How to access each byte in a bitmap image

Question

Say I have a bitmap image, is it possible to iterate through all the individual bytes in the image? If yes, how?

Answer 1

Another solution is to use LockBits and Marshal.Copy to convert your bitmap into an array. I needed this solution because I had two images that differed only in their color depth and the other proffered solutions don't handle that well (or are too slow).

using (Bitmap bmp = new Bitmap(fname)) {
    // Convert image to int32 array with each int being one pixel
    int cnt = bmp.Width * bmp.Height * 4 / 4;
    BitmapData bmData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height),
                            ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
    Int32[] rgbValues = new Int32[cnt];

    // Copy the RGB values into the array.
    System.Runtime.InteropServices.Marshal.Copy(bmData.Scan0, rgbValues, 0, cnt);
    bmp.UnlockBits(bmData);
    for (int i = 0; i < cnt; ++i) {
        if (rgbValues[i] == 0xFFFF0000)
            Console.WriteLine ("Red byte");
    }
}