JP2006262161A - Image processor, image processing method, and storage medium with the method stored therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce recording capacity and to perform image compression, wherein an image is hardly deteriorated. <P>SOLUTION: An edge determining part 11 determines 10-bit image data inputted to this image processor 10, and an image dividing part 12 divides the image data into higher-order 8 bits and lower-order 2 bits. In the higher-order 8 bits, higher-order bit data subjected to JPEG compression by a first image compressing part 13 are stored in a storage part 15. The lower-order 2-bit data are subjected to JPEG compression by a second image compressing part 14 in accordance with a result of the edge determining part 11, and the entire pixel values are made to be "0" or input lower-order 2-bit data are output as it is to be stored in the storage part 15. The lower-order bit data and the higher-order bit data stored in the storage part 15 are inputted to a first expanding part 17 and a second expanding part 18 to be expanded, 2-bit bit shift is subsequently applied to the higher-order bits, and an adder 19 obtains the sum of the lower-order bit data and the higher-order bit data and outputs the sum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus, an image processing method, and a storage medium for compressing image data when the image data is stored in a storage medium.

  In recent years, many copiers equipped with a hard disk have been introduced. In such a copying machine, the copied image is stored in a hard disk (HD) and printed without a document, or the image stored in the hard disk is viewed on a personal computer (PC) or the like. Is possible.

  In addition, when saving to the hard disk, some compression is generally performed to save the hard disk capacity, but JPEG compression is frequently used because of its high penetration rate for general users and high compression rate. Yes.

  A method for creating this JPEG data will be briefly described. First, an image is divided into 8 × 8 pixel blocks, and discrete cosine transform (DCT), which is a kind of orthogonal transform, is performed. As for the value in the block after the DCT, the average value of the pixels in the block called DC component is stored in the upper left pixel. In addition, waveform components having various frequencies and amplitudes such that when other values are integrated to “0” are stored, this is called an AC component. In the block, the lower frequency is stored in the block and the higher frequency component is stored in the block.

  Next, each block after DCT is quantized using an 8 × 8 quantization mask. This quantization is an operation of replacing a certain numerical value with a numerical value that is closest to a predetermined value. For example, when a numerical value of 50 is quantized by 8, a value after quantization by 50≈8 × 6 Becomes 6. In this example, the amount of information is reduced because the value of each pixel that originally had 255 gradations is reduced to 255 ÷ 8 = 32 gradations in the above-described example. Furthermore, if the numerical value to be quantized is increased, the gradation information is further reduced. Usually, in the 8 × 8 quantization mask, a small number is set at the upper left and a large number is set at the lower right, and the amount of information is increased as the low frequency component is decreased and the amount of information is decreased as the higher frequency component. This is a process that takes into account the human visual characteristics that the human eye is sensitive to low frequency components and insensitive to high frequency components.

  When it is desired to increase the compression rate, a large number is arranged in the lower right area of the quantization mask to actively reduce high frequency information. Then, a JPEG image is created by performing Huffman coding thereafter.

  As described above, JPEG is particularly excellent in that it can be viewed from various applications on a PC because it is highly compressed and has a high penetration rate to the general public. Note that the number of gradations of JPEG that is generally used is 8 bits, that is, 256 gradations. According to the JPEG standard, 16-bit, that is, 65536 gradation JPEG is also defined, but it is not as common as 8-bit JPEG.

  On the other hand, in recent years, a processing system having a larger number of gradations (for example, about 10 bits) has been desired due to the demand for higher image quality of copying machines. However, since the general JPEG has 8 bits as described above, it is desirable that the storage to the hard disk is performed with 8 bits. Therefore, there is a demand for a method for holding information of 8 bits or more without losing the versatility of JPEG.

  The following two methods are conceivable as methods for meeting such demands. The first is a method of storing the upper 8 bits data separately from the lower 2 bits data. In a tape recorder or video tape, the upper 8 bits data is divided into upper bits and lower bits and stored in separate channels. A method has been devised (see Patent Document 1).

  The second is a method of embedding lower 2-bit image data in upper-bit image data. In Patent Document 2, browsing is performed by replacing a high-frequency region of data quantized by DCT with lower-bit data. In this case, a method has been devised that can be handled as ordinary JPEG and retain lower-order bit data.

JP 2000-149454 A JP 2000-312296 A

  However, when the method of the above-mentioned Patent Document 1 is used, there is a problem that the hard disk capacity is pressed more than necessary in order to save the lower-order bit data even in an area where gradation is hardly a problem such as a character area. was there.

  Further, when the method of Patent Document 2 is used, the edge region and the like are similarly cut off in the high frequency region and the lower bit data is embedded, so that the edge may become dull.

  The present invention has been made in view of the above, and an image processing apparatus, an image processing method, and an image processing apparatus capable of reducing the recording capacity and performing image compression in which an image is hardly deteriorated while retaining lower-order bit data. And a storage medium for storing the method.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is an image dividing means for dividing image data into two image data of upper bits and lower bits, and image data of the upper bits. A first image compressing means for compressing; a second image compressing means for compressing the lower bit image data; a storing means for storing the compressed upper bit and lower bit image data; Image processing means for reading out image data of bits and lower bits and performing image processing, and reading out the upper bit image data from the storage means and transmitting it to an external device.

  According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the first image compression unit and the second image compression unit have different compression ratios.

  The invention according to claim 3 is the image processing apparatus according to claim 1, wherein the first image compression means and the second image compression means have different compression methods.

  According to a fourth aspect of the present invention, in the image processing apparatus according to the first aspect of the present invention, the image processing apparatus further includes a feature determination unit that determines a feature of the attention area, and a gradation change greater than or equal to a predetermined gradient is observed in the attention area. If so, the lower bit data of the corresponding area is discarded.

  The invention according to claim 5 is the image processing apparatus according to claim 1, further comprising attribute determination means for determining an attribute of the attention area, and corresponds to the case where a character area exists in the attention area. The low-order bit data of the area is discarded.

  According to a sixth aspect of the present invention, there is provided a feature determining means for determining the feature of the attention area, an image dividing means for dividing the image data into two image data of upper bits and lower bits, and direct execution of the upper bit image data. An orthogonal transformation means for transforming, a quantization means for quantizing the data after the orthogonal transformation, a compression means for compressing the lower-bit image data, and a compressed lower-bit image data is added to the quantized data. Data adding means, storage means for storing image data to which data is added, decompressing means for reading out image data from the storage means and decompressing the image, and performing predetermined image processing on the decompressed image And an image processing means.

  According to a seventh aspect of the present invention, in the image processing apparatus according to the sixth aspect, the data adding means adds compressed lower-bit image data in an area where a gradation change exceeding a predetermined gradient is seen. It is characterized by not.

  According to an eighth aspect of the present invention, there is provided an attribute determination unit that determines an attribute of a region of interest, an image dividing unit that divides image data into two image data of an upper bit and a lower bit, and the image data of the upper bit. An orthogonal transform means for performing an orthogonal transform, a quantizing means for quantizing the data after the orthogonal transform, a compressing means for compressing the lower-order bit image data, and the lower-order bit image compressed into the quantized data Data adding means for adding data; storage means for storing image data to which the data is added; decompression means for reading out image data from the storage means and decompressing the image; and for the decompressed image And image processing means for performing predetermined image processing.

  The invention according to claim 9 is the image processing apparatus according to claim 8, wherein the data adding means does not add compressed lower-bit image data in an area including a character area.

  According to a tenth aspect of the present invention, in the image processing apparatus according to any one of the sixth to ninth aspects, the data adding unit simultaneously holds a flag indicating whether or not data has been added. And

  According to an eleventh aspect of the present invention, in the image processing apparatus according to any one of the sixth to ninth aspects, the image processing means determines a characteristic of the image with respect to the expanded image. The determination means is included.

  According to a twelfth aspect of the present invention, in the image processing apparatus according to the eleventh aspect of the present invention, the image processing apparatus further includes a second image dividing unit that divides the data added according to the second feature determining unit again. It is characterized by that.

  According to a thirteenth aspect of the present invention, in the image processing apparatus according to any one of the sixth to ninth aspects, the image processing means determines a second attribute of the image with respect to the expanded image. It includes an attribute determination means.

  The invention according to claim 14 is the image processing apparatus according to claim 13, further comprising second image dividing means for dividing again the data added according to the second attribute determining means. It is characterized by that.

  According to a fifteenth aspect of the present invention, in the image processing apparatus according to the sixth aspect, the compression unit holds at least an average value of lower-order bit images.

  According to a sixteenth aspect of the present invention, in the image processing apparatus according to the sixth aspect, the compression means holds at least a gradient value of the lower-order bit image.

  The invention according to claim 17 is the image processing apparatus according to claim 6, wherein the compression means holds at least the gradient direction of the lower-order bit image.

  According to an eighteenth aspect of the present invention, there is provided image dividing means for dividing image data into two image data of upper bits and lower bits, first storage means for storing the upper bit image data, and the lower bits. Second storage means for storing the image data, and reading the upper bit image data from the first storage means, and performing image processing while referring to the lower bit image data read from the second storage means Image processing means for performing the processing, and reading out the high-order bit image data from the first storage means and transmitting it to an external device.

  According to a nineteenth aspect of the present invention, in the image processing apparatus according to the eighteenth aspect, the second storage means temporarily stores lower-order bit image data.

  The invention according to claim 20 is the image processing apparatus according to claim 18 or 19, wherein the lower-order bit image data divided by the image dividing means is the first storage means and the second storage means. It is characterized by comprising a selection means capable of selecting whether to store in either of these according to the user's intention.

  The invention according to claim 21 is the image processing apparatus according to claim 18 or 19, wherein the lower-order bit image data divided by the image dividing means is the first storage means and the second storage means. It is characterized by comprising selection means that can select whether to store in either of the above, depending on the configuration of the apparatus.

  According to a twenty-second aspect of the present invention, the step of dividing the image data into two image data of upper bits and lower bits, the step of compressing the image data of the upper bits, and the image data of the lower bits Storing the compressed upper bit and lower bit image data in storage means, and reading the stored upper bit and lower bit image data and performing image processing, the storage means The high-order bit image data is read out and transmitted to an external device.

According to a twenty-third aspect of the present invention, the step of determining the feature of the region of interest, the step of dividing the image data into two image data of upper bits and lower bits, and the step of performing direct conversion on the image data of the upper bits A step of quantizing the data after the orthogonal transformation, a step of compressing the lower-bit image data, a step of adding the compressed lower-bit image data to the quantized data, and an image to which the data is added Storing the data;
The step includes reading the stored image data and decompressing the image, and performing predetermined image processing on the decompressed image.

  According to a twenty-fourth aspect of the present invention, the step of determining the attribute of the attention area, the step of dividing the image data into two pieces of image data of upper bits and lower bits, and the step of performing direct conversion on the image data of the upper bits A step of quantizing the data after the orthogonal transformation, a step of compressing the lower-order bit image data, a step of adding the compressed lower-order bit image data to the quantized data, and the data Storing the image data to which is added, reading the stored image data and decompressing the image, and performing predetermined image processing on the decompressed image. .

  According to a twenty-fifth aspect of the present invention, the step of dividing the image data into two image data of upper bits and lower bits, the step of storing the image data of the upper bits, and the image data of the lower bits And reading the stored upper bit image data and performing image processing while referring to the stored lower bit image data, and reading the stored upper bit image data to an external device. It is characterized by transmitting.

  An invention according to claim 26 is a storage medium for storing the image processing method according to any one of claims 22 to 25.

  The image processing apparatus according to claim 1 divides the image data into two image data of upper bits and lower bits by the image dividing means, compresses the upper bit image data by the first image compression means, and The lower bit image data is compressed by the image compression means, the upper bit and the lower bit image data compressed by the storage means are stored, and the upper bit and lower bit image data read from the storage means by the image processing means By processing, it is possible to efficiently compress the image data of the upper bits and the lower bits, respectively, and to prevent image deterioration.

  In the image processing apparatus according to the second aspect, since the compression ratios are different between the first image compression unit and the second image compression unit, the compression can be efficiently performed, and the capacity of the storage unit can be reduced. Play.

  In the image processing apparatus according to the third aspect, the first image compression unit and the second image compression unit have different compression methods, so that efficient compression can be performed while minimizing image degradation. There is an effect.

  The image processing apparatus according to claim 4 determines the feature of the attention area by the feature determination means, and discards the lower-order bit data of the corresponding area when a gradation change of a predetermined gradient or more is found in the attention area. Therefore, the lower bit data is discarded in the edge region where the upper bits are relatively unaffected by the lower bit data, so that the amount of information can be reduced and the compression rate can be improved.

  In the image processing apparatus according to the fifth aspect, the attribute determination unit determines the attribute of the attention area, and when a character area exists in the attention area, the lower bit data of the corresponding area is discarded. By discarding lower bit data in a character area that is relatively unaffected by lower bit data, the amount of information is expected to be reduced, and the compression rate is expected to be improved.

  The image processing apparatus according to claim 6 determines the feature of the attention area by the feature determination unit, divides the image data into two image data of the upper bit and the lower bit by the image division unit, and the upper bit by the direct conversion unit. The image data is subjected to orthogonal transform, the quantized data is quantized, the lower bit image data is compressed by the compression means, and the lower bit image data is compressed to the quantized data by the data adding means. The image data to which the data is added is stored by the storage means, the image data is read from the storage means by the decompression means, the image is decompressed, and predetermined image processing is performed on the image decompressed by the image processing means. Since the lower bit data is embedded in the upper bit data string, the upper bit data and the lower bit data are embedded. The result can be handled as one file, an effect that the handling of the file becomes easy.

  In the image processing apparatus according to the seventh aspect of the present invention, the lower bit image data compressed by the data adding means is not added in an area where a gradation change of a predetermined gradient or more is seen. By discarding the lower-order bit data in the edge area that is not affected by the above, it is possible to reduce the amount of information and to improve the compression rate.

  The image processing apparatus according to claim 8 determines the attribute of the attention area by the attribute determining means, divides the image data into two image data of the upper bit and the lower bit by the image dividing means, and sets the upper bit by the direct conversion means. The image data is subjected to orthogonal transform, the quantized data is quantized, the lower bit image data is compressed by the compression means, and the lower bit image data is compressed to the quantized data by the data adding means. Is added, and the storage means stores the image data to which the data has been added, the expansion means reads out the image data from the storage means, expands the image, and the image processing means applies the predetermined image to the expanded image. Since processing is performed, the upper bit data and the lower bit data are embedded by embedding the lower bit data in the upper bit data string. It is possible to handle the data as one file, an effect that the handling of the file becomes easy.

  In the image processing apparatus according to claim 9, since the lower bit image data compressed by the data adding means is not added to the area including the character area, the upper bit is relatively unaffected by the lower bit data. By discarding the lower-order bit data, the amount of information is expected to be reduced, and the compression rate is expected to be improved.

  Since the image processing apparatus according to the tenth aspect of the present invention is configured to simultaneously hold a flag indicating whether or not data has been added by the data adding unit, the flag information indicating whether or not the low-order bit data has been added is provided. There is no need to determine the addition of data at the time of decompression, and the circuit scale is expected to be reduced.

  Since the image processing apparatus according to the eleventh aspect includes the second feature determining means for determining the image characteristics of the image expanded by the image processing means, it is determined whether or not data has been added. Since it is not necessary to have flag information, the amount of information to be embedded in the image file is reduced, and it is possible to prevent image deterioration due to data embedding when browsing with an external device or the like.

  Since the image processing apparatus according to the twelfth aspect of the present invention further includes second image dividing means for dividing again the data added according to the second feature determination means, it is determined whether or not the data has been added. Since it is not necessary to have flag information, the amount of information to be embedded in the image file is reduced, and there is an effect that image deterioration due to data embedding can be prevented when browsing with an external device or the like.

  Since the image processing apparatus according to the thirteenth aspect includes the second attribute determination unit that determines the attribute of the image with respect to the decompressed image, the flag indicating whether or not data has been added. Since it is not necessary to have information, the amount of information to be embedded in the image file is reduced, and there is an effect that image deterioration due to data embedding can be prevented when browsing with an external device or the like.

  The image processing apparatus according to the fourteenth aspect further includes second image dividing means for dividing again the data added in accordance with the second attribute determining means, so whether or not data addition has been performed. Since it is not necessary to have flag information, the amount of information to be embedded in the image file is reduced, and there is an effect that image deterioration due to data embedding can be prevented when browsing with an external device or the like.

  In the image processing apparatus according to the fifteenth aspect, since the compression unit holds at least the average value of the lower-order bit images, the lower-order bit data to be added to the higher-order bits is compressed in this manner, so that the upper-order bit image file is compressed. The amount of information to be embedded is reduced, and there is an effect that image deterioration due to data embedding can be prevented when browsing with an external device.

  In the image processing apparatus according to the sixteenth aspect, since the compression means holds at least the gradient value of the lower-order bit image, the lower-order bit data added to the higher-order bits is compressed in this way, thereby converting the lower-order bit image into an upper-order bit image file. The amount of information to be embedded is reduced, and there is an effect that image deterioration due to data embedding can be prevented when browsing with an external device.

  In the image processing apparatus according to the seventeenth aspect, since the compression means retains at least the gradient direction of the lower-order bit image, the lower-order bit data added to the higher-order bits is compressed in this manner, so that the upper-order bit image file is compressed. The amount of information to be embedded is reduced, and there is an effect that image deterioration due to data embedding can be prevented when browsing with an external device.

  The image processing apparatus according to claim 18 divides the image data into two image data of upper bits and lower bits by the image dividing unit, stores the upper bit image data by the first storage unit, and stores the second bit data. The lower bit image data is stored by the means, and the upper bit image data read from the first storage means by the image processing means is referred to the lower bit image data read from the second storage means to perform image processing. As a result, it is possible to save the storage capacity of the storage unit while improving the image quality at the first output by storing the lower-order bit data only in the temporary storage area.

  In the image processing apparatus according to claim 19, since the lower bit image data is temporarily stored by the second storage unit, the lower bit data is stored only in the temporary storage area, so that the first time output can be performed. There is an effect that the storage capacity of the storage means can be saved while improving the image quality.

  The image processing apparatus according to claim 20 uses the selection means to determine whether the lower-order bit image data divided by the image dividing means is stored in the first storage means or the second storage means. Therefore, it is possible to save images that are required to have high image quality and images that are not required by a suitable method, and the storage capacity of the storage means can be used efficiently.

  According to a twenty-first aspect of the present invention, the image processing apparatus can select whether to store the low-order bit image data divided by the image dividing means in either the first storage means or the second storage means depending on the configuration of the apparatus. For this reason, it is possible to store images that are required to have high image quality and images that are not required by a suitable method, and the storage capacity of the storage means can be used efficiently.

  An image processing method according to claim 22 divides image data into two image data of upper bits and lower bits, compresses upper bit image data, compresses lower bit image data, and compresses the upper bit Since the bit and lower bit image data are stored in the storage means, and the stored upper bit and lower bit image data are read and image processing is performed, the upper bit and lower bit image data are compressed efficiently. At the same time, the image can be prevented from being deteriorated.

  The image processing method according to claim 23 determines the characteristics of the region of interest, divides the image data into two image data of upper bits and lower bits, performs orthogonal conversion on the upper bit image data, and performs data after the orthogonal conversion. , Quantize the lower bit image data, add the compressed lower bit image data to the quantized data, store the image data with the data added, and read the stored image data Since the image is decompressed and predetermined image processing is performed on the decompressed image, the upper bit data and the lower bit data are combined into one by embedding the lower bit data in the upper bit data string. It is possible to handle it as a file, and there is an effect that handling of the file becomes easy.

  25. The image processing method according to claim 24, wherein the attribute of the region of interest is determined, the image data is divided into two image data of upper bits and lower bits, the upper bit image data is subjected to direct conversion, and the data after direct conversion , Quantize the lower bit image data, add the compressed lower bit image data to the quantized data, store the image data with the data added, and read the stored image data Since the image is decompressed and predetermined image processing is performed on the decompressed image, the upper bit data and the lower bit data are combined by embedding the lower bit data in the upper bit data string. It is possible to handle them as one file, and the file handling is facilitated.

  The image processing method according to claim 25 divides image data into two image data of upper bits and lower bits, stores upper bit image data, stores lower bit image data, and stores the upper bits stored therein. Bit image data is read and image processing is performed while referring to the stored lower bit image data, so the lower bit data is saved only in the temporary storage area, improving the image quality at the first output. However, the storage capacity of the storage means can be saved.

  The invention according to claim 26 has an effect that the image processing method according to any one of claims 22 to 25 can be stored in a storage medium and used.

  Embodiments of an image processing apparatus, an image processing method, and a storage medium storing the method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(First embodiment)
FIG. 1 is a block diagram for explaining the configuration of the image processing apparatus according to the first embodiment of the present invention, FIG. 2-1 is a waveform diagram of input image data, and FIG. 2-1 is a waveform diagram of upper bits when the waveform of FIG. 2-1 is divided into upper bits and lower bits, FIG. 2-3 is a waveform diagram of lower bits, and FIG. FIG. 3-2 is a waveform diagram of data, FIG. 3-2 is a waveform diagram of upper bits when the waveform of FIG. 3-1 is divided into upper bits and lower bits, and FIG. 3-3 is a waveform diagram of lower bits. FIG. 4 is a detailed block diagram illustrating a configuration example of the image processing unit in FIG. 1.

  An image processing apparatus 10 shown in FIG. 1 includes an edge determination unit 11 as a feature determination unit, an image division unit 12 as an image division unit, a first image compression unit 13 as a first image compression unit, and a second image. A second image compression unit 14 as a compression unit, a storage unit 15 as a storage unit, an image processing unit 16 as an image processing unit, and the like are included.

  The edge determination unit 11 performs edge determination of input image data. For example, edge determination is performed by performing predetermined threshold determination on the absolute value of the difference between each of eight adjacent pixels for a certain region of interest. It can be carried out.

  The image dividing unit 12 extracts the lower 2 bits of the input 10-bit image data, and then performs 2-bit bit shift to divide the upper 8 bits and the lower 2 bits.

  The first image compression unit 13 performs JPEG compression on the upper 8 bits divided by the image division unit 12.

  The second image compression unit 14 determines whether or not the lower 2-bit data, which is the other output of the image division unit 12, is JPEG compressed according to the determination result of the edge determination unit 11. For example, it is determined whether there is a pixel for which the output of the edge determination unit 11 is true for each 8 × 8 pixel DCT block, and if there is a pixel for which the determination result is true, All pixel values are output as “0”. If there is no pixel for which the edge determination result is true, the input lower 2-bit data is output as it is. Note that the compression rate of the second image compression unit 14 is lower than that of the first image compression unit 13.

  The storage unit 15 holds the upper bit data that has been JPEG-compressed by the first image compression unit 13 and also holds the output of the second image compression unit 14.

  As shown in FIG. 4, the image processing unit 16 includes a first decompression unit 17, a second decompression unit 18, an adder 19 that takes the sum of the outputs of both, and the like, and is held in the storage unit 15. After the lower bit data is input to the first decompression unit 17 and the upper bit data held in the storage unit 15 is input to the second decompression unit 18 and decompressed, the upper bits are shifted by 2 bits. The adder 19 calculates the sum of the two and outputs the result.

  As shown in FIG. 1, the operation in the first embodiment is that the 10-bit image data input to the image processing apparatus 10 is edge-determined by the edge determination unit 11 and the lower-order 2 bits are converted by the image division unit 12. After extraction, it is divided into upper 8 bits and lower 2 bits by performing a 2-bit bit shift. The divided upper 8 bits are JPEG compressed by the first image compression unit 13, and the compressed upper bit data is held in the storage unit 15. The held upper bit data is used when browsing with an external device.

  Further, the lower 2 bit data which is the other output of the image dividing unit 12 is JPEG compressed by the second image compressing unit 14 in accordance with the result of the edge determining unit 11. It is determined whether there is a pixel for which the output of the edge determination unit 11 is true for each 8 × 8 pixel DCT block. If there is a pixel for which the determination result is true, the pixel value of the DCT block is determined. Are all output as “0”. If there is no pixel for which the edge determination result is true, the input lower 2-bit data is output as it is. The output of the second image compression unit 14 is also held in the storage unit 15.

  Then, as shown in FIG. 4, the image processing unit 16 inputs the lower bit data and the upper bit data held in the storage unit 15 to the first decompression unit 17 and the second decompression unit 18, respectively, and decompresses them. Thereafter, the upper bits are subjected to 2-bit bit shift, and the adder 19 calculates the sum of the two before being output.

  Note that the reason why the lower 2-bit data is discarded according to the determination result of the edge determination unit 11 described above is that an area where gradation is most important for an image is an area where gradation changes smoothly. Because it can be said. Thus, when expressing a smooth gradation, if there are not enough gradations, there is a possibility that a so-called pseudo contour, in which a contour line appears at a place where it does not actually exist, may occur. On the other hand, in a region with a large edge amount typified by characters and the like, the pixel value changes abruptly, so even if the amount of change changes slightly, it is difficult to notice the malfunction. This is because the lower bits are retained only for the areas that are likely to benefit from the above, thereby saving the capacity of the storage unit 15 while maximizing the merit of increasing the number of gradations.

  The reason why the compression ratio of the second image compression unit 14 is lower than that of the first image compression unit 13 is because it cannot be generally said which of the high-frequency component and the low-frequency component is important in the lower 2-bit data. It is. This will be described with a one-dimensional example. For example, when the waveform shown in FIG. 2-1 is divided into upper bits and lower bits, they are divided as shown in FIG. 2-2 (upper bits) and FIG. 2-3 (lower bits), respectively. The numerical values of the lower bits in this example frequently change, and it can be said that the waveform is high frequency. On the other hand, when the waveform shown in FIG. 3A is divided into upper bits and lower bits, they are divided as shown in FIG. 3-2 (upper bits) and FIG. 3-3 (lower bits), respectively. The lower bits in this example have a gentle change, and the waveform can be said to be low frequency. However, since both the waveforms in FIGS. 2 and 3 are image data showing gentle changes, it is desirable to retain both high and low frequencies for the lower bits in order to faithfully reproduce them. Because it seems.

  As described above, according to the first embodiment, the image data to be compressed is divided into upper bits and lower bits, and the characteristics in the attention area of the image are determined. Since it is possible to perform image processing, it is possible to perform compression processing with the image data amount reduced as much as possible while preventing image deterioration.

(Second Embodiment)
FIG. 5 is a block diagram illustrating the configuration of the image processing apparatus according to the second embodiment of the present invention, and FIG. 6 is a detailed block diagram illustrating a configuration example of the character determination unit in FIG.

  An image processing apparatus 20 shown in FIG. 5 includes a character determination unit 21 as an attribute determination unit, an image division unit 22 as an image division unit, a first image compression unit 23 as a first image compression unit, and a second image. A second image compression unit 24 as a compression unit, a storage unit 25 as a storage unit, an image processing unit 26 as an image processing unit, and the like are included.

  In the second embodiment, most of the configuration is the same as that of the first embodiment, but in which area the lower-order bit data is to be discarded, and the image compression unit performs the first implementation. The form is different. Therefore, the description of the configuration of the same components will be omitted, and the following description will be given with emphasis on different points.

  Which area of lower bit data is to be discarded is determined by the character determination unit 21 that determines the attribute of the attention area of the image data. The character determination unit 21 shown in FIG. 6 includes a density determination unit 27, a pattern matching unit 28, an expansion unit 29, a contraction unit 30, an edge determination unit 31, and an AND circuit 32.

  As shown in FIG. 6, when image data is input to the character determination unit 27, the density determination unit 27 determines whether the density is lower than a predetermined density. Then, in the subsequent pattern matching unit 28, pattern matching is performed. Here, when all the five pixels on both sides of the target pixel are low in density, true is output. It is led to the AND circuit 32 through the expansion part 29 and the contraction part 30 in the subsequent stage.

  On the other hand, the edge determination unit 31 performs the same operation as the edge determination unit 110 of FIG. The output of the edge determination unit 31 is also guided to the AND circuit 32. For this reason, the AND circuit 32 determines that only an area having an edge and determined to be a low density area is a character area, and discards lower-order bit data only when the result is true.

  In this way, the reason why the lower-order bit data is discarded only in the area such as characters on the white ground is as follows. That is, the edge region not corresponding to the above includes, for example, hair in a person photo image. In the second embodiment, assuming that JPEG compression is performed, processing is performed with 8 × 8 pixels. Therefore, if the lower bits are simply discarded in the edge area, the image of the image around the hair of the human photograph etc. This is because it is desirable to discard the lower-order bit data only in a so-called character area because there is a possibility of causing discontinuity.

  Next, regarding the image compression method, the first image compression unit 23 that compresses the upper bits uses JPEG compression, and the second image compression unit 24 that compresses the lower bits uses the run-length method. Let it be compressed. In general, any compression method is not good at the nature of the image to be compressed. For example, JPEG compression shows a high compression ratio and high versatility for images that contain many high frequencies such as natural images, but it is composed of only edges and several types of colors found in, for example, anime cell images. For such specific images, the compression performance is not so high. Further, JPEG compression is irreversible compression, and it is impossible to completely restore information. Therefore, when an image having a large number of uniform areas is compressed, deterioration in image quality is conspicuous.

  On the other hand, when using the run-length method, that is, a compression method that retains how many times the same numerical value continues, information compression is hardly expected for images such as natural images, but high compression is required for images such as animation. You can expect rates. Further, since the run length method is lossless compression, it has a feature that information can be completely restored.

  In view of the technique of the second embodiment, there is a high possibility that lower-bit data will frequently appear in the same value, that is, in the area of 0 by the adaptive processing. Further, as described in the first embodiment, it is desirable to hold both high frequency and low frequency information. For this reason, in the second embodiment, a method is employed in which the upper bits are compressed by JPEG, which can be used for relatively many purposes, and the lower bits are compressed by an uncompressed run length method.

  As described above, according to the second embodiment, since the character determination unit 21 which is an attribute determination unit is provided, information can be adaptively selected, which is suitable for the upper bit and the lower bit, respectively. By using the compression method described above, efficient compression processing can be performed while minimizing image degradation.

(Third embodiment)
FIG. 7 is a block diagram illustrating the configuration of an image processing apparatus according to the third embodiment of the present invention. FIG. 8 is a detailed block diagram illustrating a configuration example of the compression unit in FIG. FIG. 10 is a diagram showing areas 1 to 4 in which the average density is calculated in the block average calculation unit in FIG. 8, and FIG. 10 is a diagram showing a correspondence relationship between the determination result in the edge direction determination unit in FIG. FIG. 11 is a detailed block diagram illustrating an example of the configuration of the data adding unit in FIG. 7, and FIG. 12 is a diagram illustrating an 8 × 8 pixel mask of the upper bit data quantized in the truncation unit in FIG. FIG. 13 is a state diagram in which the density values of the three pixels at the lower right are set to 0. FIG. 13 is a detailed block diagram showing a configuration example of the image processing unit in FIG. 7, and FIG. DC from various values read from the pixel to which data is added A corresponding pattern diagram illustrating the value to be stored separately pixels corresponding to the block into two regions.

  An image processing apparatus 40 shown in FIG. 7 includes an edge determination unit 41, an image division unit 42, an orthogonal transform unit 43, a quantization unit 44, a compression unit 45, a data addition unit 46, an encoding unit 47, a storage unit 48, and an image. It consists of a processing unit 49 and the like.

  First, a third embodiment will be described with reference to FIG. In the image processing apparatus 40 shown in FIG. 7, when 10-bit image data is input, the edge determination unit 41 performs edge determination. Since the edge determination unit 41 performs the same operation as the edge determination unit 11 in FIG. 1 shown in the first embodiment, the description of the configuration is omitted.

  On the other hand, the input image data is also sent to the image dividing unit 42 and divided into upper 8 bits and lower 2 bits. First, the upper 8-bit data undergoes DCT conversion and quantization as described above in the JPEG compression section through the direct conversion unit 43 and the quantization unit 44, and then the data is sent to the data addition unit 46. It is done.

  The lower 2 bit data is compressed by the compression unit 45 in the amount of information. The compression unit 45 will be further described with reference to FIG. The compression unit 45 includes a block average calculation unit 50, an edge direction determination unit 51, an edge amount calculation unit 52, an average value calculation unit 53, and the like. Information is stored in units of 8 × 8 pixels when JPEG compression is performed. It is processed.

  First, the block average calculation unit 50 calculates the average densities of the regions 1 to 4 shown in FIG. Then, in the edge direction determination unit 51, the absolute value of the average density difference between the region 1 and the region 4, the absolute value of the average density difference between the region 2 and the region 3, the average of each of the region 1 and the region 3, and the region 2 and the region 4 Calculate the average of the absolute values of the density differences and the average of the absolute values of the average density differences of the areas 1 and 2 and the areas 3 and 4 and compare them to change the output according to the maximum value. Let In this edge direction determination unit 51, what kind of signal is output in which case is shown in the list of FIG.

  The subsequent edge amount calculation unit 52 calculates the edge amount with reference to the output value from the edge direction determination unit 51. More specifically, the difference between regions existing in the edge direction is calculated. For example, when the output of the edge direction determination unit 51 is “0”, the edge amount calculation unit 52 outputs the value obtained by subtracting the average density of the region 4 from the region 1. Further, the average value calculation unit 53 outputs the average of the regions 1 to 4 as an output.

  Next, the data adding unit 46 will be described with reference to FIG. The data adding unit 46 includes a truncation unit 54, an adding unit 55, a selector 56, and the like. This truncation unit 54 performs DCT, and forcibly sets the density values of the lower right three pixels (solid black) in FIG. 12 in the mask of 8 × 8 pixels of the quantized upper bit data to “0”.

  Further, the adding unit 55 forcibly adds the edge direction, the edge amount, and the average density value obtained by the compression unit 45 to “0”. Then, the selector 56 outputs the data with the lower bits added if the edge determination result is true. On the other hand, if the edge determination result is false, data with no lower bit added is output.

  In this way, the output of the data adding unit 46 is subjected to the Huffman encoding process described above by the encoding unit 47 and is once stored in the storage unit 48. The image stored here can be browsed in the same way as normal JPEG when browsing with an external device.

  The image data stored in the storage unit 48 is read out in response to a request from the user and sent to the image processing unit 49. FIG. 13 shows a detailed block of the image processing unit 49, which includes a first expansion unit 57, an edge determination unit 58, a second expansion unit 59, an adder 60, and the like. The input image input to the image processing unit 49 is expanded by the first expansion unit 57 and then subjected to edge determination by the edge determination unit 58. Since the edge determination unit 58 operates in the same manner as the edge determination unit 11 of FIG. 1 described in the first embodiment, description thereof is omitted.

  Next, referring to the edge determination result by the second decompression unit 59, the 8-bit JPEG is output while being divided into upper 8 bits and lower 2 bits. At this time, if the edge determination result is true, the output of the lower bit data is “0”, and if the edge determination result is false, the edge of the lower bit from the pixel to which the data is added by the data adding unit 46 Read the quantity, edge direction and average value. Then, 8 × 8 pixels corresponding to the upper 8-bit DCT block are divided into two areas according to the read value, and the same value is stored in each area to output the lower bits. The lower bit data created by performing the above processing is added to the upper bits that have been bit shifted to 10 bits and output. FIG. 14 shows the correspondence between values stored in the respective areas, storage patterns, and edge directions.

  As described above, according to the third embodiment, by embedding the lower bit data in the upper bit data string, the upper bit and the lower bit data can be handled as one file. Handling becomes easy.

  In the third embodiment, the edge determination unit 41 of FIG. 7 and the edge determination unit 58 of FIG. 13 control whether or not data is added. By replacing each of the above with the character determination unit shown in the second embodiment, it is possible to control to hold the lower 2 bits in the photo area.

(Fourth embodiment)
The fourth embodiment has almost the same configuration as the image processing apparatus 40 shown in FIG. 7 of the third embodiment, but the internal configurations of the data adding unit 46 and the image processing unit 49 are different. Yes. FIG. 15 is a detailed block diagram illustrating a configuration example of the data adding unit according to the fourth embodiment, and FIG. 16 is a detailed block diagram illustrating a configuration example of the image processing unit according to the fourth embodiment. is there.

  First, the data addition unit 46 shown in FIG. 15 includes a first truncation unit 61, a first addition unit 62, a second truncation unit 63, a second addition unit 64, a selector 65, and the like. The first truncation unit 61 performs DCT, truncates the density values of the lower right four pixels (black and gray in FIG. 12) in the 8 × 8 pixel mask of the quantized upper bit data, and forces To “0”.

  Next, the first addition unit 62 adds the edge direction, edge amount, average density value, and edge determination result obtained by the compression unit 45 of FIG. To do. Note that the edge determination result is stored in the lower right pixel.

  On the other hand, the second truncation unit 63 performs DCT, truncates the density value of the lower right pixel in the 8 × 8 pixel mask of the quantized upper bit data, and forcibly sets it to “0”. . In addition, the second addition unit 64 stores the edge determination result in the lower right pixel in the 8 × 8 pixel mask. Further, the selector 65 outputs the data with the lower bit added if the edge determination result is true, or the data without the lower bit added if the edge determination result is false. To do.

  Next, the image processing unit 49 shown in FIG. 16 includes an expansion unit 66 and an adder 67. The image processing unit 49 refers to the pixel value at the bottom right in the 8 × 8 pixel mask of the input image, and determines the value. Is true, the decompression unit 66 performs decompression processing as it is, and outputs only the upper bits. If the value is false, lower bit data created in the same manner as in the third embodiment from the lower right four pixels (black and gray pixels in FIG. 12) and other than the lower right four pixels are used. Output the higher-order bits. The upper bits are bit-shifted by 2 bits, and an adder 67 sums the lower bits and outputs the result.

  As described above, according to the fourth embodiment, by further adding the edge determination result to the JPEG image, it is not necessary to perform the edge determination again in the image restoration unit, leading to cost reduction.

  In the fourth embodiment, the addition of the lower-order bit data is controlled based on the edge determination result. However, the present invention is not limited to this, and the same processing is naturally performed based on the character determination result. Anyway.

(Fifth embodiment)
FIG. 17 is a block diagram illustrating a configuration of an image processing apparatus according to the fifth embodiment of the present invention. An image processing apparatus 70 illustrated in FIG. 17 includes an image dividing unit 71, a compression unit 72, a storage unit 73, an expansion unit 74, a temporary storage unit 75, an image processing unit 76, and the like.

  The 10-bit image data input to the image processing device 70 is divided into upper 8 bits and lower 2 bits by the image dividing unit 71. The upper 8-bit data is JPEG compressed by the compression unit 72 and then stored in the storage unit 73. The image data stored in the storage unit 73 is read from the storage unit 73 in response to a user request, decompressed by the decompression unit 74, and sent to the image processing unit 76.

  On the other hand, the lower 2-bit data is temporarily stored in the temporary storage unit 75 and is read in time with the upper bit data. In the image processing unit 76, the upper bits are shifted by 2 bits, and a sum with the lower bits is taken by an adder (not shown) and output. The temporary storage unit 75 is overwritten when the next image data is input.

  As described above, according to the fifth embodiment, the capacity of image data in the storage unit 73 as the first storage unit used for long-term storage while maintaining at least 10-bit image quality for the first copy. Can be reduced.

(Sixth embodiment)
FIG. 18 is a block diagram illustrating a configuration of an image processing apparatus according to the sixth embodiment of the present invention. 18 includes an edge determination unit 81, an image division unit 82, a first image compression unit 83, a second image compression unit 84, a temporary storage unit 85, a first switch 86, a storage unit 87, The second switch 88 and the image processing unit 89 are included. The sixth embodiment is a combination of the first or second embodiment and the fifth embodiment described above.

  The 10-bit image data input to the image processing device 80 is subjected to edge determination by the edge determination unit 81. The edge determination unit 81 functions in the same manner as the edge determination unit 11 of FIG. 1 in the first embodiment described above, and thus description thereof is omitted here.

  On the other hand, the input image data is divided by the image dividing unit 82 into upper 8 bits and lower 2 bits. The upper 8-bit image data is JPEG compressed by the first image compression unit 83 and held in the storage unit 87. The lower two bits of image data are compressed by the second image compression unit 84 in accordance with the edge determination result from the edge determination unit 81. The compression method in the second image compression unit 84 operates in the same manner as the second image compression unit 14 in the first embodiment or the second image compression unit 24 in the second embodiment. Therefore, the description is omitted here.

  The low-order bit data compressed in this way is held in the temporary storage unit 85 and also guided to the first switch 86. The first switch 86 is a means for allowing the user to select whether or not to hold the lower-order bit data in the storage unit 87. When the image data is read from the storage unit 87 at the request of the user, the lower bit data is read from the temporary storage unit 85 or the storage unit 87 by the second switch 88 linked to the first switch 86, and the image It is sent to the processing unit 89.

  Further, the first switch 86 or the second switch 88 may be automatically switched depending on the device configuration, not on the intention of the user. For example, it is conceivable to automatically switch according to the capacity of the storage unit provided in the apparatus.

  As described above, according to the sixth embodiment, it is possible to select whether to store the lower bits for many years or discard the lower bit data except for the first copy according to the intention of the user or the device configuration. Image data can be recorded and used according to the circumstances of the user.

  As described above, the image processing apparatus, the image processing method, and the storage medium storing the method according to the present invention are capable of image degradation as much as possible when the read image data of a copying machine or the like is accumulated in a hard disk or the like. Is suitable for an image processing apparatus capable of compression processing capable of reducing storage capacity, an image processing method, and a storage medium storing the method.

It is a block diagram explaining the structure of the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a waveform diagram of input image data. FIG. 2 is a waveform diagram of upper bits when the waveform of FIG. 2-1 is divided into upper bits and lower bits. It is a wave form diagram of a low-order bit. It is a waveform diagram of input image data. FIG. 3 is a waveform diagram of upper bits when the waveform of FIG. 3A is divided into upper bits and lower bits. It is a wave form diagram of a low-order bit. FIG. 2 is a detailed block diagram illustrating a configuration example of an image processing unit in FIG. 1. It is a block diagram explaining the structure of the image processing apparatus which concerns on the 2nd Embodiment of this invention. It is a detailed block diagram which shows the structural example of the character determination part of FIG. It is a block diagram explaining the structure of the image processing apparatus which concerns on the 3rd Embodiment of this invention. It is a detailed block diagram which shows the structural example of the compression part of FIG. It is a figure which shows the area | regions 1-4 which calculate an average density | concentration in the block average calculation part of FIG. It is a figure which shows the correspondence of the determination result in the edge direction determination part of FIG. 8, and output content. It is a detailed block diagram which shows the structural example of the data addition part of FIG. FIG. 12 is a state diagram in which the density values of the lower right three pixels in the 8 × 8 pixel mask of the upper bit data quantized in the truncation unit of FIG. 11 are set to 0; FIG. 8 is a detailed block diagram illustrating a configuration example of an image processing unit in FIG. 7. FIG. 8 is a correspondence pattern diagram for explaining values in which pixels corresponding to a DCT block are divided into two areas and stored from various values read from pixels to which data has been added by the data addition means of FIG. 7. It is a detailed block diagram which shows the structural example of the data addition part which concerns on 4th Embodiment. It is a detailed block diagram which shows the structural example of the image process part which concerns on 4th Embodiment. It is a block diagram explaining the structure of the image processing apparatus which concerns on the 5th Embodiment of this invention. It is a block diagram explaining the structure of the image processing apparatus which concerns on the 6th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image processing apparatus 11 Edge determination part 12 Image division part 13 1st image compression part 14 2nd image compression part 15 Memory | storage part 16 Image processing part 17 1st expansion | extension part 18 2nd expansion | extension part 19 Adder 20 Image Processing device 21 Character determination unit 22 Image division unit 23 First image compression unit 24 Second image compression unit 25 Storage unit 26 Image processing unit 27 Density determination unit 28 Pattern matching unit 29 Expansion unit 30 Contraction unit 31 Edge determination unit 32 AND circuit 41 Edge determination unit 42 Image division unit 43 Direct transform unit 44 Quantization unit 45 Compression unit 46 Data addition unit 47 Encoding unit 48 Storage unit 49 Image processing unit 50 Block average calculation unit 51 Edge direction determination unit 52 Edge amount calculation Unit 53 average value calculation unit 54 truncation unit 55 addition unit 56 selector 57 first extension unit 58 edge determination unit 59 second Expansion unit 60 Adder 61 First truncation unit 62 First addition unit 63 Second truncation unit 64 Second addition unit 65 Selector 66 Expansion unit 67 Adder 70 Image processing device 71 Image division unit 72 Compression unit 73 Storage Unit 74 decompression unit 75 temporary storage unit 76 image processing unit 80 image processing device 81 edge determination unit 82 image division unit 83 first image compression unit 84 second image compression unit 85 temporary storage unit 86 first switch 87 storage unit 88 Second switch 89 Image processing section

Claims (26)

Image dividing means for dividing the image data into two image data of upper bits and lower bits; first image compression means for compressing the image data of the upper bits;
Second image compression means for compressing the lower-bit image data;
Storage means for storing compressed upper and lower bit image data;
Image processing means for reading out image data of upper bits and lower bits from the storage means and performing image processing;
An image processing apparatus, comprising: reading out upper bit image data from the storage means and transmitting the image data to an external device.   The image processing apparatus according to claim 1, wherein the first image compression unit and the second image compression unit have different compression ratios.   The image processing apparatus according to claim 1, wherein the first image compression unit and the second image compression unit have different compression methods. It further comprises a feature determination means for determining the feature of the attention area,
2. The image processing apparatus according to claim 1, wherein, when a gradation change equal to or greater than a predetermined gradient is observed in the attention area, lower-order bit data of the corresponding area is discarded. Attribute determination means for determining the attribute of the attention area is further provided,
The image processing apparatus according to claim 1, wherein if a character area exists in the attention area, lower-order bit data of the corresponding area is discarded. A feature determination means for determining the feature of the region of interest;
Image dividing means for dividing the image data into two image data of upper bits and lower bits;
Direct conversion means for performing direct conversion on the upper bit image data;
A quantization means for quantizing the data after the orthogonal transformation;
Compression means for compressing the lower bit image data;
Data adding means for adding compressed lower-bit image data to the quantized data;
Storage means for storing image data to which data is added;
Decompression means for reading out image data from the storage means and decompressing the image;
Image processing means for performing predetermined image processing on the expanded image;
An image processing apparatus comprising:   The image processing apparatus according to claim 6, wherein the data adding unit does not add compressed lower-bit image data in an area where a gradation change equal to or greater than a predetermined gradient is seen. Attribute determination means for determining the attribute of the attention area;
Image dividing means for dividing the image data into two image data of upper bits and lower bits;
Direct conversion means for performing direct conversion on the upper bit image data;
A quantization means for quantizing the data after the orthogonal transformation;
Compression means for compressing the lower bit image data;
Data adding means for adding the compressed lower bit image data to the quantized data;
Storage means for storing image data to which the data is added;
Decompression means for reading out image data from the storage means and decompressing the image;
Image processing means for performing predetermined image processing on the expanded image;
An image processing apparatus comprising:   The image processing apparatus according to claim 8, wherein the data adding unit does not add compressed lower-bit image data in an area including a character area.   The image processing apparatus according to claim 6, wherein the data adding unit simultaneously holds a flag indicating whether or not data is added.   The image processing apparatus according to claim 6, wherein the image processing unit includes a second feature determination unit that determines a feature of the image with respect to the decompressed image.   12. The image processing apparatus according to claim 11, further comprising second image dividing means for dividing again the data added according to the second feature determining means.   The image processing apparatus according to claim 6, wherein the image processing unit includes a second attribute determination unit that determines an attribute of the image with respect to the decompressed image. .   The image processing apparatus according to claim 13, further comprising second image dividing means for dividing again the data added according to the second attribute determining means.   The image processing apparatus according to claim 6, wherein the compression unit holds at least an average value of lower-order bit images.   The image processing apparatus according to claim 6, wherein the compression unit holds at least a gradient value of a lower-order bit image.   The image processing apparatus according to claim 6, wherein the compression unit holds at least a gradient direction of the lower-order bit image. Image dividing means for dividing the image data into two image data of upper bits and lower bits;
First storage means for storing the upper bit image data;
Second storage means for storing image data of the lower bits;
Image processing means for reading image data of upper bits from the first storage means and performing image processing while referring to image data of lower bits read from the second storage means;
An image processing apparatus comprising: reading out high-order bit image data from the first storage unit and transmitting the image data to an external device.   The image processing apparatus according to claim 18, wherein the second storage unit temporarily stores image data of lower bits.   The image processing apparatus includes a selection unit that can select whether the lower-order bit image data divided by the image division unit is stored in either the first storage unit or the second storage unit according to a user's intention. The image processing apparatus according to claim 18 or 19.   The image processing apparatus includes a selection unit that can select whether the lower-order bit image data divided by the image division unit is stored in either the first storage unit or the second storage unit depending on the configuration of the apparatus. The image processing apparatus according to claim 18 or 19. Dividing the image data into two image data of upper bits and lower bits;
Compressing the upper bit image data;
Compressing the lower bit image data;
Storing compressed upper and lower bit image data in storage means;
Reading the stored upper bit and lower bit image data and performing image processing;
An image processing method comprising: reading image data of upper bits from the storage means and transmitting the image data to an external device. Determining features of the region of interest;
Dividing the image data into two image data of upper bits and lower bits;
Direct conversion of upper bit image data;
Quantizing the data after direct transformation;
Compressing the lower bit image data;
Adding compressed low-order bit image data to the quantized data;
Storing the image data with the data added thereto;
Reading the stored image data to decompress the image;
Performing predetermined image processing on the expanded image;
An image processing method including: Determining the attribute of the region of interest;
Dividing the image data into two image data of upper bits and lower bits;
Direct conversion of the upper bit image data;
Quantizing the data after direct transformation;
Compressing the lower bit image data;
Adding the compressed lower bit image data to the quantized data;
Storing image data to which the data is added;
Reading the stored image data to decompress the image;
Performing predetermined image processing on the expanded image;
An image processing method including: Dividing the image data into two image data of upper bits and lower bits;
Storing the upper bit image data;
Storing the lower bit image data;
Reading the stored upper bit image data and performing image processing while referring to the stored lower bit image data;
An image processing method comprising: reading image data of upper bits stored therein and transmitting the image data to an external device.   A storage medium for storing the image processing method according to any one of claims 22 to 25.

Images