gammaramp Subroutine

GL3.2 for AIX: Graphics Library (GL) Technical Reference

gammaramp Subroutine

Purpose

Defines a color map ramp for gamma correction.

Libraries

Graphics Library

C (libgl.a)

FORTRAN (libfgl.a)

C Syntax

void gammaramp
(Int16 red[256], Int16 green[256], Int16 blue[256])

FORTRAN Syntax

SUBROUTINE GAMMAR(red, green, blue)
INTEGER*2 red(256), green(256), blue(256)

Description

The gammaramp subroutine supplies a level of indirection for all color map and RGB values. It can provide gamma correction, equalize monitors with different color characteristics, or modify the color warmth of the monitor. The default setting has red[i]=green[i]=blue[i]=i.

When the system draws an object in RGB mode, it writes the actual red, green, and blue values to the bitplanes. However, the values displayed on the screen are the indirect values: red, green, blue (where red, green, blue are the arrays last specified by the gammaramp subroutine).

In color map mode, objects written in color i are displayed as red, green, blue.

Notes:
The operation of this subroutine for the Supergraphics Processor Subsystem is modified. (See "Hardware Considerations".)

This subroutine cannot be used to add to a display list.

Parameters

red	Specifies an array of 256 elements, each containing a setting for the red electron gun.
green	Specifies an array of 256 elements, each containing a setting for the green electron gun.
blue	Specifies an array of 256 elements, each containing a setting for the blue electron gun.

Implementation Specifics

This subroutine is part of GL in the AIXwindows Environment/6000 Version 1, Release 2 with AIXwindows/3D Feature.

The POWERgraphics GXT1000 supports entire-screen gammaramps. Setting the gammaramp on the GXT1000 will affect all windows on the screen, including X11 windows.

Files

/usr/include/gl/gl.h	Contains C language constant and variable type definitions for GL.
/usr/include/gl/fgl.h	Contains FORTRAN constant and variable type definitions for GL.

Related Information

Setting color map mode as the current mode with the cmode subroutine.

Setting the current color in color map mode with the color subroutine.

Changing a color map entry to an RGB value with the mapcolor subroutine.

Setting the current color in RGB mode with the RGBcolor subroutine.

Working in Color Map and RGB Modes.