Dear all,
I know there have been some interest about the so-called PseudoGrey technique for color to B&W conversion. I've just done some 'research' (very basic indeed), and have found a nice extension of the original pseudogray technique, allowing even more colors than 1786 (more than 6000 in fact !) in the resulting image.
I've called this technique 'Extended PseudoGray', or XPseudoGray

I've described all I've done in the Flickr Gimp user forum, so maybe you could be interested in it :

http://www.flickr.com/groups/gimpusers/ ... 0325496356

Of course, this is already implemented in the G'MIC Black & White conversion filter, just refresh your filter, and you should be ready to use it :



Any comments is appreciated

Bonjour,

I find that the rendering of this option is actually very interesting. The first tests on images with people (with the maximum of color) are really beautiful

As i wrote on the same topic i found the pseudogray ,and even more this new variant much closer to the results of good analogical print (as from good old darkroom ) because also that process was creating subtle shades of colors so close to gray that were not usually seen as colored, but on the contrary as a reach B&W

Now will be long explain why in detail...to summarize the color of the support , of the paper was never a perfect white, the type, the age and even the temperature and the degree of oxidation of the chemical used to develop and fix introduce also some more or less subtle color shade...so the "white" was the paper color never perfectly white, the black the less influenced by color shift when was supposed to be 100% black in the darkest spot(the darkest black created darkening a yellowish color is identical to the darkest created darkening a bluish color )... and more influenced in the middle tones even if the hue shift were always so subtle to not be felt as Colors

So this fake BW looks to me much closer to the good old B&W print from Darkroom then the proper B&W,

I've even extended it with a new algorithm so that new intermediate colors can be rendered.
Check this out !

Very cool stuff David. The biggest advantage that the extended encoding will give you is poster reduction. My favorite test is the to create a black to white gradient in GIMP and then count how many colors you get. That will shut up the non-believers. lol

Look forward to trying your updates soon.