Hello, please, ¿does anyone know any program that can reduce the number of colors in an image to 4 colors?.

No phosothop.

I want to reduce to 4 colors of this picture.

Given that your image is indexed already, you could use GrafX2's palette editor to reduce it. First, use the reduce function to reduce it to a manageable number of colors, say, about 16 colors -- whatever looks 'decent quality' to you. Then you can Merge remaining colors as you see fit, until you end up with a 4-color result. This gives you a fair bit of control over the result.

Surt: Most image editors use some kind of median cut. GIMP in particular uses a median cut in LAB colorspace. The overall effect tends to reduce extreme values.

You can compensate for this effect by preprocessing the image with color adjustments (Saturation, Contrast, Brightness) and sharpening (my favorite is GMIC 'freaky details' filter on default settings), possibly Retinex or tone mapping. This is.. kind of something you should really consider doing anyway, get the image just right before you go nuking its colorcount.

Here's what you get, quantizing after applying Freaky Details once.


IMO this is pretty acceptable; it's about as good a result as you could hope for from such a poorly defined input image.

BTW NeuQuant is pretty much the best quantization algorithm I've come across.. IF you want 64-256c palette. It's not very helpful for palettes this small, unfortunately.


Edited by neota - 07 March 2015 at 2:16am