JP2002135600A - Image compression processing apparatus and image compression processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To store all data into a storage medium with a limited capacity and to store data of more number of pages by processing an original image while minimizing deterioration in the image quality. SOLUTION: The image compression processing apparatus that receives an object image of a processing object, compresses the object image and provides an output, is provided with a compression rate calculation/ discrimination section 11 that calculates a compression rate of the object image and compares the compression rate with a predetermined rate so as to discriminate the magnitude of the compression rate and with a correction section 12 that revises and corrects the compression rate when the compression rate calculation/discrimination section 11 discriminates that the compression rate is greater than the prescribed rate and feeds back the result to the compression rate calculation/discrimination section 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is incorporated in a preceding stage of an encoding process in order to improve a compression ratio of image data after binarization, and data representing encoding efficiency of an object to be processed is represented by: For example, the present invention relates to an image compression processing apparatus and an image compression processing method for repeatedly executing correction until a predetermined value such as a storable capacity is satisfied.

[0002]

2. Description of the Related Art When printing a printer image created by application software of a personal computer on a printer, the image is compressed after being binarized.
A model for saving data in a storage medium mounted on a printer is known. One of the reasons for installing a storage medium is when a paper jam or other transport failure (jam) occurs in the printer.
One example is to enable jam recovery in which an image is automatically read from a storage medium and output again.
However, when the storage medium is used in this way and the storage capacity is further increased, there are economic restrictions and limitations on the hardware configuration.

In recent years, however, printers have been changed to full-color printers and resolutions (recording densities) from 600 dpi to 1200 dpi due to advances in technology, and high-quality image output has been realized. However, when such high-quality image output is performed, an increase in image capacity is a bottleneck. In order to solve this, it is conceivable to increase the capacity of the storage medium or to improve the compression ratio of the stored image.

As an example of a method for compressing a binary image, there is a run-length encoding method. In this method, an image is scanned in the main scanning direction, the number of pixels in which white pixels and black pixels continue is used as a coefficient, and the length is encoded. further,
In some cases, the coding efficiency is further increased by coding the repetition of the run length. Therefore, this run-length encoding method is excellent in that the processing speed is high and the amount of hardware is small. In order to further improve the compression ratio, a technique for rearranging the pseudo halftone signal formed by the dither method in the order of the values of the respective elements of the dither matrix to increase the black-and-white run length has been disclosed in Japanese Patent Application Laid-Open No. Sho 60 (1994). −
No. 93880.

However, due to the enhancement of the capabilities of personal computers and the enhancement of applications, very complicated images that are difficult to compress (BMP (Windows and O / S2, which are used as standard in Windows and O / S2 in which many dots exist at random positions). (Eg, a file format of a bitmap image) or a document that uses an image as a background). Such a complex image is binarized with the original image as it is,
A high compression rate cannot be obtained even in combination with the encoding according to Japanese Patent Laid-Open No. 93880/90. Therefore, the technology of encoding the original image in order to obtain a higher compression rate,
For example, Japanese Patent Application Laid-Open Nos.
It is disclosed in Japanese Patent No. 55667. This image encoding apparatus reduces the resolution of the area information and the original image of each object such as an image and text, encodes them, and transmits them.

[0006]

However, in the conventional image coding apparatus as described above, when storing a compressed image in a storage medium, even if the compression ratio is improved, the storage of the compressed image is prevented. Since the capacity of the medium is limited, there is a problem that there is no guarantee that all of the medium is stored. Further, even if the data can be stored in the storage medium from the beginning, it has not been considered to accommodate data of a larger number of pages.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made to enable all data to be stored in a limited storage medium while processing an original image to minimize image quality deterioration. The purpose of the present invention is to make it possible to accommodate data of the number of pages.

[0008]

In order to achieve the above object, an image compression processing apparatus according to claim 1 comprises:
In an image compression processing device that inputs an object image to be processed, compresses and outputs the object image, calculates an encoding efficiency of the object image, and compares the encoding efficiency with a predetermined value. The coding efficiency calculating / judging means for judging the magnitude of the coding efficiency, and if the judgment by the coding efficiency calculating / judging means is judged to be larger than a predetermined value, the coding efficiency is changed and corrected. Correction means for returning to the coding efficiency calculating / judging means.

According to the present invention, the object image to be processed is input to the coding efficiency calculating / judging means, where the coding efficiency is calculated, and the calculated value is set to a predetermined value (for example, a compressible storage capacity of a storage medium). If the ratio is less than (ratio), the data cannot be stored in the storage medium. Therefore, the correction is performed by the correction means, and this processing is repeated until the predetermined value is satisfied, and then output to the subsequent stage.

Further, in the image compression processing apparatus according to the second aspect, the object image is an image object, and the correction means performs a γ characteristic conversion of the object image.

According to the present invention, in claim 1, for the image to be processed of the image object, the correction means sets the γ characteristic, which is the input / output characteristic of the brightness of the image, to a γ table (for example, when the image object is shifted toward a lower density). In the case of, the density is further lowered, and in the case of high density, it is further converted to a higher direction. Enables changing the brightness level to match.

According to a third aspect of the present invention, in the image compression processing apparatus, the object image is an image object, and the correcting means performs a correction by lowering the resolution of the object image to a low resolution. It is.

According to the present invention, in claim 1, the correcting means executes, for example, a thinning-out process on the image to be processed of the image object, and then returns the image to the original size by a simple enlargement process. Accordingly, the number of pixels of the image object is physically reduced, which is particularly effective for a large image.

Further, in the image compression processing apparatus according to claim 4, the object image is an image object, and the correcting means corrects the object image by a combination of the γ characteristic conversion and the resolution reduction. It is what you do.

According to the present invention, in claim 1, the correction means executes the γ characteristic conversion and the resolution reduction in combination with the above-mentioned claim 2 and claim 3 for the image to be processed of the image object. Accordingly, correction according to the density distribution and resolution level of the image of the processing target can be performed, and this is effective when the compression ratio is further increased.

Further, in the image compression processing apparatus according to the present invention, the object image is a graphics object or an image object, and the correcting means performs γ characteristic conversion of the object image.

According to the present invention, in claim 1, the correction means converts a γ characteristic, which is an input / output characteristic of the brightness of the image, according to a γ table for an image to be processed of a graphics object or an image object. Thus, the brightness level can be changed according to the characteristics of the image.

Further, in the image compression processing apparatus according to the present invention, the object image is a graphics object or an image object, and the correction means corrects the object image by lowering the resolution to make the resolution coarse. Is performed.

According to the present invention, in claim 1, the correcting means performs, for example, a thinning-out process on the image to be processed of the graphics object or the image object, and then returns the image to the original size by a simple enlargement process. By executing the processing, the processing for lowering the resolution is realized.

Further, in the image compression processing apparatus according to the present invention, the object image is a graphics object or an image object, and the correcting means is a combination of the gamma characteristic conversion and the resolution reduction of the object image. Is to be corrected.

According to the present invention, in claim 1, the correction means combines the γ characteristic conversion and the resolution reduction described in claims 2 and 3 with respect to the image to be processed of the graphics object or the image object. By executing the correction, it is possible to perform correction in accordance with the density distribution and the resolution level of the image of the processing target.

Further, in the image compression processing apparatus according to the present invention, the ratio of the object image occupying the page is calculated, and the calculated value is compared with a predetermined value. Area ratio calculating / judging means for judging the size of the image data, wherein the correcting means changes the coding efficiency and corrects when the value calculated by the area ratio calculating / judging means is determined to be smaller than a predetermined value. Then, the processing returns to the coding efficiency calculating / determining means.

According to the present invention, the ratio of the object to the page (area ratio) is obtained by using all the pixels of the object or a sampled part, and when the text object has a large area ratio, the influence on the compression ratio is reduced. When the area ratio is small, the process is advanced, and when the area ratio is small, the process is skipped because the effect on the image is small, so that the process according to the size of the object area ratio is realized.

In the image compression processing apparatus according to the ninth aspect, the image compression processing apparatus may further include an object determination unit configured to determine a type of the object image.
The correction is performed according to the type of the object determined by the object determining means.

According to the present invention, when image, graphics, and text objects are mixed, the type of the object is determined by the object determining means, so that a correction suitable for the object can be performed.

According to a tenth aspect of the present invention, there is provided an image compression processing method for inputting an object image to be processed and compressing and outputting the object image. A calculating step for calculating the efficiency, an encoding efficiency determining step for comparing and determining the coding efficiency calculated in the first step with a predetermined value, and a determination made by the coding efficiency determining step being smaller than a predetermined value. A correction step of changing the coding efficiency and repeatedly executing the correction until the coding efficiency becomes equal to or smaller than a predetermined value when the coding efficiency is determined to be larger.

According to the present invention, an object image to be processed is input and its coding efficiency is calculated. When the calculated value is less than a predetermined value (for example, a compression ratio that can be stored in the storage medium), the storage medium Since the image data cannot be stored in the storage medium, by repeatedly executing a process of applying a predetermined correction to the image until a predetermined value is satisfied, an image correction that can be stored in a storage medium is realized.

In the image compression processing method according to the eleventh aspect, in the image compression processing method for inputting an object image to be processed and compressing and outputting the object image, the object image may include a page. Calculating an occupying ratio, comparing the calculated value with a predetermined value, and determining an area ratio determining step of determining the magnitude of the calculated value; and determining that the calculated value in the area ratio determining step is smaller than a predetermined value. In this case, the coding efficiency is changed and the correction is repeatedly performed until the coding efficiency becomes equal to or less than a predetermined value.

According to the present invention, the ratio (area ratio) of an object to a page is determined, and is determined using all pixels or a sampled part of the object. When a text object has a large area ratio, the effect on the compression ratio is obtained. Is large, the processing is advanced, and when the area ratio is small, the processing is skipped because the influence on the image is small, thereby realizing the processing according to the size of the object area ratio.

According to a twelfth aspect of the present invention, there is provided an image compression processing method for inputting an object image to be processed and compressing and outputting the object image. The method includes an object discriminating step of discriminating, and a correcting step of changing the coding efficiency according to the type of the object discriminated in the object discriminating step and repeatedly executing the correction until the coding efficiency becomes equal to or less than a predetermined value.

According to the present invention, when image, graphics, and text objects are mixed, the type of the object is determined in the object determining step, so that a correction suitable for the object can be performed.

Further, in the image compression processing method according to claim 13, the object image is an image object, and the correcting step is a γ characteristic conversion of the object image.

According to the present invention, in any one of the tenth to twelfth aspects, γ, which is the input / output characteristic of the brightness of the image, is applied to the image to be processed of the image object in the correcting step.
The characteristics are converted in accordance with a γ table (for example, a table for converting the density to a lower direction when the image object is closer to a lower density, and to a higher direction when the image object is higher) to increase the run length, which is advantageous for compression. This makes it possible to change the brightness level according to the characteristics of the image.

Further, in the image compression processing method according to claim 14, the object image is an image object, and the correcting step is a low-resolution process for reducing the resolution of the object image.

According to the present invention, after the image to be processed of the image object is subjected to, for example, a thinning process in the correcting step,
By executing the process of returning to the original size by the simple enlargement process, the number of pixels of the image object is physically reduced, which is particularly effective for a large image.

Further, in the image compression processing method according to claim 15, the object image is an image object, and the correcting step is a combination of the γ characteristic conversion and the reduction of the resolution of the object image.

According to the present invention, the processing according to any one of claims 10 to 12 is performed by combining the above-mentioned γ-characteristic conversion and reducing the resolution in the correction step with respect to the image to be processed of the image object. Correction according to the density distribution and resolution level of the image possessed by the object becomes possible.

Further, in the image compression processing method according to claim 16, the object image is a graphics object or an image object, and the correcting step is a γ characteristic conversion of the object image.

According to the present invention, the gamma characteristic, which is the input / output characteristic of the brightness of the image, is set in the gamma table in the correction step for the image to be processed of the graphics object or the image object. , The brightness level can be changed in accordance with the characteristics of the image.

[0040] In the image compression processing method according to claim 17, the object image is a graphics object or an image object, and the correcting step is a low-resolution process for reducing the resolution of the object image. .

According to the present invention, the image to be processed of the graphics object or the image object is subjected to, for example, thinning-out processing in the correction step, and then to the original size by simple enlargement processing. By executing the process of returning to the original state, the process of lowering the resolution is realized.

Further, in the image compression processing method according to claim 18, the object image is a graphics object or an image object, and the correcting step is a combination of the γ characteristic conversion and the resolution reduction of the object image. It is.

According to the present invention, in any one of the tenth to twelfth aspects, in the correction step, the γ characteristic conversion and the lowering of the resolution are performed on the image to be processed of the graphics object or the image object. Accordingly, it is possible to perform correction in accordance with the density distribution and the resolution level of the image of the processing target.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an image compression processing apparatus and an image compression processing method according to the present invention will be described below in detail with reference to the accompanying drawings. Further, the present invention is not limited to this embodiment. The present invention provides a printer image before conversion into a binary image, for example, a business document (report, report, etc.) created by an application installed in a personal computer.
Presentation materials).

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an image compression processing apparatus according to Embodiment 1 of the present invention. The image compression processing apparatus 10 calculates a compression ratio (encoding efficiency) of an input object, and compares the calculated value with a predetermined value (a value of a compression ratio that can be stored in a storage medium) to determine a compression ratio. A determination unit 11; and a correction unit 12 that changes and corrects the compression ratio of the object. Reference numeral 20 denotes a storage medium in which the corrected object is stored. As the storage medium 20, in addition to various magnetic storage media (floppy disk, hard disk, etc.), an optical disk, a magneto-optical disk, or the like is used, but a storage device capable of storing information may be used.

The values representing the coding efficiency in this embodiment include a compression ratio and a run length (Run Le
ngth), frequency distribution of run length, and the like. If the resolution of the object is reduced, the ratio of the object before correction to the page and the size after correction may be used. In this way, it means a value that can predict or calculate how much compression the object can compress. Hereinafter, a description will be given assuming that a value representing the coding efficiency = compression ratio.

Next, the operation of the image compression processing apparatus 10 configured as described above will be described. FIG. 2 is a flowchart illustrating an operation of the image compression processing device according to the first embodiment of the present invention. First, an object is input to the compression rate calculation / judgment unit 11 (step S11), and the compression rate calculation / judgment unit 11 inputs the object compression rate Rate.
Is calculated (step S12). If the type of the object is graphics or text, the compression ratio Rate is calculated after the object is expanded into an image.

Subsequently, the calculated compression rate Rate is compared with a predetermined value ThR, and it is determined whether or not the compression rate Rate <the predetermined value ThR (step S1).
3). Here, if it is determined that the compression ratio Rate <the predetermined value ThR, it means that the object exceeds the storage capacity of the storage medium 20, so that the compression ratio of the object is changed and corrected (step S14). Step S
Returning to step 12, the operations in steps S12 to S14 are repeatedly executed until the compression ratio reaches the predetermined value ThR.

Therefore, by performing the above-described operation, the correction processing is repeatedly performed by the correction unit 12 until the compression ratio satisfies a predetermined value. Therefore, the input object data is reliably stored in the storage medium 20. Can be.

FIG. 3 is a flowchart showing a first operation example of the correction unit of the image compression processing apparatus according to the first embodiment of the present invention, in which the correction unit 12 corrects an image by γ conversion. I have. Here, the case where the input object is an image object is targeted. First, an image object is input (step S21), and brightness data v (v is normalized to, for example, 0 ≦ v ≦ 100) is converted from the RGB data to a general HSV conversion using color graphics for each pixel of the image object. It is calculated (step S22). The calculation of the brightness data v may be performed by sampling instead of all pixels to reduce the calculation amount.

Subsequently, the frequency distribution of the brightness data v is obtained (step S23), and the determination of the brightness is executed (step S23).
24) It is determined whether or not the brightness is brighter than the intermediate value (step S25). Here, when it is determined that the data is lighter than the intermediate value, a γ table to be made brighter is selected (step S26), and γ conversion is executed according to the selected γ table (step S27). On the other hand, if it is determined in step S24 that the data is not lighter than the intermediate value, a γ table to be darkened is selected (step S28), and γ conversion is performed according to the selected γ table (step S27).

As described above, when the object is an image, the image is converted by γ conversion. The image in this case refers to a BMP image (Windows standard image data format) pasted on a page, a DSVC photographed image, or the like. Here, the reason why the γ conversion is used to increase the compression ratio for the image object will be described. FIG. 4 shows an image obtained by extracting a part of the image after binarization. (A) is often seen in the low density portion and has a long white run length. (B) is (a)
Which is often seen in high density areas and has a long black run length. On the other hand, as shown in (c), when the intermediate density portion is large, it can be seen that the longest white and black lengths are both shorter than (a) and (b).

Therefore, when the image object is closer to the lower density, the density is converted to a lower direction. On the other hand, when the image object is closer to the higher density, it is converted to a higher direction.
It can be seen that the run length becomes longer, which is advantageous for compression.

FIG. 5 is a graph showing an example of a frequency distribution of the brightness data v. In this case, the peak of the distribution is the intermediate value v5
Since it is larger than 0 (right side), it can be seen that the object is slightly bright. Therefore, in order to increase the white run length, a gamma table to be made brighter as shown in FIG. 6 is selected, and the image object is converted.

Therefore, by performing the above-described operation, the correction processing by the correction unit 12 is γ conversion.
The input object data can be reliably stored in the storage medium 20 in a state where the compression ratio is increased without greatly impairing the original image quality.

FIG. 7 is a flowchart showing a second operation example of the correcting section of the image compression processing apparatus according to the first embodiment of the present invention, in which the correcting section 12 corrects an image by thinning-out / simple enlargement processing. Is shown. First, an image object is input (step S31), an original is sampled at a predetermined sampling rate, and a thinning process is performed on the sampled pixels (step S32). Subsequently, a simple enlargement process is performed on the image subjected to the thinning process (step S33). That is, instead of enlargement using an interpolation formula or the like, enlargement is performed using an enlargement method that only copies data of adjacent pixels, and the original size is restored.

Therefore, by performing the above-described operation, the correction process by the correction unit 12 is a thinning process, which is a low-resolution process, and is effective for compression of an image in which black pixels that are extremely difficult to compress exist randomly. It is. Also,
Even if the resolution is reduced for a random tone image, there is an effect that deterioration of the image quality is hard to be recognized.

FIG. 8 is a flowchart showing a third operation example of the correction unit of the image compression processing apparatus according to the first embodiment of the present invention. An example is shown. First, an image object is input as described above (step S4).
1) The original is sampled from the image object at a predetermined sampling rate, and a thinning process is performed on the sampled pixels (step S42). Subsequently, the above-described γ conversion processing of FIG. 3 is performed on the image on which the thinning processing has been performed (step S43). Further, simple enlargement processing is performed on the γ-converted image (step S44). Therefore, when the γ conversion is performed after the thinning processing, the number of pixels is reduced, and the processing speed is increased.

Therefore, by performing the above-described operation, the correction processing by the correction unit 12 is performed using both the γ conversion and the thinning-out processing. Therefore, the image object is stored in the storage medium 20 with the compression ratio further increased. can do.

Next, processing when the input objects are graphics and text objects will be described. FIG. 9 is a flowchart illustrating a fourth operation example in the correction unit of the image compression processing device according to the first embodiment of the present invention. First, graphics and a text object are input (step S51), and low gradation number processing described later is executed (step S52). The low gradation number processing is processing of the number of colors of the graphics object, and is realized, for example, by applying the color data constituting the object as shown in FIG. That is, by changing the color designated by the intermediate density to a density direction that is convenient for compression, the compression efficiency of graphics or text objects can be increased.

FIG. 11 is a flowchart showing a fifth operation example of the correction unit of the image compression processing apparatus according to the first embodiment of the present invention. First, in the same manner as described above, graphics and text objects are input (step S61), and γ conversion processing described later is executed (step S61).
62). This gamma conversion process can improve the characteristics shown in FIG. 12 as an example. The density is maintained as low as possible for low density and high density parts, and the medium density part is distributed to low / high density parts.

FIG. 13 is a flowchart showing a sixth operation example of the correcting section of the image compression processing apparatus according to the first embodiment of the present invention, which is a combination of the above-described operations of FIGS. . First, as in FIG. 9 described above,
Graphics and text objects are input (step S71), and low gradation number processing is executed (step S72). Further, similarly to FIG. 11 described above, a γ conversion process is executed (step S73).

FIG. 14 is a flowchart showing a seventh operation example of the correction unit of the image compression processing apparatus according to the first embodiment of the present invention, which is a combination of the above-described operations of FIGS. . This operation is different from the operation in FIG. 13 in the order of the γ conversion and the gradation reduction. That is, graphics and text objects are input (step S81), and γ conversion processing is executed (step S82) as in FIG. 11 described above. Further, similarly to the above-described FIG. 9, low gradation number processing is executed (step S83).

It is desirable to convert the characteristics of the text object as shown in FIG. This characteristic rounds the high density portion to 255 at the time of output. Most of the text in general business documents is expressed in full black, that is, R = G = B = 0. The print is CMYK converted to improve text quality,
K = 255 (a black character is reproduced in one black color and no coloring occurs around the character). Where K = 25
The fact that the text is drawn in 5 means that the text portion is a sequence of black pixels.

On the other hand, in the case of a high-density gray character of R = G = B = 50, the text portion is halftone, white pixels are included, and the black run length when R = G = B = 0 is smaller. Be shorter. Therefore, the shadow part destroys the data, but it is difficult to recognize the state of the density change in the high density part, so that the effect of the image quality is small. In addition,
If the same processing is performed even in a low density portion, the characters will disappear, and the quality will be significantly reduced.

Therefore, by performing the above-described processing on graphics and text objects, it is possible to increase the compression ratio even for graphics that make extensive use of gradation. When the number of gradations is large, the number of binarized patterns increases, and as a result, the run length is not constant. However, when the number of gradations is small, the number of binarized patterns is limited. And the coding efficiency is improved. Further, since the modification of the graphics and text objects is performed by a combination of the γ conversion and the reduction of the number of gradations, the coding efficiency is further improved.

(Embodiment 2) FIG. 16 is a block diagram showing a configuration of an image compression processing apparatus according to Embodiment 2 of the present invention. This image compression processing apparatus 30 is obtained by adding an area ratio calculation / determination unit 31 for calculating and determining the ratio of an object occupying a page to the image compression processing apparatus 10 shown in FIG. That is, the area ratio calculation / judgment unit 31
In the subsequent stage, a compression ratio calculation / judgment unit 11 and a correction unit 12 are provided.

Next, the operation of the image compression processing device 30 configured as described above will be described. FIG. 17 is a flowchart illustrating the operation of the image compression processing device according to the second embodiment of the present invention. First, the object is input to the area ratio calculation / judgment unit 31 (step S91), and the area ratio S is calculated as the ratio of the object to the page (step S92). Subsequently, the calculated area ratio S is compared with a predetermined value ThS set in advance.
It is determined whether or not> ThS (step S93).
Here, if S> Th is not satisfied, that is, if the area ratio is small, the influence on the compression ratio is small, and the subsequent processing is skipped. On the other hand, if it is determined that S> ThS,
Since the influence on the compression ratio is large, the compression ratio calculation / determination unit 11 calculates the compression ratio Rate of the object as in the first embodiment (step S94). If the type of the object is graphics or text, the compression ratio Rate is calculated after the object is expanded into an image.

Subsequently, the calculated compression rate Rate is compared with a predetermined value ThR, and it is determined whether or not the compression rate Rate <the predetermined value ThR (step S9).
5). Here, if it is determined that the compression ratio Rate <the predetermined value ThR, it means that the object exceeds the storage capacity of the storage medium 20, so the compression ratio of the object is changed and corrected (step S96). Returning to step S94, the operations of steps S94 to S96 are repeatedly executed until the compression ratio reaches the predetermined value ThR.

Therefore, the area ratio S is obtained as the ratio of the object to the page, and when the area ratio S is smaller than the predetermined value ThS, the subsequent processing is skipped, thereby shortening the processing time. This effect is highest in an image object, and in the case of text, the area can be obtained from a rectangular area surrounding the text. However, the text itself may have a small area ratio to the page, so that the text may be excluded.

(Embodiment 3) FIG. 18 is a block diagram showing a configuration of an image compression processing apparatus according to Embodiment 3 of the present invention. This image compression processing apparatus 40 is obtained by adding an object determination unit 41 for determining whether the type of an object is an image, graphics, or text to the image compression processing apparatus 10 shown in FIG. That is,
The compression ratio calculation / judgment unit 1 is provided after the object judgment unit 41.
1 and a correction unit 12.

Next, the operation of the image compression processing device 40 configured as described above will be described. FIG. 19 is a flowchart illustrating an operation of the image compression processing device according to the third embodiment of the present invention. First, an image to be processed is input (step S101), and it is determined whether or not the object determination has been completed (step S102). Here, if it is determined that the object determination has not been completed, the object is determined (step S103), and it is first determined whether or not the object is an image (step S104). Here, if the object is an image, a correction for the image is executed (step S105).

On the other hand, if it is determined in step S104 that the object is not an image, it is determined whether the object is graphics (step S104).
106). If the object is a graphic, a correction for the graphic is executed (step S).
107). On the other hand, if it is determined in step S106 that the object is not a graphic, a text correction is performed (step S108).

As described above, by sequentially confirming the types of the objects constituting the page and determining which type of the object corresponds, a correction suitable for the type of the object is realized.

[0075]

As described above, according to the image compression processing apparatus according to the present invention (claim 1), the object image to be processed is input to the coding efficiency calculating / judging means, where the coding efficiency is determined. When the calculated value is less than the predetermined value, it cannot be stored in the storage medium. Therefore, the correction is performed by the correction means, and the processing is repeated until the predetermined value is satisfied, and is output to the subsequent stage. In addition, all data can be stored in a limited number of storage media while minimizing deterioration in image quality by processing the image data, and data of a larger number of pages can be accommodated.

According to the image compression processing apparatus according to the present invention (claim 2), in claim 1, the correction means for the image to be processed of the image object is an input / output characteristic of the brightness of the image. Since the γ characteristic is converted in accordance with the γ table, it is possible to change the brightness level according to the characteristic of the image while minimizing the deterioration of the image quality of the original image.

According to the image compression processing apparatus according to the present invention, the correcting means may perform, for example, thinning processing on the image to be processed of the image object, and then perform simple enlargement. Since the processing for returning to the original size is executed by the processing, the processing for lowering the resolution is realized.

Further, according to the image compression processing apparatus according to the present invention (claim 4), in claim 1, the correction means for the image to be processed of the image object, the correction means according to claim 2 and claim 3 Since the gamma characteristic conversion and the resolution reduction are performed in combination, a correction that is effective when the compression ratio is further increased while minimizing the image quality deterioration of the original image is realized.

Further, according to the image compression processing device of the present invention, the correction means for the image to be processed of the graphics object or the image object, the input / output of the brightness of the image is performed. Since the γ characteristic, which is the characteristic, is converted in accordance with the γ table, it is possible to change the brightness level in accordance with the characteristic of the image while minimizing the deterioration of the image quality of the original image.

Further, according to the image compression processing apparatus according to the present invention (claim 6), in claim 1, after the correction means performs, for example, a thinning process on the processing object image of the graphics object or the image object. In addition, since the processing for returning to the original size is executed by the simple enlargement processing, the processing for lowering the resolution is realized.

Further, according to the image compression processing apparatus according to the present invention (claim 7), the correction means for the processing object image of the graphics object or the image object in claim 1, Since the γ characteristic conversion and the resolution reduction in the item 3 are performed in combination, it is possible to perform the correction according to the density distribution and the resolution level of the image of the processing target while minimizing the degradation of the image quality of the original image. .

According to the image compression processing apparatus of the present invention, the ratio of the object to the page (area ratio) is determined, and when the text object has a large area ratio, the effect on the compression ratio is not affected. Since it is large, the following correction processing is advanced, and when the area ratio is small, the processing is skipped because the effect on the image is small, so that processing according to the magnitude of the area ratio of the object is realized. Processing efficiency is improved.

Further, according to the image compression processing apparatus of the present invention, when objects of image, graphics, and text are mixed, the type of the object is determined by the object determining means. Therefore, a modification suitable for the object can be performed, so that a modification process suitable for each object is realized.

Further, according to the image compression processing method of the present invention, the encoding efficiency is calculated by inputting the object image to be processed, and when the calculated value is less than the predetermined value, the image is stored. Because it cannot be stored on media,
By repeatedly executing a process of applying a predetermined correction to an image until a predetermined value is satisfied, an image correction that can be accommodated in a storage medium is realized. All data can be stored in a limited storage medium, and more pages of data can be accommodated.

Further, according to the image compression processing method of the present invention (claim 11), the ratio (area ratio) of the object to the page is determined, and when the text object has a large area ratio, the influence on the compression ratio is not affected. Since the size is large, the image correction process is advanced, and when the area ratio is small, the image is not greatly affected. By passing the image correction process through, the process according to the size of the object area ratio is realized. The processing efficiency of the image image is improved.

According to the image compression processing method of the present invention (claim 12), the image, graphics,
When text objects are mixed, the type of the object is determined in the object determination step, so that a correction suitable for the object can be performed. Therefore, a correction process suitable for each object is realized.

Further, according to the image compression processing method according to the present invention (claim 13), in any one of claims 10 to 12, the image object to be processed is
In the correction process, the gamma characteristic, which is the input / output characteristic of the brightness of the image, is converted according to the gamma table. Is realized.

According to the image compression processing method of the present invention (claim 14), the image compression processing method according to any of claims 10 to 12
In the correction process, for example, after performing a thinning-out process, a process for returning to the original size by the simple enlargement process is executed, so that a lower resolution in the correction process is realized.

According to the image compression processing method of the present invention (claim 15), the image compression processing method according to any of claims 10 to 12
In the correction process, since the above-described γ characteristic conversion and resolution reduction are performed in combination, it is effective when it is desired to further improve the compression ratio while minimizing the degradation of the image quality of the original image.

Further, according to the image compression processing method of the present invention (claim 16), in any one of claims 10 to 12, an image to be processed of a graphics object or an image object is corrected in the correction step. Since the γ characteristic, which is the brightness input / output characteristic, is converted according to the γ table, it is possible to change the brightness level according to the characteristic of the image while minimizing the deterioration of the image quality of the original image.

Further, according to the image compression processing method of the present invention (claim 17), in any one of claims 10 to 12, the image to be processed of the graphics object or the image object is corrected in the correction step, for example, by thinning. After the processing, the processing for returning to the original size by the simple enlargement processing is executed, so that the correction processing for lowering the resolution is realized.

Further, according to the image compression processing method according to the present invention (claim 18), in any one of claims 10 to 12, the above-mentioned γ-characteristic conversion and image processing are performed on the image to be processed of the graphics object or the image object. Since the correction process is performed in combination with lowering the resolution (lowering the number of pixels), the correction according to the density distribution and the resolution level of the image to be processed can be realized while minimizing the deterioration of the image quality of the original image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image compression processing device according to a first embodiment of the present invention;

FIG. 2 is a flowchart illustrating an operation of the image compression processing device according to the first exemplary embodiment of the present invention;

FIG. 3 is a flowchart illustrating a first operation example in the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 4 is an explanatory diagram showing an example of an image in a state where a part is cut out from an image after binarization.

FIG. 5 is a graph showing an example of a frequency distribution of brightness data v.

FIG. 6 is a graph showing an example of a γ table used for brighter γ conversion.

FIG. 7 is a flowchart illustrating a second operation example in the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 8 is a flowchart illustrating a third operation example in the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 9 is a flowchart illustrating a fourth operation example of the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 10 is a graph showing an example of a gradation image in FIG. 9;

FIG. 11 is a flowchart illustrating a fifth operation example of the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 12 is a graph showing an example of γ conversion in FIG. 11;

FIG. 13 is a flowchart illustrating a sixth operation example in the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 14 is a flowchart illustrating a seventh operation example in the correction unit of the image compression processing device according to the first embodiment of the present invention;

FIG. 15 is a graph showing an example of reduction in the number of gradations and γ conversion.

FIG. 16 is a block diagram illustrating a configuration of an image compression processing device according to a second embodiment of the present invention;

FIG. 17 is a flowchart illustrating an operation of the image compression processing device according to the second embodiment of the present invention;

FIG. 18 is a block diagram illustrating a configuration of an image compression processing device according to a third embodiment of the present invention.

FIG. 19 is a flowchart illustrating an operation of the image compression processing device according to the third embodiment of the present invention;

[Explanation of symbols]

 10, 30, 40 Image compression processing device 20 Storage medium 11 Compression ratio calculation / judgment unit 12 Correction unit 31 Area ratio calculation / judgment unit 41 Object judgment unit

Continued on the front page F-term (reference) 5C053 FA07 FA23 GA11 GB26 KA04 LA03 5C059 KK08 MA04 MB14 ME05 PP01 PP28 SS11 TA58 TC24 TC34 TC38 TD10 TD12 TD15 UA02 5C078 CA02 DA00 DA01 DB00 DB04

Claims (18)

[Claims] An image compression processing apparatus for inputting an object image to be processed, compressing and outputting the object image, calculates an encoding efficiency of the object image, and determines the encoding efficiency in advance. A coding efficiency calculating / judging means for comparing the coding efficiency with the predetermined value, and judging the magnitude of the coding efficiency. An image compression processing apparatus comprising: a correction unit that changes and corrects and returns to the coding efficiency calculation / judgment unit. 2. The image compression processing apparatus according to claim 1, wherein the object image is an image object, and wherein the correction unit performs gamma conversion of the object image. 3. The image compression processing apparatus according to claim 1, wherein the object image is an image object, and wherein the correction unit performs a correction by lowering the resolution of the object image. . 4. The image compression apparatus according to claim 1, wherein said object image is an image object, and said correction means corrects the object image by a combination of gamma characteristic conversion and resolution reduction. Processing equipment. 5. The image compression processing apparatus according to claim 1, wherein the object image is a graphics object or an image object, and the correction unit performs a γ characteristic conversion of the object image. 6. The image according to claim 1, wherein the object image is a graphics object or an image object, and wherein the correction unit performs the correction by reducing the resolution of the object image to a lower resolution. Compression processing device. 7. The object image processing method according to claim 1, wherein the object image is a graphics object or an image object, and wherein the correction unit corrects the object image by a combination of γ characteristic conversion and resolution reduction. Image compression processing device. 8. An area ratio calculating / judging means for calculating a ratio of the object image occupying a page, comparing the calculated value with a predetermined value, and judging the size of the calculated value. The correction unit, when it is determined that the value calculated by the area ratio calculation / determination unit is smaller than a predetermined value, changes and corrects the coding efficiency, and returns to the coding efficiency calculation / determination unit. The image compression processing apparatus according to any one of claims 1 to 7, wherein: 9. The image processing apparatus according to claim 1, further comprising: an object determining unit configured to determine a type of the object image, wherein the correcting unit performs correction according to the type of the object determined by the object determining unit. An image compression processing apparatus according to any one of claims 1 to 8. 10. An image compression processing method for inputting an object image to be processed and compressing and outputting the object image, wherein: a calculating step of calculating the encoding efficiency of the object image; An encoding efficiency determining step of comparing the calculated encoding efficiency with a predetermined value determined in advance; and, if the determination by the encoding efficiency determining step is determined to be larger than the predetermined value, changing the encoding efficiency to a predetermined value. A correction step of repeatedly executing correction until the value becomes equal to or less than a value. 11. An image compression processing method for inputting an object image to be processed and compressing and outputting the object image, wherein a ratio of the object image occupying a page is calculated,
Comparing the calculated value with a predetermined value determined in advance, and determining an area ratio determining step of determining the magnitude of the calculated value; and determining that the calculated value in the area ratio determining step is smaller than the predetermined value, the coding efficiency. And a correction step of repeatedly executing the correction until the value becomes equal to or less than a predetermined value. 12. An image compression processing method for inputting an object image to be processed and compressing and outputting the object image, wherein the object determination step includes determining an object image type and the object determination step. A coding step of changing the coding efficiency according to the type of the object and repeatedly executing the correction until the coding efficiency becomes equal to or less than a predetermined value. 13. The image compression process according to claim 10, wherein the object image is an image object, and the correcting step is a γ characteristic conversion of the object image. Method. 14. The object image processing method according to claim 10, wherein said object image is an image object, and said correcting step is a low-resolution process for reducing a resolution of said object image.
3. The image compression processing method according to any one of 2. 15. The image processing apparatus according to claim 10, wherein the object image is an image object, and the correcting step is a combination of conversion of a gamma characteristic of the object image and resolution reduction. 2. The image compression processing method according to 1. 16. The object according to claim 10, wherein the object image is a graphics object or an image object, and the correcting step is a γ characteristic conversion of the object image. Image compression processing method. 17. The image processing method according to claim 10, wherein the object image is a graphics object or an image object, and the correcting step is a low-resolution process for reducing a resolution of the object image.
3. The image compression processing method according to any one of 2. 18. The method according to claim 10, wherein the object image is a graphics object or an image object, and the correcting step is a combination of conversion of a gamma characteristic and resolution reduction of the object image. The image compression processing method according to any one of the above.