JPH0254676A - Picture processing method - Google Patents

Abstract

PURPOSE:To avoid unevenness of an output picture by correcting an uneven gain of an input CCD line sensor and a density unevenness of an output ink jet head in a way of weight coefficient of the error spread method. CONSTITUTION:With the length of an input CCD sensor to be 210mm with a characteristic of 16 picture elements per mm, then 3380 CCD sensors are arranged in a line. It is difficult to arrange the entire characteristics and there is dispersion in each input characteristic. similarly, 128 nozzles per one line are arranged to an ink jet head, in order to arrange the density characteristic, a characteristic is provided to input coefficient registers and output coefficient registers. In the case of binarization, the input coefficient registers give a coefficient represented by an input counter to a weight circuit 18 and the output coefficient registers give a coefficient represented by an output counter to the weight circuit 18. The uneven density is corrected by multiplying the input coefficient and the output coefficient with a conventional weight coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image processing method in an image forming apparatus such as a digital reprinter and a digital copying machine that handle images as digital signals.

[Prior art] Generally, images are sampled using a CCD sensor, etc.
Image processing devices that output digitized data using inkjet printers and the like will become increasingly popular in the future.

In these devices, for example, an A3 size CCD line sensor is used as an input sensor, and an inkjet head in which nozzles are arranged in a line is used as an output element.

[Problems to be Solved by the Invention] However, in the conventional example described above, the gain characteristics of the A3-width CCD line sensor are uneven, and the inkjet head on the output side also has uneven density in the line direction, resulting in uneven shading in the output image. ′ unevenness occurred, significantly deteriorating the image quality.

[Means for Solving the Problems] According to the present invention, in the error diffusion method of binarization processing, gain unevenness of the CCD line sensor is added to a circuit that stores binarized information of surrounding pixels and multiplies it by a diffusion coefficient. The input characteristic register stores the characteristics of as coefficients, and the pixel being binarized is C
A CCD counter that indicates where on the CD line sensor corresponds, an output characteristic register that stores density unevenness characteristics of the output head as a coefficient, and a counter that indicates where on the inkjet head the pixel being binarized corresponds. By setting , and multiplying the diffusion coefficient by the input characteristic coefficient and the output characteristic coefficient, it is possible to reduce the unevenness of the output image.

[Example] FIG. 1 is a block diagram of the method according to the present invention. In FIG. 1, 16 is an output counter that indicates where in the line head the pixel being binarized is located, 17 is a head characteristic register that provides a coefficient based on the characteristics of the line head, and 18 is a weighting that applies a diffusion coefficient. circuit; 19 is an error buffer for storing errors after binarization; 20 is an arithmetic unit;
21 is a binarization circuit that compares data with a threshold value, 22 is an output buffer, 23 is a COD input characteristic register that gives the gain characteristics of the CCD sensor, and 24 is a CC
This is an input counter that indicates where on the D line sensor.

An example of weighting coefficients is shown in FIG.

If the input CCD sensor has 16 pixels per 1 mm and is 210 mm long, 3360 CCD sensors are lined up in one direction, and it is difficult to make this characteristic completely flat. For example, as shown in Figure 3 (a).
The input characteristics are uneven. Similarly, on the output side, each inkjet head has, for example, 128 nozzles lined up, and an example of the density characteristics is shown in FIG. 4(a). On the other hand, the characteristics shown in FIG. 3(b) are given to the input coefficient register, and the characteristics shown in FIG. 4(b) are given to the output coefficient register.

2(a) When converting, the input coefficient register passes the coefficient indicated by the input counter and the output coefficient register passes the coefficient indicated by the output counter to the weighting circuit, and conventional weighting is performed by multiplying the coefficient by the input coefficient and output coefficient. The density unevenness is corrected.

[Other Embodiments] The present invention can be applied to any device in which human output elements are arranged in a line, regardless of the direction in which they are arranged.

[Effects of the Invention] As described above, by correcting the gain unevenness of the input CCD line sensor and the density unevenness of the output inkjet head in the form of weighting coefficients of the error diffusion method, it is possible to eliminate unevenness in the output image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, Figure 2 is an example of the weighting coefficient. Figure 3 is an example diagram of input characteristic coefficients, FIG. 4 is an example diagram of the output characteristic coefficients.

Claims (1)

[Claims] Image data is input using CCD sensors arranged in a line,
In an image processing method that binarizes the image data and outputs it to an inkjet printer having nozzles arranged in a line, an input characteristic register that stores characteristics of gain unevenness of the CCD line sensor, and a pixel during the binarization process are provided. is CC
A CCD counter that indicates where on the D-line sensor it is located, an output characteristic register that stores the characteristics of density unevenness of the inkjet head, and an output characteristic register that stores the density unevenness characteristics of the inkjet head, and a nozzle number of the inkjet head that the pixel being binarized corresponds to. An image processing method that has a counter for counting and improves the uneven characteristics of input/output elements arranged in a line by correcting the weighting coefficients of the error diffusion method.