NAME

SYNOPSIS

DESCRIPTION

The following terms are used in the description of the program and its options:

input map:

A color map already in the input RLE file.

applied map:

The color map specified by the arguments to rleldmap. This map will be applied to or will replace the input map to produce the output map.

output map:

Unless -a or -b is specified, this is equal to the applied map. Otherwise it will be the composition of the input and applied maps.

map composition:

If the applied map is composed after the input map, then the output map will be applied map[input map]. Composing the applied map before the input map produces an output map equal to input map[applied map]. The maps being composed must either have the same number of channels, or one of them must have only one channel. If an entry in the map being used as a subscript is larger than the length of the map being subscripted, the output value is equal to the subscript value. The output map will be the same length as the subscript map and will have the number of channels that is the larger of the two. If the input map is used as a subscript, it will be downshifted the correct number of bits to serve as a subscript for the applied map (since the color map in an RLE(5) file is always stored left justified in 16 bit words). This also applies to the applied map if it is taken from an RLE(5) file (-r option below). Note that if there is no input map, that the result of composition will be exactly the applied map.

nchan:

The number of separate lookup tables (channels) making up the color map. This defaults to 3.

length:

The number of entries in each channel of the color map. The default is 256.

bits:

The size of each color map entry in bits. The default value is the log base 2 of the length.

range:

The maximum value of a color map entry, equal to 2**bits - 1.

OPTIONS

-a

Compose the applied map after the input map.

-b

Compose the applied map before the input map. Only one of -a or -b may be specified.

-n nchan length

Specify the size of the applied map if it is not 3x256. The length should be a power of two, and will be rounded up if necessary. If applying the map nchan must be either 1 or equal to the number of channels in the input map. It may have any value if the input map has one channel or is not present.

-s bits

Specify the size in bits of the color map entries. I.e., only the top bits bits of each color map entry will be set.

Exactly one of the options -l, -g, -t, -f, -m, or -r, must be specified.

-l factor

Generate a linear applied map with the nth entry equal to
range * min(1.0, factor*(n/(length-1))).
Factor defaults to 1.0 if not specified. Negative values of factor will generate a map with values equal to
range * max(0.0, 1.0 - factor*(n/(length-1))).

-g gamma

Generate an applied map to compensate for a display with the given gamma. The nth entry is equal to
range * (n/(length-1))**(1/gamma).

-t file

Read color map entries from a table in a text file. The values for each channel of a particular entry follow each other in the file. Thus, for an RGB color map, the file would look like:
red0 green0 blue0
red1 green1 blue1
... ... ...
Line breaks in the input file are irrelevant.

-f file

Reads the applied map from a text file, with all the entries for each channel following each other. Thus, the input file above would appear as
red0 red1 red2 ... (length values)
green0 green1 green2 ... (length values)
blue0 blue1 blue2 ... (length values)
As above, line breaks are irrelevant.

-m files ...

Read the color map for each channel from a separate file. The number of files specified must equal the number of channels in the applied map. (Note: the list of files must be followed by another flag argument or by the null flag -- to separate it from the infile specification.

-o outfile

The output will be written to the file outfile if this option is specified. Otherwise the output will go to stdout.

infile

The input will be taken from this file if specified. Otherwise, the input will be read from stdin.

SEE ALSO

AUTHOR