JPH11261820A - Image processing device - Google Patents

Abstract

(57) [Problem] To provide an image processing apparatus capable of reducing the cost of image processing. SOLUTION: For each row of a dither pattern for binarizing image data, a row pattern acquisition means for acquiring one row pattern (first pattern 121 to third pattern 123) obtained by repeating each row, A list acquisition unit for acquiring a list representing the order of the row patterns for continuously using these row patterns so as to be a repeat of the same row of the dither pattern, wherein pixels having the same density level When the data is continuous in one row, the data at the positions corresponding to these pixels in the first to third patterns 121 to 123 is collectively acquired as the binarized data of these pixels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus capable of reducing the cost of image processing.

[0002]

2. Description of the Related Art In a conventional image processing apparatus, when an image is printed and displayed on a printer or a display, image data for each color (RGB, CMYK, etc.) is converted into a VRAM format for each line of the image. Output.

In the process of converting to a VRAM format, as shown in FIG. 6, 4 × 4 pixels, 6 × 6 pixels
Using a dither pattern represented by blocks such as pixels, image data is divided into blocks like this dither pattern,
Binarized data is obtained from the dither pattern for each block. As such a conventional image processing apparatus, there is an image processing apparatus in which a dither pattern is determined corresponding to each density level of each color as shown in FIG. The corresponding dither pattern is selected based on the density level, and the data located at the position corresponding to the selected dither pattern in the block of the pixel to be processed is the binary value of the pixel. Data after conversion (white / black)
It is said.

[0004]

However, in the above-described conventional image processing apparatus, a dither pattern is selected for each pixel with respect to image data of each color, and binarized data is obtained from the dither pattern. There is a problem that the cost increases.

[0005] The present invention has been made to solve the above-mentioned problems, and has as its object to provide an image processing apparatus capable of performing image processing at low cost.

[0006]

According to the first aspect of the present invention,
Determined by data acquisition means for acquiring image data, density level acquisition means for acquiring the density level of each pixel of the image data acquired by the data acquisition means, and the density level and position of each pixel of the image data A dither pattern storing means for storing binarized data of each pixel, for each density level of the pixel, a dither pattern arranged at a position corresponding to the position of the pixel, and for each pixel of the image data, A binarizing unit for acquiring data at a position corresponding to the pixel in the dither pattern of the density level acquired by the acquiring unit as binarized data of the pixel; and a binarizing unit for each density level stored in the dither pattern storage unit. For each of the dither patterns, a row for each row of the dither pattern obtained by repeating each row of the dither pattern A row pattern acquisition unit for acquiring a turn, wherein the binarization unit corresponds to these pixels in the row pattern when pixels having the same density level are continuous in one row of the image data. The above-mentioned object is achieved by collectively acquiring data of the positions where the data is to be obtained as binarized data of these pixels.

According to a second aspect of the present invention, in the first aspect of the invention, a plurality of row patterns acquired by the row pattern acquisition means are used continuously so that the same row of the dither pattern is repeated. The list acquisition means for acquiring a list representing the order of the plurality of line patterns, the binarization means, using the plurality of line patterns according to the order of the list acquired by the list acquisition means,
The above object is achieved by obtaining, as binarized data, data at a corresponding position in the row pattern for pixels having the same density level in one row of the image data.

According to a third aspect of the present invention, in the first aspect of the present invention, a plurality of row patterns acquired by the row pattern acquisition means are used continuously so that the same row of the dither pattern is repeated. A list acquisition unit that acquires a list representing the order of the plurality of line patterns, and a continuous line that acquires and stores a continuous line pattern in which the plurality of line patterns are consecutive according to the order of the list acquired by the list acquisition unit. A pattern storage unit, wherein the binarization unit is configured such that, from the continuous row pattern stored in the continuous row pattern storage unit, for pixels having the same density level in one row of the image data, The above object is achieved by acquiring data at a corresponding position in a row pattern as binary data.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the above object is achieved by the continuous row pattern storage section being a cache memory.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Outline of Embodiment A pixel conversion processing pattern creating means for performing mask processing on each color pixel using a dither pattern,
A pattern list creating unit that creates a larger pattern using the pixel conversion processing pattern and uses the pattern for the pixel conversion processing to create a larger number of the patterns in order to use a plurality of the patterns in succession. There is provided means for converting pixel data at high speed using the pattern list created by the pattern list creating means. Further, there is provided a dither cache creating means for more efficiently creating a pattern by the pixel change processing pattern creating means, and a pixel converting means for performing a pixel conversion process at a high speed using the dither cache.

(2) Details of Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. The image processing apparatus according to the present embodiment includes a data acquisition unit that acquires image data for each color, a density level detection unit that detects the density level of each pixel of the image data for each color, a dither pattern storage unit, a row pattern An acquisition unit and a mask processing unit are provided.

The data acquisition unit acquires image data by exposing a document and photoelectrically converting the acquired image light, and reads out image data stored in a storage medium such as a magnetic storage medium or a magneto-optical storage medium. Such as downloading image data by communication control device, etc.
Conventionally known data acquisition means is employed.

The dither pattern storage unit stores a dither pattern for each density level of 256 gradations of 6.times.6 pixels similar to the dither pattern of the prior art (FIG. 6). The density level detection section divides each pixel of the image data of each color acquired by the data acquisition section into density levels of 256 gradations from 0 to 255. The row pattern acquisition unit acquires one row pattern obtained by repeating each row for each of the 6 × 6 dither patterns of 256 gradations stored in the dither pattern storage unit.

FIG. 1 is an explanatory diagram showing the correspondence between the row pattern obtained by the row pattern obtaining section and the dither pattern. As shown in FIG. 1, the row pattern acquisition unit according to the present embodiment performs the first pattern 121 to the third pattern for each row of the 256-gradation dither pattern for each density level.
A 32-bit row pattern is acquired for each of the three patterns 123. The first pattern 121 expresses each row of the dither pattern by repeating it five times from the upper bit of the int type, and fills the lower two bits with the starting two pixels of the row of the dither pattern. The second pattern 122 shifts the first pattern 121 to the left by two bits, and sets the middle 2 in the row of the dither pattern.
The second pattern 122 is created by packing the bits in the lower order.
When the two pixels at the start end are continuous, one row of the dither pattern is formed by these four pixels.

The third pattern 123 is the first pattern 12
1 is shifted to the left by 4 bits, and the lower 4 bits of the dither pattern are shifted.
The second pattern 12
The two pixels at the end of the second pattern are added to the two pixels at the end of the third pattern 123.
When the pixels are made continuous, one row of the dither pattern is formed by these four pixels. The last four pixels of the third pattern 123 have the same pattern as one row of the dither pattern. Therefore, by using the first pattern 121 subsequent to the third pattern 123, a state where the same row pattern is repeated can be formed.

When the first pattern 121 described above is used for mask processing (conversion of pixel data into binary data), even if the last two pixels E are continuous with the first two pixels S, one line of the dither pattern Since a pattern similar to the eye is not formed, only the first pattern 121 cannot be repeatedly used continuously. However, in the present embodiment, as described above, by using three types of row patterns, these int-width row patterns are used successively from the first pattern 121 to the third pattern 123 so that the dither pattern is used. The same pattern as that of the repetition of the row is obtained, and the pixel data can be converted.

In this embodiment, since the row pattern of the mask processing unit (32 bits) is obtained by using a 6 × 6 dither pattern, the mask processing is continuously performed using the obtained row patterns. Requires three patterns of the first pattern 121 to the third pattern 123 for each row. However, for example, in the case of performing a masking process on a 32-bit basis using a 4 × 4 dither pattern, a row pattern obtained by repeating each row of the dither pattern eight times as a row pattern corresponding to each row of the dither pattern. Using one by one, the row pattern can be repeated to perform mask processing. As described above, the number of row patterns is determined in relation to the processing unit of the mask processing and the number of pixels in each row of the dither pattern from which the row pattern is obtained.

The mask processing section (binarizing means) performs mask processing based on the density level of each pixel detected by the density level detecting section. This mask processing unit detects, when there is a continuous portion of the same density pixel in which a pixel of the same density level is continuous in each row, and uses the row pattern of the corresponding density level acquired by the row pattern acquisition unit described above. Mask processing is performed. It is to be noted that the mask processing can be performed for each of the largest possible widths to reduce the processing cost. Must be done. In the present embodiment, mask processing is performed in 32-bit units using an int-type pattern.

Further, the image processing apparatus of the present embodiment has a circular list storage unit for storing a circular list. When the pixels having the same density level continue beyond one row pattern, the mask processing unit described above acquires the row patterns in the order according to the circular list, and The data of the corresponding position is obtained, and the mask processing is performed. FIG. 2 is an explanatory diagram showing the contents of the circular list stored in the circular list storage. As shown in FIG. 2, the mask processing unit uses a row pattern in the order of the first pattern 121, the second pattern 122, and the third pattern 123 in accordance with the circulation list, and after the third pattern 123, the first pattern again. The processing is returned to 121, and the computer performs the pixel conversion processing while tracing the circular list for each int width.

As described above, in the present embodiment, the row patterns are continuously used in a predetermined order in order to efficiently convert the pixel data. When performing pixel data conversion on a computer, a larger pattern (continuous line pattern) is represented by displaying each pattern in a connectable list so that the three types of patterns can be used continuously. Can be created. The circulating list storage unit stores a circulating list for acquiring a continuous line pattern from such a line pattern by the height of the dither pattern, that is, the number of lines. The present embodiment further includes a dither cache memory (continuous row pattern storage means) 15 for storing the above-described continuous row pattern.

FIG. 3 is an explanatory diagram showing the contents of the dither cache memory in this embodiment. As described above, when pixel data is converted using a 96-bit continuous line pattern acquired based on a circular list, a continuous line pattern is newly created every time one line is processed. The processing cost of line pattern creation is high, which is not efficient. Further, the type of the continuous line pattern is at most as high as the dither pattern for each color level (256 in total from 0 to 255). Therefore, in the present embodiment, as shown in FIG. 3, the continuous line pattern once created is held in the cache area 13 and can be used again. Further, in the present embodiment, a flag area 14 for storing a flag for each line is provided in order to determine whether or not the continuous line pattern has been created. The flag area 14 is secured near the data area of the continuous row pattern so that the data of the continuous row pattern can be used more efficiently. This flag is set to 0 at the time of initial setting.

Next, the operation of the image processing apparatus of the present embodiment having the above-described configuration will be described. In the image processing apparatus according to the present embodiment, first, the image data acquisition unit acquires the image data, and the density level detection unit acquires the density level of each pixel in the first row of the image data. Subsequently, the mask processing unit
Based on the data from the density level detection unit, the same density pixel continuation section in which pixels of the same density level continue for 32 bits or more is detected. Then, for pixels other than the same density pixel continuous portion, binarized data is acquired from a dither pattern corresponding to the density level for each pixel as in the conventional image processing apparatus. For the same density pixel continuous portion, the row pattern acquired by the row pattern acquisition section is used as binary data as it is. If pixels of the same density level continue beyond each row pattern, row patterns are acquired in order according to the circulating list and used as binary data.

FIG. 4 is an explanatory diagram of an operation for creating and reading a continuous row pattern in this embodiment. When pixels of the same density level continue beyond each row pattern, as shown in FIG. 4, the setting of the flag for the first row of the dither pattern of the density level is checked in the flag area. When the flag is set to 0, the mask processing unit performs the first pattern 1 based on the circular list stored in the circular list storage unit.
The third patterns 123 are obtained in order from 21 and are directly used as binarized data. Further, a continuous line pattern connecting the first pattern 121 to the third pattern 123 is obtained,
This continuous line pattern is stored in the cache area, and the corresponding flag is set to 1. When the flag is set to 1, a continuous line pattern is obtained from the cache area, and binary data is obtained from the continuous line pattern.

FIG. 5 is a conceptual diagram showing the correspondence between the image data in this embodiment and the row patterns used for the mask processing performed on the image data. This figure 5
As shown in FIG. 5, in the present embodiment, the mask processing according to the first pattern 121, the mask processing according to the second pattern 122, and the mask processing according to the third pattern 123 are repeated for each row of the image data. The processed data (binary data) is obtained.

When the mask processing for the first line of the image data is completed, the operation from the acquisition of the line pattern is performed for the second and subsequent lines of the image data in the same manner as the first line. For the image data of the seventh and subsequent lines, n (n ≧ n)
7) The dither pattern used for the mask processing for the row is the same as that used for the (n-6) th row, and the same continuous row pattern is used if the pixel has the same density level. Therefore, depending on the density level of the pixel, the setting of the flag in the flag area may be 1 in some cases. In this case, as shown in FIG. 4, using a cache of a dither cache memory,
The pixel data is converted for each 96-bit width while tracing the circular list.

As described above, according to the image processing apparatus of the present embodiment, a row pattern in which a plurality of rows of the dither pattern are respectively obtained is obtained, and pixels having the same density level are continuously formed in one row of the image data. In this case, using the row pattern, binarized data can be efficiently obtained at once for pixels having the same density level,
Processing costs are reduced. According to the image processing apparatus of the present embodiment, since the row pattern is acquired in 32 bits, which is the unit of the mask processing, the mask processing is performed efficiently and at low cost by maximizing the processing capability of the mask processing. .

According to the image processing apparatus of the present embodiment, the first to third row patterns of each row are repeatedly used in order so that the start and end are each row of the dither pattern according to the cyclic list. Can be efficiently and at low cost even when pixels having the same pixel number continue over a row pattern in one row of the image data. According to the image processing apparatus of the present embodiment, the continuous line pattern used once is stored in the dither cache memory, and when the same continuous line pattern is used,
Since a pattern stored in the dither cache memory is read and used without acquiring a new continuous line pattern, mask processing can be performed more efficiently and at low cost.

[0028]

According to the first aspect of the present invention, a row pattern obtained by repeating each row of the dither pattern is obtained by the row pattern obtaining means, and pixels having the same density level are continuously arranged in one row of the image data. If you have
Since the binarization means collectively acquires the binarized data of these pixels from the row pattern and efficiently performs the mask processing,
Processing costs can be reduced.

According to the second aspect of the present invention, the list representing the order of the plurality of row patterns for the list obtaining means to use a plurality of row patterns continuously so as to repeat the same row of the dither pattern. By obtaining a row pattern according to this list, even when pixels having the same density level continue over the row pattern, mask processing is efficiently performed at low cost, and processing cost is reduced. be able to.

According to the third and fourth aspects of the present invention, the continuous line pattern storing means obtains and stores a continuous line pattern in which a plurality of the line patterns are continuous according to the order of the list obtained by the list obtaining means. Therefore, by reading and using the stored continuous row pattern, the mask processing can be performed more efficiently, and the processing cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows an image processing apparatus according to an embodiment of the present invention.
FIG. 9 is an explanatory diagram showing a correspondence between a row pattern and a dither pattern acquired by a row pattern acquisition unit.

FIG. 2 is an explanatory diagram showing the contents of a circulation list stored in a circulation list storage unit in the image processing apparatus of FIG.

FIG. 3 is an explanatory diagram showing the contents of a dither cache memory in the image processing apparatus of FIG. 1;

FIG. 4 is an explanatory diagram of an operation for creating and reading a continuous row pattern in the image processing apparatus of FIG. 1;

FIG. 5 is a conceptual diagram showing a correspondence between image data in the image processing apparatus of FIG. 1 and a row pattern used for mask processing performed on the image data.

FIG. 6 is a diagram illustrating an example of a dither pattern in a conventional image processing apparatus.

[Explanation of symbols]

 121 1st pattern 122 2nd pattern 123 3rd pattern 13 Cache area 14 Flag area

Claims (4)

[Claims] A data acquisition unit that acquires image data; a density level acquisition unit that acquires a density level of each pixel of the image data acquired by the data acquisition unit; and a density level and a position of each pixel of the image data. Dither pattern storage means for storing binarized data of each pixel determined by the above, for each density level of the pixel, a dither pattern arranged at a position corresponding to the position of the pixel, and each pixel of the image data In the dither pattern of the density level obtained by the density level obtaining means, binarization means for obtaining data of a position corresponding to the pixel as binarized data of the pixel, and stored in the dither pattern storage unit For each of the dither patterns for each density level, these dither patterns are obtained by repeating each row of the dither pattern. Line pattern acquiring means for acquiring a line pattern for each line of the image data, wherein the binarizing means includes a step of, when pixels having the same density level are continuous in one line of the image data, An image processing apparatus according to claim 1, wherein data of positions corresponding to these pixels is collectively acquired as binarized data of these pixels. 2. A list representing an order of the plurality of line patterns for sequentially using the plurality of line patterns obtained by the line pattern obtaining means so as to repeat the same line of the dither pattern is obtained. The binarizing means uses a plurality of the row patterns in accordance with the order of the list acquired by the list acquiring means, and the density levels which are continuous in one row of the image data are the same. The image processing apparatus according to claim 1, wherein data of a position of a pixel corresponding to the row pattern is obtained as binarized data. 3. A list representing an order of the plurality of row patterns for sequentially using the plurality of row patterns obtained by the row pattern obtaining means so as to repeat the same row of the dither pattern is obtained. A continuous line pattern storage unit that acquires and stores a continuous line pattern in which a plurality of the line patterns are continuous according to the order of the list acquired by the list acquiring unit; and the binarizing unit includes: From the continuous row pattern stored in the continuous row pattern storage means, for pixels having the same density level in one row of the image data, data at a corresponding position in the row pattern is converted to binary data. 2. The method of claim 1, wherein
An image processing apparatus according to claim 1. 4. The image processing apparatus according to claim 3, wherein the continuous row pattern storage unit is a cache memory.