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c#bitmapbinaryreader

C# Using BinaryReader to read color byte values of a bitmap image

I am using BinaryReader to read the bytes of an image, I am having some issues trying to read the ARGB values of a bitmap image using BinaryReader. Can anyone suggest a way I could get the byte value for each pixel in a bitmap image?

Thanks in advance

Solution

  • Easy way is to use unsafe context and lock some bits. Oversimplified sample:

    unsafe
{
    var bitmapData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, bmp.PixelFormat);

    byte* first = (byte*)bitmapData.Scan0;   
    byte a = first[0];
    byte r = first[1];
    byte g = first[2];
    byte b = first[3];

    ...

    bmp.UnlockBits(bitmapData);
}

    However, if you still need to use BinaryReader and you know how many bytes per pixel there are, It is possible to just skip the header (you can find it's length in @Bradley_Ufffner 's link) and access the bytes.