[cairo] RFC the idea of n-plane color support

[Bill Spitzak]

On Saturday 30 October 2004 07:15 am, Ross McFarland wrote:

> the most common case with Postscript (which is almost always bound for a
> printer) is CMYK which accounts for the majority of driver generated
> jobs. text is the biggest reason for that, you have to use pure black
> for black text or otherwise the slightest mis-alignment between color
> planes will make the text blurry and hard to read due to color shifts
> and such.

Just to note that the "blackest" black is done by printing all 4 colors, and 
this is certainly wanted for a 0,0,0 in a color image, but that is not 
necessarily what is wanted for 0,0,0 in text. So his point is that the useful 
volume of colors for the printer has 4 dimensions and thus no mapping from 
sRGB will get all the desired output.

However it may be better to have the printer analize the image. For instance 
black surrounded by white would only print the black ink. Obviously this 
would solve the black-text problem for many more programs, such as ones 
unaware of the CMYK interface. It seems to me that to do this the backend 
would have to store rgb so the analysis can be done last. This may mean that 
the backend must support both formats, or that the CMYK interface is a bad 
idea.