Image processing apparatus and method for printing and plate making, and recording medium having image processing program recorded therein for printing and plate making

Abstract

A neighboring vector, which is a boundary portion between two overlapping objects, is extracted. To calculate luminance levels of the objects on both sides of the neighboring vector, a predetermined number of coordinate points (sample points) in the vicinity of the neighboring vector are extracted at least from the image side. A rendering process is performed on an area including all the extracted sample points to acquire color values at the sample points. The luminance level of the image is calculated based on the acquired color values, and the luminance levels of the objects on both sides of the neighboring vector are compared to each other to determine the position (direction) in which to generate a trap graphic.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to image processing apparatuses and methods for printing and plate making, and more specifically to technology for trapping between objects including image objects (data).[0003]2. Description of the Background Art[0004]In the field of printing and plate making, a personal computer or such like is used to first perform an edit process based on characters that are to be contained in a print and a plurality of types of other print elements, such as logos, patterns, and illustrations, and generate page data containing a print target written in a page-description language. Thereafter, a RIP process is performed on the page data to generate image data for use in production of a plate (a press plate) that is to be placed in a printing machine.[0005]Incidentally, in the case of multicolor printing, in order to prevent an underlying portion from being exposed at a boundary between colors due to misr...

AI Technical Summary

Benefits of technology

[0016]Therefore, an object of the present invention is to provide an image processing apparatus and an image processing method that are capable of automatically generating a trap graphic in a desirable direction between an image and a color object or between images, without requiring the user's manual operation.

[0024]According to this configuration, a rendering process is performed only on the smallest possible rectangular area including all the sample coordinate points to acquire the color values at the sample coordinate points. Thus, it is possible to prevent increase of processing time for a trapping process.

[0026]According to this configuration, a predetermined number of coordinate points on the neighboring vector are extracted for sample coordinate extraction. Accordingly, coordinate points to be referenced for sample coordinate extraction can be extracted based on the entire length of the neighboring vector and lengths of line segments constituting the neighboring vector. Thus, coordinate points used for obtaining average brightness of each object in the vicinity of the neighboring vector can be suitably and readily extracted.

[0028]According to this configuration, luminance levels of two objects are compared to each other to generate a trap graphic on an object with a lower luminance level. Thus, it is possible to generate a trap graphic on a darker one of two objects including an image without requiring the user's manual operation.

Problems solved by technology

However, when the trapping process is automatically carried out between images or between an image and a color object according to the above-described trap rules, a trap graphic might be generated in an undesirable direction.

Specifically, a trap graphic is generated in an undesirable direction, so that the trap graphic is significantly noticeable.

Specifically, a trap graphic is generated in an undesirable direction, so that the halftone tint and the characters are unclear.

In addition, when the data as shown in FIG. 18A and the data as shown in FIG. 19A coexist within a single page, the conventional trap rules do not “allow a trap graphic to be generated in a desirable direction for all objects”.

As described above, when the trapping process is automatically carried out between objects including an image, a trap graphic might not be generated in a desirable direction, leading to a reduction in image quality.

In addition, the user is required to manually correct any portion in which the trap graphic is generated in an undesirable direction, leading to a reduction in working efficiency.