JP2004112532A - Image processing apparatus, image reading apparatus, image forming apparatus, television camera, image outputting apparatus, information processing apparatus, program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the image quality of an image reproduced in compressing and encoding image data having an anisotropy in vertical and horizontal directions like the case that variable power processing is different in vertical and horizontal directions. <P>SOLUTION: When a main scanning direction in which edge rounding is likely to occur by applying electric variable power processing by an interpolation method is in the horizontal direction of wavelet transform processing with respect to a sub-scanning direction to which mechanical variable power processing is applied, a quantization level assigned to wavelet coefficients positioned at hierarchies 1LH, 2LH and so on of a sub-band LH system is relatively suppressed (made to be a low compression rate) so as to be lower than a quantization level assigned to wavelet coefficients positioned at hierarchies 1HL, 2HL and so on of the other sub-band HL system, thereby reducing the influence of the edge rounding on the image quality to improve the image quality of an image to be reproduced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing device that handles various types of image data, an image reading device, an image forming device, a television camera, an image output device, an information processing device, a program, and a storage medium.
[0002]
[Prior art]
In recent years, with the progress of image input / output technology, demands for higher definition of images have been increasing. As an example of an image input device, taking a digital camera as an example, the price of a high-performance charge-coupled device having more than 3 million pixels has been reduced, and it has been widely used in products in a popular price range. I have. In the technical field of image output devices and image display devices, high definition and low cost in hard copy fields such as laser printers and ink jet printers are remarkable. The field of an image forming apparatus such as a multifunction peripheral (MFP) is no exception.
[0003]
With the effect of bringing high-performance, low-cost image input / output products to the market, the popularization of high-definition images has begun, and in the future, demand for high-definition images is expected to increase in all situations.
[0004]
Against the background of the above, the demand for compression / decompression technology that can easily handle high-definition images will inevitably increase in the future. Therefore, as one of the image compression techniques satisfying such a demand, conventionally, JPEG2000, which can process a high-definition image by dividing it into small units and can decode a high-quality image even at a high compression ratio, is known. There is technology.
[0005]
Accordingly, high-definition image compression / decompression technology such as JPEG2000 is also installed in image forming apparatuses such as copiers and multifunction peripherals to save memory and the like. After that, the code data is decompressed in the reverse procedure and output to the printer as image data, whereby the copy printing operation tends to be executed.
[0006]
By the way, many copiers and multifunction peripherals have an enlargement / reduction scaling function as one of the functions. In general, the scaling process is performed by an electrical scaling process such as a well-known cubic convolution interpolation method in the main scanning direction, and the moving speed of the sub-scanning means (scanner carriage) is changed in the sub-scanning direction. It is performed by a variable magnification process.
[0007]
For example, with reference to FIG. 20, an example of a case in which the image is enlarged twice vertically and horizontally will be described. Assuming that the main scanning direction and the sub-scanning direction for the document D are set as shown in FIG. By changing the moving speed of the carriage according to the scaling factor of 2 (1/2 the speed at the same magnification) and reading the original D by the scanner, as shown in FIG. (2 times) is mechanically performed. The image data read by the scanner in response to the sub-scanning scaling process is subjected to an electrical scaling process in the main scanning direction by a cubic convolution interpolation method. As shown in ()), the magnification (2 times) in the main scanning direction is electrically performed, and as a result, image data enlarged to 2 times vertically and horizontally is obtained.
[0008]
The image data that has been subjected to the scaling process in this manner is compressed and encoded once in accordance with the JPEG2000 algorithm or the like, and stored in a memory as code data. Then, the code data is decompressed in the reverse procedure and output to the printer as image data. By doing so, a copy printing operation is executed.
[0009]
[Problems to be solved by the invention]
However, the electrical interpolation method used for scaling in the main scanning direction, even with the cubic convolution interpolation method, which is said to be the most accurate, has a sharper edge than the highly accurate mechanical scaling processing. There is a problem that comes out. That is, as described above, two-dimensional image data having different scaling processes in the vertical and horizontal directions can be said to have anisotropy in the vertical and horizontal directions.
[0010]
For example, consider the case where a rectangular pulse-shaped image as shown in FIG. 21 is read. When the original image is subjected to sub-scanning and main scanning at each sampling point S1, S2,... Indicated by a circle at the same magnification, and the image data is acquired at the corresponding point on the image, for example, at the time of double magnification, Since the sampling speed in the sub-scanning direction is halved, the original image is also read at a point indicated by a cross mark between the sampling points S1, S2,. The data is both data indicated by a mark and a mark. Therefore, when the state of the image data is reproduced, a high-precision data state without edge rounding is obtained as shown by a solid line in FIG. On the other hand, the sampling points in the main scanning direction remain at the sampling points S1, S2,... Shown by the circles, and the image data shown by the circles are supplemented by an electrical interpolation method. As shown by the broken line in FIG.
[0011]
Image data that has undergone such scaling processing is coded through compression coding processing as described above, but during the quantization process in the middle thereof, the same quantization threshold as in the case of equal magnification is used. The quantization is performed using the level, and as can be seen from FIG. 21B, the image data in the main scanning direction that causes edge rounding tends to be thin depending on the threshold level of the quantization. As a result, when the code data is decoded and expanded by image data expanded, the image in the main scanning direction is easily blurred as shown in FIG. 22 (the horizontal line of the grid image in the illustrated example is thin or thin). This causes a difference in image quality between the image and the image in the sub-scanning direction without edge rounding.
[0012]
Although the above description has been given of the processing example at the time of enlargement / magnification during the magnification / reduction processing, the electric magnification / reduction processing is performed at the time of reduction / enlargement, although the degree is often lower than at the time of enlargement / magnification. The edges of the image data in the main scanning direction may become dull.
[0013]
Such a situation (anisotropic in the vertical and horizontal directions for two-dimensional image data) is caused not only by the fact that the magnification process differs in the vertical and horizontal directions in a copying machine or the like, but also in various cases. There is.
[0014]
For example, even in an information processing apparatus such as a personal computer, in the case where an editing operation with a different vertical / horizontal ratio or a different horizontal / horizontal magnification is performed on captured image data, anisotropy due to a difference in vertical / horizontal magnification is required. Will be provided. In this case, the scaling process in any direction is an electrical scaling process, but the larger the scaling ratio, the greater the degree of edge rounding, resulting in a difference in the reproduced image quality in the vertical and horizontal directions. Would.
[0015]
Also, in a copying machine or a printer, even if the original image data is normal, the copying machine or the printer always has vertical lines as shown in FIG. 23 due to, for example, development conditions and transfer conditions. In some cases, the image data has a tendency to appear thicker (or opposite) than the horizontal line, and it can be said that the image data has anisotropy in the vertical and horizontal directions in the output form. In particular, in the case of a document image including a lattice image as shown in the illustrated example, it may appear remarkably. Therefore, in the case of such a copying machine, a difference in image quality occurs in the vertical and horizontal directions not only at the time of the variable-size copy but also at the time of the same-size copy.
[0016]
Further, even in a television camera which reads an image of an object to be imaged by performing two-dimensional raster scanning by an interlace method using an image sensor, image data is vertically (horizontally) and horizontally (horizontally) due to interlaced raster scanning. And the aspect ratio between the horizontal direction and the vertical direction is 4: 3 or 16: 9, so that the horizontal direction, which is the raster scanning direction, is a direction in which edge rounding is likely to occur. It can be said that.
[0017]
SUMMARY OF THE INVENTION It is an object of the present invention to improve the quality of a reproduced image when compressing and encoding image data having anisotropy in both the vertical and horizontal directions, such as in the case where scaling processing is different in vertical and horizontal directions. .
[0018]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an image processing apparatus for compressing and encoding image data in a sequence of conversion, quantization, and encoding into two-dimensional wavelet coefficients. Anisotropy determining means for determining the presence or absence of anisotropy in the vertical direction and the horizontal direction; and anisotropy factors for image data determined to have anisotropy by the anisotropy determining means. Quantizing means for performing quantization with different compression ratios on the two-dimensional wavelet coefficients in accordance with the sub-band positions in the same layer based on the two-dimensional wavelet coefficients.
[0019]
Therefore, for image data having anisotropy in the vertical direction and the horizontal direction, the compression ratio is determined in accordance with the subband position even in the same layer with respect to the two-dimensional wavelet coefficient based on the anisotropy factor. , The image quality difference caused by the anisotropy can be absorbed by the quantization having different compression rates, and the quality of the reproduced image can be improved.
[0020]
According to a second aspect of the present invention, in the image processing apparatus according to the first aspect, the quantizing means sets a compression ratio in a direction in which edge rounding is likely to occur due to the determined anisotropy factor to a compression ratio in another direction. Quantizations with different compression ratios are performed so as to relatively suppress each other.
[0021]
Therefore, by relatively suppressing the compression ratio in the direction in which edge rounding is likely to occur due to the anisotropy factor, that is, by relatively suppressing quantization, it is possible to reduce the influence on the image quality due to the edge rounding, and to achieve high image quality of the reproduced image. Can be achieved. Conversely, even if the compression ratio in the direction in which edge rounding is less likely to occur is relatively large, the image quality is hardly affected, so that efficient compression encoding can be performed as a whole.
[0022]
According to a third aspect of the present invention, in the image processing apparatus according to the first or second aspect, the quantizing means determines a direction of a wavelet transform process corresponding to a direction in which edge rounding is likely to occur due to the determined anisotropy factor. By setting the quantization level assigned to the located wavelet coefficient relatively lower than the quantization level assigned to the wavelet coefficient located in the other direction of the wavelet transform processing, quantization having different compression rates is performed.
[0023]
Therefore, specifically, by relatively suppressing the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the direction in which edge rounding is likely to occur due to anisotropic factors, the edge rounding is suppressed. The influence on the image quality can be reduced, and the quality of the reproduced image can be improved. Conversely, if the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the direction in which edge rounding is less likely to occur is relatively small, it does not affect the image quality even if it is relatively large. Compression encoding is possible.
[0024]
According to a fourth aspect of the present invention, in the image processing apparatus according to the third aspect, when the direction in which edge rounding is likely to occur is a horizontal direction of wavelet transform processing, the quantization means is located in a subband LH system hierarchy. The quantization level assigned to the wavelet coefficient to be assigned is relatively lower than the quantization level assigned to the wavelet coefficient located in the subband HL system hierarchy.
[0025]
Therefore, more specifically, when the direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform process, the quantization level assigned to the wavelet coefficient located in the subband LH system hierarchy is relatively suppressed. In addition, the influence on the image quality due to the edge rounding can be reduced, and the quality of the reproduced image can be improved. Conversely, if the quantization level assigned to the wavelet coefficient located in the subband HL system hierarchy corresponding to the direction in which edge rounding is less likely to occur is relatively small, it does not easily affect the image quality. Efficient compression encoding is possible.
[0026]
According to a fifth aspect of the present invention, in the image processing apparatus according to the third aspect, when the direction in which edge rounding is likely to occur is a vertical direction of a wavelet transform process, the quantization unit is located in a subband HL system hierarchy. The quantization level assigned to the wavelet coefficient to be assigned is relatively lower than the quantization level assigned to the wavelet coefficient located in the subband HL system hierarchy.
[0027]
Therefore, more specifically, when the direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform process, the quantization level assigned to the wavelet coefficient located in the subband HL hierarchy is relatively suppressed. In addition, the influence on the image quality due to the edge rounding can be reduced, and the quality of the reproduced image can be improved. Conversely, if the quantization level assigned to the wavelet coefficient located in the subband LH system layer corresponding to the direction in which edge rounding is less likely to occur does not affect the image quality even if the quantization level is relatively large, the overall effect is low. Efficient compression encoding is possible.
[0028]
According to a sixth aspect of the present invention, in the image processing apparatus according to any one of the second to fifth aspects, the anisotropy determining unit determines a degree of an anisotropic factor, and the quantizing unit determines The degree of compression ratio in the direction in which edge rounding is likely to occur varies according to the degree of the anisotropy factor.
[0029]
Therefore, the degree of edge rounding varies depending on the degree of the anisotropy factor. Therefore, by changing the degree of compression ratio in the direction in which edge rounding is likely to occur according to the degree of the anisotropy factor, the image quality due to the edge rounding is improved. Impact on the vehicle can be further reduced.
[0030]
According to a seventh aspect of the present invention, in the image processing apparatus according to the sixth aspect, the quantization means performs a wavelet transform process corresponding to a direction in which edge rounding is likely to occur according to the degree of the determined anisotropy factor. The quantization levels assigned to the wavelet coefficients located in the directions are made different.
[0031]
Therefore, the degree of edge rounding differs depending on the degree of the anisotropy factor. Therefore, the quantum assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the direction in which edge rounding is likely to occur according to the degree of the anisotropy factor. By changing the level of the conversion level, the influence on the image quality due to the rounded edge can be further reduced.
[0032]
According to an eighth aspect of the present invention, in the image processing apparatus of the seventh aspect, the quantizing means determines that the factor of the determined anisotropy is such that a direction in which edge rounding is likely to occur is a horizontal direction of wavelet transform processing. The quantization levels assigned to the wavelet coefficients located in the sub-band LH system hierarchy are made different according to the degree of.
[0033]
Therefore, the degree of edge rounding differs depending on the degree of the anisotropy factor. More specifically, when the direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, it is located in the subband LH system hierarchy. By making the quantization levels assigned to the wavelet coefficients different from each other, the influence on the image quality due to the edge rounding can be further reduced.
[0034]
According to a ninth aspect of the present invention, in the image processing apparatus according to the seventh aspect, the quantizing means determines the factor of the determined anisotropy when the direction in which edge rounding is likely to occur is a vertical direction of the wavelet transform processing. The quantization levels assigned to the wavelet coefficients located in the subband HL system hierarchy are made different according to the degree of.
[0035]
Therefore, the degree of edge rounding varies depending on the degree of the anisotropy factor. More specifically, if the direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform processing, the edge is positioned in the subband HL hierarchy. By making the quantization levels assigned to the wavelet coefficients different from each other, the influence on the image quality due to the edge rounding can be further reduced.
[0036]
According to a tenth aspect of the present invention, in the image processing apparatus according to any one of the seventh to ninth aspects, the quantization means changes a quantization level assigned to a wavelet coefficient according to a subband hierarchy.
[0037]
Therefore, since the thin line appears as a wavelet coefficient of a higher band hierarchy, the degree of the effect of image quality due to edge rounding differs depending on the subband hierarchy, so that the quantization level assigned to the wavelet coefficient differs depending on the subband hierarchy. By doing so, the influence on the image quality due to the edge rounding can be further reduced.
[0038]
The invention according to claim 11 is an exposure unit that exposes a document, a sub-scanning unit that relatively moves the document and the exposure unit in a sub-scanning direction, and a scanning unit that exposes and scans the document in the sub-scanning direction. A photoelectric conversion element that receives the reflected light, converts the image, and reads the image, and performs magnification in the main scanning direction of the image data read by the photoelectric conversion element by electrical scaling processing, 11. An image reading apparatus having a scaling function for performing scaling by a mechanical scaling process of the sub-scanning means, wherein two-dimensional image data after the scaling process is subjected to compression encoding. The image processing apparatus according to any one of the above, and a storage device that stores code data compression-encoded by the image processing apparatus, the anisotropy determination unit provided in the image processing apparatus, the main scanning direction And sub-scanning method It has known anisotropic in the vertical direction and the horizontal direction of the difference of the magnification processing on the image data as a factor in the main scanning direction is determined and prone direction of the edge rounding.
[0039]
Therefore, by providing the image processing device according to any one of claims 1 to 10, the image data is known in the vertical direction and the horizontal direction due to the difference in the scaling process between the main scanning direction and the sub-scanning direction. For an image reading device having anisotropy and in which the main scanning direction is determined to be a direction in which edge rounding is likely to occur, compression encoding of image data after scaling processing with small vertical and horizontal image quality differences can be performed. The quality of the reproduced image can be improved.
[0040]
According to a twelfth aspect of the present invention, in the image reading apparatus according to the eleventh aspect, the quantization means assigns a quantization level to be assigned to a wavelet coefficient located in a direction of the wavelet transform corresponding to the main scanning direction. Quantization with a different compression ratio is performed by making the quantization level relatively lower than the quantization level assigned to the wavelet coefficient located in the other direction.
[0041]
Therefore, specifically, the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the main scanning direction in which edge rounding is likely to occur due to the anisotropy factor is relatively suppressed, so that the edge The effect on image quality due to rounding can be reduced, and the quality of reproduced images can be improved. Conversely, if the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the sub-scanning direction in which edge rounding is less likely to occur is relatively small, the image quality is hardly affected even if it is relatively large. Enables efficient compression encoding.
[0042]
According to a thirteenth aspect of the present invention, in the image reading device according to the twelfth aspect, when the main scanning direction is the horizontal direction of the wavelet transform processing, the quantization means may include a wavelet coefficient located in a subband LH system hierarchy. Is relatively lower than the quantization level assigned to the wavelet coefficients located in the subband HL hierarchy.
[0043]
Therefore, more specifically, when the main scanning direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, the quantization level assigned to the wavelet coefficients located in the subband LH system hierarchy is relatively suppressed. As a result, the influence of the edge rounding on the image quality can be reduced, and the quality of the reproduced image can be improved. Conversely, if the quantization level assigned to the wavelet coefficient located in the subband HL hierarchy corresponding to the sub-scanning direction in which edge rounding is less likely to occur, the image quality is hardly affected even if the quantization level is relatively large. As a result, efficient compression encoding becomes possible.
[0044]
According to a fourteenth aspect of the present invention, in the image reading apparatus according to the twelfth aspect, when the main scanning direction is a vertical direction of the wavelet transform processing, the quantization means may include a wavelet coefficient located in a subband HL hierarchy. Is relatively lower than the quantization level assigned to the wavelet coefficients located in the subband HL hierarchy.
[0045]
Therefore, more specifically, when the main scanning direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform processing, the quantization level assigned to the wavelet coefficients located in the subband HL system hierarchy is relatively suppressed. As a result, the influence of the edge rounding on the image quality can be reduced, and the quality of the reproduced image can be improved. Conversely, if the quantization level assigned to the wavelet coefficient located in the sub-band LH layer corresponding to the sub-scanning direction in which edge rounding is less likely to occur, the image quality is hardly affected even if the quantization level is relatively large. As a result, efficient compression encoding becomes possible.
[0046]
According to a fifteenth aspect of the present invention, in the image reading apparatus according to any one of the eleventh to fourteenth aspects, the quantizing unit is configured such that, when the magnification in the main scanning direction is a reduction / magnification, it is larger than when the magnification / magnification is used. Also, the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the main scanning direction is increased.
[0047]
Therefore, even in the case of the reduction / magnification, the edge may be rounded in the main scanning direction in which the electric magnification processing is performed. However, in general, the degree thereof is often lower than that in the magnification / magnification. By setting the quantization level higher than that, it is possible to appropriately cope with the problem.
[0048]
According to a sixteenth aspect of the present invention, in the image reading apparatus according to any one of the eleventh to fifteenth aspects, the anisotropy determining unit determines a designated magnification in the main scanning direction as a factor of the anisotropy. Then, the quantizing means changes the degree of compression in the main scanning direction in accordance with the magnification in the main scanning direction.
[0049]
Therefore, the degree of edge rounding differs depending on the magnification in the main scanning direction, which is a factor of anisotropy, and the degree of edge rounding increases as the magnification increases. By varying the degree of compression ratio, the influence on the image quality due to the edge rounding can be further reduced.
[0050]
According to a seventeenth aspect of the present invention, in the image reading apparatus according to the sixteenth aspect, the quantizing means converts the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the main scanning direction in accordance with the magnification in the main scanning direction. Different quantization levels are assigned.
[0051]
Therefore, the degree of edge rounding varies depending on the magnification in the main scanning direction that causes anisotropy, and the degree of edge rounding increases as the magnification increases, so that edge rounding tends to occur depending on the magnification. By changing the degree of the quantization level assigned to the wavelet coefficient located in the direction of the corresponding wavelet transform processing, the influence on the image quality due to the rounded edge can be further reduced.
[0052]
According to an eighteenth aspect of the present invention, in the image reading apparatus according to the seventeenth aspect, when the main scanning direction is the horizontal direction of the wavelet transform processing, the quantization unit may determine the subband LH according to the magnification in the main scanning direction. Different quantization levels are assigned to the wavelet coefficients located in the system hierarchy.
[0053]
Therefore, the degree of edge rounding varies depending on the magnification in the main scanning direction which causes anisotropy. The degree of edge rounding increases as the magnification increases, and more specifically, the direction in which edge rounding is likely to occur. Is in the horizontal direction of the wavelet transform processing, by changing the quantization levels assigned to the wavelet coefficients located in the subband LH system hierarchy, the influence on the image quality due to the edge rounding can be further reduced. .
[0054]
According to a nineteenth aspect of the present invention, in the image reading device according to the seventeenth aspect, when the main scanning direction is the vertical direction of the wavelet transform processing, the quantization means may control the sub-band HL according to the magnification in the main scanning direction. Different quantization levels are assigned to the wavelet coefficients located in the system hierarchy.
[0055]
Therefore, the degree of edge rounding varies depending on the magnification in the main scanning direction which causes anisotropy. The degree of edge rounding increases as the magnification increases, and more specifically, the direction in which edge rounding is likely to occur. Is in the vertical direction of the wavelet transform processing, by changing the quantization level assigned to the wavelet coefficients located in the subband HL system hierarchy, the influence on the image quality due to the edge rounding can be further reduced. .
[0056]
According to a twentieth aspect of the present invention, in the image reading apparatus according to any one of the seventeenth to nineteenth aspects, the quantization means varies a quantization level to be assigned to a wavelet coefficient according to a subband hierarchy.
[0057]
Therefore, since the thin line appears as a wavelet coefficient of a higher band hierarchy, the degree of the effect of image quality due to edge rounding differs depending on the subband hierarchy, so that the quantization level assigned to the wavelet coefficient differs depending on the subband hierarchy. By doing so, the influence on the image quality due to the edge rounding can be further reduced.
[0058]
According to a twenty-first aspect of the present invention, there is provided an image forming apparatus, comprising: an image reading device according to any one of the eleventh to twentieth aspects; and decoding means for decoding code data read by the image reading device and subjected to image processing by the image processing device. A printer engine for forming an image on a sheet based on the image data decompressed by the printer engine.
[0059]
Therefore, by providing the image reading device according to any one of claims 11 to 20, it is possible to perform compression encoding on image data after scaling processing with a small difference in image quality in the vertical and horizontal directions, and to perform image encoding of an image reproduced by the printer engine. High image quality can be achieved.
[0060]
According to a twenty-second aspect of the present invention, in a television camera which reads an object to be imaged in a two-dimensional manner by an image sensor in a two-dimensional raster scanning manner, two-dimensional image data taken is to be subjected to compression encoding. 10. The image processing apparatus according to claim 10, further comprising: a storage device configured to store code data compression-encoded by the image processing device. Due to the raster scanning of the system, the image data has a known anisotropy in the vertical and horizontal directions, and the horizontal direction, which is the raster scanning direction, is determined as the direction in which edge rounding is likely to occur.
[0061]
Therefore, by providing the image processing apparatus according to any one of claims 1 to 10, the image data has a known anisotropy in the vertical direction and the horizontal direction due to the interlaced raster scanning, and the raster scanning is performed. For a television camera in which the horizontal scanning direction is determined to be a direction in which edge rounding is likely to occur, compression encoding with small vertical and horizontal image quality differences becomes possible for image data after image capturing, and an image reproduced on a television or the like can be encoded. High image quality can be achieved.
[0062]
According to a twenty-third aspect of the present invention, there is provided an image processing apparatus as set forth in any one of the first to tenth aspects, wherein input means for inputting image data, and two-dimensional image data input by the input means are subjected to compression encoding. Device, a storage device for storing code data compressed and encoded by the image processing device, decoding means for decoding the code data stored in the storage device into image data, and a known device in the vertical direction and the horizontal direction. And output means for performing a two-dimensional image output process based on the image data decoded by the decoding means, wherein the anisotropy determination means provided in the image processing apparatus, The image data has a known anisotropy in the vertical direction and the horizontal direction due to a difference in the known output characteristics between the vertical direction and the horizontal direction in the output unit. Judges prone direction of Ri.
[0063]
Therefore, by providing the image processing device according to any one of claims 1 to 10, the image data is output in the vertical direction and the horizontal direction due to a difference in known output characteristics between the vertical direction and the horizontal direction in the output unit. In an image output device having a known anisotropy in an output direction determined as a direction in which edge rounding is likely to occur due to a difference in a known output characteristic, quantization of image data is performed so that anisotropy in an output unit is eliminated. By giving the opposite anisotropy at each stage and canceling each other, it is possible to improve the image quality of the image reproduced by the output unit.
[0064]
According to a twenty-fourth aspect of the present invention, in the image output device according to the twenty-second aspect, the input means is a scanner, the output means is a printer, and the difference between the known output characteristics in the vertical direction and the horizontal direction is printed. This is the difference in the direction in which the thick line / thin line appears on the image.
[0065]
Therefore, in the case where the image output apparatus according to claim 22 is a copying machine, and the model has a characteristic that printout characteristics are likely to produce a thick line in either the vertical direction or the horizontal direction, the characteristic is It is possible to obtain a high-quality copy image that is canceled out and has no difference in image quality between the vertical direction and the horizontal direction.
[0066]
According to a twenty-fifth aspect of the present invention, the data acquisition means for acquiring image data, and the two-dimensional image data acquired by the data acquisition means is subjected to a compression encoding in accordance with a user operation. An image processing device according to any one of the above, a storage device that stores code data that has been compression-encoded by the image processing device, and a decoding unit that decodes the code data stored in the storage device into image data. And the anisotropy determination means included in the image processing apparatus estimates that the image data has anisotropy in the vertical direction and the horizontal direction due to a specification of a user operation for editing processing.
[0067]
Therefore, by providing the image processing apparatus according to any one of claims 1 to 10, it is estimated that the image data has anisotropy in the vertical direction and the horizontal direction due to the specified content of the user operation for the editing process. With respect to an information processing device such as a personal computer, it is possible to perform compression encoding on image data after an editing operation with a small difference in image quality in the vertical and horizontal directions, thereby improving the image quality of an image reproduced by a display, a printer, or the like.
[0068]
A program according to a twenty-sixth aspect causes a computer of the image processing apparatus to execute the function of each unit in the image processing apparatus according to any one of the first to tenth aspects.
[0069]
Therefore, the same operation as the invention according to any one of claims 1 to 10 is achieved.
[0070]
A computer-readable storage medium according to a twenty-seventh aspect stores the program according to the twenty-sixth aspect.
[0071]
Accordingly, an effect similar to that of the twenty-second aspect is obtained.
[0072]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
[0073]
[Outline of JPEG2000]
First, JPEG2000 will be briefly described.
[0074]
FIG. 1 is a functional block diagram for explaining the basics of the JPEG2000 algorithm. As shown in FIG. 1, the JPEG2000 algorithm includes a color space transform / inverse transform unit 101, a two-dimensional wavelet transform / inverse transform unit 102, a quantization / inverse quantize unit 103, an entropy encoding / decode unit 104, a tag process It is configured by the unit 105. Hereinafter, each unit will be described.
[0075]
The color space transform / inverse transform unit 101 and the two-dimensional wavelet transform / inverse transform unit 102 will be described with reference to FIGS.
[0076]
FIG. 2 is a schematic diagram illustrating an example of each of the divided components of an original image that is a color image. In a color image, as shown in FIG. 2, components R, G, and B (111) of the original image are generally separated by, for example, an RGB primary color system. Then, the components R, G, and B of the original image are further divided by the tiles 112, which are rectangular regions. Each tile 112, for example, R00, R01, ..., R15 / G00, G01, ..., G15 / B00, B01, ..., B15 constitutes a basic unit when executing the compression / decompression process. Therefore, the compression / expansion operation is performed independently for each of the components R, G, B (111) and for each tile 112.
[0077]
Here, at the time of encoding the image data, the data of each tile 112 is input to the color space conversion / inverse conversion unit 101 shown in FIG. At 102, a two-dimensional wavelet transform (forward transform) is applied and spatially divided into frequency bands.
[0078]
FIG. 3 is a schematic diagram showing subbands at each decomposition level when the number of decomposition levels is three. The two-dimensional wavelet transform / inverse transform unit 102 performs a two-dimensional wavelet transform on the tile original image (0LL) (decomposition level 0) obtained by dividing the original image into tiles, Separate the bands (1LL, 1HL, 1LH, 1HH). Then, the two-dimensional wavelet transform / inverse transform unit 102 continuously performs a two-dimensional wavelet transform on the low-frequency component 1LL in this layer, and outputs the sub-bands (2LL, 2HL, 2LH, 2HH) shown in the decomposition level 2. Is separated. Similarly, the two-dimensional wavelet transform / inverse transform unit 102 sequentially performs the two-dimensional wavelet transform on the low-frequency component 2LL, and separates the sub-bands (3LL, 3HL, 3LH, 3HH) shown in the decomposition level 3. I do. In FIG. 3, the subbands to be coded at each decomposition level are shown in gray. For example, if the number of decomposition levels is 3, the gray subbands (3HL, 3LH, 3HH, 2HL, 2LH, 2HH, 1HL, 1LH, 1HH) are to be encoded, and the 3LL subband is not encoded. .
[0079]
Next, in the quantization / inverse quantization unit 103, after bits to be encoded are determined in the specified encoding order, a context is generated from bits around the target bits.
[0080]
FIG. 4 is a schematic diagram illustrating a precinct. The wavelet coefficients after the quantization process are divided into non-overlapping rectangles called “precincts” for each subband. This was introduced to make efficient use of memory in the implementation. As shown in FIG. 4, one precinct is composed of three rectangular regions that spatially match. Furthermore, each precinct is divided into non-overlapping rectangular “code blocks”. This is a basic unit when performing entropy coding.
[0081]
FIG. 5 is a schematic diagram showing an outline of a process of decomposing the values of the two-dimensional wavelet coefficients after the two-dimensional wavelet transform into “bit planes” and ranking the “bit planes” for each pixel or code block. . The coefficient value after the wavelet transform can be quantized and coded as it is. However, in JPEG2000, in order to increase the coding efficiency, the coefficient value is decomposed into "bit planes" and " A "bit plane" can be ranked. FIG. 5 briefly shows the procedure. In this example, the original image (32 × 32 pixels) is divided into four 16 × 16 pixel tiles, and the size of the precinct at the decomposition level 1 and the size of the code block are each 8 × 8 pixels. And 4 × 4 pixels. The precinct and code block numbers are assigned in raster order. The pixel expansion outside the tile boundary is performed by using a mirroring method, performing a wavelet transform using a reversible (5, 3) filter, and obtaining a wavelet coefficient value of decomposition level 1.
[0082]
FIG. 5 also shows a conceptual schematic diagram of a representative “layer” for tile 0 / precinct 3 / code block 3. The layer structure is easy to understand when the wavelet coefficient value is viewed from the horizontal direction (bit plane direction). One layer is composed of an arbitrary number of bit planes. In this example, layers 0, 1, 2, and 3 are each composed of three bit planes of 1, 3, and 1. Then, a layer including a bit plane closer to the LSB is subject to quantization first, and conversely, a layer closer to the MSB remains unquantized to the end. A method of discarding from a layer close to the LSB is called truncation, and it is possible to finely control the quantization rate.
[0083]
Next, the entropy encoding / decoding unit 104 will be described with reference to FIG. FIG. 6 is a schematic diagram illustrating a code stream of encoded image data. The entropy encoding / decoding unit 104 (see FIG. 1) encodes each component RGB tile 112 by probability estimation from the context and the target bit. In this way, the encoding process is performed on all the components RGB of the original image in tile 112 units.
[0084]
Next, the tag processing unit 105 will be described. The tag processing unit 105 combines all encoded data from the entropy encoding / decoding unit 104 into one code stream and performs a process of adding a tag to the code stream. FIG. 6 briefly shows the structure of the code stream. Tag information called a header is added to the head of such a code stream and the head of a partial tile constituting each tile 112, and thereafter, encoded data of each tile 112 follows. Then, a tag is placed again at the end of the code stream.
[0085]
On the other hand, at the time of decoding, image data is generated from the code stream of each tile 112 of each component RGB, contrary to the encoding. Such a process will be briefly described with reference to FIG. The tag processing unit 105 interprets the tag information added to the code stream input from the outside, decomposes the code stream into a code stream of each tile 112 of each component RGB, and a code stream of each tile 112 of each component RGB. A decryption process is performed for each. At this time, the positions of the bits to be decoded are determined in the order based on the tag information in the code stream, and the quantization / dequantization unit 103 sets the peripheral bits of the target bit positions (decoding has already been performed. Is generated from the sequence of Then, the entropy coding / decoding section 104 performs decoding by probability estimation from the context and the code stream to generate a target bit, and writes it to the position of the target bit. Since the data decoded in this manner is spatially divided for each frequency band, the two-dimensional wavelet transform / inverse transform unit 102 performs an inverse two-dimensional wavelet transform on the data to obtain each component in the image data. Each tile 112 in RGB is restored. The restored data is converted into the original color system data by the color space conversion / inversion unit 101.
[0086]
[Configuration Example of Image Forming Apparatus Including Image Processing Apparatus and Image Reading Apparatus]
This embodiment shows an example of application to a digital full-color copying machine as an image forming apparatus having the above-described JPEG2000 function in an image processing apparatus, and FIG. 7 shows a schematic configuration example thereof.
[0087]
The digital color copying machine 1 has a function as a multifunction machine as will be described later. The printer 2 is a color printer functioning as a printer engine, and a color image as an image reading device installed on the printer 2. And a scanner 3 which is a scanner.
[0088]
The printer 2 forms an image by an electrophotographic method in an image forming unit 4 based on image data of a document optically read by a scanner 3 and image data transmitted from an external device, and sends the image to a paper feeding unit. 5 is transferred to a sheet P which is a recording medium conveyed through a sheet conveying path 7 by a sheet conveying section 6, and the sheet P on which an image is transferred is conveyed to a fixing section 9 by a conveying belt 8, and the transferred image of the sheet P is transferred. Is heated and pressurized by a fixing unit 9 and is discharged and discharged to a discharge tray 10.
[0089]
The image forming unit 4 includes a charging unit 12 that uniformly charges the surface of the photoconductor 11 around the rotating drum-shaped photoconductor 11, and an image for each color obtained by exposing and scanning the uniformly charged surface of the photoconductor 11. Exposure unit 13 for forming an electrostatic latent image based on data on photoconductor 11, electrostatic latent image for each color including cyan (C), magenta (M), yellow (Y), and black (K) toners A revolver type color developing unit 14 for forming a visible toner image by adhering toner corresponding to the image, and an intermediate for sequentially transferring toner images of respective colors onto an intermediate transfer belt 15 supported by a plurality of rollers. The transfer unit 16 is formed by arranging a photoconductor cleaning unit 17 for scraping off toner remaining on the photoconductor 11 without being transferred onto the intermediate transfer belt 15, a charge removing unit 18 for removing charges on the photoconductor 11, and the like. Have Further, a transfer unit 19 for collectively transferring the toner images on the intermediate transfer belt 15 onto the sheet P and a belt cleaning unit 20 for scraping off the toner remaining on the intermediate transfer belt 15 without being collectively transferred onto the sheet P are provided. Is formed.
[0090]
Next, the scanner 3 will be described. The scanner 3 includes a scanner body 21 and an ADF (automatic document feeder) 22 which is a document feeder provided on the upper part of the scanner body 21. On the upper surface of the housing 23 of the scanner body 21, a placed original glass 24 on which an original is placed when reading an original image in the original fixed mode, and a transport used when reading the original image in the original transport mode. A document glass 25 is provided. Here, the document fixing mode is an operation mode for reading an image of a document placed on the placed document glass 24, and the document transport mode is for automatically feeding a document by the ADF 22 and automatically feeding the document. This is an operation mode in which an image of a paper document is read when the paper document passes over the glass sheet 25 for conveyance.
[0091]
Further, an illumination lamp (high-intensity Xe lamp) 26 and a mirror 27 as exposure means for irradiating the original with light are provided at a position inside the housing 23 and facing the placed original glass 24 from below. One traveling body 28 is disposed movably in the sub-scanning direction along the placed original glass 24. A second traveling body 31 including two mirrors 29 and 30 is arranged on the reflected light path of the first traveling body 28 so as to be movable in the sub-scanning direction along the placed document glass 24. An SBU (Sensor Board Unit) 34 mounted with a CCD (Charge Coupled Device) 33 which is a color line sensor via a lens 32 is located in the reflected light path of the two-wheeled vehicle 31. Note that the CCD 33 functions as a photoelectric conversion element.
[0092]
A stepping motor 35 is connected to the first traveling body 28 and the second traveling body 31 as sub-scanning means by pulleys, wires, or the like (neither is shown). The body 31 is movable in the same sub-scanning direction from the left side to the right side in FIG. 7 at a speed ratio of 2: 1. Note that the digital color copying machine 1 of the present embodiment has a scaling function, and at the time of enlarging / reducing copying, the speed of the stepping motor 35 is controlled in accordance with the scaling factor, thereby making the first step. By changing the moving speed of the second traveling bodies 28 and 31 with respect to the original, the magnification change processing in the sub-scanning direction is mechanically performed. The scaling in the main scanning direction is performed by an electrical scaling process described later.
[0093]
Next, FIG. 8 is a block diagram showing the electrical connection of such a digital color copying machine 1. The reading unit (CCD) 33 in the scanner 3 for optically reading a document image is mounted on the SBU 34 as described above, and the image signal converted into an electric signal in the reading unit (CCD) 33 is converted into a digital image signal. Thereafter, the data is output from the SBU 34. The image signal output from the SBU 34 is input to a CDIC (compression / decompression and data interface control unit) 41. The transmission of image data between the functional device and the data bus is entirely controlled by the CDIC 41. The CDIC 41 performs data transfer between the SBU 34, parallel bus 42, and IPP (image processing processor) 43, and communication between a system controller (CPU) 44 that controls the entire system and a process controller 45 for image data. Do. Reference numerals 44a and 44b are ROM and RAM used by the system controller 44. The image signal from each SBU 34 is transferred to the IPP 43 via the CDIC 41, and the signal deterioration (referred to as the signal deterioration of the scanner system) due to the quantization into the optical system and the digital image signal is corrected and output to the CDIC 41 again. Is done.
[0094]
That is, the system controller 44 is a microcomputer that has a CPU and controls each unit of the apparatus according to a control program written in the ROM 44a while using the RAM 44b as a work area. The ROM 44a is a memory that stores an image processing program for the system controller 44 to control each unit of the above-described apparatus, and other control programs. That is, in the present embodiment, the ROM 44a stores an image processing program for realizing various functions described later, and the ROM 44a functions as a storage medium storing the program. For this reason, in the present embodiment, the ROM 44a is composed of, for example, an EEPROM or a flash memory, and the program stored in the ROM 44a is rewritable. Although not shown, if a program is to be downloaded via a network, a network interface may be added.
[0095]
In the digital color copying machine 1, there are a job for storing the image read by the reading unit 33 in the memory for reuse and a job for not storing the image in the memory. Each case will be described below. As an example of storing the data in the memory, when a plurality of copies of the same document are copied, the reading unit 33 performs the reading operation of the document only once, stores the document in the memory, and reads the stored data a plurality of times. As an example in which no memory is used, when only one document is copied, the read image may be printed as it is, so that it is not necessary to access the memory.
[0096]
First, when the memory is not used, the image data transferred from the IPP 43 to the CDIC 41 is returned from the CDIC 41 to the IPP 43 again. In the IPP 43, image quality processing for converting the luminance data by the CCD 33 into the area gradation is performed. The image data after the image quality processing is transferred from the IPP 43 to the VDC (video data control) 46. The post-processing relating to the dot arrangement and the pulse control for reproducing the dots are performed on the signal changed to the area gradation, and the image forming unit 4 which is a printer engine for forming an image in an electrophotographic system performs transfer paper P. A reproduced image is formed thereon.
[0097]
The flow of image data in the case where image data is stored in a memory and additional processing such as rotation in the image direction and image synthesis are performed when image data is read will be described. The image data transferred from the IPP 43 to the CDIC 41 is sent from the CDIC 41 to the IMAC 19 (image memory access control) 47 via the parallel bus 42. The IMAC 47 controls access of image data to a MEM (memory module) 48 as a storage device, develops print data to an external PC (personal computer) 49, and effectively utilizes the memory of the MEM 48 under the control of the system controller 44. Compression / decompression of image data for The image data sent to the IMAC 47 is stored in the MEM 48 after data compression, and the stored data is read out as needed. The read image data is decompressed and returned to the original image data, and is returned from the IMAC 47 to the CDIC 41 via the parallel bus.
[0098]
After the transfer from the CDIC 41 to the IPP 43, the image data is subjected to image quality processing and pulse control by the VDC 46, and an image is formed on the transfer paper P in the image forming unit 4 using the image data.
[0099]
The digital color copying machine 1 is a so-called multifunction machine, and has a facsimile transmission function. The FAX transmission function performs image processing on the read image data by the IPP 43 and transfers the read image data to the FCU (FAX control unit) 50 via the CDIC 41 and the parallel bus 42. The FCU 50 converts the data into a communication network, and transmits the data to a PN (public line) 51 as FAX data. For FAX reception, the line data from the PN 51 is converted into image data by the FCU 50 and transferred to the IPP 43 via the parallel bus 42 and the CDIC 41. In this case, the VDC 46 performs dot rearrangement and pulse control without performing any special image quality processing, and the image forming unit 4 forms a reproduced image on the transfer paper P.
[0100]
In a situation where a plurality of jobs, for example, a copy function, a facsimile transmission / reception function, and a printer output function operate in parallel, the assignment of the right to use the reading unit 33, the imaging unit 4, and the parallel bus 42 to the job is performed by the system controller 44 and the process. It is controlled by the controller 45.
[0101]
A process controller (CPU) 45 controls the flow of image data, and a system controller 44 controls the entire system and manages activation of each resource. Reference numerals 45a and 45b denote ROM and RAM used by the process controller 45.
[0102]
The user selects various functions by selecting and inputting the operation panel 52, and sets processing contents such as a copy function and a FAX function.
[0103]
The system controller 44 and the process controller 45 communicate with each other via the parallel bus 42, the CDIC 41, and the serial bus 53. At this time, in the CDIC 41, data format conversion for a data interface between the parallel bus 42 and the serial bus 53 is performed.
[0104]
FIG. 9 is a block diagram showing a configuration of the IPP 43. The read image is transmitted from the input I / F 61 of the IPP 43 to the scanner image processing unit 62 via the SBU 34 and the CDIC 41. The processing performed by the scanner image processing unit 62 performs shading correction, scanner γ correction, MTF correction, and the like for the purpose of correcting the deterioration of the read image signal. Although not a correction process, the electric enlargement / reduction scaling process in the main scanning direction, which is a target in the present embodiment, is also performed using a cubic convolution interpolation method or the like. After the correction processing of the read image data is completed, the image data is transferred to the CDIC 41 via the output I / F 63. For output to transfer paper, image data from the CDIC 41 is received from the input I / F 64, and the image quality processing unit 65 performs area gradation processing. The data after the image quality processing is output to the VDC 46 via the output I / F 66. The area gradation processing includes density conversion, dither processing, error diffusion processing and the like, and the main processing is area approximation of gradation information. Once the image data subjected to the scanner image processing is stored in the memory 48, various reproduced images can be confirmed by changing the image quality processing. For example, by changing the density of the reproduced image or changing the number of lines of the dither matrix, the atmosphere of the reproduced image can be changed. At this time, it is not necessary to reread the image from the reading unit 38 every time the processing is changed, and if the stored image is read from the MEM 20, different processing can be performed on the same data any number of times.
[0105]
FIG. 10 is a block diagram showing the configuration of the IMAC 47. As shown in FIG. 10, the IMAC 47 manages an interface of image data with the parallel bus 42 in the parallel data I / F 71. The IMAC 47 controls storage / reading of image data to / from the MEM 48 and expansion of code data mainly input from the external PC 49 into image data. Examples of the MEM 48 here include a semiconductor memory, a hard disk, or both. The code data input from the PC 49 is stored in the local area in the line buffer 72. The code data stored in the line buffer 72 is developed into image data in the video control unit 74 based on a development processing command from the system controller 44 input via the system controller I / F 73. The expanded image data or the image data input from the parallel bus 42 via the parallel data I / F 71 is stored in the MEM 48. In this case, the image data to be stored is selected by the data conversion unit 75, data compression is performed as necessary in order to increase the memory use efficiency in the data compression unit 76, and the address of the MEM 48 is stored in the memory access control unit 77. While storing image data in the MEM 48. When reading the image data stored in the MEM 48, the memory access control unit 77 controls the read destination address, and the read data is expanded by the data expansion unit 78 as necessary. An example of an encoding method used for compression and decompression in the data compression unit 76 and the data decompression unit 78 is a highly efficient encoding method suitable for saving the memory area of the MEM 48. This is an encoding system that emphasizes efficiency, unlike the encoding system that emphasizes functions required for the CDIC 41 described above. In the present embodiment, the JPEG2000 format as described above is used. That is, the data compression unit 76 is configured as a JPEG2000 format encoding unit that compresses and encodes image data into code data in the order of two-dimensional wavelet transform, quantization, and encoding, and the data decompression unit 78 performs compression encoding. It is configured as JPEG2000 format decoding means for expanding code data in the reverse order of decoding, inverse quantization, and inverse two-dimensional wavelet transform. When transferring the decompressed image data to the parallel bus 42, the data transfer is performed via the parallel data I / F 71.
[0106]
[Resize copy operation]
The digital color copying machine 1 according to the present embodiment has an enlargement / reduction scaling function as described above, but the cubic convolution interpolation known in the scanner image processing unit 62 is performed in the main scanning direction as in the related art. In the sub-scanning direction, the speed of the stepping motor 35 is controlled in accordance with the magnification to change the moving speed of the first traveling body 28. Is what you do.
[0107]
For example, with reference to FIG. 11, a description will be given of an example of the case where the image is enlarged twice in length and width. Assuming that the main scanning direction and the sub-scanning direction for the document D are set as shown in FIG. The original D is read by the scanner 3 by changing the moving speed of the first traveling body 28 in accordance with the scaling factor of 2 (1/2 the speed at the same magnification), and as shown in FIG. Thus, the magnification (2 times) in the sub-scanning direction is mechanically performed. Then, the image data read by the scanner 3 after receiving the sub-scanning scaling process is subjected to an electrical scaling process by the cubic convolution interpolation method in the main scanning direction in the scanner image processing unit 62. As a result, the magnification (2 times) in the main scanning direction is electrically performed as shown in FIG. 3 (c), and as a result, image data that is enlarged twice and vertically and horizontally is obtained.
[0108]
The image data that has been subjected to the scaling process in this manner is compressed and encoded according to the JPEG2000 algorithm or the like, and stored in the MEM 48 as code data. The copy print operation is executed by outputting the print data to the printer.
[0109]
Here, the image data has a known anisotropy in the vertical and horizontal directions for the digital color copying machine 1 due to the difference in the magnification processing between the main scanning direction and the sub-scanning direction. Under the situation where the main scanning direction in which the processing is performed is a direction in which edge rounding is likely to occur, the two-dimensional wavelet coefficient is subjected to the same hierarchy as the two-dimensional wavelet coefficient in the quantization process during the compression encoding processing according to the JPEG2000 algorithm. It has a quantizing means or a quantizing function for performing a quantization with a different compression ratio according to the subband position. That is, as shown as a low compression rate and a high compression rate in FIG. 11D, the quantization level (compression rate) assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the main scanning direction is determined by the wavelet transform processing. Quantization with a different compression ratio is performed by making the quantization level (compression ratio) relatively lower than the quantization level (compression ratio) assigned to the wavelet coefficient located in the other direction.
[0110]
This utilizes the feature of the wavelet transform described in FIG. 3 and the like in the JPEG2000 algorithm. Now, when the image data of the document D as shown in FIG. 12A is subjected to the wavelet transform, the result of the conversion can be represented as shown in FIG. 12B. That is, the entire image in the image data appears in the sub-band LL as a low-frequency component in the horizontal direction and the low-frequency component in the vertical direction, which is reduced to １ ／, and becomes a sub-band LH as a low-frequency component in the horizontal direction and a high-frequency component in the vertical direction. Indicates a horizontal line (horizontal line) image, and a vertical band (vertical line) image appears in the subband HL, which is a horizontal high frequency / vertical low frequency component, and is a horizontal high frequency / vertical high frequency component. The sub-band HH has a characteristic that an oblique line image appears.
[0111]
Therefore, for example, as shown in FIG. 13 (decomposition level = 2), when the main scanning direction corresponds to the horizontal direction of the wavelet transform processing and the sub-scanning direction corresponds to the vertical direction of the wavelet transform processing, the edge in the main scanning direction Image data components that are likely to be rounded appear in the wavelet coefficients of the subband LH system hierarchy, and image data components in the sub-scanning direction appear in the wavelet coefficients of the subband HL system hierarchy. Therefore, the subbands 1LH and 1HL and the subbands 2HL and 2LH of the same layer, to which the same quantization level is assigned to the wavelet coefficients, usually have the subband 1HL at the quantization level on the subband 1LH and 2LH side. , And 2HL, the quantization level is made different so as to be relatively lower than the quantization level on the side of the main scanning direction in which the electrical scaling process is performed. It can be understood that the influence on the image can be reduced and the quality of the reproduced image can be improved. Conversely, if the quantization level assigned to the wavelet coefficients located in the sub-bands 1HL and 2HL corresponding to the sub-scanning direction in which edge rounding is less likely to occur, the image quality is hardly affected even if the quantization level is relatively large. Can also be understood that efficient compression encoding becomes possible.
[0112]
For this reason, in the present embodiment, for example, when the conditions shown in FIG. 13 (decomposition level = 2, main scanning direction = horizontal direction, sub-scanning direction = vertical direction) are set, the enlargement / reduction processing is performed as shown in FIG. A table relating to the quantization level for each subband as shown in FIG. The quantization level in this case is represented by a denominator for quantizing the wavelet coefficients, and “1” is 2 ⁰ "2" indicates that quantization is not performed. ¹ , "4" is 2 ² , "8" is 2 ³ Respectively. According to this table, at the same magnification, the same quantization level “2” is assigned to the sub-bands 2HL and 2LH, and the same quantization level “4” is assigned to the sub-bands 1HL and 1LH. At the time of enlargement / reduction, the quantization level “1” is assigned to the sub-band 2LH of the same hierarchy with respect to the quantization level “2” of the sub-band 2HL, and the quantization is suppressed (low compression ratio). With respect to the quantization level "4" of the band 1HL, the quantization level "2" is assigned to the sub-band 1LH in the same hierarchy, and the quantization is suppressed (low compression rate). The same applies to the enlargement / reduction by four times. For example, the quantization level “1” is assigned to the subband 1LH, and the quantization is further suppressed (lower compression ratio).
[0113]
The degree of edge rounding varies depending on the magnification in the main scanning direction, which is a factor of anisotropy. The degree of edge rounding increases as the magnification increases, and as shown in the numerical example shown in this table, By changing the quantization levels assigned to the wavelet coefficients of the sub-band 1LH accordingly, it is possible to further reduce the influence of the rounded edges on the image quality. Further, the thin line appears as a wavelet coefficient of a higher band hierarchy, and the degree of the influence of the rounded edge on the image quality differs depending on the subband hierarchy. Therefore, as shown in the numerical example shown in this table, the subband 2LH and 1LH hierarchy By changing the quantization level assigned to the wavelet coefficient in accordance with, the influence on the image quality due to the edge rounding can be further reduced.
[0114]
A description will be given with reference to the flowchart of FIG. 15 schematically illustrating an example of processing control at the time of a copy operation that refers to such a table. The copying operation is started when the operator presses a start key after setting copy conditions such as the number of copies and a magnification (Y in S1). Then, it is checked whether or not the magnification is designated at the copy condition setting stage (S2). The process of step S2 is executed as a function of the anisotropy determination unit, and when magnification is designated, the degree of anisotropy is determined based on the magnification. Note that whether or not the two-dimensional image data to be compression-encoded has anisotropy in the vertical and horizontal directions is determined by the digital color copier 1 in the main scanning direction and the sub-scanning direction. It has been recognized that there is a known anisotropy due to the difference in the scaling processing of the above, and this known information becomes valid by specifying the scaling.
[0115]
If the magnification is not specified (N in S2), the scanner 3 performs the normal reading operation at the same magnification (S3), and acquires the read image data of the original. On the other hand, when magnification is designated (Y in S2), the scanner 3 (stepping motor 35) is controlled in accordance with the magnification to perform the reading operation while performing mechanical magnification in the sub-scanning direction. (S4) The scanner image processing unit 62 performs electrical scaling processing by cubic convolution interpolation in the main scanning direction on the obtained sub-scan scaled image data (S5).
[0116]
The image data obtained in this manner is subjected to two-dimensional wavelet transform in the data compression unit 76 (S6), and is further compression-coded into code data by a procedure of quantization and coding with reference to the table described above (S7). ). The processing in step S7 is executed as a function of the quantization means. In this processing, the quantization level shown in the table is used at the time of variable-size copying, so that the compression ratio of the wavelet coefficient in the main scanning direction in which edge rounding is likely to occur is suppressed.
[0117]
The encoded data is temporarily stored in the MEM 48 (S8), and the encoded data read out of the MEM 48 and compressed and encoded by the data decompression unit 78 is decoded, inversely quantized, and inversely transformed by the two-dimensional wavelet. The decoding process for the original image data is performed in the reverse procedure (S9), and the image data is output to the image forming unit 4 to execute the copy printing operation.
[0118]
Therefore, according to the present embodiment, it is possible to perform compression coding on the image data after the scaling process with little difference in image quality in the vertical and horizontal directions, and to improve the image quality of the image reproduced on the image forming unit 4 side.
[0119]
In the above description, the magnification / magnification is assumed. However, the same applies to reduction / magnification such as 1/2, 1/4,..., For example, as shown in FIG. What is necessary is just to refer to the table which prescribed the quantization level allocated to each subband for every. In this case, even in the case of the reduction / magnification, the edge may be rounded in the main scanning direction in which the electric magnification processing is performed. However, in general, the degree thereof is often lower than that in the case of the magnification / magnification. By setting the quantization level higher than at the time, it is possible to appropriately cope with the situation. In the illustrated example, the quantization level of the sub-band 1LH is higher than the quantization level “2” “1” at the time of enlargement, such as “3” “2”.
[0120]
In the above description, attention has been paid to the quantization level in the case where linear quantization is performed at the stage of encoding the wavelet coefficients. However, if the level at which the code of the unnecessary bit plane after encoding is discarded (truncated) is different, You may make it do. In this case, for example, a table defining the truncation of the bit plane to be allocated to each sub-band for each magnification ratio as shown in FIG. 18 may be referred to. Each value “0” to “3” is 2 ⁰ ~ 2 ³ "0" indicates that the bit plane is not discarded, "1" indicates that the least significant bit plane is discarded, and "2" indicates the least significant bit plane. Is discarded, and "3" indicates that the least significant three bit planes are discarded.
[0121]
According to this table, at the same magnification, the same truncation “1” is allocated to the subbands 2HL and 2LH and the same truncation “2” is allocated to the subbands 1HL and 1LH. In contrast to the truncation "1" of the subband 2HL, the truncation "0" is allocated to the subband 2LH of the same layer, and the quantization thereof is suppressed (low compression ratio), and the truncation "2" of the subband 1HL is reduced. On the other hand, a truncation “1” is assigned to the sub-band 1LH in the same hierarchy, and the quantization thereof is suppressed (low compression ratio). The same applies to the enlargement / reduction of four times. For example, a truncation “0” is assigned to the sub-band 1LH, and the quantization is further suppressed (lower compression ratio).
[0122]
Further, in the above description, an example of similar scaling in the vertical and horizontal directions has been described. In this case, the magnification in the sub-scanning direction where the mechanical magnification processing is performed and the edge is not rounded does not particularly matter, and the magnification in the main scanning direction in which the electric magnification processing is performed may be focused.
[0123]
In the present embodiment, the relationship between the scanning direction in the scanner 3 and the direction of the two-dimensional wavelet transform processing is such that the main scanning direction = horizontal direction and the sub-scanning direction = vertical direction, as shown in FIG. However, in the case where the relationship of the main scanning direction = vertical direction and the sub-scanning direction = horizontal direction is satisfied, the sub-band LH system is replaced with the sub-band HL system hierarchy corresponding to the main scanning direction. (The quantization levels of the subband LH system and the subband HL system may be interchanged).
[0124]
A second embodiment of the present invention will be described with reference to FIG. In the above-described embodiment, as a typical example of two-dimensional image data having anisotropy in the vertical direction and the horizontal direction, a scanner is used which is caused by a difference in scaling between the main scanning direction and the sub-scanning direction. As described above, the present embodiment shows an example of application to a television camera as another example in which two-dimensional image data has anisotropy in the vertical and horizontal directions.
[0125]
FIG. 18 is a block diagram schematically illustrating a hardware configuration of the television camera 80. The television camera 80 includes an image input device 81 and an image compression device 82. The image input device 81 and the image compression device 82 are connected to a CPU 84 via a bus 83. In addition, a memory 85, an operation panel 86, an external output interface 87, and the like are provided.
[0126]
Here, the image input device 81 includes an image sensor such as a CCD or a MOS image sensor, and reads an image of an object to be imaged by raster scanning in a two-dimensional interlaced manner, and outputs the read image data to the image compression device 82. The image compression device 82 is a representative representation of a compression processing system such as a quantization unit in the image processing device, and performs compression encoding according to the JPEG2000 algorithm. The generated code string data is output to the outside via the external output interface 87.
[0127]
In such a television camera 80, in the present embodiment, the image data has known anisotropy in the vertical direction and the horizontal direction due to the interlaced raster scanning, and the horizontal direction that is the raster scanning direction is The self-determination is performed as a direction in which edge rounding is likely to occur. Furthermore, since there is a difference between the horizontal direction and the vertical direction such as an aspect ratio of 4: 3 or 16: 9, it can be said that the horizontal direction which is the raster scanning direction is a direction in which edge rounding is likely to occur. Therefore, as in the case of the above-described embodiment, the raster scanning direction (horizontal direction), which is a direction in which edge rounding is likely to occur at the stage of quantization processing in the image compression device 82, is also performed for such anisotropy. The degree of quantization differs between the vertical direction, which is the direction. As a result, it is possible to perform compression encoding of image data after image pickup with little difference in image quality in the vertical and horizontal directions, and to improve the image quality of an image reproduced on a television or the like.
[0128]
A third embodiment of the present invention will be described with reference to FIG. This embodiment shows an example of application to a personal computer (PC), which is an information processing device, as another example having two-dimensional image data having anisotropy in the vertical and horizontal directions.
[0129]
FIG. 19 is a block diagram schematically illustrating a hardware configuration of the PC 90. The PC 90 includes a CPU 91 for performing information processing, a primary storage device such as a ROM 92 and a RAM 93 for storing information, an HDD (Hard Disk Drive) 95 for storing compression codes downloaded from the outside via the Internet or another network 94, A CD-ROM drive 96 for storing information, distributing information to the outside, and obtaining information from the outside, and a communication control device 97 for transmitting information by communication with another external computer or the like via a network 94. A display device 98 such as a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display) for displaying the progress and results of processing to the operator, and a keyboard and a mouse for the operator to input commands and information to the CPU 91. Of the input device 99 etc. Cage, the data between these units is a bus controller 100 operates to arbitrate.
[0130]
In the PC 90, a program for realizing a function of performing a compression encoding process and a function of performing a decoding process in accordance with the JPEG2000 algorithm as part of image processing is stored in the ROM 92 together with various control programs. It is configured to have functions of an encoding unit and a decoding unit. Further, the input device 99 that accepts a user operation also functions as a data acquisition unit that acquires image data.
[0131]
In general, this type of PC 90 incorporates image editing software, and can perform an editing operation of changing the aspect ratio of the captured image data to a different vertical or horizontal length. In such a case, there is anisotropy in the vertical and horizontal directions due to the difference in the vertical and horizontal scaling factors. In other words, the scaling process in any direction is an electrical scaling process using an interpolation method or the like. However, the larger the scaling ratio, the greater the degree of edge rounding. The difference comes out.
[0132]
Therefore, in the present embodiment, when a magnification process with different vertical / horizontal scaling factors is specified as a user operation for editing image data, the vertical and horizontal scaling factors of the image data are caused by the difference in vertical / horizontal scaling factors. It is estimated that the direction has anisotropy in both directions (anisotropy determination means), and the direction that is more affected by the electrical scaling process (the direction with the larger scaling ratio) is estimated to be the direction in which edge rounding is likely to occur. Different quantization is applied to the direction and other directions in the same manner as in the above-described embodiment.
[0133]
As a result, the image data after the editing operation can be compressed and encoded with a small difference in image quality in the vertical and horizontal directions, and the quality of an image reproduced by a display, a printer, or the like can be improved. For example, in the case of the vertical enlargement / reduction, the quantization of the image data in the vertical direction may be suppressed.
[0134]
A fourth embodiment of the present invention will be described. The present embodiment relates to an image output apparatus. Specifically, for example, a copier or a printer as described in the first embodiment is assumed. That is, the input unit (scanner 3) for inputting image data and the two-dimensional image data input by the input unit (scanner 3) are the same as those in the first embodiment in which compression encoding is performed. An image processing device, a storage device (MEM48) for storing code data compressed and encoded by the image processing device, decoding means for decoding the code data stored in the storage device (MEM48) into image data, and decoding. Output means (printer 2) for outputting a two-dimensional image based on the image data decoded by the means.
[0135]
In such a copying machine 1, even if the original image data is normal, the copying machine or the printer always has vertical lines as shown in FIG. 23, for example, due to factors such as development conditions and transfer conditions. In some cases, the two-dimensional image data has an anisotropy in the vertical direction and the horizontal direction in the output form in some cases. In particular, in the case of a document image including a lattice image as shown in the illustrated example, it may appear remarkably. Therefore, in the case of such a copying machine, a difference in image quality occurs in the vertical and horizontal directions not only at the time of the variable-size copy but also at the time of the same-size copy.
[0136]
Therefore, in the present embodiment, not only the input side but also the case where the output side has anisotropy in the vertical direction and the horizontal direction can be appropriately dealt with by applying the same manner. It was made. That is, the copying machine 1 according to the present embodiment is configured to output image data in the vertical direction due to a difference in the known output characteristic that the line thickness of the output means (printer 2) in the vertical direction and the horizontal direction is different. Is determined to have a known anisotropy in the lateral direction. Then, the anisotropy determination unit determines a direction in which edge rounding is likely to occur due to such a difference in the known output characteristics. Based on such a determination result, image data that is originally uniform in the vertical direction and the horizontal direction is described above at the stage of image data quantization so that output anisotropy in the output unit (printer 2) is eliminated. As in the case of the embodiment, the degree of quantization is made different in the vertical direction and the horizontal direction to intentionally have the opposite anisotropy to cancel each other out, so that it is reproduced by the output means (printer 2). This is to improve the image quality of the image.
[0137]
That is, in the case of a model having a characteristic in which a thick line is likely to appear in either the vertical direction or the horizontal direction as a characteristic of the print output of the printer 2, the characteristic is canceled and the image quality difference between the vertical direction and the horizontal direction is canceled out. It is possible to obtain a high-quality copy image without the image. More specifically, the quantization level of the wavelet transform is set so that the quantization level in the direction in which the thick line appears (the direction in which the print image becomes thicker) is relatively higher than the other direction (the compression ratio is increased). What is necessary is just to make it different according to a direction.
[0138]
【The invention's effect】
According to the image processing apparatus of the first aspect, image data having anisotropy in the vertical direction and the horizontal direction is assigned to the two-dimensional wavelet coefficient in the same hierarchy based on the anisotropy factor. Even so, quantization with different compression ratios is performed according to the subband position, so that image quality differences due to anisotropy can be absorbed by quantization with different compression ratios, and the reproduced image Higher image quality can be achieved.
[0139]
According to the second aspect of the present invention, in the image processing apparatus according to the first aspect, a compression ratio in a direction in which edge rounding is likely to occur due to an anisotropy factor, that is, quantization is relatively suppressed. In addition, the effect on the image quality due to the edge rounding can be reduced, and the quality of the reproduced image can be improved. Therefore, it is possible to perform efficient compression encoding as a whole.
[0140]
According to the third aspect of the present invention, in the image processing apparatus according to the first or second aspect, specifically, the image processing apparatus is located in a direction of the wavelet transform processing corresponding to a direction in which edge rounding is likely to occur due to anisotropic factors. Since the quantization level assigned to the wavelet coefficient is relatively suppressed, the influence on the image quality due to the edge rounding can be reduced, and the image quality of the reproduced image can be improved. Even if the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the direction in which dullness is less likely to occur, even if the quantization level is relatively large, the image quality is hardly affected. Can be made possible.
[0141]
According to the fourth aspect of the present invention, in the image processing apparatus according to the third aspect, more specifically, when the direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, the subband LH system hierarchy is used. , The quantization level assigned to the wavelet coefficient located at the position is relatively suppressed, so that the effect on the image quality due to the edge rounding can be reduced, and the image quality of the reproduced image can be improved. For example, even if a relatively large quantization level is assigned to a wavelet coefficient located in a subband HL system layer corresponding to a direction in which edge rounding is unlikely to occur, image quality is hardly affected even if the quantization level is relatively large. Compression encoding can be enabled.
[0142]
According to the fifth aspect of the present invention, in the image processing apparatus according to the third aspect, more specifically, when the direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform processing, the subband HL system hierarchy is used. , The quantization level assigned to the wavelet coefficient located at the position is relatively suppressed, so that the effect on the image quality due to the edge rounding can be reduced, and the image quality of the reproduced image can be improved. For example, even if the quantization level assigned to the wavelet coefficient located in the sub-band LH system layer corresponding to the direction in which edge rounding is less likely to occur, the image quality is hardly affected even if the quantization level is relatively large, so that the overall efficiency is high. Compression encoding can be enabled.
[0143]
According to the sixth aspect of the present invention, in the image processing apparatus according to any one of the second to fifth aspects, the degree of edge rounding varies depending on the degree of the anisotropy factor. The degree of compression ratio in the direction in which edge rounding is likely to occur is made different accordingly, so that the influence of edge rounding on image quality can be further reduced.
[0144]
According to the seventh aspect of the present invention, in the image processing apparatus according to the sixth aspect, the degree of edge rounding varies depending on the degree of the anisotropy factor. Since the degree of quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform process corresponding to the easy direction is made different, the influence on the image quality due to the rounded edge can be further reduced.
[0145]
According to the eighth aspect of the present invention, in the image processing apparatus according to the seventh aspect, the degree of edge rounding varies depending on the degree of the anisotropy factor. In the horizontal direction of the wavelet transform processing, the quantization levels assigned to the wavelet coefficients located in the subband LH system hierarchy are made different, so that the influence of the rounded edges on the image quality can be further reduced. .
[0146]
According to the ninth aspect of the present invention, in the image processing apparatus according to the seventh aspect, the degree of edge rounding varies depending on the degree of the anisotropy factor. In the vertical direction of the wavelet transform processing, the quantization levels assigned to the wavelet coefficients located in the subband HL hierarchy are made different, so that the influence of the rounded edges on the image quality can be further reduced. .
[0147]
According to the tenth aspect of the present invention, in the image processing apparatus according to any one of the seventh to ninth aspects, the thin line appears as a wavelet coefficient of a higher band hierarchy, so that the image quality due to edge rounding also depends on the subband hierarchy. Since the degree of influence is different, the quantization level assigned to the wavelet coefficient is changed according to the sub-band hierarchy, so that the influence of the rounded edge on the image quality can be further reduced.
[0148]
According to an eleventh aspect of the present invention, by providing the image processing apparatus of any one of the first to tenth aspects, the image data is vertically lengthened due to a difference in magnification processing between the main scanning direction and the sub-scanning direction. For image reading devices that have a known anisotropy in the direction and the horizontal direction, and in which the main scanning direction is determined to be a direction in which edge rounding is likely to occur, a compression code with small vertical and horizontal image quality differences for image data after scaling processing. It is possible to improve the quality of an image reproduced by a printer or the like.
[0149]
According to the twelfth aspect of the present invention, in the image reading apparatus according to the eleventh aspect, specifically, the image reading apparatus is positioned in a direction of the wavelet transform processing corresponding to a main scanning direction in which edge rounding is likely to occur due to anisotropic factors. Since the quantization level assigned to the wavelet coefficient is relatively suppressed, the influence on the image quality due to the edge rounding can be reduced, and the image quality of the reproduced image can be improved. Even if the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the sub-scanning direction in which dullness is less likely to occur, even if the quantization level is relatively large, the image quality is hardly affected. Can be made possible.
[0150]
According to a thirteenth aspect of the present invention, in the image reading device according to the twelfth aspect, more specifically, when the main scanning direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, the sub-band LH system is used. Since the quantization level assigned to the wavelet coefficients located in the hierarchy of is relatively suppressed, the influence on the image quality due to the edge rounding can be reduced, and the image quality of the reproduced image can be improved. In other words, even if the quantization level assigned to the wavelet coefficient located in the subband HL hierarchy corresponding to the sub-scanning direction in which edge rounding is less likely to occur, the image quality is hardly affected even if the quantization level is relatively large. Can enable efficient compression encoding.
[0151]
According to the fourteenth aspect of the present invention, in the image reading apparatus according to the twelfth aspect, more specifically, when the main scanning direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform processing, the subband HL system is used. Since the quantization level assigned to the wavelet coefficients located in the hierarchy of is relatively suppressed, the influence on the image quality due to the edge rounding can be reduced, and the image quality of the reproduced image can be improved. In other words, even if the quantization level assigned to the wavelet coefficient located in the sub-band LH system hierarchy corresponding to the sub-scanning direction in which edge rounding is less likely to occur, the image quality is hardly affected even if the quantization level is relatively large. Can enable efficient compression encoding.
[0152]
According to the fifteenth aspect, in the image reading apparatus according to any one of the eleventh to fourteenth aspects, even in the case of reduction / magnification, edge rounding may occur in the main scanning direction in which the electric magnification processing is performed. However, in general, the level is often lower than at the time of enlargement / reduction, so that the quantization level is set lower than at the time of enlargement / reduction, so that appropriate measures can be taken.
[0153]
According to the sixteenth aspect of the present invention, in the image reading apparatus according to any one of the eleventh to fifteenth aspects, the degree of edge rounding varies depending on the magnification in the main scanning direction which causes anisotropy. The larger the size, the greater the degree of edge rounding, so the degree of compression in the direction in which edge rounding is likely to be varied according to the scaling factor, further reducing the effect on image quality due to edge rounding. be able to.
[0154]
According to the seventeenth aspect of the present invention, in the image reading apparatus according to the sixteenth aspect, the degree of edge rounding varies depending on the magnification in the main scanning direction which causes anisotropy. The degree of quantization increases, so the degree of quantization assigned to the wavelet coefficient located in the direction of the wavelet transform processing corresponding to the direction in which edge rounding is likely to occur varies according to the scaling factor. Impact on the vehicle can be further reduced.
[0155]
According to the eighteenth aspect of the present invention, in the image reading apparatus according to the seventeenth aspect, the degree of edge rounding varies depending on the magnification in the main scanning direction which causes anisotropy. More specifically, if the direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, the quantization levels assigned to the wavelet coefficients located in the subband LH system hierarchy are made different. Therefore, the influence of the rounded edge on the image quality can be further reduced.
[0156]
According to the nineteenth aspect of the present invention, in the image reading apparatus according to the seventeenth aspect, the degree of edge rounding varies depending on the magnification in the main scanning direction which causes anisotropy. More specifically, if the direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform processing, the quantization levels assigned to the wavelet coefficients located in the subband HL system hierarchy are made different. Therefore, the influence of the rounded edge on the image quality can be further reduced.
[0157]
According to the twentieth aspect, in the image reading apparatus according to any one of the seventeenth to nineteenth aspects, the thin line appears as a wavelet coefficient in a higher-band hierarchy, so that the image quality due to edge rounding also depends on the sub-band hierarchy. Since the degree of influence is different, the quantization level assigned to the wavelet coefficient is changed according to the sub-band hierarchy, so that the influence of the rounded edge on the image quality can be further reduced.
[0158]
According to the image forming apparatus of the present invention, since the image reading apparatus of any one of claims 11 to 20 is provided, it is possible to perform the compression encoding of the image data after the scaling process with small vertical and horizontal image quality differences. This makes it possible to improve the quality of an image reproduced by the printer engine.
[0159]
According to the twenty-second aspect of the present invention, since the image processing apparatus according to any one of the first to tenth aspects is provided, the known anisotropy of the image data in the vertical direction and the horizontal direction due to the raster scanning of the interlace method is caused. With respect to a television camera which has a characteristic and a horizontal scanning direction which is a raster scanning direction is determined to be a direction in which edge rounding is likely to occur, it is possible to perform compression encoding of image data after imaging with little difference in image quality in vertical and horizontal directions, It is possible to improve the image quality of the image reproduced by the above method.
[0160]
According to a twenty-third aspect of the present invention, since the image processing apparatus according to any one of the first to tenth aspects is provided, image data is generated by a difference in known output characteristics between a vertical direction and a horizontal direction in output means. For an image output device that has a known anisotropy in the vertical direction and the horizontal direction, and is determined to be in a direction in which edge rounding is likely to occur due to a difference in known output characteristics, the anisotropy in the output unit is eliminated. By imparting the opposite anisotropy at the stage of quantizing the image data to cancel each other, it is possible to improve the image quality of the image reproduced by the output unit.
[0161]
According to a twenty-fourth aspect of the present invention, the image output apparatus according to the twenty-second aspect is a copier, and has a characteristic that a thick line is likely to appear in either the vertical direction or the horizontal direction as print output characteristics. In the case of a model, the habit is canceled and a high-quality copy image having no image quality difference between the vertical direction and the horizontal direction can be obtained.
[0162]
According to the twenty-fifth aspect, by providing the image processing device according to any one of the first to tenth aspects, the image data can be vertically and horizontally shifted in accordance with the specification of the user operation for the editing process. For information processing devices such as personal computers that are determined to have anisotropy, image data after editing operations can be compressed and encoded with little difference in image quality in the vertical and horizontal directions, resulting in higher image quality of images reproduced on displays, printers, etc. Can be achieved.
[0163]
According to the program of the twenty-sixth aspect, the same effects as those of the first aspect can be obtained.
[0164]
According to the computer-readable storage medium of the twenty-seventh aspect, the same effects as those of the twenty-sixth aspect can be obtained.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a system for realizing a basic algorithm of the JPEG2000 system which is a premise of a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a divided rectangular area of each component of an original image.
FIG. 3 is an explanatory diagram showing subbands at each decomposition level when the number of decomposition levels is three.
FIG. 4 is an explanatory diagram showing a precinct.
FIG. 5 is an explanatory diagram showing an example of a procedure for ranking bit planes. It is.
FIG. 6 is a schematic diagram illustrating a code stream of encoded image data.
FIG. 7 is a schematic configuration diagram of a digital full-color copying machine to which the embodiment is applied;
FIG. 8 is a block diagram showing the electrical connection.
FIG. 9 is a block diagram showing a configuration example of the IPP.
FIG. 10 is a block diagram showing a configuration example of an IMAC.
FIG. 11 is an explanatory diagram schematically showing a difference in scaling processing between a main scanning direction and a sub-scanning direction.
FIG. 12 is an explanatory diagram schematically showing characteristics of each subband by a wavelet transform process.
FIG. 13 is an explanatory diagram showing the relationship between the hierarchical structure of subbands and the main scanning direction / sub-scanning direction.
FIG. 14 is an explanatory diagram showing an example of a quantization level assignment table.
FIG. 15 is a schematic flowchart illustrating a control example of a variable-size copy operation.
FIG. 16 is an explanatory diagram showing an example of a quantization level assignment table during scaling.
FIG. 17 is an explanatory diagram showing an example of a quantization level assignment table by truncating bit planes.
FIG. 18 is a schematic block diagram illustrating a hardware configuration example of a television camera according to a second embodiment of the present invention.
FIG. 19 is a schematic block diagram illustrating a hardware configuration example of a PC according to the third embodiment of this invention.
FIG. 20 is an explanatory diagram schematically showing a difference in scaling processing between the main scanning direction and the sub-scanning direction.
FIG. 21 is an explanatory diagram of edge rounding due to a difference in scaling processing.
FIG. 22 is an explanatory diagram illustrating a print output example affected by edge rounding.
FIG. 23 is an explanatory diagram illustrating a print output example based on the habit of the printer.
[Explanation of symbols]
2 Printer, output means
3 Scanner, input means
26 Exposure means
28 Sub-scanning means
33 photoelectric conversion element
48 storage device
81 Image input device

Claims (27)

In an image processing apparatus that compresses and encodes image data in a procedure of conversion, quantization, and encoding into two-dimensional wavelet coefficients,
Anisotropic determining means for determining whether or not the two-dimensional image data to be compression-coded has anisotropy in the vertical and horizontal directions;
The image data determined to have anisotropy by the anisotropy determining means has a different compression ratio for the two-dimensional wavelet coefficient according to the subband position in the same layer based on the anisotropy factor. Quantization means for performing quantization,
An image processing apparatus comprising: 2. The quantization unit according to claim 1, wherein the quantization unit performs quantization with different compression ratios such that a compression ratio in a direction in which edge rounding is likely to occur is relatively suppressed with respect to a compression ratio in another direction due to the determined anisotropy factor. The image processing apparatus according to claim 1. The quantizing means assigns a quantization level to be assigned to a wavelet coefficient located in a direction of a wavelet transform process corresponding to a direction in which edge rounding is likely to occur due to the determined anisotropy factor. 3. The image processing apparatus according to claim 1, wherein the quantization is performed at a different compression ratio by making the quantization level relatively lower than a quantization level assigned to the coefficient. If the direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, the quantization means positions the quantization level assigned to the wavelet coefficient located in the subband LH system hierarchy in the subband HL system hierarchy. 4. The image processing device according to claim 3, wherein the quantization level is relatively lower than a quantization level assigned to the wavelet coefficient. If the direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform process, the quantization means positions the quantization level assigned to the wavelet coefficient located in the subband HL hierarchy in the subband HL hierarchy. 4. The image processing device according to claim 3, wherein the quantization level is relatively lower than a quantization level assigned to the wavelet coefficient. The anisotropy determination means also determines the degree of an anisotropy factor,
The image processing apparatus according to claim 2, wherein the quantization unit changes a degree of a compression ratio in a direction in which edge rounding is likely to occur according to the determined degree of an anisotropy factor. 7. The quantization unit according to claim 6, wherein the quantization unit changes a quantization level to be assigned to a wavelet coefficient located in a direction of a wavelet transform process corresponding to a direction in which edge rounding is likely to occur according to the degree of the determined anisotropy factor. Image processing device. If the direction in which edge rounding is likely to occur is the horizontal direction of the wavelet transform processing, the quantization means allocates the wavelet coefficients located in the subband LH system hierarchy according to the determined anisotropy factor. 8. The image processing apparatus according to claim 7, wherein the quantization levels are different. If the direction in which edge rounding is likely to occur is the vertical direction of the wavelet transform processing, the quantization means allocates the wavelet coefficients located in the subband HL hierarchy according to the determined degree of the anisotropy factor. 8. The image processing apparatus according to claim 7, wherein the quantization levels are different. The image processing apparatus according to claim 7, wherein the quantization unit changes a quantization level assigned to a wavelet coefficient according to a subband hierarchy. Exposure means for exposing a document, sub-scanning means for relatively moving the document and the exposure means in the sub-scanning direction, receiving reflected light from the document which is exposed and scanned in the sub-scanning direction, and A photoelectric conversion element that converts and reads the image data, performs magnification in the main scanning direction of the image data read by the photoelectric conversion element by an electric magnification process, and performs magnification in the sub-scanning direction by the sub-scanning means. In an image reading apparatus having a scaling function performed by mechanical scaling processing,
The image processing apparatus according to claim 1, wherein two-dimensional image data after the scaling processing is to be subjected to compression encoding.
A storage device that stores code data that has been compression-encoded by the image processing device,
The anisotropy determination means provided in the image processing apparatus has a known anisotropy in the vertical direction and the horizontal direction with respect to the image data due to a difference in magnification processing between the main scanning direction and the sub-scanning direction. Determining that the main scanning direction is a direction in which edge rounding is likely to occur.
An image reading apparatus, comprising: The quantization means assigns a quantization level assigned to a wavelet coefficient located in the direction of the wavelet transform process corresponding to the main scanning direction relative to a quantization level assigned to a wavelet coefficient located in the other direction of the wavelet transform process. 12. The image reading apparatus according to claim 11, wherein quantization with different compression ratios is performed by lowering the quantization. When the main scanning direction is the horizontal direction of the wavelet transform process, the quantization means assigns a quantization level to be assigned to a wavelet coefficient located in the subband LH layer to a wavelet coefficient located in the subband HL layer. 13. The image reading device according to claim 12, wherein the quantization level is set relatively low with respect to the assigned quantization level. When the main scanning direction is the vertical direction of the wavelet transform processing, the quantization means assigns a quantization level to be assigned to a wavelet coefficient located in the subband HL hierarchy to a wavelet coefficient located in the subband HL hierarchy. 13. The image reading device according to claim 12, wherein the quantization level is set relatively low with respect to the assigned quantization level. The quantizing means increases the quantization level assigned to the wavelet coefficient located in the direction of the wavelet transform process corresponding to the main scanning direction when the magnification in the main scanning direction is reduction / magnification, compared with the case of enlargement / magnification. The image reading device according to claim 11, wherein the image reading device performs the image reading. The anisotropy determination means determines the designated magnification in the main scanning direction as a degree of an anisotropy factor,
16. The image reading device according to claim 11, wherein the quantization unit changes a degree of a compression ratio in the main scanning direction according to a magnification in the main scanning direction. 17. The image reading apparatus according to claim 16, wherein the quantization means changes a quantization level assigned to a wavelet coefficient located in a direction of a wavelet transform process corresponding to the main scanning direction according to a magnification in the main scanning direction. When the main scanning direction is the horizontal direction of the wavelet transform processing, the quantization means changes a quantization level to be assigned to a wavelet coefficient located in a subband LH hierarchy according to a scaling factor in the main scanning direction. 18. The image reading device according to item 17. When the main scanning direction is the vertical direction of the wavelet transform processing, the quantization means changes a quantization level to be assigned to a wavelet coefficient located in a subband HL hierarchy according to a scaling factor in the main scanning direction. 18. The image reading device according to item 17. 20. The image reading apparatus according to claim 17, wherein the quantization unit changes a quantization level assigned to a wavelet coefficient according to a subband hierarchy. An image reading device according to any one of claims 11 to 20,
A printer engine for forming an image on a sheet based on image data read by the image reading device and decompressed by decoding means from code data image-processed by the image processing device;
An image forming apparatus comprising: 2. Description of the Related Art In a television camera which reads an object to be imaged by raster scanning in a two-dimensional manner by an image sensor using an interlace method,
The image processing apparatus according to claim 1, wherein the captured two-dimensional image data is a target of compression encoding.
A storage device that stores code data that has been compression-encoded by the image processing device,
The anisotropy determination unit included in the image processing apparatus has a known anisotropy in the vertical direction and the horizontal direction with respect to the image data due to the interlaced raster scanning, and the horizontal direction becomes a raster scanning direction. Is determined as a direction in which edge rounding is likely to occur,
A television camera, characterized in that: Input means for inputting image data;
The image processing apparatus according to claim 1, wherein two-dimensional image data input by the input unit is to be subjected to compression encoding.
A storage device for storing code data compressed and encoded by the image processing device;
Decoding means for decoding the code data stored in the storage device into image data;
An output unit having a known output characteristic difference between the vertical direction and the horizontal direction, and performing a two-dimensional image output process based on the image data decoded by the decoding unit;
With
The anisotropy determining means included in the image processing apparatus is configured to determine a known anisotropy in the vertical direction and the horizontal direction of the image data due to a difference in a known output characteristic between the vertical direction and the horizontal direction in the output unit. Has a property, and determines a direction in which edge rounding is likely to occur due to a difference in known output characteristics.
An image output device characterized by the above-mentioned. Wherein the input means is a scanner, the output means is a printer, and a difference between known output characteristics in the vertical direction and the horizontal direction is a difference in a direction in which a thick line / thin line appears on a print image. 23. The image output device according to claim 22, wherein: Data acquisition means for acquiring image data;
The image processing apparatus according to any one of claims 1 to 10, wherein the two-dimensional image data acquired by the data acquisition unit is subjected to compression encoding according to a user operation.
A storage device for storing code data compressed and encoded by the image processing device;
Decoding means for decoding the code data stored in the storage device into image data;
With
The anisotropy determination unit included in the image processing apparatus estimates that the image data has anisotropy in the vertical direction and the horizontal direction due to a specified content of a user operation for an editing process,
An information processing apparatus characterized by the above-mentioned. A program for causing a computer of the image processing apparatus to execute a function of each unit in the image processing apparatus according to any one of claims 1 to 10. A computer-readable storage medium storing the program according to claim 26.

Images