How to Convert an Image to 16-Bit Grayscale?

16-bit Grayscale Image Conversion Techniques

This guide explains how to convert images to 16-bit grayscale format without manually adjusting RGB components to luminance values.

Creating a New 16-bit Grayscale Bitmap:

The simplest method involves using the System.Drawing.Bitmap constructor with the System.Drawing.Imaging.PixelFormat parameter. This directly creates a new bitmap with the desired 16-bit grayscale format:

Bitmap grayScaleBP = new System.Drawing.Bitmap(2, 2, System.Drawing.Imaging.PixelFormat.Format16bppGrayScale);

This code snippet generates a 2x2 pixel bitmap in 16-bit grayscale. Adjust the dimensions as needed for your image.

Converting an Existing Image to 16-bit Grayscale:

To convert an existing bitmap, you'll need to iterate through each pixel and redefine its color properties. While possible, this method is less efficient for larger images.

// (Pixel iteration code would go here – omitted for brevity due to inefficiency)

Optimized Grayscale Conversion using ColorMatrix:

For a significantly faster and more efficient grayscale conversion, leverage a ColorMatrix. This approach applies a transformation matrix to the image's color data, resulting in a grayscale conversion.

ColorMatrix colorMatrix = new ColorMatrix(
    new float[][] 
    {
        new float[] {.3f, .3f, .3f, 0, 0},
        new float[] {.59f, .59f, .59f, 0, 0},
        new float[] {.11f, .11f, .11f, 0, 0},
        new float[] {0, 0, 0, 1, 0},
        new float[] {0, 0, 0, 0, 1}
    });

using (ImageAttributes attributes = new ImageAttributes()) {
    attributes.SetColorMatrix(colorMatrix);
    // ... (Drawing code using attributes to apply the ColorMatrix) ...
}

This utilizes standard luminance weighting (.3, .59, .11) for a perceptually accurate grayscale conversion. Remember to replace the commented section with the appropriate code to draw the image using the modified ImageAttributes. This method is far more efficient than pixel-by-pixel manipulation, especially for larger images.

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