Interpretation of raster data

Michael Sweet mike at easysw.com
Sun Mar 27 05:42:02 PST 2005


Christian Walther wrote:
> I'm writing a raster printer driver (filter) that receives
> 8-bit-per-pixel CUPS_CSPACE_W grayscale raster data, halftones it to
> black-and-white, and outputs it in a format suitable for sending to
> the printer.
> 
> What I'm not sure about, and have found nowhere in the documentation,
> is how to interpret the 8-bit pixel values I get. How do they map to
> linear intensity? Linearly, e.g. 128 means middle gray, where half of
> the paper area has to be covered with black? Or encoded through a
> power function, e.g. 174 means middle gray for an exponent of 1.8? Or
> anything else?

Normally, the _W and _RGB colorspaces are sRGB-based, however that
varies depending on the platform and configuration.

You can set the color profile to use on MacOS X with the
cupsICCProfile attribute - look on the Apple developer site for
the technote.

-- 
______________________________________________________________________
Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Publishing Software        http://www.easysw.com




More information about the cups-devel mailing list