JPS6133299B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to preprocess sampled image information in a two-dimensional binary image signal such as a facsimile signal to increase the effect of data compression processing performed later. do.

Conventionally, band compression technology such as facsimile uses an image sensor to sample the original image to be transmitted at a predetermined resolution, as shown in Figure 1, and redundancy is applied to the extent that the sampled original image signal can be faithfully reproduced on the receiving side. Attention has been focused on eliminating signals that result in . However, in reality, there are flaws in the original painting,
Due to the effects of stains, variations in sensor sensitivity, and when the sensor input is close to the black and white judgment threshold,
The sampling signal already contains noise components. For example, when an original image as shown in FIG. 2a is sampled, an uneven signal as shown in FIG. 2b is output. This situation frequently occurs with documents such as paperbacks, graphs, or typefaces that contain many linear components. Further, the sharp black signal as shown in FIG. 2c is considered to be noise due to some cause. If we try to compress such original image information as it is, even though it does not essentially contain large information as shown in Figure 2 b and c, the presence of such information will significantly reduce the compression efficiency. Cause. For example, even in the case of run-length encoding, if patterns such as those shown in FIG. 2b and c exist, the run lengths will be cut off and the compression effect will be limited.

The present invention is intended to eliminate the above-mentioned drawbacks, and as shown in Figure 3, the sampling noise contained in the original image signal is removed before data compression processing is performed, thereby greatly improving the effect of subsequent data compression processing. can do.

Hereinafter, details before the present invention will be explained according to the drawings. In FIG. 4, the center pixel a ₁₁ of the 3×3 sample original image signal a is surrounded by the surrounding pixels a ₀₀ ,
If the pattern of a ₀₁ , a ₀₂ , a ₁₀ , a ₁₂ , a ₂₀ , a ₂₁ , a ₂₂ can be replaced with white or black, then Fig. 4b
Replace it with a ₁₁ ′ as in Specific examples of replaceable patterns are shown in FIG. 5 a, c, and e, and changed patterns are shown in b, d, and f, respectively. However, a, b,
The same applies to the rotating bodies of c and d.

Next, a specific circuit configuration of the processing method is shown in FIG. The original image signal S ₁ outputted together with the clock signal S ₂ is sequentially stored in shift registers (SR) 10, 13, 16 each having a capacity for one line, and at the same time is stored in flip-flops 11, 12, 1.
It is also shifted to 4, 15, 17, and 18. At the start of one page transmission, all shift registers and flip-flops 10 to 18 are reset by the PRST signal, and at the start of one line, all flip-flops 11, 12, 14, 15, 17, and 18 are reset.
By resetting the shift register and flip-flops 10 to 18, the fourth
Sample values corresponding to a ₀₀ to a ₂₂ in the figure are output. This situation is shown in FIGS. 7 and 8. That is, assuming that each pixel in each line is given a symbol as shown in FIG. 7, the i-1st row, the i-th row, the
The state in which the rows are stored in the shift registers 10, 13, and 16 is shown in FIG. 8a. At this time, the start signal LRST of the next line causes the flip-flop (F/
F) 11, 12, 14, 15, 17, and 18 have been reset. Next, the state at the time when the first pixel of the i+2th row is input is shown in FIG. 8b. In order i
When the contents of the +2nd line are input and the j-th pixel is input, the timing is as shown in FIG. 8c, and when the (j+1)th pixel is input, the timing is as shown in FIG. Therefore, eight pixel patterns of sample values _a00 to _a22 , excluding _a11 , output from each shift register and flip-flops 10 to 18 are input to a read-only memory (RM) 19 having a capacity of 256 x 2 bits. as output
a Get the replaceability signal (EN) of ₁₁ and the value (DATA) if it is replaceable. The contents of RM19 are shown in FIG. Set EN = 1 only when a ₁₁ can be replaced from the pattern of a _{00 , a 01} , a 02 , a ₁₀ , a ₁₂ , a ₂₀ , a 21 , a ₂₂ , and set white to the signal for a ₁₁ ' (DATA). 0 and 1 are stored depending on whether it is black or not. Therefore, by opening the gate of the AND circuit 21 when EN=0 and closing the gate of the AND circuit 22 at the same time, S ₁ '=a ₁₁ , and when EN=1, the AND circuits 21 and 22 open and close conversely, so S ₁ ′=a ₁₁ ′. 24 to 26 are the bit synchronization clock _S2 for the original image signal _S1 , the page synchronization signal _S3 , and the image signal modified from the line synchronization signal.
This is a 2 _- line + 1-bit delay circuit (DELAY) for generating the respective synchronizing signals S ₂ ′, S ₃ ′, and S ₄ ′ for S 1 ′.

As described above, in the present invention, when an original image is scanned to obtain a binary signal, the black and white signal may be reversed due to noise, etc., or dust or other foreign matter may be attached to an area that should be white or black. death,
This is to prevent the binary signal string from having unevenness where it should originally be flat, and from losing its effect when the binary signal string is later compressed by converting it into a run-length code or the like. In other words, according to the present invention, noise caused by dust and scratches is removed, but the white signal surrounded by the black signal of a complex kanji character such as "column" is not replaced, and the image is compressed while remaining clear. can. In addition, the present invention improves compression processing efficiency by removing burrs on the edges of characters, etc. in the original image itself and reproducing an image that is different from the original image but approximate. It is something that makes you

[Brief explanation of the drawing]

Fig. 1 is a system diagram explaining the conventional facsimile signal band compression transmission technology, Fig. 2 a to c are explanatory diagrams of the original image signal, and Fig. 3 is band compression transmission using the concept of preprocessing of the present invention. A system diagram explaining the technology; FIGS. 4a and 4b are diagrams explaining the principle of a signal processing method according to an embodiment of the present invention; FIGS. 5a to 5f are diagrams showing a specific example of pixel conversion; FIG. is a diagram showing an embodiment embodying the signal processing method of the present invention, FIGS. 7 and 8 a to 8 d are explanatory diagrams of the operation of FIG. 6, and FIG. 9 is an explanation of the operation of one component of FIG. 6. It is a diagram. 10, 13, 16...shift register, 11,
12, 14, 15, 17, 18...flip-flop, 19...read-only memory, 20...inhibition gate, 21, 22...and gate, 23,
27... OR gate, 28, 29... Noah gate, 24, 25, 26... delay circuit.

Claims (1)

[Claims] 1. 2 of {(2n+1) ² -1} pixel patterns (n=1, 2, 3, ...) around a pixel with binary information obtained from the image of the original to be read By comparing the value information with the binary information of predetermined {(2n+1) ² -1} pixel patterns, it is determined whether the binary information of the certain pixel can be replaced, and if the replacement is possible, An image signal processing method, characterized in that the binary information of the certain pixel is replaced with binary information unique to the surrounding pixel pattern. 2. Three shift registers connected in series for recording scanning signals for three lines of an image, two flip-flops each connected in series on the output side of the shift registers, and a connection between the output of each shift register and the flip-flop. By inputting eight binary signals excluding the output corresponding to a certain pixel among the outputs of and comparing them with binary information of a predetermined pixel pattern, a signal indicating whether or not the binary signal of the pixel can be replaced is determined. and converts the binary signal of the certain pixel into a binary signal unique to the eight binary signal patterns when the replacement possibility signal generating means issues a replacement command signal. An image signal processing device characterized by replacing. 3. Claim 2, characterized in that the replaceability signal generating means is constituted by a read-only memory that receives the eight binary signals as address inputs.
The image signal processing device described in .