JPH031867B2 - - Google Patents

Description

[Detailed description of the invention]

This invention is intended to remove jitter inserted when extracting a transmitted original image for a facsimile machine having a recording device that scans transmitted pixels in the main scanning direction and the sub-scanning direction and has a resolution that is an even number multiple of the resolution of the transmitted pixels. The present invention relates to a jitter processing method. Conventional facsimile machines have a high frequency of jitter due to the instability of the reading system when reading originals. Interpolation methods and smoothing methods are considered to focus on a certain pixel and modify the image based on image information around that pixel. FIG. 1 is a diagram when the interpolation method is applied to a 45° diagonal line. In this FIG. 1, 1 is an added pixel. Figure 2 is a diagram when the smoothing method is applied to a 45° diagonal line. In FIG. 2, 1 is an added pixel and 2 is a deleted pixel. Next, the operation will be explained. FIG. 3 shows a case where the interpolation method is applied to jitter in the sub-scanning direction, and FIG. 4 shows a case where the smoothing method is applied. In Fig. 3, 1 indicates a unit pixel added by the interpolation method, in Fig. 4, 1 indicates a unit pixel added by the smoothing method, and 2 indicates a unit pixel deleted by the smoothing method. . The interpolation method increases smoothness for protrusions, but increases the area of jitter, and for depressions,
It has the effect of filling it up. In the smoothing method, addition or deletion of unit pixels is determined depending on the jitter direction. As described above, conventional interpolation methods and smoothing processing have the disadvantage that, depending on the direction of protrusions or depressions corresponding to one large pixel on a straight line, jitter is emphasized instead of increasing smoothness. This invention was made to eliminate the drawbacks of the conventional ones as described above, and focuses on a protrusion or depression corresponding to one large pixel on a straight line, and for the protrusion, a unit pixel not touching the straight line is The aim is to reduce jitter while preserving image information by deleting unit pixels that touch a straight line for depressions, and adding unit pixels that touch straight lines for depressions. There is. An embodiment of the present invention will be described below with reference to the drawings. Figure 5 shows a matrix of unit pixels obtained by dividing the large image pixel X into two in the main scanning direction and the sub-scanning direction.

It is arranged in [Formula]. Figure 6 shows the range of large pixels that serve as reference large pixels to be referred to when deciding whether to record a unit pixel. Take an area for three large pixels. Each large pixel A~
N and X are image information that takes a logic "0" or "1"; when the logic is "0", it is not recorded and represents "white";
When the logic is "1", it is recorded and represents "black". A standard pattern corresponding to the reference large pixel is shown in FIG.
Jitter on a straight line in the main scanning direction is detected using the standard pattern, and the jitter on the straight line in the main scanning direction is detected.
Jitter can be reduced by deleting or adding processing unit pixels in the figure. Deletion or addition of unit pixels as described above can be determined based on the following simple logical formula. The symbols in the formula correspond to those in FIGS. 5 and 6. X ₁₁ ,X ₁₂ =X.(A・B・C・D・E・G・H・
J・K・L・M・N)+X・A・B・C・D・
E・G・H・J・K・L・M・N…(1) X ₂₁ , X ₂₂ = (J・K・L・M・N・G・H・
A・B・C・D・E)+X・J・K・L・M・
N・G・H・A・B・C・D・E…(2) Actually, the logical formulas (1) and (2) are converted into a circuit, and the image information of the large pixel corresponding to Fig. 6 is expressed as above. Logical formulas (1), (2)
It is possible to control the recording of the unit pixels by substituting them into the terms of the unit pixels X ₁₁ , X ₁₂ , X ₂₁ , and X ₂₂ to obtain the logical values of the unit pixels. FIG. 9 is a block diagram of an embodiment of the present invention. The image information is sequentially loaded line by line into the line memory 3, and based on the image information for 5 large pixels in the main scanning direction in the line memory 3 for 3 lines, the following logical formulas (1) and (2) are calculated. A logic circuit 4 having a logical configuration determines _the logical values of unit pixels X ₁₁ , X ₁₂ , _{X 21} , and _{X 22 ,} and unit pixels X ₁₁ ,
are stored in the line memory 5 as new lines including the respective lines. X ₁₁ obtained in this way,
Two lines 5 including X ₁₂ and X ₂₁ and X ₂₂ are recorded by a recording device 6 having twice the resolution of the transmitted image. Next, the operation will be explained. 10 is a diagram in which an embodiment of the present invention is applied to a single jitter in the sub-scanning direction. In the figure, 1 is an added unit pixel,
(2) is the deleted unit pixel. For one-off jitters, it is possible to reduce the jitters while preserving image information. FIG. 11 is a diagram in which an embodiment of the present invention is applied to continuous jitter in the sub-scanning direction. Continuous jitter is corrected so that the boundary line between "black" and "white" becomes flat at a position where the average displacement of the unevenness is taken. Although the processing results for single jitters and continuous jitters are different, the intention of the present invention is to detect jitters of only one large pixel on a straight line, and if it is a protrusion, delete the unit pixel that is not in contact with the straight line, and if it is a concavity, it is detected. For example, by deleting unit pixels that are not in contact with a straight line, and adding unit pixels that are in contact with a straight line in the case of a depression, jitter can be reduced while preserving image information. Next, a case where jitter processing is performed and a case where jitter processing is not performed will be described using FIG. 12. In FIG. 12, A1 and B1 are the patterns of the received image, and A2 and B2 are the patterns after being compared with the standard pattern, respectively. As shown in A1, for example, in the case of a reception pattern including a rectangular corner, no jitter processing is performed as shown in A2, and as a result, the original image can be saved without deterioration. On the other hand, when one jitter occurs on the above-mentioned straight line, that is, in the case shown in B1, the jitter processing is effectively performed as shown in B2, and the jitter is reduced. As described above, since the jitter processing method according to the present invention judges jitter using a 5×3 large pixel area as a reference area, it is possible to perform jitter processing with high precision without unnecessarily deteriorating the received image. Is possible. In other words, for example, when comparing patterns of 3×3 large pixels centered on the target large pixel, the above-mentioned A1 and B1 cannot be distinguished, but according to the jitter processing method according to the present invention, the 12th As shown in the figure, only jitter can be determined and effectively reduced. That is, by referring to an area of 5 large pixels in the main scanning direction and 3 large pixels in the sub-scanning direction, jitter occurring in a straight line in the main scanning direction can be determined and reduced. The recording method to which the present invention is applicable can be applied to any of electrostatic recording, thermal recording, inkjet, electrophotography, dot printer, discharge destruction recording, etc., and the shape of the printed dots can also be square, rectangular, rectangular, etc. It is not limited to a specific shape such as a circle or an oval. Also, the relationship between large pixels and unit pixels is 4 lines/mm versus 8
Lines/mm, 5 lines/mm versus 10 lines/mm, 6 lines/mm versus 12 lines/
mm, 8 lines/mm vs. 16 lines/mm, 12 lines/mm vs. 24 lines/mm, the ratio of resolution between large pixels and unit pixels is 1:2.
It is applicable as long as there is a relationship between As described above, according to the present invention, the image quality of the resulting recording can be improved without increasing the transmission time. Therefore, it can be widely applied to systems where the reading system is unstable during reading, such as facsimile machines.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram when the interpolation method is applied to a 45° diagonal line, Figure 2 is an explanatory diagram when the smoothing method is applied to a 45° diagonal line, and Figure 3 is an illustration in the sub-scanning direction. Fig. 4 is an explanatory diagram when the interpolation method is applied to jitter in the sub-scanning direction, Fig. 5 is an explanatory diagram when the smoothing method is applied to jitter in the sub-scanning direction, and Fig. 5 is a large pixel which is the basis of this invention. A diagram showing the arrangement of unit pixels in
FIG. 6 is a diagram showing a large pixel to be processed according to an embodiment of the present invention and an arrangement of 14 reference large pixels surrounding it, and FIG. 7 is a diagram showing a standard pattern used in an embodiment of the present invention. Figures 8 and 9 are diagrams showing unit pixels processed in accordance with standard patterns.
The figure is a block diagram of an embodiment of the present invention, FIG. 10 is an explanatory diagram of a case where a single jitter is processed using an embodiment of the present invention, and FIG. 11 is a block diagram of a continuous jitter. Explanatory diagram when processing, 1st
FIG. 2 is an explanatory diagram showing cases in which jitter processing is performed and cases in which it is not performed. In the figure, 1 is an added unit pixel, 2 is a deleted unit pixel, 3 is a line memory, and 6 is a recording section.

Claims (1)

[Claims] 1 On the transmitting side, pixels extracted from a portion of the original image to be transmitted consisting of one scanning unit in the main scanning direction and one scanning unit in the sub-scanning direction are transmitted to the receiving side, and the receiving side converts the received pixels into large pixels. Then, this large pixel is divided into two in the main scanning direction and the sub-scanning direction as a unit pixel, and 5 large pixels in the main scanning direction and 3 large pixels in the sub-scanning direction are referred to with the target large pixel as the center. area, and when the pattern of received pixels in this reference area corresponds to a standard pattern having a predetermined protrusion, a part of the unit pixel within the target large pixel is deleted, and a part of the unit pixel in the target large pixel is deleted, and if the pattern of received pixels in this reference area corresponds to a standard pattern having a predetermined protrusion, a part of the unit pixel within the target large pixel is A jitter processing method characterized by adding a part of a target large pixel size unit pixel when corresponding to a standard pattern, and recording this with a recording device having an even number times the resolution of that on the transmitting side.