JPH04196972A - Contour printing method for two-dimensional image - Google Patents

Abstract

PURPOSE:To print and output only the contours of two-dimensional images by detecting the edges of the images in a perpendicular direction in picture element unit while referencing the picture elements of the line before a noticed line and the next line and printing and outputting only the picture elements satisfying the OR of these detected picture elements. CONSTITUTION:The edges in a horizontal direction are detected 2 by determining the beginning end and terminal end of the continuous black picture elements among the picture elements for one line while the two-dimensional images stated on a document are horizontally scanned 1 at every noticed line. The edges in the perpendicular direction are detected 3 by finding the black picture elements on the corresponding noticed line where the picture elements of the previous line or the next line are white picture elements by referencing the picture elements of the line before the noticed line and the next line while the images are horizontally scanned by every noticed line. The OR 4 of these detected picture elements is determined and the picture elements satisfying the same are printed and outputted 5. The contours of the two-dimensional images are printed and outputted in this way.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for printing outlines of two-dimensional images, and more specifically, to copying machines, printers, etc. that perform electronic printing using toner. , which is characterized by printing only the outline of the original image to reduce toner consumption.

[Prior Art] Recently, copy machines and printers using electronic printing methods have been developed and used. Printing is performed by depositing toner on a rotating drum and pressing this drum against the recording paper. Compared to dot or thermal transfer printing methods, the operating time of the mechanical parts is reduced and high-speed printing is possible. .

By the way, in this electronic printing method that prints black as image information, toner is used as ink, so
For example, if a document contains a large figure filled in black, toner consumption will increase, but in general, printing only the outline of such a figure is often sufficient as image information. , improvement was desired.

[ff that the invention tries to solve! ] The present invention, proposed in view of the above circumstances, aims to provide a method for printing the outline of a two-dimensional image that reduces toner consumption by printing only the outline of the image filled in black. .

[Means for Solving the Problems] The present invention proposed to achieve the above object detects edges of the image in the horizontal direction pixel by pixel while horizontally scanning a two-dimensional image for each line of interest. The edges of the image in the vertical direction are detected pixel by pixel, taking into account the pixels in the line before and next to the line of interest, and only the pixels that satisfy the logical sum of these detected pixels are printed out. .

[Operations] In the present invention, edge detection processing for pixels in the horizontal direction is performed while horizontally scanning a two-dimensional image written on a document for each line of interest. At the same time, edge detection processing for pixels in the vertical direction is performed while examining pixels in the line before and next to the line of interest. Then, pixels that satisfy the logical sum of these detected pixels are printed out, thereby printing out only the outline of the two-dimensional image.

[Example] The present invention will be described in detail below with reference to the drawings.

Figure 1 shows the procedure of the method of the present invention, in which a two-dimensional image written on a manuscript is horizontally scanned (1) for each line of interest, and the starting point of a continuous black pixel among the pixels of one line is scanned horizontally (1). Edge detection in the horizontal direction (2) is performed by finding the end and the end. At the same time, while horizontally scanning each line of interest, pixels on the line before and next to the line of interest are explained, and the black pixel on the corresponding line of interest where the pixel on the previous line or the next line becomes a white pixel is determined. Vertical edge detection (3) is performed by this. Then, the logical sum (4) of these detected pixels is calculated, and the pixels that satisfy this are printed out (5), thereby printing out the outline of the two-dimensional image.

FIGS. 2(a) to 2(d) show the method of the present invention in more detail using a convex image as an example. As shown in FIG. 2(a), for example, the line of interest L1 is When horizontally scanning, as shown in Fig. 2(b), the starting edge S and ending edge E of consecutive black pixels are determined from among the pixel signals of one line.
This allows the horizontal edges of the image to be detected. That is, by detecting edges in the horizontal direction, the vertical contour of the image is determined.

Further, as shown in FIGS. 2(a) and (c), with reference to the previous line LO and the next line I72 of the line of interest L1, the line of interest Ll where the pixels of the previous line LO or the next line L2 are white pixels. The upper black pixel group B is determined, and the vertical edge of the image is detected using this. By this vertical edge detection, the horizontal contour of the image is determined.

Then, the line L1 of interest is
By sequentially moving down, the outline of the two-dimensional image is obtained (see FIG. 2(d)).

Figures 3(a) and 3(d) show examples of edge detection in the horizontal and vertical directions of a diagonally tilted image, and the edge detection process is the same as in Figure 2. Since there is, I will omit the explanation. In this example, the logical sum of the pixel whose edge was detected in the vertical direction and the pixel obtained by the edge detection in the horizontal and vertical directions are the same.

As described above, according to the present invention, since only the outline of the black image on the document is detected and printed, the amount of toner used can be significantly reduced, and the loss of image information can be minimized. I can do it.

In the above explanation, edge detection in the horizontal and vertical directions is described as being determined by a change in image color, but for example, as shown in FIGS. 4(a) to (C), When a pixel rLJ level and black pixel are made to correspond to a voltage signal of "HJl/Hel", edge detection processing in the horizontal direction is performed by differentiating the pixel signal of the line of interest using a differentiating circuit (not shown). is possible.

[Effects of the Invention] As can be understood from the above explanation, according to the present invention, even if there is a large image filled in black on a document, only the outline of the image is printed out, thereby reducing toner consumption. It becomes possible to significantly reduce the amount.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the procedure of the method of the present invention, and Figures 2 (a) to (
d) is an explanatory diagram when the method of the present invention is applied to a convex image;
Figures 3 (a) to (d) are explanatory diagrams when the method of the present invention is applied to a diagonal line image, and Figures 4 (a) to (C) are explanatory diagrams when edges in the horizontal direction are detected by differential processing. It is. [Explanation of symbols] LO・◆・Previous line Ll... Line of interest L 2nd・nth line

Claims (1)

[Claims] (1) While scanning the two-dimensional image horizontally for each line of interest,
In addition to detecting pixels that are edges in the horizontal direction of the image, pixels that are edges in the vertical direction of the image are detected by referring to the presence or absence of pixels in the line before and next to the line of interest. A two-dimensional image outline printing method that prints out only pixels that satisfy the logical sum of pixels.