Browse Prior Art Database

Overpaint Function for Color Printer

IP.com Disclosure Number: IPCOM000038598D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Leontiades, KL: AUTHOR [+2]

Abstract

In graphic presentations it is not uncommon for two objects of different colors to overlap, that is, to occupy the same area. For example, it may be desired to show a green box in the background, partially hidden behind a red circle. In a color printer the print head makes a separate pass for each ribbon color, and normally considers only the print tasks of that color in building the dot image for that pass. Therefore, in the above example, if the green box is printed first, on the subsequent red pass the printer overstrikes the area where the green box and the red circle overlap. Since the inks are not opaque, the overlap area is seen as a mixture of the two colors and the desired effect is not achieved. The present implementation permits "overpainting" without mixing colors.

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Overpaint Function for Color Printer

In graphic presentations it is not uncommon for two objects of different colors to overlap, that is, to occupy the same area. For example, it may be desired to show a green box in the background, partially hidden behind a red circle. In a color printer the print head makes a separate pass for each ribbon color, and normally considers only the print tasks of that color in building the dot image for that pass. Therefore, in the above example, if the green box is printed first, on the subsequent red pass the printer overstrikes the area where the green box and the red circle overlap. Since the inks are not opaque, the overlap area is seen as a mixture of the two colors and the desired effect is not achieved. The present implementation permits "overpainting" without mixing colors. Each print head pass covers a band or swath across the page. The present printer control programming technique requires that all print tasks, in all colors, intersecting that swath, must be included in creating the dot image for the current pass. If a given task is to be printed in the current ribbon color, that part of the task in the current swath is written into the dot image by setting the required bit positions to 1; otherwise, those positions are "erased" by setting them to 0. The printer places dots only in those locations corresponding to the bit positions set to 1. Therefore, it is seen, in the example above, that this procedure deletes that par...