JPS58200660A - Conversion system of picture element density - Google Patents

Abstract

PURPOSE:To prevent the generation of void and defacement by means of a simplified circuit, by deciding the value of a picture element having the picture element density of 1/2 corresponding to adjacent there picture elements according to a specific logical expression when converting the picture density of a picture signal train to 1/2. CONSTITUTION:Inverted picture signals are inputted to an input terminal 1. Three picture elements adjacent to the picture signal train are set as A, B and C, and a picture element having a half picture element density corresponding to A and B of the three picture elements is set as D. The inputted picture signal is delayed by D type FFs 2, 3 and 4 by one clock each, outputs of A', B and C' are obtained at terminals 7, 8 and 9. Therefore, an output D' expressed by an expression 1 is obtained at the output of a NAND gate 5 and at the output of an AND gate 6 where A' and the output of the gate 5. As a result, since B can be saved whenever an black isolated point comes to the B by setting D to black when A is black, or even when A is white, by setting D to black if B is black and C is white, picture element density conversion is performed with lesser void and defacement.

Description

[Detailed Description of the Invention] The present invention is a high-precision facsimile/millimeter transmitter, etc.
Dono) From a binary image signal with a resolution of 7 mm, the pixel density is 1
The present invention relates to a pixel density conversion method for converting the pixel density to 1/2, which is used when obtaining an image signal of 8 dots/rrIm.

Conventional methods to reduce the pixel density in the main scanning direction to 1/2 include a thinning method that uses every other pixel, and if one of the two pixels corresponding to one pixel after conversion is black, it is considered black. Black OR methods have been considered. [7] However, when using the thinning method, if a black isolated point appears in a pixel that was not referenced, it may become blank, or the picture may be blurred with black 011f, etc. There were some drawbacks that I couldn't take advantage of.

In order to eliminate such drawbacks, the present invention provides a simple pixel density conversion method that does not cause problems even when a black isolated point appears in a pixel that has not been referenced, and does not cause image collapse. This will be explained in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram of a pixel density conversion method according to the present invention.

(1) is a human image signal sequence, and adjacent 3
Let the pixels be ABC.

Let (If) be an output image signal sequence with a pixel density of ]/2,
Let D be one pixel corresponding to the ll111 element AB.

This h71 is a method in which the pixel value is usually determined by the pixel operator, but when a black isolated point occurs where A and C are white and B is black, D is set to black. , the logical formula is expressed as D=Au(nnC), where the black pixel is Il+''.

If you use this method, the black OR method will fail (])
(2) The white pixel between pixels can be displayed as shown in Dl, and even in (5), which would be missed by the thinning method, it can be displayed as a black pixel as shown in B5.

In the figure, (It) is the output image signal sequence by the black OR method, (P
/) is an output image signal sequence obtained by the thinning method, and is used to clarify the difference from the output image signal sequence (11) according to the present invention.

FIG. 2 is a circuit configuration diagram of an embodiment for realizing the method of the present invention, where ] is an input terminal, 2, 3, and 4 are D-type flip-flops, 5 is a NAND gate, and 6 is an AND gate.
The gates ; 7, 8 and 9 are the output side terminals of the D type flip-flops 2, 3 and 4.
C is output to the A1 terminal 8 and the B1 terminal 9, 10 is an output terminal, and 11 is a clock input terminal.

An inverted signal 1 is inputted to the input terminal 1, and outputs λ, B, and i are obtained by delaying each clock by one clock using (2) type flip-flops 2, 3, and 4.

Therefore, (Br+c) is obtained from the NAND gate 5, and An(BnC), that is, AU(HnC) is obtained as the output of the AND gate 6, which is output to the output terminal 10.

Therefore, as explained in Figure 1, if A is black, then D is black; even if A is white, B is black and C is white, then D is black;
It can be rescued if a black isolated point appears.

Figure 3 shows an image read at a main scanning resolution of 16 dots/mm by the method of the present invention and converted to 8 dots/mm, and an image obtained by the black OR method and thinning method.
It shows the results of a comparison using the il ranking method, where the vertical axis shows the average score when 1st place is given 4 points, 2nd place is 3 points, 3rd place is 2 points, and 4th place is 1 point, and the horizontal axis is the number of points for letters. 31 is by the method of the present invention, 32 is by the black OR method, 33
The following shows the evaluation results using the thinning method, which were conducted for 10.5 point, 8 point, and 6 point font sizes, respectively, and the best evaluation results were for 8 point and 6 point fonts. Obtained.

As described above, the present invention can relieve the case where a black isolated point occurs in pixel B among the adjacent pixels A, B, and C used for processing as a human image signal sequence using a simple circuit.
This method has the advantage of being able to provide a pixel density conversion method that is less prone to whiteout and collapse, and can be put to practical use with extremely high effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the pixel density conversion results according to the present invention, and FIG.
The figure is a circuit configuration diagram of an embodiment for realizing the method of the present invention, and FIG. 3 is a diagram showing evaluation of pixel density conversion results by the method of the present invention and another method. 1... input end), 2.3.4...
...D type Furi 7 Pflo knob, 5... Song NA
ND gate, 6...AND gate, lo, A, river, output terminal, 11...Clock input terminal. Figure 1 Figure 2 Figure 3 05P8P6P Arrow 4 point platform (

Claims (1)

[Claims] Let A, B, and C be three adjacent pixels of a binarized image signal string obtained by a Facun Milli transmitter, etc., and when converting the image density of the image signal string to 1/2, the A, B , C3
It is characterized in that the value of a pixel with a pixel density of 1/2 corresponding to the middle pixel and 8 pixels is determined as D2AU (BnC) with "ll" when the pixel is black. Pixel density conversion method 0