JP2009065322A - Image output device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a thin line in image data of an output target without requiring much cost. <P>SOLUTION: This image output device includes: a tag data inputting means for inputting tag data showing an attribute of an image data of an output target; a thin line detecting means for detecting a thin line included in the image data of the output target on the basis of the tag data input by the tag data inputting means; a thin line adjusting means for executing thin line adjustment with respect to the image data of the output target on the basis of a thin line detection result by the thin line detecting means; and an image outputting means for outputting the image data of the output target subjected to the thin line adjustment by the thin line adjusting means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image output apparatus and an image output method for outputting an image.

  When outputting an image using an image output apparatus (for example, printing or display), screen processing is performed to output an image. When an image is output by screen processing, there is a problem that a ruled line (thin line) in a figure or a table included in the image is interrupted or an edge portion of a character included in the image is wobbled. As a solution for discontinuity of fine lines and shakiness of edges, character edge portions and fine lines are detected from input image data, and only the character edge portions and fine line portions are printed by processing different from screen processing. Yes. By performing such processing, it is possible to improve the reproducibility of the edge portion of characters and fine lines.

  As a technique for detecting an edge portion or a fine line of a character, for example, Patent Document 1 describes detecting an edge or a thin line from input image data. Further, for example, Patent Document 2 describes that a pixel serving as an edge is extracted from bitmap data, and that an edge is added as tag information.

Japanese Patent Laying-Open No. 2005-341249 (paragraphs 0044-0045, FIG. 2) JP 2006-262204 A (paragraph 0024, FIG. 1)

  When configured to detect edge portions and fine lines of characters in an image, an image processing device (image output device) generally detects edges and thin lines using input image data. Therefore, the circuit scale required for this becomes enormous. Further, since the image processing apparatus needs to perform an operation for referring to a 5 × 5 image in order to detect an edge or a thin line, a necessary line memory becomes enormous.

  For example, in the image processing apparatus described in Patent Document 1, since character edge detection and fine line detection are performed using image data, the circuit scale increases and the required line memory also increases. Further, for example, in the image processing apparatus described in Patent Document 2, when an edge is detected, it is added as tag information, thereby reducing the processing load related to subsequent edges to some extent. However, in order to add tag information, an edge must first be detected using image data, which also increases the circuit scale and the required line memory. Therefore, the cost for detecting edges and fine lines in the image is high.

  SUMMARY An advantage of some aspects of the invention is that it provides an image output apparatus and an image output method capable of detecting fine lines and edges in image data to be output without cost.

  An image output apparatus according to the present invention includes tag data input means for inputting tag data indicating attributes of image data to be output, and fine lines included in the image data to be output based on tag data input by the tag data input means. A fine line detecting means for detecting the image, a fine line adjusting means for performing fine line adjustment on the image data to be output based on the thin line detection result by the thin line detecting means, and outputting the output target image data adjusted by the thin line adjusting means. And an image output means.

  An image output method according to the present invention includes a step of inputting tag data indicating an attribute of image data to be output, a step of detecting fine lines included in the image data to be output based on the input tag data, and a thin line detection The method includes a step of performing fine line adjustment on the image data to be output based on the result, and a step of outputting the image data to be output subjected to the fine line adjustment.

  According to the present invention, the tag data indicating the attribute of the output target image data is input, and the thin line included in the output target image data is detected based on the input tag data. It is possible to detect a thin line in the image data to be output without applying.

Embodiment 1. FIG.
A first embodiment of the present invention will be described below with reference to the drawings. First, the concept of an image output apparatus using the image output method according to the present invention will be described. In the present invention, the image output apparatus detects edges and thin lines using tag data indicating image attributes in 2 to 3 bits (bits) per pixel. Assume that the image output apparatus is a system that inputs image data and TAG (tag) data as input signals. The image output apparatus stores the tag data of the four lines and the four pixels surrounding the target pixel in the tag storage memory prior to the image data of the target pixel in the input image.

  Note that the image output apparatus, when not performing enhancement processing or thin line detection for the surrounding two pixels of the entire input image, tag data for the surrounding two lines and two pixels before the image data of the target pixel. Only in the tag storage memory. At that time, the image output apparatus adds dummy data to the tag data of the surrounding two pixels, and performs control so as not to perform enhancement processing or fine line detection.

  The fine line detection unit of the image output apparatus uses the reference pixel density Ci (i = 1) with respect to the target pixel based on the tag data stored in the tag data storage memory and the tag data newly input from the input unit. ,..., 16) are selected (see FIG. 2). Then, the thin line detection unit searches the difference between the tag data of the target pixel and the tag data of the reference pixel in each of the vertical, horizontal, and diagonal four directions.

  Further, the thin line detection unit gives weights Wi (i = 1,..., 16) to the detected difference in accordance with the position from the target pixel. Then, when the maximum sum of the weighted differences in each direction is greater than or equal to a preset threshold value Cth1, the fine line detection unit detects a 1-bit fine line represented by 1 as a fine line portion. The signal THIN is stored in the memory. The fine line detection unit stores the value other than the fine line in the memory with the value of the fine line detection signal THIN being 0.

  Note that when the thin line is detected only in the horizontal direction (main scanning direction), the thin line detection unit need not store the thin line detection signal THIN in the memory.

  The image output device receives the tag data of the reference pixels (density Ci) around the target image and the thin line detection signal THIN, as well as the obtained image data of the target pixel, tag data, and the thin line detection signal THIN in the fine line adjustment portion. . The image output apparatus thickens the thin line by replacing the pixel of interest according to the density of the image data of the thin line when the pixel adjacent to the pixel of interest (for example, when the reference pixel having a density of C4, C5, C8, etc. is a thin line) The image output apparatus adjusts how to thin the thin line by adding a preset adjustment value CTHIN according to the difference between the thin line and the background portion when replacing the pixel of interest. Then, the image output device replaces the tag data of the target pixel with the tag data of the thin line, and by performing such a replacement process, the target pixel can be regarded as the character portion or the table portion.

  Further, the image output apparatus has a function of executing color conversion processing for converting an image from RGB space to CMYK space, output gamma correction, and screen processing as image processing. In this case, the image output apparatus can switch the output results of the color conversion process, the output gamma correction, and the screen process based on the tag data.

  There are various known color conversion methods, but the color conversion method is not limited in the present invention. In addition, when CMYK is already used in the input data, the image output apparatus may not perform the color conversion process through.

  The image output apparatus performs gamma correction and screen processing in synchronization with switching by tag data, and performs appropriate output gamma correction for the selected screen pattern.

  Further, the image output apparatus detects the edge of the character by filtering processing using a 5 × 5 filter and weighting processing based on tag data of the target pixel and surrounding reference pixels in the edge emphasis portion. In addition, when the image output apparatus determines that the target pixel is an edge, the image output apparatus recalculates the character density. Then, the image output device outputs the target pixel together with the edge detection signal EDGE indicating that the target pixel is detected as an edge.

  When the output selection unit of the image output apparatus determines that the edge is based on the signal EDGE representing the edge of the character, the output selection unit selects the character density from the edge enhancement unit of the image output apparatus and generates output image data. If the output selection unit does not determine that the edge is an edge, the output selection unit selects the input image data subjected to the screen processing, and generates output image data.

  Next, the configuration of the image output apparatus will be described. FIG. 1 is a block diagram showing a configuration of an image output apparatus using an image output method according to the present invention. In the present embodiment, a case where the image output apparatus is a printing apparatus such as a printer will be described. Note that the image output method may be applied to a display device such as a display device.

  As shown in FIG. 1, the image output device includes a fine line detection unit 10, a tag storage memory 20, a fine line adjustment unit 30, a color conversion unit 40, a gamma correction unit 50, a screen processing unit 60, an edge enhancement unit 70, and an output selection unit. 80.

  The image output apparatus uses multi-value image data (for example, 8-bit image data for each color) as input data and attributes (for example, image data) of input target data (for example, a document including image data). Tag data indicating the pixel density of the data). The tag data is data of about 2 to 3 bits for one pixel indicating a photograph, a character, a figure, a table, a background or the like in the input document.

  Note that the tag data input by the image output apparatus is data that has been created in advance for use in switching screen patterns. Therefore, it is not necessary to add new tag data in order to realize the present invention.

  The thin line detection unit 10 has a function of inputting tag data of image data and storing the input tag data in the tag storage memory 20. Further, the thin line detection unit 10 has a function of detecting a thin line in the input image based on tag data stored in the tag storage memory 20.

  When performing vertical line, horizontal and diagonal thin line detection and edge enhancement, the tag storage memory 20 has a capacity to store tag data for the number of main scanning pixels (for example, 8912 pixels) × 4 lines + 4 pixels. is required. In this case, the thin line detection unit 10 inputs tag data corresponding to the number of main scanning pixels × 4 lines + 4 pixels, and stores the input tag data in the tag storage memory 20.

  When edge enhancement and thin line detection are performed only in the vertical and horizontal directions, the tag storage memory 20 needs to have a capacity to store tag data for the number of main scanning pixels × 4 lines. In this case, the thin line detection unit 10 inputs tag data for the number of main scanning pixels × 4 lines, and stores the input tag data in the tag storage memory 20.

  FIG. 2 is an explanatory diagram illustrating an example of a certain pixel of interest included in an image and reference pixels for four surrounding lines and four pixels. Hereinafter, a case where fine line detection and edge detection in the vertical, horizontal, and diagonal directions are performed on an input image will be described as an example.

  The thin line detection unit 10 obtains the difference between the density P of the target pixel shown in FIG. 2 and the density Ci of the surrounding reference image shown in FIG. 2 in each of the vertical, horizontal, and diagonal directions. XOR (exclusive OR) with the pixel density Ci is obtained. Specifically, the thin line detection unit 10 calculates the XOR between the density P of the target pixel and the density Ci of each reference pixel based on the density indicated in each tag data stored in the tag storage memory 20. The difference between the pixel density P and the density Ci of each reference pixel is obtained.

  Further, the thin line detection unit 10 performs predetermined weighting on the obtained XOR calculation result. FIG. 3 is an explanatory diagram illustrating an example of weighting factors Wi (i = 1,..., 16) in which the thin line detection unit 10 performs weighting processing on the XOR calculation result.

  Further, the thin line detection unit 10 performs a calculation process in which the maximum value of XOR obtained in the vertical, horizontal, and diagonal directions is used as the calculated value COUNT of the target pixel (see Expression (1)). The calculated value COUNT takes a value from 0 to 6, and can be expressed by 3 bits.

  Then, the thin line detection unit 10 performs a calculation process for generating a thin line detection signal THIN indicating that the target pixel is detected as a thin line by performing a comparison process between the calculated value COUNT obtained and a preset threshold value Cth1. (See equation (2)). Here, as a condition, it is assumed that the tag data of the pixel of interest is only the data (for example, character tag data) for which thin line detection is selected in advance. When THIN = 1 is obtained using equation (2), it indicates that the pixel of interest has been detected as a thin line. Further, when THIN = 0 is obtained, it indicates that the pixel of interest has not been detected as a thin line.

THIN = 1: (COUNT ≦ Cth1, where it is specified that thin line detection should be performed with the tag data of the target pixel)
0: (others) Formula (2)

  As described above, the fine line detection unit 10 detects the fine line in the image by obtaining the fine line detection signal THIN. Then, the fine line detection unit 10 sends the fine line detection signal THIN and the calculated value COUNT to the subsequent fine line adjustment unit 30 together with the tag data.

  The fine line adjustment unit 30 has a function of performing a fine line adjustment process such as performing a process of thickening a fine line based on the fine line detection result of the fine line detection unit 10. For example, the fine line adjustment unit 30 performs adjustment to thicken the fine line by performing a process of replacing the density of the pixels arranged on the left and right of the fine line with the THIN value, the COUNT value, and the preset threshold value Cth2 of the target pixel. Process. Alternatively, for example, the fine line adjustment unit 30 performs a process of adjusting the thickness of the thin line by performing a process of replacing the density of the target pixel.

  For example, the densities of the reference pixels on the left and right of the target pixel are C8 and C9, and the density of the target pixel is P. An adjustment value set in advance by the thin line and the density difference between the left and right pixels of the target pixel is defined as CTHIN. In this case, the fine line adjustment unit 30 performs density replacement by performing the following arithmetic processing (see Expression (3)). The adjustment value CTHIN takes a value between 0 and 1 and approaches the density P of the pixel of interest replaced as it approaches 0. Further, the adjustment value CTHIN becomes closer to the density C8, C9 of the original peripheral pixels as it approaches 1.

Ci = P + CTHIN × (Ci−P): (when THIN = 1 and COUNT ≦ Cth2 and (P−Ci) ≧ 0)
Ci = P−CTHIN × (Ci−P): (when THIN = 1 and COUNT ≦ Cth2 and (P−Ci) <0)
Formula (3)

  Further, the fine line adjustment unit 30 performs a process of replacing the tag data for the left and right pixels of the target pixel of the thin line where the replacement has occurred with the same value as the tag data of the target pixel (see Expression (4)). Here, in Expression (4), TAGout is output tag data. Further, TAGp is assumed to be fine line tag data, and TAGin is assumed to be input tag data.

TAGout = TAGp: (THIN = 1 and COUNT ≦ Cth2)
TAGin: (others) Formula (4)

  Then, the fine line adjustment unit 30 outputs to the color conversion unit 40, the image data in which the thickness of the fine line is corrected and the tag data in which the pixels around the pixel of interest of the fine line are replaced.

  The color conversion unit 40 has a function of executing color conversion processing for converting image data from the RGB space to the CMYK space. The gamma correction unit 50 has a function of performing gamma correction on the image data. The screen processing unit 60 has a function of performing screen processing on the image data. Note that the gamma correction unit 50 and the screen processing unit 60 have a function capable of switching processing based on tag data.

  The edge emphasizing unit 70 has a function of detecting an edge of a character or the like included in an image based on tag data of a target pixel and a surrounding reference image. The edge emphasizing unit 70 has a function of obtaining the density after emphasis of the detected edge when performing edge emphasis by detecting an edge of a character or the like.

  The edge enhancement unit 70 inputs the tag data and the image data, and takes the difference between the density P of the target pixel shown in FIG. 2 and the density Ci of the surrounding reference image for each of the vertical, horizontal, and diagonal directions. XOR (exclusive OR) is obtained. Further, the edge emphasizing unit 70 performs weighting similar to the weighting illustrated in FIG. 3 on the obtained XOR calculation result. The edge emphasizing unit 70 performs a calculation process in which the minimum value of XOR obtained in the vertical, horizontal, and diagonal directions is used as the calculated value E of the target pixel (see Expression (5)). Here, as a condition, it is assumed that the tag data of the pixel of interest is only that for which edge enhancement is selected in advance (for example, character tag data).

  Further, the edge emphasizing unit 70 performs a calculation process for determining whether the edge should be emphasized by performing a comparison process between the calculated value E obtained and a preset threshold value Eth, and detects that the target pixel is detected as an edge. The edge detection signal EDGE shown is obtained (see equation (6)). When EDGE = 1 is obtained using Equation (6), it indicates that the pixel of interest has been detected as an edge. Further, when EDGE = 0 is obtained, it indicates that the target pixel has not been detected as an edge.

EDGE = 1 (E ≧ Eth)
EDGE = 0 (others) Equation (6)

  Further, the edge emphasizing unit 70 obtains the density Eout after edge enhancement of the target pixel by a calculation using Expression (7).

Eout = P / (maximum value of the number of input bits) × (maximum value of the number of output bits): (EDGE = 1)
Eout = P (others) Equation (7)

  Then, the edge enhancement unit 70 outputs the density Eout after edge enhancement of the target pixel and the edge detection signal EDGE indicating the edge portion to the output selection unit 80.

  The output selection unit 80 has a function of inputting the density SCRout after the screen processing from the screen processing unit 60, the density Eout after the edge enhancement from the edge enhancement unit 70, and the edge detection signal EDGE indicating the edge portion. Is provided. Further, the output selection unit 80 has a function of obtaining the final output density IMGout of the pixel of interest using Expression (8) based on the density SCRout after the screen processing, the density Eout after the edge enhancement, and the edge detection signal EDGE. .

IMGout = Eout: (EDGE = 1)
IMGout = SCRout: (others) Equation (8)

  In other words, the output selection unit 80 performs processing using the equation (8), so that pixel data that has been edge-enhanced by the edge enhancement unit 70 is obtained from the pixel that has been edge-enhanced by the edge enhancement unit 70. Select and control to output. Further, the output selection unit 80 performs control so that the pixel data that has been screen-processed by the screen processing unit 60 is output to the pixels that have not been subjected to edge enhancement by the edge enhancement unit 70.

  Further, the output selection unit 80 has a function of outputting an image based on the obtained final output density IMGout. For example, the output selection unit 80 of the image output apparatus that is a printing apparatus such as a printer prints an image based on the obtained final output density IMGout.

  Next, the operation will be described. FIG. 4 is a flowchart illustrating an example of a process in which the image output apparatus performs fine line detection and edge detection in an image and performs image output. When performing image output, first, the thin line detection unit 10 of the image output apparatus starts input of tag data, and stores the input tag data in the tag storage memory 20 (step S10).

  When performing fine line detection in vertical, horizontal and diagonal directions and edge enhancement, the fine line detection unit 10 repeatedly outputs tag data until the input of tag data for four lines and four pixels around the target pixel is completed. The data is input and stored in the tag storage memory 20 (step S11).

  When the necessary number of tag data is written in the tag storage memory 20 and the detection of the fine line is completed, the fine line detection unit 10 asserts the ready signal to transfer the image data in order to request the image data to be output. Prompt. Further, the fine line detection unit 10 performs fine line detection based on the tag data of the reference pixels around the target pixel and the tag data of the target pixel (step S12).

  FIG. 5 is an explanatory diagram illustrating an example of fine line detection performed by the fine line detection unit 10. As shown in FIG. 5, the thin line detection unit 10 obtains a COUNT value based on the tag data, and performs a comparison process with the threshold value Cth1 (assumed to be 5 in this example) for the obtained COUNT value. Thus, the thin line detection signal THIN is obtained. For example, as illustrated in FIG. 5, the thin line detection unit 10 determines that a pixel having a COUNT value equal to or greater than a threshold Cth1 is a thin line, and generates a thin line detection signal THIN having a value of 1. Then, the fine line detection unit 10 sends the obtained fine line detection signal THIN, the calculated value COUNT, and the image data to the fine line adjustment unit 30.

  Next, the fine line adjustment unit 30 adjusts the thickness of the fine line by performing a process of replacing the density of pixels arranged on the left and right of the fine line based on the fine line detection signal THIN input from the fine line detection unit 10 and the calculated value COUNT. Processing is performed (step S13).

  FIG. 6 is an explanatory diagram illustrating an example of fine line adjustment performed by the fine line adjustment unit 30. As illustrated in FIG. 6, the fine line adjustment unit 30 determines a pixel for thickening the fine line by performing a process of comparing the input COUNT value, the fine line detection signal THIN, and the threshold value Cth2. Then, the fine line adjustment unit 30 performs a process of thickening the fine line to adjust the density of the fine line. For example, as illustrated in FIG. 6, the fine line adjustment unit 30 determines that a pixel having a COUNT value equal to or greater than the threshold value Cth2 is to be thickened, and changes the density so as to increase the density.

  In addition, the fine line adjustment unit 30 changes the pixel density and also changes the tag data of the pixel whose density has been changed. Then, the fine line adjustment unit 30 outputs the tag data to the subsequent color conversion unit 40 in synchronization with the image data output after the fine line adjustment.

  By executing the process of step S13, the thin line is thickened, and the disappearance of the fine line due to the printing condition can be prevented when outputting the image.

  Next, when the input image data uses RGB or the like, the color conversion unit 40 performs a color conversion process for converting the input image data from the RGB space to the CMYK space (step S14). In addition, the color conversion unit 40 selects a conversion coefficient for performing color conversion according to the value of the input tag data. When the color conversion process is completed, the color conversion unit 40 sends the tag data to the gamma correction unit 50 together with the image data converted into the CMYK space.

  Next, the gamma correction unit 50 performs gamma correction processing on the input image data (step S15). The gamma correction unit 50 selects a conversion coefficient for performing gamma correction according to the tag data value input from the color conversion unit 40. When the gamma correction is completed, the gamma correction unit 50 sends the tag data together with the gamma-corrected image data to the screen processing unit 60 and the edge enhancement unit 70.

  Next, the screen processing unit 60 performs screen processing on the input image data (step S16). Further, the screen processing unit 60 selects a conversion coefficient for performing screen processing according to the value of the tag data input from the gamma correction unit 50. When the screen processing is completed, the screen processing unit 60 sends the screen-processed image data to the output selection unit 80.

  Further, the edge enhancement unit 70 performs a process of performing edge enhancement on the input image data (step S17). FIG. 7 is an explanatory diagram illustrating an example of edge enhancement performed by the edge enhancement unit 70. The edge emphasis unit 70 first receives tag data and image data from the gamma correction unit 50. Further, as shown in FIG. 7, the edge enhancement unit 70 obtains an EDGE signal and an output image Eout by performing a comparison process between the tag data and the threshold Eth. For example, as illustrated in FIG. 7, the edge enhancement unit 70 determines that a pixel having a calculated value E equal to or greater than the threshold Eth as an edge, and generates an edge detection signal EDGE having a value of 1. Then, the edge enhancement unit 70 sends the obtained edge detection signal EDGE to the output selection unit 70.

  Next, the output selection unit 80 performs screen processing and edge enhancement on the target pixel based on the output image density SCRout obtained by the screen processing unit 60 and the EDGE signal and output image density Eout obtained by the edge enhancement unit. Which of the processed pixels is selected as the output pixel is selected (step S18). Then, the output selection unit 80 obtains the density IMGout of the final output image based on the selection result.

  Then, the output selection unit 80 outputs (prints) an image based on the obtained final output density IMGout.

  As described above, according to the present embodiment, the image output apparatus detects fine lines and edges included in image data to be output based on tag data indicating attributes of image data. Therefore, it is possible to detect thin lines and edges in the image data to be output without cost. For example, in the image processing apparatus described in Japanese Patent Application Laid-Open No. 2005-341249, fine line detection and edge detection of characters in an image are performed with image data having a large data capacity, so that necessary memory for fine line detection and edge detection is used. The cost of etc. is large. On the other hand, according to the present embodiment, since thin line detection and edge detection can be performed based on tag data having a data capacity as small as 2 to 3 bits, the necessary memory can be minimized, and fine line detection and Costs such as required memory capacity and circuit scale for edge detection can be reduced.

  For example, when edge enhancement and fine line detection / adjustment are performed using image data, for example, if 8-bit CMYK input is used for each color, a memory for storing data corresponding to the number of main scanning pixels × the number of necessary lines × 32 bits is required. It becomes. In this case, edge enhancement and fine line detection / adjustment are performed on the basis of tag data information of about 2 bits per pixel, so that 16 lines are compared with the case where fine line detection and edge detection are performed using image data. It becomes possible to perform processing with a memory capacity of 1 / min.

  Further, according to the present embodiment, it is possible to output an image output device that performs screen processing without erasing thin lines of characters and figures.

  In addition, according to the present embodiment, edge-emphasized pixels are output for edge portions in the image data, and screen-processed pixels are output for portions other than the edges. Can be reduced. For example, if only the screen processing is performed on the entire image data to be output, rattling occurs at the edge portion of the character. In this embodiment, since edge enhancement is performed separately for the pixels of the edge portion in the image data, it is possible to reduce rattling of the character edge in the image data.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the basic configuration of the image output apparatus is the same as the configuration shown in the first embodiment (see FIG. 1).

  In the first embodiment, a case is shown in which the thin line is thickened in the thin line adjustment processing after the thin line is detected. However, the thin line may be further thinned. Specifically, by changing the generation method of the fine line detection signal THIN performed by the fine line detection unit 10, it is possible to make the characters thicker and thinner.

  In the present embodiment, the thin line detection unit 10 performs the following arithmetic processing.

  The thin line detection unit 10 is the same as in the first embodiment in order to obtain the difference between the pixel density P of the pixel of interest and the density Ci of the surrounding reference pixels shown in FIG. 2 in each of the vertical, horizontal, and diagonal directions. In accordance with the above processing, XOR (exclusive OR) between the density P of the target pixel and the density Ci of the reference pixel is obtained. In addition, the thin line detection unit 10 performs predetermined weighting on the obtained XOR calculation result according to the same processing as in the first embodiment (see FIG. 3). Further, the thin line detection unit 10 performs a calculation process in which the maximum value of XOR obtained in the vertical, horizontal, and oblique directions is set to the calculated value COUNT of the target pixel according to the same process as in the first embodiment (formula (See (1)).

  Then, the thin line detection unit 10 performs a calculation process for generating a thin line detection signal THIN indicating that the target pixel is detected as a thin line by performing a comparison process between the calculated value COUNT obtained and a preset threshold value Cth1. . In this case, in this embodiment, the thin line detection unit 10 obtains the thin line detection signal THIN as a condition regardless of the tag data of the target pixel (see Expression (9)).

THIN = 1: (COUNT ≦ Cth1)
0: (others) Formula (9)

  Then, the fine line detection unit 10 sends the fine line detection signal THIN and the calculated value COUNT to the subsequent fine line adjustment unit 30 together with the tag data.

  As described above, in the present embodiment, the fine line adjustment unit 10 calculates the fine line detection signal THIN without being limited to pixels that are designated to perform fine line detection by tag data. By doing so, in the present embodiment, the fine line adjustment unit 30 can execute both thickening and thinning of characters and the like in the image.

  Next, the operation will be described. In the present embodiment, the basic process of outputting an image by the image output apparatus is the same as the process flow shown in the first embodiment (see FIG. 4). FIG. 8 is an explanatory diagram showing another example of fine line detection performed by the fine line detection unit 10 and fine line adjustment performed by the fine line adjustment unit 30.

  The fine line detection unit 10 performs fine line detection based on tag data of reference pixels around the target pixel and tag data of the target pixel (see step S12). In this case, the fine line detection unit 10 obtains a COUNT value based on the tag data, and performs a comparison process with the threshold value Cth1 (assumed to be 5 in this example) on the obtained COUNT value, thereby detecting a fine line. The signal THIN is obtained. In the example illustrated in FIG. 8, the thin line detection unit 10 determines that THIN = 1 for the thin line in the background portion between characters and graphics, and determines that it is a thin line.

  Next, the fine line adjustment unit 30 thins characters and figures based on the COUNT value input from the fine line detection unit 10, the fine line detection signal THIN, and the threshold value Cth2, and thins the background fine lines between the characters and figures. By doing so, fine line adjustment processing is performed (see step S13). In addition, the fine line adjustment unit 30 changes the pixel density and also changes the tag data of the pixel whose density has been changed.

  As described above, according to the present embodiment, the image output apparatus can perform thinning and thinning of the detected thin line, so that, for example, thinning characters and figures in the image data, Processing to thicken the line of sight of the background between characters and figures can be performed. Therefore, it is possible to output the characters and the fine lines of the image data without erasing them more appropriately.

  Next, the minimum configuration of the image output apparatus according to the present invention will be described. FIG. 9 is a block diagram illustrating a minimum configuration example of the image output apparatus. As shown in FIG. 9, the image output apparatus includes a fine line detection unit 10, a fine line adjustment unit 30, and an output selection unit 80 as minimum components.

  The fine line detection unit 10 has a function of inputting tag data of image data and detecting a fine line in the input image based on the input tag data. Further, the fine line adjustment unit 30 has a function of performing fine line adjustment processing such as processing for thickening a fine line based on the thin line detection result of the fine line detection unit 10. The output selection unit 80 has a function of outputting an image that has been subjected to the fine line adjustment processing.

  According to the image output apparatus having the minimum configuration shown in FIG. 9, tag data indicating attributes of image data to be output is input, and fine lines included in the image data to be output are detected based on the input tag data. Therefore, it is possible to detect a thin line in image data to be output without incurring costs.

  In each of the above embodiments, the characteristic configuration of the image output apparatus as shown in the following (1) to (6) is shown.

  (1) An image output device includes tag data input means (for example, realized by the thin line detection unit 10) for inputting tag data indicating an attribute of image data to be output, and tag data input by the tag data input means. Based on the fine line detection means (for example, realized by the fine line detection unit 10) for detecting a fine line included in the image data to be output, and the fine line for the image data to be output based on the thin line detection result by the fine line detection means. Fine line adjustment means (for example, realized by the fine line adjustment unit 30) that performs adjustment, and image output means (for example, the output selection unit 80) that outputs image data to be output that has been fine line adjusted by the fine line adjustment means. ). According to such a configuration, since thin line detection can be performed based on tag data having a data capacity as small as 2 to 3 bits, the necessary memory can be minimized, and the required memory capacity and circuit for thin line detection Costs such as scale can be reduced.

  (2) The image output device includes an edge detection unit (for example, realized by the edge enhancement unit 70) that detects an edge included in the image data to be output based on the tag data input by the tag data input unit. Edge enhancement means (for example, realized by the edge enhancement unit 70) that performs edge enhancement on the image data to be output based on the edge detection result by the edge detection means, and the image output means includes the edge enhancement means. The image data to be output with edge enhancement may be output. According to such a configuration, since edge detection can be performed based on tag data having a data capacity as small as 2 to 3 bits, the necessary memory can be minimized, and the necessary memory capacity and circuit for edge detection can be minimized. Costs such as scale can be reduced.

  (3) The image output apparatus includes screen processing means (for example, realized by the screen processing unit 60) that executes screen processing on image data to be output, and the image output means performs edge enhancement by the edge enhancement means. Pixels that have been edge-enhanced by the edge enhancement means are selected and output for the pixels that have been subjected to edge enhancement, and pixels that have not been subjected to edge enhancement by the edge enhancement means are subjected to screen processing by the screen processing means The data may be output. According to such a configuration, the edge-enhanced pixel is output for the edge part in the image data to be output, and the screen-processed pixel is output for the part other than the edge. Stickiness can be reduced.

  (4) The image output device includes tag data storage means (for example, realized by the tag storage memory 20) that stores tag data input by the tag data input means, and the tag data input means outputs image data to be output. The tag data corresponding to the pixels corresponding to the four lines and the four pixels around the target pixel may be input before the target pixel data and stored in the tag data storage unit. According to such a configuration, it is possible to read the tag data necessary for fine line detection in the vertical, horizontal, and oblique directions with respect to the target pixel data prior to the tag data storage unit and perform the fine line detection.

  (5) In the image output apparatus, the fine line adjusting unit is configured to execute an adjustment process for thickening the thin line by performing a process of replacing the density of the images arranged on the left and right of the thin line detected by the thin line detecting unit. It may be. According to such a configuration, it is possible to output without erasing the thin lines of characters and figures in the image data to be output by performing the adjustment process for thickening the thin lines.

  (6) In the image output device, the fine line adjusting unit is configured to execute an adjustment process for thinning a thin line by performing a process of replacing the density of the images arranged on the left and right of the thin line detected by the thin line detecting unit. It may be. According to such a configuration, it is possible to perform a process of thinning characters and graphics in the image data and thickening the line of sight of the background between the characters and graphics. Therefore, it is possible to output the characters and the fine lines of the image data without erasing them more appropriately.

  The present invention can be applied to image output devices such as printers and display devices.

It is a block diagram which shows the structure of the image output apparatus using the image output method by this invention. It is explanatory drawing which shows the example of a certain attention pixel contained in an image, the surrounding 4 lines, and the reference pixel for 4 pixels. It is explanatory drawing which shows the example of the weighting coefficient Wi which a thin line detection part performs a weighting process with respect to the calculation result of XOR. It is a flowchart which shows an example of the process which an image output apparatus performs the fine line detection and edge detection in an image, and performs image output. It is explanatory drawing which shows the example of the thin line detection which a thin line detection part performs. It is explanatory drawing which shows the example of the fine line adjustment which a fine line adjustment part performs. It is explanatory drawing which shows the example of the edge emphasis which an edge emphasis part performs. It is explanatory drawing which shows the other example of the thin line detection which a thin line detection part performs, and the fine line adjustment which a thin line adjustment part performs. It is a block diagram which shows the minimum structural example of an image output device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fine line detection part 20 Tag preservation | save memory 30 Fine line adjustment part 40 Color conversion part 50 Gamma correction part 60 Screen processing part 70 Edge emphasis part 80 Output selection part

Claims (8)

Tag data input means for inputting tag data indicating attributes of image data to be output;
Fine line detection means for detecting a fine line included in the image data to be output based on tag data input by the tag data input means;
Fine line adjustment means for performing fine line adjustment on the image data to be output based on the thin line detection result by the fine line detection means;
An image output device comprising: image output means for outputting the image data to be output that has been subjected to fine line adjustment by the fine line adjustment means. Edge detection means for detecting an edge included in image data to be output based on tag data input by the tag data input means;
An edge enhancement unit that performs edge enhancement on the image data to be output based on an edge detection result by the edge detection unit;
The image output apparatus according to claim 1, wherein the image output unit outputs the image data to be output that has been edge-enhanced by the edge enhancement unit. Screen processing means for executing screen processing on image data to be output;
The image output means
For the pixels on which edge enhancement has been performed by the edge enhancement means, select and output the pixel data edge-enhanced by the edge enhancement means,
The image output apparatus according to claim 2, wherein pixel data that has undergone screen processing by the screen processing unit is output to pixels that have not been subjected to edge enhancement by the edge enhancement unit. Tag data storage means for storing tag data input by the tag data input means,
The tag data input means inputs tag data corresponding to pixels for four lines and four pixels around the target pixel in the output target image data before the target pixel data, and inputs the tag data to the tag data storage unit. The image output apparatus according to claim 1, wherein the image output apparatus is stored.   4. The fine line adjusting unit according to claim 1, wherein the fine line adjusting unit performs an adjustment process for thickening a thin line by performing a process of replacing the density of images arranged on the left and right sides of the thin line detected by the thin line detecting unit. The image output apparatus according to item 1.   The image output apparatus according to claim 5, wherein the fine line adjusting unit executes an adjustment process for thinning the thin line by performing a process of replacing the density of the images arranged on the left and right of the fine line detected by the thin line detecting unit. Inputting tag data indicating attributes of image data to be output;
Detecting fine lines included in the image data to be output based on the input tag data;
Performing fine line adjustment on the image data to be output based on the thin line detection result;
Outputting the image data to be output that has been fine-line-adjusted. Detecting an edge included in the image data to be output based on the input tag data;
Performing edge enhancement on the image data to be output based on the edge detection results;
The image output method according to claim 7, further comprising a step of outputting edge-enhanced image data to be output.

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