KR101769945B1 - Method and apparatus for pre-treating image for printing - Google Patents

Abstract

A computer program stored on a computer-readable recording medium so that a processor can perform the image preprocessing method according to the present invention includes the steps of extracting an image to be printed with pixel units of M × M size, Converting a color value of a center pixel into a predetermined reduced color value based on a color value of surrounding pixels in the image, and selectively applying a conversion to the predetermined reduced color value to each pixel constituting the image . ≪ / RTI >

Description

TECHNICAL FIELD [0001] The present invention relates to a method and an apparatus for pre-

The present invention relates to an image preprocessing technique, and more particularly, to an image preprocessing method and apparatus for printing suitable for reducing the amount of ink consumed when printing an image such as a photograph through a printer.

Generally, it is necessary to reduce the amount of ink used for printing in order to improve ink efficiency when printing photographs or documents using a printer. In this case, it is necessary to reduce the amount of ink used, Technique is required.

Conventionally, a user has operated an operation key provided in the printer itself to confirm a message displayed on the display panel of the printer, thereby performing an ink usage reduction process.

However, since the conventional ink saving method as described above can not arbitrarily set the saving rate of the ink desired by the user and is set only at a predetermined saving rate set by the manufacturer of the printer, it is inconvenient to use and the resolution of the printed photo or document Is very low.

Korean Patent Publication No. 2010-0005884 (published on Jan. 18, 2010)

The present invention proposes a new image preprocessing technique for converting a color value of a central pixel into a predetermined reduced color value based on the color value of peripheral pixels in an M × M pixel unit.

According to an embodiment of the present invention, there is provided a method of selectively converting a color value of each pixel in an image into a reduced color value, a computer program for executing such a printing image preprocessing method, and a computer- Lt; / RTI >

The problems to be solved by the present invention are not limited to those mentioned above, and another problem to be solved by the present invention can be clearly understood by those skilled in the art from the following description will be.

According to one aspect of the present invention, there is provided a method of processing a color image, comprising the steps of extracting an image to be printed with pixel units of MxM size, and calculating a color value of a center pixel based on color values of surrounding pixels in the extracted pixel unit Converting the image into a predetermined color value, and selectively applying a conversion to the predetermined reduced color value to each pixel constituting the image, the method comprising: And a computer program stored in the recording medium.

According to another aspect of the present invention, there is provided an image processing method including a first step of separating an image of a print object into N sub-images which are layers of a printed material model, a step of extracting each separated sub- A third step of determining whether the extracted pixel unit is a target pixel unit based on the color values of neighboring pixels adjacent to the center pixel in the pixel unit; And a fourth step of performing the second through fourth processes until the color preprocessing for each of the sub images is completed. In the fifth step, when the color preprocessing is completed And a sixth step of synthesizing each changed sub-image into a changed image. The image preprocessing method for printing may be computer readable It provides a computer program stored in the recording medium.

The N sub-images of the present invention may be four CMYK sub-images constituting the print model.

Each pixel unit of the present invention can have a size of 3x3.

The third step of the present invention comprises the steps of classifying the pixel unit as a candidate pixel unit when the center pixel has an arbitrary color value and calculating a color value of neighboring pixels adjacent to the center pixel of the classified candidate pixel unit And determining the candidate pixel unit as the target pixel unit when the summed color value exceeds the reference color value.

The reference color value of the present invention can be calculated in inverse proportion to the ratio of the distance from the center pixel to the surrounding pixels.

The predetermined reduction color value of the present invention can be changed and set by the user.

Each of the pixels constituting each sub image of the present invention can be set to be placed at least once in the center pixel.

According to still another aspect of the present invention, there is provided a method of extracting a print object, comprising: a first step of dividing an image of a print object into N sub-images which are layers of a print model; A third step of determining whether the extracted pixel unit is a target pixel unit based on a color value of neighboring pixels adjacent to the center pixel in the pixel unit; A fourth step of converting the value of the color image into a predetermined reduced color value, a fifth step of repeating the second through fourth processes until the color preprocessing for each sub image is completed, And a sixth step of synthesizing each changed sub-image into a changed image.

According to still another aspect of the present invention, there is provided a computer program for causing a processor to perform the image preprocessing method for printing according to claim 9.

According to another aspect of the present invention, there is provided an image processing apparatus including an image decomposing section for separating an image of a print object into N sub-images which are layers of a printed material model, A unit determination unit for determining a target pixel unit for adjustment of an ink amount based on a color value of peripheral pixels adjacent to a center pixel in a pixel unit; A color conversion unit for converting a color value into a predetermined reduced color value; and an image compositing unit for composing each changed sub-image into a changed image when the color preprocessing for each sub-image is completed to provide.

The unit determination unit of the present invention may further include a pixel classification block that classifies the pixel unit into candidate pixel units when the center pixel has an arbitrary color value and a color classification unit that determines a color of neighboring pixels adjacent to the center pixel of the classified candidate pixel unit And a target decision block for determining the candidate pixel unit as the target pixel unit when the summed color value exceeds a reference color value.

The present invention selectively reduces a color value of each pixel constituting an image by converting a color value of a center pixel into a predetermined reduced color value based on a color value of peripheral pixels in an MxM pixel unit, It is possible to effectively reduce the amount of ink used in the printer while excluding the visual recognition of the ink.

1 is a block diagram of a printing image preprocessing apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating a main process of selectively reducing a color value of each pixel constituting an image according to an exemplary embodiment of the present invention.
3 is an illustration of a 3x3 pixel unit applied to an embodiment of the present invention.
4A and 4B are photographs of simulation results of the original image and the modified image to which the present invention is applied.
5A and 5B are photographs of the result of another simulation of the original image and the modified image to which the present invention is applied.

First, the advantages and features of the present invention, and how to accomplish them, will be clarified with reference to the embodiments to be described in detail with reference to the accompanying drawings. While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. It is to be understood that the following terms are defined in consideration of the functions of the present invention, and may be changed according to intentions or customs of a user, an operator, and the like. Therefore, the definition should be based on the technical idea described throughout this specification.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an image preprocessing apparatus for printing according to an embodiment of the present invention. The image decomposition unit 102, the unit extraction unit 104, the unit determination unit 106, the color conversion unit 108, And the unit determination unit 106 may include a pixel classification block 1062, a color value calculation block 1064, and a target decision block 1066, for example.

1, the image decomposing unit 102 divides an image of an object to be printed through a printer into N sub-images which are layers of a print model, that is, four C (cyan) sub- A yellow sub-image, a K (black) sub-image, and delivering the separated sub-images to the unit extracting unit 104. The sub-

The unit extracting unit 104 extracts (generates) each of the sub images separated through the image decomposing unit 102 by a plurality of pixel units of M × M size (for example, 3 × 3 size) And sequentially delivering the pixel units to the unit determination unit 106. [ Here, the unit extracting unit 104 may generate pixel units so that all of the pixels constituting each subimage are placed at least once in the center pixel.

Meanwhile, the size of the pixel unit extracted through the unit extraction unit 104 is not necessarily limited to 3x3. The size of the pixel unit may be enlarged according to necessity or usage, The smaller the pixel unit size, the smaller the time required to calculate the pixel amount of the unit is, and the faster the pixel unit amount is, the larger the size of the pixel unit is, A more detailed and smooth ink saving effect can be obtained.

3, A, B, C, D, E, F, and G (see FIG. 3, for example) adjacent to the center pixel The unit determination unit 106 may determine the target pixel unit for adjusting the amount (usage) of the ink based on the color value of the pixel classification block 1062, A color value calculating block 1064, an object determining block 1066, and the like.

First, the pixel classification block 1062 classifies the pixel unit as a candidate pixel unit when the center pixel of the pixel unit delivered from the unit extraction unit 104 has an arbitrary color value (i.e., not white) And delivering the classification result to the color value calculation block 1064, for example. At this time, when the center pixel is white, the pixel classification block 1062 will not classify the pixel unit as a candidate pixel unit but exclude it as a color preprocessing target.

In addition, the color value calculation block 1064 calculates the color value of the adjacent candidate pixel unit by summing up the color values of neighboring pixels adjacent to the center pixel of the classified candidate pixel unit, i.e., considering the ratio of the distance between the pixels adjacent to the upper, And the summed value is calculated.

As shown in FIG. 3, when A, B, E, G, and H are target pixels having color values, and B, E, and G are 1 and A and H are 0.7 The color value calculation block 1064 may calculate a color sum value for the target pixels as shown in Equation (1).

[Equation 1]

0.7 / sqrt (2) + 1 + 1 / sqrt (2) * 2 + 0.7 = 3.61

When the color sum value calculated through the hue value calculation block 1064 exceeds the reference hue value, the target decision block 1066 determines the target pixel unit as a target pixel unit and supplies it to the color conversion unit 108 And excluded from the color preprocessing object when the calculated color sum value is less than or equal to the reference color value.

Here, the reference color value means a value obtained by summing the color values of all the surrounding pixels except for the center pixel in the target pixel unit, and can be calculated in inverse proportion to the ratio of the distance from the center pixel to the surrounding pixels have. For example, when it is assumed that all of the peripheral pixels in FIG. 3 have a color value of "1 ", the reference color value can be calculated as shown in Equation 2 below.

&Quot; (2) "

1 * 4 + 1 / sqrt (2) * 4 = 6.83

Therefore, assuming that the sum of neighboring pixels is calculated as in Equation (1) above and the reference color value is calculated as in Equation (2), the object decision block 1066 determines It is determined that the color preprocessing (i.e., the color value reduction processing of the center pixel) is not performed.

For example, assuming that the color sum value of the surrounding pixels is set to apply the color preprocessing to the center pixel when the color sum value exceeds 0.7 times the reference color value, the sum value 3.61 is only 52.86% of the reference color value 6.83 , And in the target decision block 1066, the target pixel unit will be excluded from the color preprocessing target.

Next, when notified from the target decision block 1066 to the target pixel unit, the color conversion unit 108 converts the color value of the center pixel of the target pixel unit into a predetermined reduction color value, for example, To 70% of the value (reduction in ink consumption), and the like. Here, the reduction color value may be any one selected by the user under predetermined conditions such as 80%, 70%, 60%, and the like. That is, the reduced color value can be changed by the user.

Finally, when the color preprocessing for each separated sub-image (CMYK sub-image) is completed, each of the changed sub-images (i.e., each sub-image in which color preprocessing is selectively applied to each pixel) And the like can be provided.

Next, a series of processes for performing color preprocessing on an image to be printed using the printing image preprocessing apparatus according to the present embodiment having the above-described configuration will be described in detail.

2 is a flowchart illustrating a main process of selectively reducing a color value of each pixel constituting an image according to an exemplary embodiment of the present invention.

2, the image decomposition unit 102 divides an image of an object to be printed into N sub-images which are layers of a print model, that is, four C (cyan) sub-images, M (magenta) Image, a yellow sub-image, and a K (black) sub-image (step 202).

Then, the unit extracting unit 104 extracts (generates) each of the separated sub-images into a plurality of pixel units of M × M size, for example, 3 × 3 size (step 204). At this time, the unit extracting unit 104 extracts the pixel units so that all the pixels constituting each sub image can be placed at least once in the center pixel.

Next, in the pixel classification block 1062, it is checked whether or not the center pixel of the extracted pixel unit has an arbitrary color value (step 206), and when it is judged to have an arbitrary color value, Pixel unit. At this time, when it is determined that the center pixel does not have a color value, the corresponding pixel unit is excluded from the color preprocessing object, and the processing proceeds to step 214, which will be described later.

In response, the color value calculation block 1064 calculates the sum of the color values of neighboring pixels adjacent to the center pixel of the candidate pixel unit, that is, considering the ratio of the distance between the pixels adjacent to the upper, lower, left, and right diagonally adjacent pixels And the sum value is calculated as in Equation (1) (Step 208).

The target decision block 1066 again checks whether the calculated color sum value exceeds the reference color value (step 210), and when it is determined that the color sum value exceeds the reference color value, the color conversion section 108 ) To execute the color preprocessing. At this time, when it is determined that the color sum value does not exceed the reference color value, the pixel unit is excluded from the color preprocessing object, and the process proceeds to step 214, which will be described later.

Next, when the execution of the color preprocessing is notified from the target decision block 1066, the color conversion unit 108 converts the color value of the center pixel of the target pixel unit into a predetermined reduction color value, for example, 70 % (Step 212).

Thereafter, the image combining unit 110 checks whether or not the color preprocessing for each separated sub-image (CMYK sub-image) is completed (step 214), and if the color preprocessing is not completed, (214). ≪ / RTI >

If it is determined in step 110 that the color preprocessing for each subimage (CMYK subimage) has been completed, the image compositing unit 110 extracts each changed subimage, that is, 4 (Step 216), and ends the color preprocessing process for one image.

Meanwhile, the inventors of the present invention conducted a simulation in which the method of the present invention was applied to an image to be printed, and the results are shown in FIGS. 4 and 5.

4A and 4B are photographs of a simulation image of the original image and the modified image to which the present invention is applied. As a result of applying the image preprocessing method of the present invention to the original image of FIG. 4A, it is found that the ink usage is reduced by 5.346% As shown in FIG. 4B, the subsequent image is also similar to the original image.

5A and 5B are photographs of different images of the original image and the modified image using the present invention. As a result of applying the image preprocessing method of the present invention to the original image of FIG. 5A, it was found that the ink usage was reduced by 3.14% , And the image after the preprocessing is almost similar to the original image as shown in FIG. 5B.

Meanwhile, the image preprocessing method for printing according to the present invention, which has been described above, can be implemented as a code (computer program code) that can be executed by a computer on a recording medium readable by a computer (or a portable computer) The computer-readable recording medium may include any type of recording device in which data that can be read by a computer system is stored. Examples of such computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, mobile app, and the like.

And, combinations of each block of the accompanying block diagrams and each step of the flowchart may be performed by computer programstations. These computer program instructions may be loaded into a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus so that the instructions, which may be executed by a processor of a computer or other programmable data processing apparatus, And means for performing the functions described in each step are created.

The computer program instructions may also be stored in a computer usable or computer readable memory capable of directing a computer or other programmable data processing apparatus to implement the functionality in a particular manner, It is also possible for the instructions stored in the memory to produce manufacturing items that contain instruction means for performing the functions described in each block or flowchart of each block diagram.

Here, the computer program instructions may also be loaded onto a computer or other programmable data processing equipment, so that a series of operating steps may be performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other It is also possible that the instructions that perform the programmable data processing equipment provide the steps for executing the functions described in each block of the block diagram and at each step of the flowchart.

Also, each block or each step may represent a module, segment, or portion of code that includes at least one or more executable instructions for executing the specified logical function (s). It should also be noted that in some alternative embodiments, the functions mentioned in the blocks or steps may occur out of order. For example, two blocks or steps shown in succession may in fact be performed substantially concurrently, or the blocks or steps may sometimes be performed in reverse order according to the corresponding function.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. It is easy to see that this is possible. That is, the embodiments disclosed in the present invention are not intended to limit the scope of the present invention but to limit the scope of the present invention.

Therefore, the scope of protection of the present invention should be construed in accordance with the following claims, and all technical ideas within the scope of equivalents should be interpreted as being included in the scope of the present invention.

Claims (12)

Extracting an image to be printed with pixel units of M × M size,
Converting a color value of a center pixel into a predetermined reduced color value based on a color value of peripheral pixels in the extracted pixel unit;
A process of selectively applying the conversion to the predetermined reduced color value to each pixel constituting the image
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The conversion process includes:
And changing the center pixel to the predetermined reduced color value when the sum color value of the surrounding pixels exceeds a reference color value calculated in inverse proportion to the distance ratio from the center pixel
A computer program stored on a computer readable recording medium so that a processor can perform an image preprocessing method for printing.
A first process of separating an image of a print object into N sub-images which are layers of a print model;
A second step of extracting each of the separated sub-images into a plurality of M × M pixel units,
A third step of determining whether the extracted pixel unit is a target pixel unit based on a color value of neighboring pixels adjacent to a center pixel in the pixel unit,
A fourth step of converting the color value of the center pixel into a predetermined reduced color value when the target pixel unit is a unit;
A fifth step of repeating the second to fourth steps until the color preprocessing for each sub image is completed;
A sixth step of synthesizing each changed sub-image into a changed image when the color pre-processing is completed;
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In the third step,
Classifying the pixel unit into a candidate pixel unit when the center pixel has an arbitrary color value;
Summing color values of neighboring pixels adjacent to a central pixel of the classified candidate pixel unit;
Determining the candidate pixel unit as the target pixel unit when the summed color value exceeds a reference color value calculated in inverse proportion to the ratio of the distance from the center pixel to the surrounding pixels
A computer-readable recording medium on which a processor can perform a method for image preprocessing for printing.
3. The method of claim 2,
The N sub-
The four CMYK sub-images constituting the print model
A computer program stored on a computer readable recording medium so that a processor can perform an image preprocessing method for printing.
3. The method of claim 2,
Each pixel unit includes:
3 x 3 size
A computer program stored on a computer readable recording medium so that a processor can perform an image preprocessing method for printing.
delete delete 3. The method of claim 2,
The predetermined reduction color value is a value
Changeable by user
A computer program stored on a computer readable recording medium so that a processor can perform an image preprocessing method for printing.
3. The method of claim 2,
Wherein each of the pixels constituting each sub-
At least once in the center pixel
A computer program stored on a computer readable recording medium so that a processor can perform an image preprocessing method for printing.
A first process of separating an image of a print object into N sub-images which are layers of a print model;
A second step of extracting each of the separated sub-images into a plurality of M × M pixel units,
A third step of determining whether the extracted pixel unit is a target pixel unit based on a color value of neighboring pixels adjacent to a center pixel in the pixel unit,
A fourth step of converting the color value of the center pixel into a predetermined reduced color value when the target pixel unit is a unit;
A fifth step of repeating the second through fourth steps until the color preprocessing for each of the sub images is completed;
A sixth step of synthesizing each changed sub-image into a changed image when the color pre-processing is completed;
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In the third step,
Classifying the pixel unit into a candidate pixel unit when the center pixel has an arbitrary color value;
Summing color values of neighboring pixels adjacent to a center pixel of the classified candidate pixel unit;
Determining the candidate pixel unit as the target pixel unit when the summed color value exceeds a reference color value calculated in inverse proportion to the ratio of the distance from the center pixel to the surrounding pixels
Wherein the pre-processing step comprises the steps of:
A computer-readable recording medium having a computer program for causing a processor to execute the image preprocessing method for printing according to claim 9.
An image decomposition section for separating the image of the print object into N sub-images which are layers of a print model,
A unit extracting unit for extracting each separated sub-image into a plurality of M × M pixel units,
A unit determination unit for determining a target pixel unit for adjustment of the amount of ink based on a color value of peripheral pixels adjacent to a center pixel in the pixel unit,
A color conversion unit for converting a color value of the center pixel into a predetermined reduced color value when the target pixel unit is determined;
When the color preprocessing for each sub image is completed, an image compositing unit
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Wherein the unit determination unit comprises:
A pixel classification block for classifying the pixel unit as a candidate pixel unit when the center pixel has an arbitrary color value;
A color value calculation block for summing color values of neighboring pixels adjacent to the center pixel of the classified candidate pixel unit;
When the summed color value exceeds a reference color value calculated in inverse proportion to the ratio of distances from the center pixel to the surrounding pixels,
And an image processing unit for processing the image. delete

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