Replace (swap) colour in Bitmap

Question

I have googled loads and all I can find is changing the whole bitmap to a new colour. The basis of it is that I want to swap all the Red in an image (RGB: 23199. Hex E70909) to lets say Fushia or another RGB colour. I can't seem to work out how to specifically swapp just a single colour for another. The image is only 80x80px so I don't think GetPixel (which supposedly is slow) would impact it that much. That is if GetPixel is the correct thing to use.

Vulpes · Answer

He's written it as 'extension method' - notice the 'this' in front of the Bitmap parameter bmp. So as long as you include the BitmapExt static class in your project you can call it like this: b.ChangeColour(01280000); where 'b' is a Bitmap variable. Alternatively you can call it 'statically' like this: BitmapExt.ChangeColour(b01280000);

Jay S · Answer

Kinda got it to work...thanks anyway.

Jay S · Answer

I've seen that suggestion and cannot for the life of me get it to work. When he calls it: bmp.ChangeColour(01280000); This doesn't work as ChangeColour isn't and extension of Bitmap... Guess i will keep googling.

Vulpes · Answer

Image manipulation is not really my thing but there's a method in this SO thread (posted by Sayse) which purports to change a particular color in a bitmap to another color. As you'll see this uses LockBits rather than SetPixel and so should be reasonably efficient: http://stackoverflow.com/questions/16346212/can-you-change-one-colour-to-another-in-an-bitmap-image