PDL::Transform::Color now has support for pseudocolor mapping, and a basic suite of named color tables. They are accessible via the “t_pc” (“pseudocolor”) and “t_pcp” (pseudocolor, perceptual) transforms.
The difference between t_pc and t_pcp is how luminance is treated. t_pc is for handling of photometric or pseudo-photometric data (e.g. brightness values from a scientific digital camera, gamma=1). t_pcp is for handling of perceptual data (typically encoded with gamma=2.2). Both transforms use the same color tables — the tables that use primarily non-luminance qualities (saturation or hue) act exactly the same for either transform. I’ve also modified PDL::Graphics::Gnuplot to support using the PDL::Transform::Color pseudocolors. This is implemented using the plot options “pseudocolor” (or its abbrev “pc”) and “perceptual” (or its abbrev “pcp”). This should prevent having to square-root scale photometric data before plotting it — a solution that is lame at best since sRGB encoding is more complicated than that, but also practically universal at present. The new builds are available for testing at https://www.github.com/drzowie/pdl-graphics-gnuplot https://www.github.com/drzowie/pdl-transform-color You can, for example, compare the output from: $w=gpwin(wxt,size=>[12,4],{j=>1}); $w->multiplot(layout=>[3,1]); $w->image(rvals(50,50),{clut=>’sepia’}); # built-in $w->image(rvals(50,50),{pcp=>’sepia’}); # perceptual $w->image(rvals(50,50),{pc=>’sepia’}); # photometric You can get a list of available PDL::Transform::Color palettes by feeding the empty string into the ‘pc’ or ‘pcp’ plot options in PDL::Graphics::Gnuplot::plot(), or by calling t_pc or t_pcp with no options in PDL::Transform::Color. I’m open to suggestions for favorite color tables people would like to see added. Cheers, Craig ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ pdl-devel mailing list pdl-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/pdl-devel
