JPH0588829A - Artificial variable density image display - Google Patents

Abstract

PURPOSE:To fast output the variable density image by generating a special compressed image, preparing a binary pattern in accordance with a sub-matrix corresponding to the density value of respective picture elements and outputting a hard copy. CONSTITUTION:An original image is stored, for example, into a magnetic memory 10, and placed onto a first main memory 12 for the processing such as displaying. Next, an image compressed variable density pattern conversion processor 13 compresses to the image ((k) is the integer of 2 or above.) of (m/k)X(n/k) composed of an MXn picture element ((m) and (n) are the integers of 2 or above.). Next, the compressed image is converted into the variable density displaying pattern constituted of the sub-matrix of KXK and the artificial variable density image of the mXn picture element is generated. Image data for variable density output are stored onto a second main memory 14. The data are displayed at an image display 11, from here, the data are transferred to a binary displaying exclusive-use hard copy printer device 15 or a color copy printer device 16 and the hard copy is outputted.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pseudo grayscale image display device, and more particularly to a hardcopy for grayscale image data having no grayscale output dedicated to binary display having a resolution equal to or less than that of a display device such as a computer graphics display. The present invention relates to a device suitable for creating output on a printer device.

2. Description of the Related Art In a system including a hard copy printer device dedicated to binary display having a resolution equal to or less than that of a display device such as a computer graphics display,
When a hard copy of the screen is taken, even image data having gradation is output as binary data of only white or black. In order to solve this, in the prior art, there is a systematic dither method, etc. (Image analysis handbook, supervised by Mikio Takagi,
Shimoda, Y., 1991, Page 493-501). This method can reproduce the gradation of a grayscale image as a whole with the same number of output pixels as the number of input pixels (see FIG. 11). The feature of this method is that output: input can be output in a 1: 1 relationship. However, in this method, the logic determination process is required for all pixels, and the processing time is not taken into consideration in the case of a large image such as 1000 × 1000 pixels. Although there is a density pattern method as another technique, this method outputs k × k = k squared pixels for one input pixel, which actually exceeds the resolution of hard copy. It wasn't done.

In the above-mentioned prior art, the hard copy printer device for displaying the grayscale data had to have a performance equal to or higher than the resolution of the display device such as a computer graphics display. Further, in order to output a pseudo grayscale display on a printer having a resolution lower than that of the display device, there is a problem that the processing time is significantly increased when the systematic dither method processing is executed. An object of the present invention is to enable high-speed output of a grayscale image in a system including an image display device such as a computer graphics display and a hard copy printer device dedicated to binary display having a resolution equal to or less than that of the display device. The present invention is to provide a pseudo grayscale image display device.

The feature of the present invention for achieving the above object is that image data is taken into a grayscale image processing apparatus and image data consisting of m × n pixels is compressed to m / k × n / k. Means, a means for generating a sub-matrix k × k in the gradation pattern method, a means for converting and outputting the compressed image in a gradation conversion display, and a means for reproducing the original image data. Here, m, n, and k are integers of 2 or more. Specifically, when using the sub-matrix 4 × 4, a compressed image of m / 4 × n / 4 = (m × n) / 16 is created, and for each pixel of the compressed image, Correspond to the sub-matrix 4 × 4 according to the density value. According to this sub-matrix, a binary pattern is generated to create a pseudo grayscale image. This can be realized by outputting a hard copy (see FIG. 1).

In the grayscale image compression method, for example, k × k pixels in the original image are considered as a unit of gradation expression, and one arbitrary pixel (for example, one pixel at the upper left) is extracted from the data of k × k pixels.
Next, the unit of k × k pixels is shifted to the right, and one pixel is extracted from the new k × k pixel data. The same method can be used to compress an image of m / k × n / k. The grayscale pattern sub-matrix is stored in advance as data,
In addition, by dividing the maximum density value by the number of sub-matrix patterns and determining the range of density value classification, the density value can be associated with the corresponding sub-matrix. By associating with this sub-matrix, the compressed image can be displayed in pseudo-density. As described above, since the grayscale image is compressed using the grayscale pattern method,
High-speed processing becomes possible. The above method is applied not only to monochrome but also to R, G, B images for R, G, B images.
By applying the above method for each case and creating a pseudo R, G, B density display image, a pseudo color grayscale image can be output to a multi-color (for example, 7 colors) or full-color color hard copy device. Further, the size of this gradation expression unit can be easily changed to 2 × 2, 3 × 3, and the gradation can be controlled.

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, "0: OFF", "1: ON"
The area gradation method that reproduces gradation by changing the ratio of "1: on" in the image is used by using the printer device capable of only the binary display. In particular, the density pattern method of the area gradation method is used in this embodiment. In this method, one pixel of a grayscale image is made to correspond to a sub matrix of k × k pixels (k is an integer of 2 or more), and the density of each pixel is reproduced by the area of black dots in the sub matrix. In this case, the density information of each pixel can be reproduced relatively faithfully, but n2 times the number of output pixels is required to reproduce n2 + 1 gradation. This is effective when the number of output pixels can be set sufficiently larger than the number of input pixels. The dither method compares the density of the original image with a threshold value calculated according to a certain rule, and binarizes the output according to the magnitude relationship. In the systematic dither method, a threshold matrix of k × k is created, and this is used as a mask to overlay the original image and compare it with the threshold value corresponding to the density of each pixel and binarize it. Unlike the density pattern method, the gradation of each pixel of a grayscale image is not reproduced in a sub-matrix,
With the same number of output pixels as the input pixels, the gradation of the grayscale image can be reproduced as a whole. Here, in order to make the number of output pixels the same as the number of input pixels as in the dither method, the original image is compressed and the gradation for each pixel is reproduced in a sub-matrix like the density pattern method in order to reduce the processing time. , Display a pseudo gray image. FIG. 1 shows the system configuration of the pseudo grayscale image display device of this embodiment. The original image is stored, for example, in the magnetic storage device 10 and is on the first main memory 12 for processing such as display. Next, the image is converted by the image compression / grayscale pattern conversion processing device 13, and the image data for grayscale output is stored in the second main memory 14. Then, it is displayed on the image display device 11 such as a computer graphics display. From here, the data is transferred to the hard copy printer device 15 or the color copy printer device 16 dedicated to the binary display, and the hard copy is output. After the hard copy output, the original image data is reproduced in the first main memory 12. Hereinafter, specific processing of the system shown in FIG. 1 will be described. FIG. 2 shows a basic processing flow of the system of FIG. In the first process shown as a box 21, the original image data is displayed in both the vertical and horizontal directions like the pixel 41 and the pixel 42 (each corresponding to one pixel) shown in FIG. The image is skipped according to the size of and the compressed image is created. The gradation can be controlled by changing the size of the gradation pattern 32 to 2 × 2 or 3 × 3. As a specific example, if the size of the original image is 920 × 1000 pixels,
The gradation pattern 32 having a size of 4 × 4 is used. In this case, 17 gradations can be expressed because 4 patterns can be combined in 17 patterns. In the grayscale pattern generation process shown as a box 22, one pixel of the grayscale image is made to correspond to a k × k pixel sub-matrix, and the density of each pixel is reproduced by the area ratio of black dots in the sub-matrix. An example of a 2 × 2 size grayscale display pattern using a 2 × 2 sub-matrix is shown in FIG. The gradation reproducibility changes depending on the arrangement of dots in the sub-matrix. Generally, a k × k matrix can reproduce k 2 +1 gradations. The generation of the grayscale pattern is performed in the 2 × 2 size grayscale gradation display pattern 50 to FIG.
54, and 2 × 2 size grayscale display patterns 55-5
As shown in FIG. 9, the combination can be freely changed. As a concrete example, the display patterns 804 to 820 of FIG.
Is used. In the grayscale image output processing shown as a box 23, the grayscale image is output using the printer device 15 dedicated to the binary display. For example, in FIG. 4, one pixel 41 of the original grayscale image is converted and output in a 4 × 4 grayscale pattern 43. The original image 41 and the converted and output image 46 have the same size. In the reproduction processing of the original image data shown as a box 24, the reproduction is performed by replacing the pseudo grayscale image generated for the printer output of the first main memory 12 with the original image data for the other processing thereafter. Next, a detailed processing flow will be described with reference to FIG.
The pseudo grayscale image creation is executed by selecting "screen copy" on the display screen of the display device shown in FIG.
After outputting the pseudo grayscale image with respect to the original image, a determination process 70 is performed to avoid outputting the pseudo grayscale image. In the case of the grayscale image hard copy output, the process proceeds to the saving process of the original image data in the box 71. If not, the pseudo gray-scale image on the main memory is reproduced into the original image data by the process in box 78, and the original image data is output to the image display device 11 shown in FIG. In the box 71, since the original image data is destroyed by the grayscale image generation processing, the original image data is moved to the magnetic storage device 10 for temporary saving to prevent it. The process in box 72 determines the size of the grayscale pattern as described with reference to FIGS. In this embodiment, 4 × 4 size 17 gradation display processing is performed. The size is increased when the gray level of the original image is wide, and is decreased otherwise. Next, in the processing of box 73, a gradation pattern is created. FIG. 8 shows a process of generating a grayscale pattern. The patterns of 17 gradations having the gradation levels of 0 to 16 are shown as patterns of reference numerals 804 to 820, respectively. Here, a halftone dot type is used. Next,
An algorithm for generating a grayscale pattern will be described. First, an array is used, and the elements in the array are denoted by reference numeral 801.
And a list of. This value is one in which addresses are sequentially assigned to the array from 1 to 16 (reference numeral 802), and it is known what number the bit "1: On" is set in the array of the address. This process can easily generate a pattern by looping 16 times. In this embodiment, since the color image is used as the original image, the processing of box 74 selects the R, G, B used bands of the color image. Each of the bands used has a flag, and this is judged. This is used when converting the average of R, G, and B in the processing of box 76 into gradation display. As shown in FIG. 4, the process in the box 75 reads every 4 pixels in the vertical and horizontal directions for image compression. In the processing of box 76, the original light and shade levels of R, G, and B are averaged from the information of the processing of box 74,
This performs gradation display conversion. The processing in box 79 is processing in the color hard copy printer device 16.
That is, gradation display conversion is performed for each of R, G, and B. FIG. 9 shows an example of the conversion function. In this embodiment, a function for converting the original light and shade level 0 into 0 and converting the original light and shade levels 1 to 16 into the display level 1 is used. Conversion functions other than those shown in FIG. 9 can also be used. By taking a hard copy of the image converted and output in this way, a grayscale image can be output to the binary hard copy printer 15 that can output only binary display. In the process in box 78, the data in the magnetic storage device 10, which is the original image data temporarily saved in the process in box 71, is moved to the first main memory 12. If the original image data has a size that can be saved in the first main memory 12, the data is replaced as it is. A grayscale image is displayed in the image data portion of FIG. FIG. 10 shows a modification of the embodiment shown in FIG. That is, the grayscale image processing is not performed by the processing system of the main body, but the original image is passed to the hardcopy printer device 104 including the liquid crystal display and the binary printer 15, and the grayscale conversion process is performed exclusively in the hardcopy printer device 104. It is also possible. The image display device 11 of FIG. 10 is different from the image display device 11 of FIG. 1 in that it also includes an image processing means. The present invention is not limited to the above description and can be modified within the scope of the gist of the present invention.

According to the present invention, a grayscale image display output can be performed at high speed by a binary display dedicated hard copy printer device and a color hard copy printer device having a resolution equal to or less than that of the image display device. In addition, it is possible to combine gradation patterns and change the sub-matrix size, so that gradation control can be performed easily. After the display, the original image can be reproduced and other processing thereafter can be performed. Furthermore, the existing system can be used, and the cost of introducing equipment can be reduced.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of basic functions of an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of a sub-matrix size according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of an example of compression conversion according to an embodiment of the present invention.

FIG. 5 is a diagram showing an example of a light and shade pattern combination according to an embodiment of the present invention.

FIG. 6 shows an example of hard copy output according to an embodiment of the present invention.

FIG. 7 is a diagram showing an example of a processing flow of an embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a grayscale pattern according to an embodiment of the present invention.

FIG. 9 is a diagram showing an example of a grayscale conversion function according to an embodiment of the present invention.

FIG. 10 is a conceptual diagram of a modified example of the present invention.

FIG. 11 is an explanatory view of the concept of the systematic dither method.

[Explanation of symbols]

10 ... Magnetic storage device, 11 ... Image display device 12 ... First main memory, 13 ... Image compression / gray pattern conversion processing device, 14 ... Second main memory, 15 ... Binary hard copy printer device.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hitoshi Fushimi 5-2-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Omika factory

Claims (6)

[Claims] 1. A system comprising a display device and a hard copy printer device having a resolution equal to or less than that of the display device, wherein m × n pixels (m and n are 2 or more) displayed on the display device. Means for compressing a grayscale image consisting of (integer) into an (m / k) × (n / k) image (k is an integer of 2 or more), and a grayscale display composed of the compressed image by a k × k sub-matrix A pseudo grayscale image display device, comprising: means for converting into a pattern to generate a pseudo grayscale image of m × n pixels, and outputting the grayscale image to the hard copy printer device. 2. The pseudo grayscale image display device according to claim 1, wherein the hardcopy printer device is dedicated to binary display. 3. The grayscale image consisting of m × n pixels is a color image consisting of R, G and B, and the pseudo grayscale image is generated for each R, G and B. Pseudo gray image display device. 4. The grayscale image processing apparatus according to claim 1, wherein the grayscale image processing apparatus receives the image data, compresses the image data, and generates a grayscale pattern.
A grayscale image display device, characterized in that the original image data is stored by means of a grayscale conversion display output of a compressed image and means of reproducing the original image data. 5. A pseudo grayscale image display device, characterized in that the data capturing means of claim 3 and the subsequent means are implemented by a hard copy printer. 6. The pseudo grayscale image display device according to claim 1, wherein the gradation is controlled by changing the size of the k × k sub-matrix.