JPS60137171A - Facsimile equipment with picture element density converting mechanism - Google Patents

Abstract

PURPOSE:To reduce deterioration in picture quality by laying emphasis on correlations among original image signals at four points which surround a converted picture element in a main scanning, a subscanning, and a diagonal direction. CONSTITUTION:Logical values of two binary signals in the main scanning direction as to four original picture elements surrounding the converted picture element, logical values of two binary signals in the subscanning direction, and logical values of two binary signals in the diagonal directions are processed and then ORed. Then it is decided whether the image signal of the converted picture element is at a black or white level according to the OR result is ''0'' or ''1''. Therefore, white is reduced, and an increase in the number of black isolated points is suppressed and the reggedness of a segment due to jitters is reduced.

Description

TECHNICAL FIELD The present invention relates to a facsimile device having a pixel density conversion mechanism.

(Prior Art) Conventionally, when communicating between facsimile apparatuses having different pixel densities, if the pixel density cannot be matched to the other apparatus, the recorded image will be reduced or enlarged. There are several ways to solve this problem.

The other method is to insert it. Although this method has a simple algorithm and hardware configuration, white spots and blurring are noticeable and the image quality is greatly degraded.

To reduce the deterioration of image quality, there are the OR method, majority voting method, OPC method, SPC method, etc., which determine the pixel signal level of the converted pixel by considering the information of the previous line or the next line of the original pixel. However, in general, the algorithm becomes complicated and the hardware configuration becomes large.Furthermore, methods have been proposed to simplify the algorithm using this method, but when the conversion rate becomes large, the deterioration of image quality becomes noticeable. As a result, we adopted a method that takes into account 1) degrees of image data for two lines, the previous line and the next line of the original pixel, for the converted pixel, applied a simple algorithm, and reduced the hardware scale. In order to reduce white spots, isolated black points, and jitter, which are causes of image quality deterioration,
The object of the present invention is to provide a facsimile apparatus having a pixel density conversion mechanism that reduces the above-mentioned drawbacks and reduces image quality deterioration by placing emphasis on blindness in the scanning direction and diagonal direction.

(Structure of the Invention) According to the present invention, there is a memory circuit capable of storing three lines of binary image signals, and two pixels in the main scanning direction of four original pixels surrounding a converted pixel of the binary image signal stored in the memory circuit. a circuit for calculating the logical product of binary image signals, the logical product of two binary image signals in the sub-scanning direction, and the logical product of two binary image signals in the diagonal direction; and a logic of the results obtained by the arithmetic circuit. 411
The present invention provides a facsimile apparatus having a pixel density conversion mechanism that includes an arithmetic circuit for calculating , and determines whether the pixel signal of the converted pixel is at a black level or a white level depending on whether the result is 0 or 1.

(Example) Next, an example of the present invention will be described with reference to the drawings. 3. Figure 1 explains the algorithm of the present invention, and the pixel density was changed from 10 pet/fIm to 3 pel/
This is a case of converting to mm. The formula for determining the image signal level of a converted pixel when converting an original pixel to a converted pixel ' is shown below. ■ is the image signal (Δ) of each converted pixel,
When ■ is the image signal (0) of the original pixel, ■ on each coordinate is Vi, j −v+, j ” vj, j Vj + ], j ”” Vi+1.j ” vLl−
2, jVi, j+i -vi, j+t @ vj, jl
Vl+1. j+x −vLlx, j+x6vi+z, j
+t +vi+x, j+t1vi+l, j+2 +vi
+x, j+1avi+z, j+2 +v i-+-z
, j+x°vi+1. j+2+vi+2. j+] 0v
i+2.2+z+v1+1. j+2"v1+2.ノ+2...Equation (1) Here, 6." is a logical product operator, and ``'+'' is a logical sum operator.The image signal has a black level of 0, a white level of 1, and If the value of ■ in equation (1) is O, the image signal at that point is black, and if it is 1, it is white.

The algorithm shown in 2 (1) is based on two or more black image signals in the main scanning direction, sub-scanning direction, and diagonal direction of the original pixel when the conversion rate from 12 pe 1/+m to 8 pel/xi is relatively large. Since the painting No. 1g of the Red Conversion Art Garden where there are consecutive − numbers is Black No. 1, 1,
White spots are reduced. Clause/This: When the original pixel is one black point, the image signal of the nearest converted pixel becomes a white point, so this method has the effect of suppressing the increase in black isolated points and the effect of reducing jaggedness of line segments due to jitter, etc. be. Apply this calculation sequentially) - VFh
FIG. 2 shows an embodiment of the present invention. Picture d No. 1
The signals are synchronized line by line using the image signal clock 2 and the synchronization signal 3, and then led line by line to the line memory circuit 5 via the selenium recirculating circuit 4, where three lines are stored. At this time, writing to the memory 5 is controlled by the write address counter circuit 13, the write one and both circuits 11, and the selector circuits 10 and 15.

After 3 lines have been stored, the image signal 6 read out from the line memory 5 by the read address counter circuit 4 and the read 1 block 1 circuit 12 VC is shifted by 1 bit shift circuit 7 for each line, and then subjected to calculation. In circuit 8, the formula (1
) is performed and the converted image 9 is obtained.

In addition, Figure 3 shows the pixel density from q8pel/ram to 12pe.
This is to explain the algorithm for conversion to lfia, and the formula for determining the pixel level of the converted pixel when converting from the original pixel to the converted pixel is shown below. P is both signals of the converted pixel, p is the original t (1 pixel No. 15 and 1,
Pilj "" pil
j ・I)i, jPi+1. j-pl, j ”pi+1
．． j+pi+1. j' I)i+1. j+1P l+
2+ip i+t + j rii+2+j +l)i+
1. j oPi+t, j−nPi, j+x −Pilj
-pi,j+1. +pi, j+isui publication, 'Published Pi+1
,3+t-pi,j0-pi+1. j + pi, j
#pi,j+i +1)i,j ” pi+x,j+
i “pi+x,j” p1+1. j+t ten pi
+l,j ” pi,j+1 +pi+1.j+1'
pi, j+1Pi+z, j+1- Pi+1. j a
pi+2. j + pi + 1. j-pi+1. j+
1 +1)i+1. j ” I)i+2.j+1 +P
i+2. j ” pi+z, j+t ten pi+2.j
” I) i+1.j+1 + pi+1.j+1 @P
I+2. j+IPi, j+2-1)i, j+x°pi,
For j+z+pi, j+t°p, Published by Pi+11j+2-
pI, j+t' pi-H, j+x +pi, j+
t ′ I)i, j+z tenpi, j+x a I)i
+x,j+z +pi+x,j+t a I)i+l,
j+z +Pi+t, j+t # pi, j+2 +p
i, j+26 pi+x, j+2Pi+2. J+2-
pi+t, j+t @ pi+2. j tent tenpi+
1. j+x l1r) i+x, j-+2+Pi+1. j
+1 ” Pi+2.j+2 +pi+2.j-H”
pi+2. j+g tenri i+2. j7 l pi+1.
j ten z ten pi+z, j+z ten pj+z, j+z...
- Equation (2) At this time, if the value of P obtained from Equation (2) is 0, the image signal at that point is black, and if it is 1, it is white. This algorithm can be implemented by simply modifying the circuit shown in FIG. 2 to correspond to the calculation method (2) of the calculation circuit 8.

(Effects of the Invention) As explained above, the present invention converts a converted pixel into a black signal when there are two or more black signals in the main scanning direction, sub-scanning direction, and diagonal direction of each original image signal, and blacks out isolated points. Since the signal is a white signal, there are no white spots, and it is effective in reducing image quality deterioration by suppressing black isolated points (6) and increase in jitter.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the conversion algorithm from pixel density 12 pe i to 8 pel/y*, and Figure 2 is a diagram explaining the conversion algorithm from pixel density 12 pe to 8 pel/y*.
・・・Binary image signal (original image signal), 2...
・Picture signal clock, 3...Picture signal synchronization signal, 4
...Selector circuit, 5 ... Line 2
In-memory circuit・6°゛・・・Memory readout image signal,
7...1-bit shift register circuit, 8...
... Arithmetic circuit, 9... Converted image signal, 1o...
...Selector circuit, 11...4f included system-
Circuit, 12...Reading system 7By+circuit, 13
...Write address counter circuit, 14...
...Read address counter circuit, 15...
・Selector circuit. +7+lj'+17. '+7. i+11jiflJQ111fig J9anna I, lsu6'21j啼2 Fig.3

Claims (1)

[Claims] A memory circuit capable of storing 3 lines of binary image signals, and 4 pixels surrounding conversion pixels of the binary image signals stored in the memory circuit.
A circuit that calculates the logical product of two binary image signals in the main scanning direction, the logical product of two binary image signals in the sub-scanning direction, and the logical product of two binary image signals in the diagonal direction of the original pixel of a point. and an arithmetic circuit that calculates the logical sum of the results obtained by the arithmetic circuit, and determines whether the pixel signal of the converted pixel is a black level or a white level depending on whether the result is 0 or 1. A facsimile machine with a pixel density conversion mechanism.