Posterize adds extra colors?

Programming Questions

JeffThomp..

in Programming Questions • 8 months ago

Maybe I'm going crazy: I'm trying to find the most common colors in an image. Using filter(POSTERIZE, n) seems the easiest solution. However, if I put in a number of values, the result is always more than the # specified.

For example:
2 steps = 5 colors
3 steps = 13 colors
4 steps = 23 colors!

Many of these are grayscale values, which leads me to suspect that POSTERIZE limits to colors + grayscale? Any ideas on getting rid of those "extra" grayscale values but leave them if they are really the most dominant?

If it makes any difference, I'm posterizing the image, then loading the pixels into a HashSet to remove duplicates quickly, then spitting the results back out as a color array. Maybe something weird is happening there?

Replies(2)

PhiLho

Re: Posterize adds extra colors?

8 months ago

" Maybe something weird is happening "
As usual, particularly in this section (otherwise, that's just General Discussion...), show your code, so we can see if there is something odd in your code.

JeffThomp..

Re: Posterize adds extra colors?

8 months ago

Sure - the "problem" occurs using just filter(POSTERIZE, n), but below is the parsing code I'm using in addition:

color[] mostDominantColors(int steps) {
PImage posterized = createImage(img.width, img.height, RGB);
posterized.copy(img, 0,0, img.width,img.height, 0,0, img.width,img.height);
posterized.filter(POSTERIZE, steps);
posterized.loadPixels();
Integer[] cast = new Integer[posterized.pixels.length];
int i=0;
for (int value : posterized.pixels) {
cast[i++] = Integer.valueOf(value);
}
Set<Integer> colors = new HashSet<Integer>(Arrays.asList(cast));
color[] c = new color[0];
for (color n : colors) {
c = append(c, n);
}
return c;
}

A bit messy at this point, but it posterizes the image, converts all pixels to Integers so I can then add them to the HashSet; this process removes duplicates, so I add the result to a color array and return.

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