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Last modified: Tue Dec 20 11:48:25 2005.
NAME: ct_fiddle PURPOSE: To fiddle with the color table. The user can select which channels of the color table to manipulate. The user can change the gamma correction and the range of the color table indices. CALLING SEQUENCE: CT_FIDDLE [, CHANNELS] [, LOW=value] [, HIGH=value] [, GAMMA=value] [, GRANGE=[min,max]] OPTIONAL INPUTS: CHANNELS: A string argument. CHANNELS sets which color channels ('R' for red, 'G' for green, 'B' for blue) will be manipulated in the color table. The user can manipulate one, two or all channels. To fiddle with the red and blue channels simultaneously, set channels equal to the string 'rb'. KEYWORD PARAMETERS: LOW = The lowest pixel value to use. If this parameter is omitted, 0 is assumed. Appropriate values range from 0 to the number of available colors-1. HIGH = The highest pixel value to use. If this parameter is omitted, the number of colors-1 is assumed. Appropriate values range from 0 to the number of available colors-1. GAMMA = Gamma correction factor. If this value is omitted, 1.0 is assumed. Gamma correction works by raising the color indices to the Gamma power, assuming they are scaled into the range 0 to 1. GRANGE = The desired range of the gamma axis, a 2-element vector. The first element is the axis minimum, and the second is the maximum. The default is [0.1,10.0]. OUTPUTS: None. COMMON BLOCKS: COLORS: The common block that contains R, G, and B color tables loaded by LOADCT, HSV, HLS and others. SIDE EFFECTS: Image display color tables are changed. RESTRICTIONS: If using TrueColor visual class, color decomposition must be switched off in order for this routine to work. EXAMPLE: Load the BLUE/GREEN/RED/YELLOW color table and fiddle with the red and blue channels: IDL> loadct, 4 % LOADCT: Loading table BLUE/GREEN/RED/YELLOW IDL> ct_fiddle, 'rb' MODIFICATION HISTORY: 08 May 2004 Written by Tim Robishaw, Berkeley Heavily modified version of Carl Heiles's DIDDLE.
(See /dzd2/heiles/idl/gen/colortest/ct_fiddle.pro)