The Scitex CT File Format

This document outlines as much of the Scitex CT (CH) file format as I have been able to reverse engineer. It works for all the files I have tried it on, but you probably have different files than I have.

The scitex ct file format is a common file format used in the prepress industry. Ct files will almost always will contain either a CMYK or a greyscale image.

Common extentions are .ch .ct and .sct

I think that ct stands for "continuous tone"

NOTE: All numbers are stored in the big endian byte order

Offset Length Description
0x0 0x50 Comment string padded with spaces
0x50 2 Text "CT"
0x400 1 Units (0=MM,1=INCH)
0x401 1 Number of Channels
0x402 2 Format (7=RGB, 8=GREYSCALE, 0xF=CMYK)
0x404 14 Height in Units stored as a Scitex FP
0x412 14 Width in Units stored as a Scitex FP
0x420 12 Height in pixels.
Stored as 12 digits of text including sign ("%+012d").
0x42C 12 Width in pixels.
Stored as 12 digits of text including sign ("%+012d").
0x800 W*H*C Image Pixels stored in row interleaved format.

The spaces from 0x52 to 0x399 and from 0x43A to 0x799 may safely be written out as zeroes

The Scitex Floating Point number format

The Scitex FP format is a textual representation of a floating point
number expressed in a very specific form of scientific notation.
This format is not necesarly the default formating of your *printf

+.<number (8 digits)>e<sign><exponent (2 digits)>
This works out to exactly 14 characters.

Good examples

Bad examples

Download an example ct file

If you have any information on the scitex lw (linework), nct (new ct), or nlw (new lw) file formats, please pass it along

If you have any questions or comments about this document email me at

Jay Cox
Last modified: Tue Jan 30 21:46:46 PST 2001