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I realize IRAS-C supports images with a .CRL extension. Could you tell me what a CRL file is? What does CRL stand for? Is it a ZIImaging proprietary format?

by ddoud on ‎03-23-2016 12:48 PM - edited on ‎09-21-2017 06:44 AM by Technical Evangelist (481 Views)

Question

I realize IRAS-C supports images with a .CRL extension. Could you tell me what a CRL file is? What does CRL stand for? Is it a ZIImaging proprietary format?

Answer

CRL == Color Run Length.

Typically, run length encoded (RLE) data is binary, or single bit pixels. The COLOR run length format is for 8 or 16 bit pixels, possibly in combination with a color table -- but it uses run length compression. This is an Intergraph format, type 10 file. The format has been published, but there is little support outside of INGR/ZI software.

This type of compression is typically not very effective with photography or satellite imagery (because there are very few "runs" of identical pixels) . However, it is effective for computer generated imagery, or imagery that has been zoomed up in preparation for printing/plotting. The map setter software that INGR sells (sold ?) used this format extensively for color separates and plot files.

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