JPH0398383A - Contour emphasis circuit - Google Patents

Abstract

PURPOSE:To obtain an output subjected to accurate contour emphasis without being affected of a stored heat by differentiating the coefficient for contour emphasis from the direction of detecting a picture data. CONSTITUTION:The rate of emphasis to an input data is differentiated before and after two contour lines by differentiating the coefficient for contour emphasis of each picture data. Thus, when the circuit is integrated in a video image printer or the like, the coefficient is selected in such a way that the heat dissipation of thermal heads before and after one contour line is increased and the heat dissipation of thermal heads before and after the other contour line is eliminated to eliminate the effect of heat stored in the thermal heads thereby obtaining an accurate output of contour emphasis.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a video printer device, etc.
The present invention relates to an outline emphasizing circuit used for emphasizing the outline of an image in a printer device that prints a multivalued image using a thermal head.

[Prior Art] FIG. 3 is a block diagram showing an example of the configuration of a conventional contour enhancement circuit. (18b). (1
The image signal input from 8c) is held for calculation.

(lo) is an arithmetic circuit, and the above latches (11) to (l5)
Performs calculations to emphasize the outline according to the output from the .

Figure 4 is a model of the conventional example of the arithmetic circuit (10), and in Figure (A), (4) is an example of quantized image data, and bico represents each image data. , its distribution is in the range 1≦i≦m, 1≦j≦n,
The greater the value corresponding to the image before quantization, the greater the color density.

FIG. 4(B) shows an example of the range of use of each image data used in calculations to detect and emphasize the outline of an image, and the coefficients applied thereto. In this example, the coefficients applied to the image data bij are 2, image data bi-1,j.
bill, j. The coefficients applied to bi, j-1, and bi, j+1 are each set to -1/4.

Next, the operation of the above structure will be explained.

Figure 5 is an example of image data with a contour, b1''=O
(1≦i<k.k+2<i≦m, 1≦
j≦m), bij =8 (k≦i≦k+2, l≦
j≦n), and the data value limit is -32≦blj≦32
It is said that Note that (3a) and (3b) in the figure indicate contour lines.

FIG. 6 shows a data waveform of a conventional example of edge enhancement, and (7) in the figure is the waveform of image data input to the arithmetic circuit (10), and among the image data in FIG. The data when j=M is converted into a waveform in the contour detection direction, (8) is the waveform obtained by calculating the data shown in (7) above in the arithmetic circuit (10), and (9) is the result of the calculation. The result (8) is a waveform of the density value printed by a thermal head (not shown) of a video printer device.

In the contour emphasizing circuit configured as described above, the contours are detected and emphasized by paying attention to each image data and performing the calculation shown in (2) in the following equation in the arithmetic circuit (lO). In addition, the image data bi
” shall be emphasized as Bij as a result of the calculation.

Bij = 2bij − 1/4 {(bi−1,
j }+(bi,j-1)+(bi,j+1)
+(bi+1,j)}...■Here, the calculation result (8) will be explained.

Regarding the contour line (3a), the data value changes from small to large in the contour detection direction, and the data value before the contour line (3a) is smaller than the input value, and the data value after the contour line (3a) is smaller than the input value. The outline is emphasized by emphasizing the image so that it also becomes larger. Similarly, regarding the contour line (3b),
This is a contour line where the data value decreases, and contour enhancement is performed by emphasizing the previous data value so that it is larger than the input value, and the later data value so that it becomes smaller than the input value.

The contour enhancement circuit that performs the contour enhancement operation described above is
When used in a video printer device equipped with a thermal head, the amount of heat generated by the thermal head can be controlled according to the magnitude of the data value by inputting the data shown in (8) in Figure 6 to the thermal head. (9) in Figure 6
), the output has different color densities and enhanced contours.

[Problems to be Solved by the Invention] Since the conventional contour enhancement circuit is structured as described above, when used in a video printer device equipped with a thermal head, for example, the density of the printed color is determined by the thermal Since it is controlled according to the amount of heat generated by the head, the amount of heat generated increases when printing a high-density area, and heat accumulates in the thermal head.

For this reason, the contour line with greater density (
In 3a), the outline can be emphasized as specified, but in the outline (3b) where the density is smaller, the 6th
As shown in (8) in the figure, there is a problem in that the high-density portion is stretched in the contour detection direction, making it impossible to obtain a print with accurate contour emphasis.

This invention was made to solve the above-mentioned problems, and is not affected by the accumulated heat.
It is an object of the present invention to provide an edge enhancement circuit capable of obtaining an output with accurate edge enhancement.

[Means for Solving the Problems] The edge enhancement circuit according to the present invention is characterized in that coefficients for edge enhancement are made different depending on the detection direction of quantized image data.

[Operation] According to the present invention, by using different coefficients for contour enhancement of each image data, it is possible to make a difference in the ratio of emphasis to input data before and after two contour lines.

Therefore, when used in a video printer or the like, the coefficient is set to increase the amount of heat generated by the thermal head before and after one contour line, and to eliminate the amount of heat generated by the thermal head before and after the other contour line. By doing so, it is possible to eliminate the influence of heat accumulated in the thermal head and obtain accurate contour enhancement output.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an example of coefficients applied to each image data used in calculations for detecting and emphasizing the outline of an image in an outline emphasizing circuit according to an embodiment of the present invention. The coefficient applied to image data b i-1,j is -3/8, the coefficient applied to image data bi+1,j is -1/8, the coefficient applied to image data bi
, j-1 and bi, j+1, respectively -
174.

Figure 2 shows data waveforms when contours are emphasized using the coefficients described above. In the figure, (7) is the input image data waveformed in the contour detection direction, and (2) is the waveform of the input image data. (3) is a waveform of the calculation result, and (3) is a waveform of the density value printed by the thermal head of the video printer, and (3a) and (3b) in the figure are contour lines. Note that the overall configuration of the contour enhancement circuit is the same as the conventional example shown in FIG. 3, and the configuration of the arithmetic circuit (IO) is also the same as the conventional example shown in FIG. 4(A). The drawings and descriptions thereof will be omitted.

Next, the operation of the above-mentioned Kaikai will be explained.

In the contour emphasizing circuit configured as described above, image data is calculated according to the following equation (2), as in the conventional example.

Bij = 2bij − 1/4((bi,j−1
) + (bi, j+1)+ (bi-1, j)
+ 1/2 (bi-1, j) + (bi+1, j)
}・・・・・・■ Here, when comparing the result (2) obtained by calculating the input image data (7) according to the above formula ■ with the result (8) calculated according to the conventional formula ■, it is found that the conventional example Now the outline (3a)
The ratio of emphasis before and after contour line (3b) was the same as ±2 relative to the input value, whereas the ratio of emphasis according to this example was relative to the input value before and after contour line (3a). Te-
There is a difference in the emphasis ratio of +1, +3, and +1, -3 with respect to the input value before and after the contour line (3b).

Therefore, when such an edge enhancement circuit is incorporated into a video printer device equipped with a thermal head, the amount of heat generated by the thermal head before and after the contour line (3a) is increased compared to the conventional one, and at the same time, the amount of heat generated by the thermal head before and after the contour line (3b) is increased. The amount of heat generated by the thermal head can be reduced compared to the conventional one. This results in
By eliminating the influence of the heat accumulated in the thermal head on the printing, it is possible to obtain an output with accurately enhanced contours, as shown in (3) of FIG.

In addition, although the above embodiment shows an edge enhancement circuit configured using an arithmetic circuit, a C
Even if an arithmetic unit such as a PU is used, the same effects as in the above embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, by varying the coefficients of the calculation formula for each image data for contour enhancement, it is possible to differentiate the emphasis ratio before and after two contour lines. can be attached. Therefore, when applied to a video printer, it is possible to obtain an output with accurately emphasized outlines without being affected by the heat accumulated in the thermal head.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of setting coefficients applied to image data in an edge enhancement circuit according to an embodiment of the present invention, and FIG.
The figure is a waveform diagram of each data to explain the operation. Figure 3 is an explanatory diagram showing an example of the configuration of a conventional contour enhancement circuit and an example of setting coefficients applied to the data. Figure 5 is an example of image data with a contour. FIG. 6 is a data waveform diagram illustrating the conventional operation. (8)...Image data, (10)...Arithmetic circuit, (
1l) to (15)...Latch. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) Detection of the image data in an edge enhancement circuit equipped with a latch that holds each quantized image data and a calculation means that detects the edge of the image and performs an enhancement calculation for each image data. A contour enhancement circuit characterized in that coefficients for contour enhancement are varied depending on the direction.