Scanning recording type printing method and apparatus for increasing image quality by controlling tone dot locations within image pixels

Abstract

A scanning recording type printing method, in which sampled image of tone data is printed by controlling the scanning length and position of a dot which may include a plurality of different colors in the interior of a pixel such that the dots in two adjacent pixels are paired such that no interruptions exist between the dots.

Description

BACKGROUND OF THE INVENTIONThis invention relates to a monochrome or color printing method and an apparatus for realizing the same and in particular to a scanning recording type printing method and an apparatus for improving the image quality in a high precision fine image recording apparatus.As a method for varying the recording area of each pixel in order to express light and shade of the image in a scanning recording type printing apparatus, there is known a method, by which image recording pulse signals are modulated in pulse width by means of data representing the tone. Apparatuses described in Japanese Patent Application un-examined publications (Kokais) Nos. 82-57679 and 82-99866 are examples of this type of system.In such a printing recording apparatus it is necessary to reduce each cell in size and increase the pixel density in order to be able to record an image with high precision and high fineness. The scanning direction and the size of each pixel in the scanning recordi...

AI Technical Summary

Benefits of technology

The object of this invention is to provide a scanning recording type printing method and an apparatus for increasing the image quality in a high precision fine image recording by controlling the location of dots of at least one color printed within a pixel.

According to this invention, in a scanning recording type print recording apparatus, in which tone data of each of the pixels in the image signal are transformed into an image recording pulse signal having a time width proportional to the tone for each of the pixels and production of recording energy is controlled so as to be interrupted by this image recording pulse signal, decreases in the image quality are reduced by reducing the proportion of the area of unstable regions. That is, this invention is characterized in that, by producing the rear end of the recording pulse signal of the preceding recording side pixel in a pair of pixels adjacent to an arbitrarily selected pixel in the recording scanning direction in accordance with the rear end of the relevant pixel and the front end of the recording pulse signal of the succeeding recording side pixel in accordance with the front end of the relevant pixel, so that the production of the recording energy between this pair of pixels is continuous and by making the region where the recording tone is unstable, smaller, decreases in the image quality are reduced.

The "pixel" is the smallest unit of spatial resolving power, when an original analogue image is quantized (digitalized) and in general it is defined so as to be sufficiently small. In a digital printer, however, many dots are formed in this pixel and wherever the dots are written in this pixel the differences therebetween cannot be recognized by the human eye. In other words, within a pixel, wherever the dots are moved, the movement itself doesn't lower the resolving power. For example, in the case where a pixel is large, the Bayer method is adopted, by which one pixel is represented by many small dots, or a dot is formed at a position deviated from the center of the pixel in order to have a screen angle. Also according to this invention attention is paid to this point and in full color printing by multi-color printing, the dots of each of the colors formed within one pixel are not concentrated to one point, which is the center of the pixel, in contrast to those in the concentric solution model, but are instead suitably arranged within the pixel for every color. In this way superposition of the dots of different colors can be controlled and as a result a high quality full color printing can be effected.

Problems solved by technology

In a digital printer, however, many dots are formed in this pixel and wherever the dots are written in this pixel the differences therebetween cannot be recognized by the human eye.

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