JP5523226B2 - Image processing apparatus, image processing program, and image processing method - Google Patents

Description

  The present invention relates to an image processing apparatus, an image processing program, and an image processing method.

  In computer graphics, sampling in the process of image display causes aliasing problems. For this reason, an anti-aliasing algorithm for removing aliasing, such as a supersampling method, has been proposed.

  In addition, a certain image processing device (first image processing device) determines whether or not each pixel is on the side of the polygon, and for each pixel on the side, the area of the pixel and the direction of the side apart from the frame memory. Is stored, and an accurate color is obtained from the area of the pixel on the side and the direction of the side at the time of output (see, for example, Patent Document 1).

  Another image processing apparatus (second image processing apparatus) generates color data and shape data indicating a pattern of a minute pixel in each pixel for each pixel, and outputs a high resolution by the minute pixel at the time of output. The color based on the color data is applied to the shape (see, for example, Patent Document 2).

Japanese Patent No. 3609189 JP 2009-169727 A

  However, the supersampling method requires a large memory area. Further, in the first image processing apparatus described above, it is necessary to calculate the direction of the side of the polygon and hold the area and color information for all the pixels on the side of the polygon. A large memory area is required.

  Further, since the technique of the second image processing apparatus described above has only one color data indicating the color of a minute pixel per pixel, it can be applied only when the background color is white.

  The present invention has been made in view of the above problem, and is an image processing apparatus, an image processing program, and an image processing apparatus that generate data that is small in size and capable of expressing a high-resolution shape even when the background color is other than white. The object is to obtain a processing method.

  In order to solve the above problems, the present invention is configured as follows.

An image processing apparatus according to the present invention includes a low resolution color data generation unit that generates low resolution color data from high resolution image data, and a low resolution pixel shape data generation unit that generates low resolution pixel shape data from high resolution image data. Is provided. The low resolution pixel shape data is data indicating the low resolution pixel shape. The low-resolution pixel shape is a part or all of the basic pixel set of high-resolution pixels. The high resolution pixels are pixels at the resolution of the high resolution image data, and the basic pixel set has high resolution pixels in the vertical and / or horizontal direction that are larger than the resolution ratio of the high resolution image data and the low resolution image data. Then, when the color of the high resolution pixel located at the center of the basic pixel set is other than white, the low resolution color data generation unit converts the color value of the high resolution pixel located at the center of the basic pixel set to the low resolution color data. Color value. Furthermore, the low-resolution pixel shape data is data having the same number of bits as the number of high-resolution pixels constituting the basic pixel set, and the low-resolution pixel shape data generation unit includes, among the high-resolution pixels constituting the basic pixel set, The shape of the set of high resolution pixels having the same color value as the color value of the low resolution color data is the low resolution pixel shape, and the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set. A bit value corresponding to a high resolution pixel having a color value is set to one of 0 and 1, and a bit value corresponding to a high resolution pixel not having the same color value as that of the low resolution color data is set to 0 and 1. The other of them.

  Thereby, the boundary between two adjacent low-resolution pixels can be expressed in a high-resolution shape. Therefore, data capable of expressing a high-resolution shape even if the size is small and the background color is other than white can be generated.

The image processing apparatus according to the present invention, in addition to the image processing equipment described above may be as follows. In this case, when the color of the high resolution pixel located at the center of the basic pixel set is white, the low resolution color data generation unit calculates the color values of the high resolution pixels other than the high resolution pixel located at the center of the basic pixel set. The color values specified in a predetermined order and the first specified color value other than white are set as the color values of the low resolution color data.

  The image processing apparatus according to the present invention may be as follows in addition to any of the image processing apparatuses described above. In this case, the shape of the basic pixel set is one of a plurality of patterns of high resolution pixels, and varies depending on the position of the low resolution pixels.

  The image processing apparatus according to the present invention may be as follows in addition to any of the image processing apparatuses described above. In this case, the image processing apparatus includes a storage unit that stores low resolution color data and low resolution pixel shape data, a resolution conversion unit that generates high resolution image data from the low resolution color data and low resolution pixel shape data, a low resolution And a color determination unit that determines the color value of an indefinite pixel whose color value is not specified by the color data and the low-resolution pixel shape data from the color value of the surrounding pixels.

  Thereby, high-resolution image data can be generated from small-size image data (low-resolution color data and low-resolution pixel shape data).

An image processing program according to the present invention includes a computer, a low resolution color data generation unit that generates low resolution color data from high resolution image data, and low resolution pixel shape data that generates low resolution pixel shape data from high resolution image data. It functions as a generator. The low resolution pixel shape data is data indicating the low resolution pixel shape. The low-resolution pixel shape is a part or all of the basic pixel set of high-resolution pixels. The high resolution pixels are pixels at the resolution of the high resolution image data, and the basic pixel set has high resolution pixels in the vertical and / or horizontal direction that are larger than the resolution ratio of the high resolution image data and the low resolution image data. Then, when the color of the high resolution pixel located at the center of the basic pixel set is other than white, the low resolution color data generation unit converts the color value of the high resolution pixel located at the center of the basic pixel set to the low resolution color data. Color value. Furthermore, the low-resolution pixel shape data is data having the same number of bits as the number of high-resolution pixels constituting the basic pixel set, and the low-resolution pixel shape data generation unit includes, among the high-resolution pixels constituting the basic pixel set, The shape of the set of high resolution pixels having the same color value as the color value of the low resolution color data is the low resolution pixel shape, and the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set. A bit value corresponding to a high resolution pixel having a color value is set to one of 0 and 1, and a bit value corresponding to a high resolution pixel not having the same color value as that of the low resolution color data is set to 0 and 1. The other of them.

  Thereby, the boundary between two adjacent low-resolution pixels can be expressed in a high-resolution shape. Therefore, data capable of expressing a high-resolution shape even if the size is small and the background color is other than white can be generated.

An image processing method according to the present invention includes a low resolution color data generation step for generating low resolution color data from high resolution image data, and a low resolution shape data generation step for generating low resolution pixel shape data from high resolution image data. Prepare. The low resolution pixel shape data is data indicating the low resolution pixel shape. The low-resolution pixel shape is a part or all of the basic pixel set of high-resolution pixels. The high resolution pixels are pixels at the resolution of the high resolution image data, and the basic pixel set has high resolution pixels in the vertical and / or horizontal direction that are larger than the resolution ratio of the high resolution image data and the low resolution image data. Then, in the low resolution color data generation step , when the color of the high resolution pixel located at the center of the basic pixel set is other than white, the color value of the high resolution pixel located at the center of the basic pixel set is set to the low resolution color. The color value of the data. Further, the low resolution pixel shape data is data having the same number of bits as the number of high resolution pixels constituting the basic pixel set, and in the low resolution pixel shape data generation step, among the high resolution pixels constituting the basic pixel set, The shape of the set of high resolution pixels having the same color value as the color value of the low resolution color data is the low resolution pixel shape, and the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set. A bit value corresponding to a high resolution pixel having a color value is set to one of 0 and 1, and a bit value corresponding to a high resolution pixel not having the same color value as that of the low resolution color data is set to 0 and 1. Of the other.

  Thereby, the boundary between two adjacent low-resolution pixels can be expressed in a high-resolution shape. Therefore, data capable of expressing a high-resolution shape even if the size is small and the background color is other than white can be generated.

  According to the present invention, it is possible to obtain an image processing apparatus, an image processing program, and an image processing method that can generate data that is small in size and capable of expressing a high-resolution shape even when the background color is other than white. .

FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a correspondence relationship between a pixel array of high-resolution image data and an array of low-resolution color data. FIG. 3 is a diagram illustrating a basic pixel set corresponding to a low resolution pixel. FIG. 4 is a diagram showing the arrangement of the basic pixel set shown in FIG. FIG. 5 is a flowchart for explaining generation of low-resolution pixel shape data by the image processing apparatus shown in FIG. FIG. 6 is a diagram illustrating a specific example of generation of low resolution color data and low resolution pixel shape data by the image processing apparatus shown in FIG. FIG. 7 is a diagram illustrating an example of an image based on high-resolution image data. FIG. 8 is a diagram showing the relationship between the image by the high resolution image data shown in FIG. 7 and the low resolution pixels. FIG. 9 is a diagram showing an example of an image by low resolution image data generated by the conventional method from the high resolution image data of FIG. FIG. 10 is a diagram showing the low resolution color data and the low resolution pixel shape data of the area 101 in FIG. 8 and the high resolution image data generated therefrom. FIG. 11 is a diagram showing the low resolution color data and the low resolution pixel shape data of the area 102 in FIG. 8 and the high resolution image data generated therefrom.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention.

  The image processing apparatus illustrated in FIG. 1 includes an arithmetic processing device 1, a storage device 2, and an image output device 3.

  The arithmetic processing unit 1 is a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) 1a, etc., and loads and executes a program from the ROM, the storage device 2, etc. to the RAM 1a. Various processing units are realized. The storage device 2 is a non-volatile storage device such as a hard disk drive or a flash memory, and stores the image processing program 21 and the like. The image processing program 21 can be recorded on a portable recording medium, and may be installed in this apparatus from such a recording medium.

  The arithmetic processing device 1 generates low-resolution pixel shape data 23 and low-resolution color data 22 from input data such as PDL (Page Description Language) data according to the image processing program 21, and outputs the low-resolution pixel shape data 23 at the time of image output. The low-resolution color data 22 is converted into high-resolution image data. The image output device 3 executes image output such as printing based on the high resolution image data generated by the arithmetic processing device 1.

  The arithmetic processing device 1 implements the drawing processing unit 11 and the image processing unit 12 by executing the image processing program 21 stored in the storage device 2.

  The drawing processing unit 11 is a processing unit that generates low-resolution pixel shape data 23 and low-resolution color data 22 from input data such as PDL data. In the drawing processing unit 11, first, high resolution image data is generated, and low resolution image data is generated from the high resolution image data. The low resolution image data includes low resolution color data and low resolution pixel shape data. That is, low resolution color data and low resolution pixel shape data exist for each low resolution pixel. The drawing processing unit 11 includes a high resolution data generation unit 31, a low resolution color data generation unit 32, and a low resolution pixel shape data generation unit 33.

  The high resolution data generation unit 31 is a processing unit that interprets input data and generates high resolution image data. The high-resolution image data is color image data (for example, RGB each having 8 bits, total 24 bits of data) having a predetermined resolution (for example, vertical and horizontal 1200 dpi).

  The low-resolution color data generation unit 32 is a processing unit that generates the low-resolution color data 22 having a predetermined resolution (for example, 600 dpi in length and width) from the generated high-resolution image data.

  The low resolution pixel shape data generation unit 33 is a processing unit that generates the low resolution pixel shape data 23 from the generated high resolution image data.

  The image processing unit 12 is a processing unit that converts the low resolution pixel shape data 23 and the low resolution color data 22 into high resolution image data when outputting an image. The image processing unit 12 includes a resolution conversion unit 41 and a color determination unit 42.

  The resolution conversion unit 41 is a processing unit that generates high resolution image data from the low resolution color data 22 and the low resolution pixel shape data 23.

  The color determination unit 42 is a processing unit that determines the color value of an indefinite pixel whose color value is not specified by the low resolution color data 22 and the low resolution pixel shape data 23 from the color values of the peripheral pixels.

  Here, the low resolution color data 22 and the low resolution pixel shape data 23 will be described.

  FIG. 2 is a diagram illustrating a correspondence relationship between the pixel array of the high-resolution image data and the array of the low-resolution color data 22. FIG. 2A shows a pixel array of high-resolution image data. FIG. 2B shows an arrangement of the low resolution color data 22. FIG. 2C shows the correspondence between the pixel arrangement of the high resolution image data and the arrangement of the low resolution color data 22.

  The high-resolution image data has color data for each pixel, and the pixel has no concept of shape on the data.

  FIG. 2B shows the arrangement of the low-resolution color data 22, and the shape of the low-resolution pixels will be described below.

  In FIG. 2, the resolution of the low resolution color data is half the resolution of the high resolution image data in each of the vertical and horizontal directions. That is, in the vertical and horizontal directions (that is, the sub-scanning direction and the main scanning direction), the resolution ratio between the two is 2, respectively.

  FIG. 3 is a diagram illustrating a basic pixel set corresponding to a low resolution pixel. FIG. 4 is a diagram showing the arrangement of the basic pixel set shown in FIG. The basic pixel set is a set of high-resolution pixels larger than the resolution ratio. In the case shown in FIG. 2, the resolution ratio is 2, and the number of vertical and horizontal high resolution pixels in the basic pixel set shown in FIG.

  The low resolution pixel shape is a part or all of the shape of the basic pixel set, and the low resolution pixel shape data 23 is data indicating the low resolution pixel shape.

  As shown in FIGS. 3 and 4, in this embodiment, the shape of the basic pixel set is one of a plurality of patterns of high resolution pixels, and differs depending on the position of the low resolution pixels. In this embodiment, as shown in FIG. 3, there are two basic pixel sets, and the basic pixel sets of each shape are alternately assigned to the low resolution pixels P in the vertical and horizontal directions. .

  When the color of the high resolution pixel located at the center of the basic pixel set is other than white, the low resolution color data generation unit 32 uses the color value of the high resolution pixel located at the center of the basic pixel set as the low resolution color data. Let it be a color value. When the color of the high resolution pixel located at the center of the basic pixel set is white, the low resolution color data generation unit 32 determines a color value of a high resolution pixel other than the high resolution pixel located at the center of the basic pixel set as a predetermined value. The color values are specified in order, and the first color value specified other than white is set as the color value of the low resolution color data. Here, in the order shown in FIG. 3, the low resolution color data generation unit 32 specifies the color value of the high resolution pixel, and the color value first specified other than white is the color value of the low resolution pixel. And

  The low resolution pixel shape data generation unit 33 sets a high resolution pixel having the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set to the low resolution pixel shape. The low resolution pixel shape data is data having the same number of bits as the number of high resolution pixels constituting the basic pixel set, and the low resolution pixel shape data generation unit 33 selects the low resolution pixel among the high resolution pixels constituting the basic pixel set. The bit value corresponding to the high resolution pixel having the same color value as the color value of the resolution color data is set to one of 0 and 1, and the high resolution pixel not having the same color value as the color value of the low resolution color data is set. The value of the corresponding bit is the other of 0 and 1. That is, in the case of the basic pixel set shown in FIG. 3, one low-resolution pixel shape data is 5-bit data.

  Next, the operation of the image processing apparatus will be described.

(A) Generation of low resolution color data 22 and low resolution pixel shape data 23

  The drawing processing unit 11 generates the low resolution color data 22 and the low resolution pixel shape data 23. First, the high resolution data generation unit 31 generates high resolution image data from input data. The generated high resolution image data is temporarily stored in the RAM 1a.

  The high resolution data generation unit 31, the low resolution color data generation unit 32, and the low resolution pixel shape data generation unit 33 may perform pipeline processing. That is, when the high resolution image data for the lines necessary for the low resolution color data generation unit 32 and the low resolution pixel shape data generation unit 33 is generated by the high resolution data generation unit 31, the low resolution color data generation unit 32 and The low resolution pixel shape data generation unit 33 starts generating low resolution color data and low resolution pixel shape data from the high resolution image data. Then, the high-resolution image data of the lines that are no longer needed by the low-resolution color data generation unit 32 and the low-resolution pixel shape data generation unit 33 are deleted from the RAM 1a.

  Then, the low resolution color data generation unit 32 determines the color value of the low resolution pixel as described above, and generates the low resolution color data 22 from the high resolution image data.

  In addition, the low resolution pixel shape data generation unit 33 generates the low resolution pixel shape data 23 from the high resolution image data. FIG. 5 is a flowchart for explaining generation of the low-resolution pixel shape data 23 by the image processing apparatus shown in FIG.

  In the case of the basic pixel set shown in FIG. 3, the low resolution pixel shape data generation unit 33 executes the following processing for each low resolution pixel. The low-resolution pixel shape data generation unit 33 first identifies the color of the first pixel (the pixel numbered 1 in FIG. 3) from the high-resolution image data (step S1), and the color is a low-resolution color (step S1). It is determined whether or not it is the same as the color of this pixel determined by the low-resolution color data generation unit 32 (step S2). If both are the same, the first bit of the low-resolution pixel shape data of this pixel 1 is set to 1 (step S3). Otherwise, the value of the first bit is set to 0 (step S4).

  Next, the low-resolution pixel shape data generation unit 33 specifies the color of the second pixel (the pixel numbered 2 in FIG. 3) from the high-resolution image data (step S5), and the color is a low-resolution color. It is determined whether or not it is the same as (the color of this pixel determined by the low resolution color data generation unit 32) (step S6). If both are the same, the second low resolution pixel shape data of this pixel is determined. The value of the bit is set to 1 (step S7). Otherwise, the value of the second bit is set to 0 (step S8).

  Next, the low-resolution pixel shape data generation unit 33 specifies the color of the third pixel (the pixel numbered 3 in FIG. 3) from the high-resolution image data (step S9), and the color is a low-resolution color. It is determined whether or not it is the same (the color of this pixel determined by the low resolution color data generation unit 32) (step S10). If both are the same, the third of the low resolution pixel shape data of this pixel is determined. The value of the bit is set to 1 (step S11). Otherwise, the value of the third bit is set to 0 (step S12).

  Next, the low-resolution pixel shape data generation unit 33 specifies the color of the fourth pixel (the pixel numbered 4 in FIG. 3) from the high-resolution image data (step S13), and the color is a low-resolution color. It is determined whether or not it is the same as (the color of this pixel determined by the low resolution color data generation unit 32) (step S14). If both are the same, the fourth of the low resolution pixel shape data of this pixel is determined. The value of the bit is set to 1 (step S15). Otherwise, the value of the fourth bit is set to 0 (step S16).

  Next, the low-resolution pixel shape data generation unit 33 specifies the color of the fifth pixel (the pixel numbered 5 in FIG. 3) from the high-resolution image data (step S17), and the color is a low-resolution color. It is determined whether or not it is the same as (the color of this pixel determined by the low resolution color data generation unit 32) (step S18). If both are the same, the fifth of the low resolution pixel shape data of this pixel is determined. The value of the bit is set to 1 (step S19). Otherwise, the value of the fifth bit is set to 0 (step S20).

  FIG. 6 is a diagram illustrating a specific example of generation of low resolution color data and low resolution pixel shape data by the image processing apparatus shown in FIG. FIG. 6A shows an example of the arrangement of colors and low resolution pixels P based on high resolution image data. FIG. 6B shows color data and shape data of the low resolution pixel P shown in FIG.

  In the case shown in FIG. 6A, since the color of the first pixel in the low resolution pixel P is red (R: 255, G: 0, B: 0), the color value of the low resolution pixel P is as shown in FIG. As shown in (B), the color is red (R: 255, G: 0, B: 0). The color values of the first pixel, the second pixel, the third pixel, and the fourth pixel in the low resolution pixel P are the same as the color value of the low resolution pixel P, and the color value of the fifth pixel is low. Since it is not the same as the color value of the resolution pixel P, the shape data (5 bits) of the low resolution pixel P is 11110.

  Furthermore, another specific example will be described.

  FIG. 7 is a diagram illustrating an example of an image based on high-resolution image data. The color C0 in FIG. 7 is white (R: 255, G: 255, B: 255), the color C1 is black (R: 0, G: 0, B: 0), and the color C2 is green. (R: 0, G: 255, B: 0), and the color C3 is blue (R: 0, G: 0, B: 255). FIG. 8 is a diagram showing the relationship between the image by the high resolution image data shown in FIG. 7 and the low resolution pixels. FIG. 8A shows an array of low resolution pixels, and FIG. 8B shows the color of the low resolution pixels. FIG. 9 is a diagram showing an example of an image by low resolution image data generated by the conventional method from the high resolution image data of FIG. When FIG. 9 and FIG. 8B are compared, it can be seen that they are not the same.

(B) Generation of high-resolution image data from the low-resolution color data 22 and the low-resolution pixel shape data 23

  Generation of high resolution image data from the low resolution color data 22 and the low resolution pixel shape data 23 is executed by the image processing unit 12.

  The resolution conversion unit 41 sequentially reads the color data 22 and the shape data 23 of the low resolution pixels, specifies the shape from the shape data 23 for the low resolution pixels, and converts the color values of the high resolution pixels corresponding to the low resolution pixels to The color value based on the color data 22 of the low resolution pixel is set.

  At this time, the 5-bit low-resolution pixel shape data 23 is sequentially referred from the first bit to the fifth bit, and the high-resolution pixel corresponding to the bit having the value 0 until the bit having the value 1 first appears. The color value is white (R: 255, G: 255, B: 255). On the other hand, the color value of the high-resolution pixel corresponding to the bit of value 0 that appears after the bit of value 1 appears remains indefinite. The color value of the high-resolution pixel whose color value is indefinite is specified from the color data 22 and the shape data 23 of the adjacent low-resolution pixel, or remains indefinite.

  FIG. 10 is a diagram showing the low-resolution color data 22 and the low-resolution pixel shape data 23 in the region 101 in FIG. 8 and the high-resolution image data generated from them. FIG. 10A shows the low resolution color data 22 of the area 101 and the low resolution pixel shape data 23 of the area 101.

  FIG. 10C is a diagram showing high resolution image data generated from the low resolution color data 22 and the low resolution pixel shape data 23 shown in FIGS. 10A and 10B. In FIG. 10C, the color value G means green (R: 0, G: 255, B: 0), and the color value W means white (R: 255, G: 255, B: 255). The color value K means black (R: 0, G: 0, B: 0). Then, the color value of the hatched pixel in FIG. 10C remains indefinite.

  FIG. 11 is a diagram showing the low resolution color data 22 and the low resolution pixel shape data 23 in the area 102 in FIG. 8 and the high resolution image data generated from them. FIG. 11A shows the low-resolution color data 22 of the area 102 and the low-resolution pixel shape data 23 of the area 102.

  FIG. 11C is a diagram showing high resolution image data generated from the low resolution color data 22 and the low resolution pixel shape data 23 shown in FIGS. 11A and 11B. In FIG. 11C, the color value G means green (R: 0, G: 255, B: 0), and the color value B means blue (R: 0, G: 0, B: 255). The color value K means black (R: 0, G: 0, B: 0). The color value of the hatched pixel in FIG. 11C remains indefinite.

  As described above, the color determination unit 42 determines the color value of the high resolution pixel in which the color value remains indefinite. At this time, the color determination unit 42 determines the color value of the high resolution pixel from the color values of the peripheral pixels of the high resolution pixel. However, a color value other than the color value of the low-resolution pixel to which the high-resolution pixel whose color value is not specified belongs as the color value of this high-resolution pixel.

  For example, the color determination unit 42 makes the color value of the pixel the same as or adjacent to the color value of a pixel adjacent in a predetermined direction (right, left, upper, lower, etc.) among the color values of the peripheral pixels. Of all the pixels, the color value is the same as the color value with the largest number of pixels, or edge detection is performed on the surrounding pixels, and if the pixel is on the extension line of the edge, the color value is the same as the color value of the edge. To do.

  When the high-resolution image data is generated in this way, the image output device 3 executes printing or the like based on the high-resolution image data.

  As described above, according to the embodiment described above, the low resolution color data generation unit 32 generates the low resolution color data 22 from the high resolution image data. The low resolution pixel shape data generation unit 33 generates the low resolution pixel shape data 23 from the high resolution image data. The low-resolution pixel shape data is data indicating a low-resolution pixel shape that is a shape of a part or all of a basic pixel set of high-resolution pixels larger than the resolution ratio in the vertical and / or horizontal directions.

  Thereby, the boundary between two adjacent low-resolution pixels can be expressed in a high-resolution shape. Therefore, data capable of expressing a high-resolution shape even if the size is small and the background color is other than white can be generated.

  For example, the size of the high resolution image data of 12 pixels in the vertical and horizontal directions is 3456 bits (= 12 × 12 × 24 bits), and the size of the corresponding low resolution color data of 6 pixels in the vertical and horizontal directions is 864 bits (= 6 × 6 ×). 24 bits), and the size of the low resolution pixel shape data is 180 bits (= 6 × 6 × 5 bits).

  Furthermore, even when there are multiple color borders other than white, such as text and vector graphics, where high image quality is required, images are overlaid and low resolution data (low High-resolution image data can be reproduced from the resolution color data and low-resolution pixel shape data), and the image quality of the output image is improved.

  Thus, since image output can be performed with high resolution, aliasing is reduced.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, the example of the color value in the above embodiment is a single color of R, G, and B for the sake of simplicity of explanation, but other color values may of course be used.

  The present invention is applicable to an image forming apparatus such as a printer or a multifunction peripheral.

1. Arithmetic processing device (an example of a computer)
1a RAM (an example of storage means)
22 Low-resolution color data 23 Low-resolution pixel shape data 32 Low-resolution color data generation unit 33 Low-resolution pixel shape data generation unit 41 Resolution conversion unit 42 Color determination unit

Claims (6)

In an image processing apparatus that generates low resolution color data and low resolution pixel shape data as low resolution image data from high resolution image data,
A low-resolution color data generation unit that generates the low-resolution color data from the high-resolution image data;
A low-resolution pixel shape data generation unit that generates the low-resolution pixel shape data from the high-resolution image data,
The low resolution pixel shape data is data indicating a low resolution pixel shape,
The low resolution pixel shape is a part or all of a basic pixel set of high resolution pixels,
The high resolution pixel is a pixel at a resolution of the high resolution image data,
The basic pixel set includes the high-resolution pixels that are larger in the vertical and / or horizontal direction than the resolution ratio of the high-resolution image data and the low-resolution image data.
The low resolution color data generation unit, when the color of the high resolution pixel located at the center of the basic pixel set is other than white, the color value of the high resolution pixel located at the center of the basic pixel set, As the color value of low resolution color data ,
The low resolution pixel shape data is data having the same number of bits as the number of the high resolution pixels constituting the basic pixel set,
The low resolution pixel shape data generation unit converts the shape of the set of high resolution pixels having the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set to the low resolution pixel. One of 0 and 1 is set to a bit value corresponding to the high resolution pixel having the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set and having a resolution pixel shape. The bit value corresponding to the high-resolution pixel not having the same color value as the color value of the low-resolution color data is the other of 0 and 1,
An image processing apparatus.   When the color of the high-resolution pixel located at the center of the basic pixel set is white, the low-resolution color data generation unit generates a high-resolution pixel other than the high-resolution pixel located at the center of the basic pixel set. 2. The image processing apparatus according to claim 1, wherein color values are specified in a predetermined order, and a color value first specified other than white is set as a color value of the low resolution color data. 3. The image processing apparatus according to claim 1, wherein a shape of the basic pixel set is one of a plurality of patterns of the high resolution pixels, and is different depending on a position of the low resolution pixels. . Storage means for storing the low resolution color data and the low resolution pixel shape data;
A resolution converter that generates the high-resolution image data from the low-resolution color data and the low-resolution pixel shape data;
A color determining unit that determines a color value of an indefinite pixel whose color value is not specified by the low-resolution color data and the low-resolution pixel shape data from color values of surrounding pixels;
The image processing apparatus according to any one of claims 1 to 3, characterized in that it comprises a. In an image processing program for generating low-resolution color data and low-resolution pixel shape data as low-resolution image data from high-resolution image data on a computer,

Causing a computer to function as a low resolution color data generation unit that generates the low resolution color data from the high resolution image data, and a low resolution pixel shape data generation unit that generates low resolution pixel shape data from the high resolution image data;
The low resolution pixel shape data is data indicating a low resolution pixel shape,
The low resolution pixel shape is a part or all of a basic pixel set of high resolution pixels,
The high resolution pixel is a pixel at a resolution of the high resolution image data,
The basic pixel set includes the high-resolution pixels that are larger in the vertical and / or horizontal direction than the resolution ratio of the high-resolution image data and the low-resolution image data.
The low resolution color data generation unit, when the color of the high resolution pixel located at the center of the basic pixel set is other than white, the color value of the high resolution pixel located at the center of the basic pixel set, As the color value of low resolution color data ,
The low resolution pixel shape data is data having the same number of bits as the number of the high resolution pixels constituting the basic pixel set,
The low resolution pixel shape data generation unit converts the shape of the set of high resolution pixels having the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set to the low resolution pixel. One of 0 and 1 is set to a bit value corresponding to the high resolution pixel having the same color value as the color value of the low resolution color data among the high resolution pixels constituting the basic pixel set and having a resolution pixel shape. The bit value corresponding to the high-resolution pixel not having the same color value as the color value of the low-resolution color data is the other of 0 and 1,
An image processing program characterized by the above. In an image processing method for generating low resolution color data and low resolution pixel shape data as low resolution image data from high resolution image data,
A low-resolution color data generation step for generating the low-resolution color data from the high-resolution image data;
A low-resolution shape data generation step for generating the low-resolution pixel shape data from the high-resolution image data,
The low resolution pixel shape data is data indicating a low resolution pixel shape,
The low resolution pixel shape is a part or all of a basic pixel set of high resolution pixels,
The high resolution pixel is a pixel at a resolution of the high resolution image data,
The basic pixel set includes the high-resolution pixels that are larger in the vertical and / or horizontal direction than the resolution ratio of the high-resolution image data and the low-resolution image data.
In the low-resolution color data generation step, when the color of the high-resolution pixel located at the center of the basic pixel set is other than white, the color value of the high-resolution pixel located at the center of the basic pixel set is As the color value of low resolution color data ,
The low resolution pixel shape data is data having the same number of bits as the number of the high resolution pixels constituting the basic pixel set,
In the low resolution shape data generation step, among the high resolution pixels constituting the basic pixel set, the shape of the set of high resolution pixels having the same color value as the color value of the low resolution color data is converted into the low resolution. A bit shape corresponding to the high-resolution pixel having the same color value as the color value of the low-resolution color data among the high-resolution pixels constituting the basic pixel set is set to one of 0 and 1 The bit value corresponding to the high resolution pixel not having the same color value as the color value of the low resolution color data is the other of 0 and 1,
An image processing method characterized by the above.

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