changing color order in 256 color Bitmap palette

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Hi everyone. I need help sorting the color in the ColorPalette of a 256 colors bitmap.

I load a 256 colors picture (Bitmap.FromFile), but I do not how to sort the colors in the palette. The things is I need to set color of the background(black) of the image as the first color in the palette.

I have no idea how to sort it or change color positions

please help :S

Posted 7-May-10 7:58am

luis.guevara

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mbue · Answer 1 · 2010-12-10T07:14:00

1.) the 256 color bitmap consists of palette entries (means each pixel is corresponding to a palette entry)
2.) if you want to change the palette entry order you have to change all pixels in the bitmap.
3.) if the color you want to change is on palette index 42 should become to palette index 0: you MUST move all lower indexes up to +1 and store the RGB to index 0.
4.) Then you MUST change all pixels in the bitmap <42 to index+1 and finally all pixels ==42 to 0
Thats it - nice day.

Abhinav S · Answer 2 · 2010-05-07T08:18:00

Solution 1

See here.
I dont know for sure what you mean by "sort".
However this link can get you started with "reading a bitmap".

Posted 7-May-10 8:18am

Abhinav S

Updated 7-May-10 8:19am

v3

abdurrahman oğuz · Answer 3 · 2015-09-12T03:31:00

C#

if (searching.PixelFormat == PixelFormat.Format8bppIndexed && dest.PixelFormat == PixelFormat.Format8bppIndexed)
{
    ColorPalette cp = dest.Palette;

    for (int index = 0; index < searching.Palette.Entries.Length; index++)
        cp.Entries[index] = searching.Palette.Entries[index];

    dest.Palette = cp;
    dest.Save(@"E:\Temp\" + Path.GetFileName(file.FilePath));
}

changing color order in 256 color Bitmap palette

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