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Storing and PROCESSING Digital IMAGE DATA for COLOR Screen Display and for PRODUCING COLOR SEPARATIONS for PRINTERS

IP.com Disclosure Number: IPCOM000039080D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Barthel, J: AUTHOR [+2]

Abstract

After analog image data y, q, i have been converted into digital image data Y, Q, I, the latter are compressed such that all luminance values Y are stored for adjacent pels, whereas shade value Q and saturation value I are stored only for every nth pel. Missing values may be obtained by reference to preceding values or by interpolation. Negative- to-positive analog values are digitized in an 8-bit byte such that they appear without signs, utilizing the 28 = 256 digital possibilities of representation within a byte. (Image Omitted) The image data for each pel are processed without time-consuming matrix calculations and multiplication, utilizing a table with only 2 parameters Q and I.

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Storing and PROCESSING Digital IMAGE DATA for COLOR Screen Display and for PRODUCING COLOR SEPARATIONS for PRINTERS

After analog image data y, q, i have been converted into digital image data Y, Q, I, the latter are compressed such that all luminance values Y are stored for adjacent pels, whereas shade value Q and saturation value I are stored only for every nth pel. Missing values may be obtained by reference to preceding values or by interpolation. Negative- to-positive analog values are digitized in an 8-bit byte such that they appear without signs, utilizing the 28 = 256 digital possibilities of representation within a byte.

(Image Omitted)

The image data for each pel are processed without time-consuming matrix calculations and multiplication, utilizing a table with only 2 parameters Q and I. IMAGE DATA PROCESSING FOR COLOR SCREENS From the known relation of analog values

(Image Omitted)

The time-consuming calculation according to (4) is eliminated by defining a table TABR (Q, I), TABG (Q, I), TABB (Q, I). For the parameters Q and I, this table contains associated values that have to be added to the value Y upon calculation of R, G, B. R TABR (Q, I) G = Y + TABG (Q, I)

(6)

B TABB (Q, I)

IMAGE DATA PROCESSING FOR PRODUCING COLOR

SEPARATIONS FOR PRINTERS Using the known principle of converting primary colors into secondary ones, the following values are obtained:

(Image Omitted)

B1 = black, C = cyan = complementary color to red, M = magenta = complementary colo...