Change Image Colors

Question

i have a MacBook1,1 running Snow Leopard 10.6.8. I would like to be able to change an images specific color. Lets say I have an image with only blue and black and I want to change the blue to green. Is there any app that does that?
Thank you in advance,
Eric

Answer 1

You get the colors with Image.getRGB(). You can then separate the channels with bitwise ands:
int[] pixels = new int[width * height];
img.getRGB(pixels,0,width,0,0,width,height);
int onePixel = pixels[0];
int blue = onePixel & 0xff;
int green = (onePixel & 0xff00) >> 8;
int red = (onePixel & 0xff0000) >> 16;
int alpha = (onePixel & 0xff000000) >> 24;You manipulate the channels like you see fit, then you recreate the pixel with bitwise ors, and use Image.createRGBImage() to create the new manipulated image:
int newPixel = (alpha << 24) | (red << 16) | (green << 8) | blue;
Image manipulated = Image.createRGBImage(newPixels,width,height,true);shmoove