whether or not correction is necessary based on the difference block, and when it is determined that correction is necessary for the difference block, the table selecting unit 1242 corrects the correction. The correction table for obtaining the data 843 is updated based on the prediction block. Then, a calculation of a correction coefficient and a multiplication process in the correction unit 122 are performed.

When it is determined that the correction is unnecessary, the arithmetic processing in the average value calculation unit 1241, the update processing of the correction table, the correction data generation processing performed with reference to the correction table,
Also, the multiplication processing in the correction unit 122 is not performed. As a result, the amount of calculation required for correction can be reduced. As a result, the calculation time can be reduced, the price of the system can be reduced, the size can be reduced, and the moving image can be easily corrected in real time.

The difference block and the prediction block used in the determination of the necessity of the correction and the calculation of the correction data use the ones obtained at the time of the encoding process, that is, the determination and the correction process and the code Since the encoding process is partially shared, quick correction for a moving image can be realized by a low-cost device by only adding some components to the configuration for performing the encoding process.

<2. Second Embodiment> In the first embodiment, the correction of the difference block, which is the difference image, is performed by the encoding unit 100. However, the correction unit may be provided in the decoding unit 200. is there. FIG.
And FIG. 11 show that the correction unit is connected to the decoding unit 20 respectively.
FIG. 3 is a block diagram illustrating a configuration of an encoding unit 100 and a decoding unit 200 when the encoding unit 100 is provided at 0.

The coding unit 100 shown in FIG. 10 has a configuration in which the delay unit 121 and the correction unit 122 are deleted from the coding unit 100 according to the first embodiment. Then, the correction data 843 from the correction data generation unit 124 is supplied to the decoding unit 2 together with the encoded data 82.
Passed to 00.

The decoding unit 200 shown in FIG. 11 is the inverse DCT of the decoding unit 200 according to the first embodiment.
The correction unit 212 is added between the unit 203 and the addition unit 204. The correction data 8 is stored in the correction unit 212.
43 is input, and the correction unit 212 performs correction on the difference block output from the inverse DCT unit 203 using the correction data 843, as in the first embodiment. As a result, the corrected difference block is output, and output image data 83 that is a corrected moving image is obtained.

As described above, also in the second embodiment, the necessity of correction is determined based on the difference block, so that the amount of calculation required for correction can be reduced and the moving image can be corrected in real time. It is easily realized.

The difference block and the prediction block used for determining the necessity of correction and calculating the correction data are those used in the encoding process and the decoding process. Is partially shared with the encoding process and the decoding process, so that a quick correction for a moving image can be realized by a low-cost device.

<3. Third Embodiment> Next, an embodiment will be described in which the delay unit 121, the correction unit 122, the determination unit 123, and the correction data generation unit 124 in the first embodiment are all provided in the decoding unit 200. FIG.
13 and FIG. 13 show the encoding unit 10 in the case where all the processing relating to the correction is performed in the decoding unit 200.
FIG. 2 is a block diagram showing a configuration of a decoding unit 200 according to the first embodiment.

The coding unit 100 shown in FIG. 12 has a configuration in which the delay unit 121, the correction unit 122, the determination unit 123, and the correction data generation unit 124 are deleted from the coding unit 100 according to the first embodiment. I have. Therefore, the encoding unit 100 is a unit that performs only encoding of a moving image.

The decoding unit 200 shown in FIG. 13 has a configuration in which a delay unit 211, a correction unit 212, a determination unit 213, and a correction data generation unit 214 are added to the decoding unit 200 according to the first embodiment. ing. These configurations correspond to the encoding unit 100 according to the first embodiment.
The same operation as the corresponding configuration is performed.

That is, the delay unit 211 synchronizes the difference block input to the correction unit 212 with the correction data, and the correction unit 212 corrects the difference block according to the correction data. Further, the determination unit 213 determines whether or not correction is necessary based on the preset correction parameter 84 and the difference block, and the correction data generation unit 214 refers to the prediction block from the motion compensation unit 207 and corrects the correction table. Is selected, and a correction coefficient group is obtained as correction data using the prediction block.

Then, it is determined that the correction is unnecessary.
Is determined, all of the correction coefficients from the correction data generation unit 214 are set to “1”, and the correction unit 212 performs no correction.

As described above, it is also possible to provide all the components related to the correction in the decoding unit 200, and in this case, it is also possible to reduce the amount of calculation related to the correction.

The difference block and the prediction block used for the determination of the necessity of correction and the calculation of the correction data are those used in the decoding process, that is, the determination and correction processes and the decoding are performed. Since the conversion process is partially shared, quick correction of a moving image can be realized by a low-cost device.

<4. Fourth Embodiment> In the first to third embodiments, the difference block is corrected, but the correction target may be an image of each frame.

FIG. 14 is a block diagram showing a configuration of the decoding unit 200 when correcting a block of an image decoded by the decoding unit 200.
Note that the coding unit 100 is the same as that in FIG.

In the decoding unit 200 shown in FIG.
The decoded difference block from inverse DCT section 203 is input to determination section 213 and addition section 204. Adder 2
In 04, the difference block and the prediction block of the current frame derived from the previous frame are added to generate a block of the image of the current frame. The block of the image of the current frame is output to the correction data generation unit 214 and the delay unit 211.

The determination unit 213 determines whether or not correction is necessary based on the difference block and the correction parameter 84, and inputs the determination result to the correction data generation unit 214. Similar to the first embodiment, the correction parameter 84 is stored in a memory in advance by setting by an operator or the like. The correction data generation unit 214 selects a correction table required for correction based on the determination result and the block of the image of the current frame, and passes the selected correction table to the correction unit 212 as correction data. It should be noted that the information specifying the storage location of the selected correction table may only be passed to the correction unit 212.

The correction unit 212 corrects the image block of the current frame while referring to the selected correction table, and outputs the corrected image block to the synthesizing unit 205 and the frame memory 206. As a result, an image after correction is generated by the synthesizing unit 205 and output as output image data 83, and blocks of the image after correction for motion compensation are accumulated in the frame memory 206.

Next, the operation of each component relating to the correction will be described in more detail.

The operation of the judgment section 213 is the same as the operation shown in FIG. That is, when the average value of the pixel values in the difference block is within the range of the correction parameter 84, “0” is output as the determination value, and when it is out of the range, “1” is output as the determination value.

FIG. 15 is a diagram showing a flow of the operation in which the correction data generation unit 214 selects a correction table based on the determination value. The correction data generation unit 214 outputs the selected correction table as correction data. Therefore, the configuration of the correction data generation unit 214 corresponds to the average value calculation unit 1241, the table selection unit 1242, and the memory 1243 in FIG. Only is provided.

When the judgment value is "1", the correction data generation unit 214 first obtains the average value of the pixel values in the block of the image of the current frame (steps S41 and S42).
Then, one correction table is selected from a plurality of representative correction tables stored in the memory based on the average value (step S43). The selected correction table is transferred to the correction unit 212 as correction data, and is used for correction (step S44).

FIG. 16 is a diagram for explaining the operation of selecting a correction table. Curves indicated by reference numeral 52 in FIG. 16 indicate conversion characteristics of pixel values by the correction table. The point indicated by the reference numeral 52a indicates the center of a portion having a large slope in each curve. Then, the point 52a having the horizontal axis coordinate value closest to the value of the average value A is specified, and the correction table corresponding to the curve 52 having the specified point 52a is selected.

When the determination value is “0”, the correction data generation unit 214 notifies the correction unit 212 that the correction table used in the correction unit 212 does not need to be changed (no notification is made). (It does not have to be.) (Step S45).

FIG. 17 is a diagram showing the flow of the correction processing in the correction section 212.

The correction section 212 is provided with a memory for storing a correction table used for correcting an image of one frame (that is, a plurality of correction tables corresponding to all blocks). When a new correction table is selected in the correction data generation unit 214, the correction unit 212 updates the corresponding correction table (step S51,
S52). In other cases, the correction table used when correcting the image of the previous frame is used. That is, the correction table is not updated for the block whose determination value is “0”.

After the correction table is updated as necessary, the correction unit 212 specifies one pixel in the block as a target pixel (step S53), and converts the pixel value of the target pixel using the correction table. Yes (Step S5
4). For example, a curve 52 shown by a solid line in FIG.
Is selected, the correction unit 212 converts the pixel value before correction (input pixel value) X1 into a pixel value after correction (output pixel value) X2 based on this curve.

When the pixel value correction is repeated and the pixel value conversion for one block is completed (step S55), the upper limit and the lower limit of the pixel value are limited so that the pixel value falls within the range that can be processed by the subsequent calculations. Is done. Thereafter, the corrected block is output from the correction unit 212 (step S5).
6, S57).

As described above, in the decoding unit 200 according to the fourth embodiment, a difference block is obtained from the coded data 82, and whether or not a correction table used for correction needs to be updated based on the difference block is determined. The judgment is made. As a result, the amount of calculation required for updating the correction table can be reduced.

Further, since the difference block used as a reference for the correction judgment is generated at the time of decoding, that is, the judgment processing and the decoding processing are partially shared, the difference block for the moving image is used. Rapid correction is achieved with low cost equipment.

<5. Fifth Embodiment> The encoding unit 100 and / or the decoding unit 200 described in the first to fourth embodiments can be realized by software using a computer. FIG.
8 connects the video camera 10 and the computer 40,
FIG. 2 is a diagram showing a system in which a computer 40 executes moving image correction.

As shown in FIG. 19, the computer 40 includes a CPU 401 for performing various arithmetic processing, a ROM 402 for storing a basic program, and an RA for storing various information.
This is a general computer system configuration in which M403 is connected to a bus line. In addition to the bus line,
A fixed disk 404 for storing a large amount of information, a display 405 for displaying images, a keyboard 406a and a mouse 406b for receiving input from an operator, and recording media 9 such as an optical disk, a magnetic disk, and a magneto-optical disk.
A reading device 407 for reading information from 2, and
Communication unit 408 for receiving a signal from video camera 10
Are appropriately connected via an interface (I / F) or the like.

When the moving image processing is executed by the computer 40, the moving image processing program 441 is read from the recording medium 92 via the reading device 407 in advance and stored in the fixed disk 404. . Then, the program 441 is copied to the RAM 403 and C
The moving image processing is realized by the PU 401 executing arithmetic processing according to the program 441 in the RAM 403. At this time, various information and moving images are displayed on the display 405 as necessary. Note that the keyboard 406
a and the mouse 406b are used for inputting the correction parameter 84.

When the computer 40 is used as the encoding unit 100 and the decoding unit 200 according to the first embodiment, an image signal from the video camera 10 is input as digital data via the communication unit 408,
The CPU 401 or the like in the computer 40 performs the same processing as the various configurations shown in FIG.
4 stores the corrected encoded data 82 (and the motion vector 85). When reproducing a moving image, the CPU
The moving image is displayed on the display 405 by performing processing similar to the various configurations illustrated in FIG.

If the encoding process cannot be performed in real time due to the performance of the CPU 401 or the like, the moving image data is temporarily stored in the fixed disk 404, and then the encoded data 82 is generated.

Similarly, when the second to fourth embodiments are implemented by a computer 40, the computer 40 is caused to function as the encoding unit 100 and the decoding unit 200 shown in FIGS.

Note that the computer 40 includes first to fourth
The operation of only one of the encoding unit 100 and the decoding unit 200 according to the embodiment may be realized. For example, the decoding unit 2 according to the third embodiment
When only 00 is realized by the computer 40, a device that performs only normal encoding processing is used as the video camera 10, and a moving image is corrected when the computer 40 performs decoding.

As described above, the first to fourth embodiments can be realized using a computer. Even in this case, the amount of calculation can be reduced.
It is possible to quickly perform processing on a moving image.

<6. Modifications> While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-discussed preferred embodiments, but allows various modifications.

For example, in the above embodiment, the encoding unit 100 and / or the decoding unit 200 perform the processing related to the correction of the moving image. Irrespective of this, a means for acquiring a difference image (including a difference block) may be provided, and the moving image may be corrected using the difference image. That is, when controlling the processing related to the correction using the difference image, a step of acquiring the difference image is necessary. In the above embodiment, however, the subtraction unit 1 of the encoding unit 100 is substantially used.
02 or the inverse DCT unit 203 of the decoding unit 200 realizes a step of acquiring a difference image.

Further, in the above-described embodiment, it has been described that the encoded data 82 is input from the video camera 10 to the reproducing device 20 via the magnetic tape, but any method can be used as a data transfer method. May be done. For example,
An IC memory or a recording disk may be used as a recording medium for transfer, or wireless communication or wired communication via a transmission cable or a computer network may be used. Note that various techniques may be similarly used for data transfer between the video camera 10 and the computer 40 in the fifth embodiment.

In the first to fourth embodiments, the encoding unit 100 is provided in the video camera 10 and the decoding unit 200 is provided in the playback device 20. Video camera 1
0, or may be provided in the playback device 20.
That is, the video camera 10 and the playback device 20 in the above description are merely specific examples, and various configurations of the encoding unit 100 and the decoding unit 200 may be provided in any manner.

Also, in the above-described embodiment, it has been described that image data is input from the video camera 10 to the playback device 20 or the computer 40. However, instead of the video camera 10, another image output device such as a video deck is used. May be used.

Further, in the above embodiment, the prediction block of the current frame is obtained by performing motion compensation, thereby reducing the frequency of performing correction to reduce the amount of calculation. The configuration related to motion compensation may be omitted for applications other than those with little motion, such as monitoring by a monitoring camera. In this case, the block of the previous frame is used as the prediction block. However, the prediction block is not limited to a block after motion compensation or a block corresponding to the previous frame, and is an image that is derived from an image before the previous frame and can be used as a prediction block of the current frame. Any may be used.

In the above embodiment, the necessity of correction is determined from the average value of the pixel values in the difference block. However, other statistics such as the sum of the pixel values, the sum of squares, and the variance are used for the determination. May be done.

Further, the correction in the above embodiment is not limited to the correction of the luminance gradation, but the correction of other image characteristic amounts such as saturation and color saturation, or a plurality of image characteristic amounts. You may.

Further, in the above embodiment, the correction coefficient and the correction table are used as the correction data, but other data may be used as the correction data.

In the above embodiment, the dividing unit 101
Divides the image of each frame into blocks, determines the necessity of correction for each block based on the difference block, and further corrects the image of each frame for each block, but the image is not divided Is also good. That is, the image (including the difference image) used for the determination and the correction may be a block or an image of the entire frame. Similarly, a prediction image derived from an image of a frame preceding the current frame may be a prediction block or a prediction image of the entire frame. Further, although the image of each frame is divided, the determination and the correction may be performed in units of the image of the entire frame (including the difference image).

In the above embodiment, the amount of calculation in the correction data generation unit is converted according to the judgment value from the judgment unit. Therefore, the rate of the amount of data input to the correction unit may be changed according to the determination value in order to perform processing more quickly. For example, as shown by the broken line in FIG.
The determination value may be input to the division unit 101, and when the determination value is "0", the data transfer speed may be increased, and when the determination value is "1", the data transfer speed may be decreased.

Further, in the above embodiment, the correction table is generated from the cumulative histogram of the pixel values in the prediction block (the first to third embodiments) and the generated image block (the fourth embodiment). May be done. In this case, for example, as shown in FIG. 20, as a configuration of the correction data generation unit 124 according to the first embodiment, an accumulation histogram generation unit 1246, a shaping unit 1247, a coefficient generation unit 1244, and a delay unit 1245 are provided.

In FIG. 20, a cumulative histogram of pixel values in a prediction block (prediction image data 842) is generated by a cumulative histogram generation unit 1246, and the shaping unit 124
At 7, the curve of the cumulative histogram is shaped. As the shaping processing, normalization of a frequency value, clipping of a value equal to or more than a certain value, addition of a certain value, correction of a black / white edge, and the like are performed. Then, the cumulative histogram after shaping is represented by curve 5 in FIG.
A correction table is generated by using it as 1, and the correction table is sent to the coefficient generation unit 1244. Coefficient generator 124
In No. 4, the correction data 843 is generated by the above-described processing.

When the cumulative histogram is used in the fourth embodiment, the shaped cumulative histogram is passed to the correction unit 212 as a correction table. When using the cumulative histogram, it is not necessary to store a plurality of representative correction tables in the memory.

In the fifth embodiment, the encoding unit 100 and / or the decoding unit 200 are realized by using the computer 40. However, a part of the encoding unit 100 and / or the decoding unit A part of the unit 200 may be realized by a computer. The various configurations in the first to fourth embodiments do not need to be clearly separated from each other in terms of hardware, and may be realized by appropriately using a logic circuit or a microcomputer. For example, the processing in the determination unit and the correction data generation unit may be realized by a microcomputer, and the other configuration may be realized by a logic circuit. Further, the encoding unit 100 and / or the decoding unit 200 may be constructed by a plurality of computers.

Further, as shown in the first to third embodiments, the configuration relating to the correction can be provided arbitrarily separately in the encoding unit 100 and the decoding unit 200. As a mode other than the first to third embodiments, for example, there is a mode in which the determination unit 123 is provided in the encoding unit 100 and another configuration related to correction is provided in the decoding unit 200.

Further, even when the image of each frame is corrected as in the fourth embodiment, the configuration relating to the correction is arbitrarily divided into the encoding unit 100 and the decoding unit 200. Can be arranged. When the correction is performed by the encoding unit 100, a configuration for obtaining a difference block is separately added, and a determination is performed using the difference block, and then the image block of each frame is corrected.

[0117]

According to the present invention, claims 1 to 7 and claim 11 are provided.
Since the necessity of correction of the difference image is determined based on the difference image in the inventions of the thirteenth and twelfth aspects, it is possible to reduce the amount of calculation when correcting the moving image.

According to the second aspect of the present invention, the amount of calculation when generating correction data can be reduced.

According to the third aspect of the present invention, it is possible to generate appropriate correction data based on a predicted image, and according to the fourth aspect of the present invention, it is possible to easily generate correction data by selecting a correction table. .

Further, according to the invention of claim 6, the amount of calculation can be further reduced.

Further, according to the present invention, the correction can be performed for each difference image corresponding to each of the partial images.

According to the eighth, ninth, and thirteenth aspects, it is possible to reduce the amount of calculation required for updating the correction data.

According to the tenth aspect of the present invention, a part of the process of encoding or decoding a moving image can be shared.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image processing system.

FIG. 2 is a block diagram showing a main configuration relating to processing of a moving image.

FIG. 3 is a block diagram illustrating a configuration of an encoding unit.

FIG. 4 is a block diagram illustrating a configuration of a decoding unit.

FIG. 5 is a diagram illustrating a flow of a determination process.

FIG. 6 is a block diagram illustrating a configuration of a correction data generation unit.

FIG. 7 is a diagram showing a flow of a correction data generation process.

FIG. 8 is a diagram illustrating an operation of selecting a correction table.

FIG. 9 is a diagram showing a flow of a correction process.

FIG. 10 is a block diagram illustrating a configuration of an encoding unit.

FIG. 11 is a block diagram illustrating a configuration of a decoding unit.

FIG. 12 is a block diagram illustrating a configuration of an encoding unit.

FIG. 13 is a block diagram illustrating a configuration of a decoding unit.

FIG. 14 is a block diagram illustrating a configuration of a decoding unit.

FIG. 15 is a diagram showing a flow of a correction data generation process.

FIG. 16 is a diagram illustrating an operation of selecting a correction table.

FIG. 17 is a diagram illustrating a flow of a correction process.

FIG. 18 is a diagram illustrating a system that executes correction of a moving image by a computer.

FIG. 19 is a block diagram illustrating a configuration of a computer.

FIG. 20 is a block diagram illustrating another configuration of the correction data generation unit.

[Explanation of symbols]

 Reference Signs List 1 moving image processing system 10 video camera 20 playback device 40 computer 92 recording medium 100 coding unit 101 division unit 102 subtraction unit 116 motion compensation unit 122, 212 correction unit 123, 213 determination unit 124, 214 correction data generation unit 200 decoding Unit 203 Inverse DCT unit 441 Program 1242 Table selection unit 1243 Memory 1244 Correction table S12 Step

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/32 H04N 5/91 N 5C059 9/64 5/782 K 5C066 9/68 101 5/92 H 11 / 04 7/137 ZF term (reference) 5C018 FA01 FB03 5C021 PA17 PA79 PA80 XA34 XA35 YC08 YC09 5C026 CA01 CA02 CA15 5C053 FA22 GA11 GB22 GB26 GB29 GB32 KA03 LA01 LA11 5C057 AA01 AA07 DA16 DC01 EA01 EM02 EL01 EM01 GG01 GH01 GH03 GH05 GJ09 GM01 GM08 5C059 KK01 KK11 MA05 MA23 MC11 MC38 ME02 NN01 PP04 PP14 SS11 SS20 TA36 TB08 TC02 TD03 TD04 TD06 TD12 UA02 UA05 UA33 5C066 AA01 AA05 CA05 GA01 KA01 GA01 EA01 KA01 GA01 EA01 KA01 GA01 KA01 GA01 EA01 KA01

Claims (13)

[Claims] 1. A moving image processing apparatus, comprising: means for acquiring a difference image between a predicted image derived from an image of a frame preceding a current frame and an image corresponding to a current frame; Means for determining whether or not correction of the difference image is necessary. 2. The moving image processing apparatus according to claim 1, wherein when the determination unit determines that correction is necessary,
A moving image processing apparatus further comprising: means for generating correction data used for correcting the difference image. 3. The moving image processing apparatus according to claim 2, wherein the means for generating the correction data generates the correction data based on the predicted image. 4. The moving image processing apparatus according to claim 3, wherein: a means for storing a plurality of correction tables used for generating the correction data; and 1
Means for selecting a correction table for the moving image processing apparatus, wherein the means for generating the correction data generates the correction data with reference to the selected correction table. 5. The moving image processing apparatus according to claim 1, further comprising: a unit that corrects the difference image in accordance with a result of the determination by the determining unit. Processing equipment. 6. The moving image processing apparatus according to claim 1, wherein the predicted image is an image obtained by performing motion compensation on an image corresponding to a previous frame. Moving image processing device. 7. The moving image processing apparatus according to claim 1, further comprising: means for dividing an image of each frame into a plurality of partial images; A moving image processing apparatus characterized by determining whether correction is necessary for each difference image corresponding to each of partial images. 8. A moving image processing apparatus, comprising: means for acquiring a difference image between a predicted image derived from an image of a frame preceding a current frame and an image corresponding to the current frame; Means for determining whether or not it is necessary to update correction data used for correcting a moving image. 9. The moving image processing apparatus according to claim 8, further comprising: means for correcting a moving image according to the correction data. 10. The moving image processing device according to claim 1, wherein the difference image is obtained when encoding or decoding the moving image. Processing equipment. 11. A moving image processing method, comprising: obtaining a difference image between a predicted image derived from an image of a frame preceding a current frame and an image corresponding to a current frame; Determining whether correction of the difference image is necessary. 12. A computer-readable recording medium on which a program for causing a computer to execute a moving image correction is recorded, wherein execution of the program by the computer causes the computer to execute an image of a frame earlier than a current frame. Acquiring a difference image between a predicted image derived from the above and an image corresponding to the current frame; and determining whether correction of the difference image is necessary based on the difference image. recoding media. 13. A computer-readable recording medium on which a program for causing a computer to execute a moving image correction is recorded, wherein the execution of the program by the computer causes the computer to execute an image of a frame earlier than a current frame. Acquiring a difference image between the predicted image derived from the image and the image corresponding to the current frame, and determining whether update of correction data used for correcting a moving image is necessary based on the difference image. A recording medium characterized by causing a recording medium to be read.