Browse Prior Art Database

Variable Intensity Filter Arrangement

IP.com Disclosure Number: IPCOM000074744D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 4 page(s) / 64K

Publishing Venue

IBM

Related People

Appel, A: AUTHOR

Abstract

This device relates to a novel filter arrangement for enabling the economical recording on film or photographically exposed paper, lines of variable intensity or color when the lines, as generated on a cathode-ray tube, cannot be varied in intensity or color.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 40% of the total text.

Page 1 of 4

Variable Intensity Filter Arrangement

This device relates to a novel filter arrangement for enabling the economical recording on film or photographically exposed paper, lines of variable intensity or color when the lines, as generated on a cathode-ray tube, cannot be varied in intensity or color.

It is known that the cost of generating shaded or colored pictures can be less than the cost of generating line drawings and, also, that the presentation of shaded or colored pictures is more attractive and realistic. The reason for such lower cost is the fact that the raster computer calculation is more efficiently organized for 2-dimensional or 3-dimensional complex artwork than for line drawings. In addition, techniques such as picture cropping, zooming, scaling, and the suppression of superfluous details are also more easily handled in raster displays.

However, cathode-ray tube devices for displaying shaded or colored pictures are expensive and either require complex digital-to-analog conversion circuitry or multiple processing of data for color. In addition, the cathode-ray tube devices do not lend themselves readily to high-speed photographic recording.

Prior to considering this device, there is first explained how a picture is generated for display on a cathode-ray tube screen. Normally, a computer program such as the well-known one termed LEGER is employed to calculate the intensity of points on the picture and a cathode-ray tube system with the capability of rendering variable intensity points is employed to expose photosensitive paper or film. In producing this recording, the calculation of the points may take about three seconds of which one second may be required to record the picture on magnetic tape. The reading of the tape and the exposing of the paper may require about 15 seconds. Also, about 500 feet of magnetic tape may be needed. It is to be realized that such picture, therefore, requires a recording time and a cost which is disproportionate to the calculation time and many cathode-ray tube devices do not have the capability of rendering variable intensity points. A picture such as that of a human head may require as many as 100,000 point description commands on magnetic tape. Considering this last figure, if lines of variable intensity could be recorded, then the amount of information written on the tape could be reduced to about 4,000 point description commands, thereby commensurately decreasing the picture processing time and the amount of magnetic tape consumed. In this connection, for complex pictures such as that of the human head, the degenerating of lines rather than points tend to speed up further the basic calculation of the picture.

In most interactive graphic systems, the cathode-ray tube can generate only lines of constant intensity or with overstriking lines having a limited tonal range. With these systems, a technique for recording variable intensity lines, even though constant intensity lines are drawn o...