Epson GT-30000 - Manual (Page 13)

Scanner Settings
9
scanned image for a given level of gray in the original image. When used with color scanning, gamma
correction is used to change not only the brightness level of individual colors, but also the mixture of red,
green, and blue in each color, and therefore the color balance of the image.
The EPSON GT-30000 scanner has five built-in gamma correction tables and one downloadable (user-
defined) gamma correction table:
Gamma Correction Name Purpose
CRT A Optimized for scanning pages to be displayed in black-and-
white on a computer monitor.
CRT B Default setting. Optimized for scanning pages to be displayed
in multiple shades of gray or color on a computer monitor
User defined Selects the downloaded gamma table(s) provided by the user.
Note: This setting overrides the Brightness setting. If no
gamma table has been downloaded, the scanner uses the
default gamma setting (CRT A).
Printer A/High density printing Optimized for scanning pages that were printed on a 24-pin
dot-matrix printer in “Near Letter Quality” (NLQ) mode.
Printer B/Low density printing Optimized for scanning pages that were printed on an 8-pin
dot matrix printer.
Printer C/High contrast printing Optimized for scanning pages with mixed images and
characters that have high contrast, such as those printed on a
laser printer.
Creating a Gamma File
To create a gamma table file for the EPSON GT-30000 scanner, use a text editor or word processor capable
of saving plain text (ASCII) files. Follow these steps:
1. On the very first line of the file, type a description of the file.
2. On the second line of the file, type the number of gamma file entries. The maximum size of a gamma
table is 256 entries.
3. On each of the remaining lines (line 3 through a maximum line 258), type values for gamma value 0
through gamma value 255, respectively.
Line Data
1 Description
2 Number of values
3 gamma value 0
4 gamma value 1
5 gamma value 2
.
.
.
258 gamma value 255