Get image value total

Question

Below is my code:

private double GetImageValue(Bitmap Image)
{
    double ImageValue = 0;

    for (int X = 0; X < Image.Width; X++)
    {
        for (int Y = 0; Y < Image.Height; Y++)
        {
            Color CurrentPixel = Image.GetPixel(X, Y);

            ImageValue += CurrentPixel.A + CurrentPixel.B + CurrentPixel.G + CurrentPixel.R;
        }
    }
    return ImageValue;
}

The following code returns the total value of each pixel in the image. Is there a way to speed up the procedure? Thanks for any help.

Answer 1

Bitmap data is stored in an unmanaged GDI object. Every time you call GetPixel the system needs to access this object. You can speed it up by using LockBits to directly access the raw image data.

private double GetImageValue(Bitmap image)
{
    double imageValue = 0;

    // Lock the bitmap's bits.  
    var rect = new Rectangle(0, 0, image.Width, image.Height);
    var bmpData = image.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

    // Get the address of the first line.
    var ptr = bmpData.Scan0;

    // Declare an array to hold the bytes of the bitmap.
    var bytes = Math.Abs(bmpData.Stride) * image.Height;
    var values = new byte[bytes];

    // Copy the RGB values into the array.
    System.Runtime.InteropServices.Marshal.Copy(ptr, values, 0, bytes);

    // Add the rgb values to ImageValue
    for (int y = 0; y < image.Height; y++)
    {
        int lineStart = y * Math.Abs(bmpData.Stride);
        for (int x = 0; x < image.Width * 3; x++)
        {
            imageValue += values[lineStart + x];
        }
    }

    // Unlock the bits.
    image.UnlockBits(bmpData);

    return imageValue;
}