c# - How to change color of Image at runtime

Question

I would like to know is there any way by which we can change the Image color at runtime. for e.g lets say I am having a JPG bind to an Image control of ASP.Net. Next I am having a dropdown List which gives me the various color option like red,gree,etc. I would now like to change the color of the Image to the one selected in the droprdown List.

Answer 1

Here is a code sample that loads a JPEG, changes any red pixels in the image to blue, and then displays the bitmap in a picture box:

Bitmap bmp = (Bitmap)Bitmap.FromFile("image.jpg");
for (int x = 0; x < bmp.Width; x++)
{
    for (int y = 0; y < bmp.Height; y++)
    {
        if (bmp.GetPixel(x, y) == Color.Red)
        {
            bmp.SetPixel(x, y, Color.Blue);
        }
    }
}
pictureBox1.Image = bmp;

Warning: GetPixel and SetPixel are incredibly slow. If your images are large and/or performance is an issue, there is a much faster way to read and write pixels in .NET, but it's a little bit more work.