ZLS colour tables

The ZLS System used text file based colour tables. The colour tables are written in unecrypted text format in .ctab files. The complete set of tables including this file are available as a single download (ZIP, 106kB). This also includes code for reading colour table files and writing 8 bit TIFFs.

Each file has a simple header indicating the exact variation of the format, and the number of colours in the table, followed by the colour indices and RGB values (or index + single grayscale values for simple gray tables).

There are three basic formats, indicated by the first line of the ctab file:

  • 0: Decimal values used, i.e. 0-255, or 0-65535
  • 1: Hexadecimal values used: ie 00 - FF or 0000 - FFFF
  • 2: Floating point values: 0.0 - 1.0

The next line indicates the number of bits per value. It an be 8 or 16 for decimal and hexadecimal formats, and 16 for floating point format.

The next line indicates the number of colour components, 1 (grayscale) or 3 (RGB), then the number of colours follows, and is usually 256.

Finally the indices and values follow, 1 entry per line. For grayscale there are two columns, index then value, and for RGB there are 4 columns, index and red, green, blue values.

Format Examples:

13.ps.ctab: 0.1.rss.ctab:0 31.123.ctab: 0.2.gray.ctab:
1 8 3 256 0 00 00 7f 1 00 00 83 2 00 00 87 3 00 00 8b … 1 16 3 256 0 ffff ffff ffff 1 fefe fefe f7bd 2 fdfd fdfd ef7b 3 fcfc fcfc e739 … 0 8 3 256 0 0 0 0 1 0 0 0 2 95 0 114 3 98 0 112 … 1 8 1 256 0 ff 1 fe 2 fd 3 fc …
Hex 8 bit values, RGB Hex 16 bit values, RGB Decimal 8 bit values, RGB Hex 8 bit values, Grayscale

Download code for reading colour table files and writing 8 bit TIFFs (ZIP, 106kB)

 

Colour Tables Preview

01.rss ctabs/01.rss04.grey_mod ctabs/04.grey_mod10.red ctabs/10.red13.ps ctabs/13.ps16.ag2 ctabs/16.ag219.goldblue ctabs/19.goldblue22.r3 ctabs/22.r325.p2 ctabs/25.p228.air ctabs/28.air31.123 ctabs/31.12334.blob1 ctabs/34.blob137.contour ctabs/37.contour  
02.gray ctabs/02.gray08.blue ctabs/08.blue11.blackbody ctabs/11.blackbody14.stern2 ctabs/14.stern217.ag3 ctabs/17.ag320.r1 ctabs/20.r123.r4 ctabs/23.r426.p3 ctabs/26.p329.water ctabs/29.water32.barb ctabs/32.barb35.blob2 ctabs/35.blob238.lograinbow ctabs/38.lograinbow40.bbyw ctabs/40.bbwy
03.gray_inverse ctabs/03.gray_inverse09.green ctabs/09.green12.idlstd ctabs/12.idlstd15.ag1 ctabs/15.ag118.bluegold ctabs/18.bluegold21.r2 ctabs/21.r224.p1 ctabs/24.p127.tim ctabs/27.tim30.earth ctabs/30.earth33.barb2 ctabs/33.barb236.carl ctabs/36.carl39.subdued ctabs/39.subdued