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Browse Prior Art Database

Method of Correcting Grey Value Variations

IP.com Disclosure Number: IPCOM000101132D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Maier, U: AUTHOR [+3]

Abstract

In erosion printers, printer and print medium variations lead to non- linear grey value variations during digital image processing. Such variations from the desired values may be corrected by the method described below.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Method of Correcting Grey Value Variations

       In erosion printers, printer and print medium variations
lead to non- linear grey value variations during digital image
processing.  Such variations from the desired values may be corrected
by the method described below.

      Fifteen grey wedges, for example, are printed without the user
interfering.  Before a wedge is printed, the relevant firing time is
fed to the hardware via a register. The wedge is printed, and the
firing time is increased before printing is repeated.  After a wedge
has been printed 15 times at different firing times, a predetermined
time is set by microcode.  This time, corresponding to the expected
value at the operating point (linearity of grey values), may then be
used in the printer.  The optimum firing time for a printer is
determined by the user either visually or by measurement as a
function of the grey wedge for which linearity of the printed grey
values exists.  A value for the relevant firing time is printed
preceding the respective grey wedge and may be read by the user.
This value is a measure of the optimum firing time.