C# – 转换8位或16位灰度原始像素数据

从12位GS到有效8位GS的转换将丢失数据.但是,您可以调整LUT表以聚焦较小范围的输入值,并获得更好的对比度(例如DICOM Window Center/Window Width).

class Program
{
    static void Main( string[] args )
    {
        // Test driver - create a Wedge,convert to Bitmap,save to file
        //
        int width = 4095;
        int height = 1200;
        int bits = 12;

        byte[] wedge = Wedge( width,height,bits );

        Bitmap bmp = Convert( wedge,width,bits );

        string file = "wedge.png";

        bmp.Save( file );

        Process.Start( file );
    }

    static Bitmap Convert( byte[] input,int width,int height,int bits )
    {
        // Convert byte buffer (2 bytes per pixel) to 32-bit ARGB bitmap

        var bitmap = new Bitmap( width,PixelFormat.Format32bppArgb );

        var rect = new Rectangle( 0,height );

        var lut = CreateLut( bits );

        var bitmap_data = bitmap.LockBits( rect,ImageLockMode.WriteOnly,bitmap.PixelFormat );

        ConvertCore( width,bits,input,bitmap_data,lut );

        bitmap.UnlockBits( bitmap_data );

        return bitmap;
    }

    static unsafe void ConvertCore( int width,int bits,byte[] input,BitmapData output,uint[] lut )
    {
        // Copy pixels from input to output,applying LUT

        ushort mask = (ushort)( ( 1 << bits ) - 1 );

        int in_stride = output.Stride;
        int out_stride = width * 2;

        byte* out_data = (byte*)output.Scan0;

        fixed ( byte* in_data = input )
        {
            for ( int y = 0; y < height; y++ )
            {
                uint* out_row = (uint*)( out_data + ( y * in_stride ) );

                ushort* in_row = (ushort*)( in_data + ( y * out_stride ) );

                for ( int x = 0; x < width; x++ )
                {
                    ushort in_pixel = (ushort)( in_row[ x ] & mask );

                    out_row[ x ] = lut[ in_pixel ];
                }
            }
        }
    }

    static uint[] CreateLut( int bits )
    {
        // Create a linear LUT to convert from grayscale to ARGB

        int max_input = 1 << bits;

        uint[] lut = new uint[ max_input ];

        for ( int i = 0; i < max_input; i++ )
        {
            // map input value to 8-bit range
            //
            byte intensity = (byte)( ( i * 0xFF ) / max_input );

            // create ARGB output value A=255,R=G=B=intensity
            //
            lut[ i ] = (uint)( 0xFF000000L | ( intensity * 0x00010101L ) );
        }

        return lut;
    }

    static byte[] Wedge( int width,int bits )
    {
        // horizontal wedge

        int max = 1 << bits;

        byte[] pixels = new byte[ width * height * 2 ];

        for ( int y = 0; y < height; y++ )
        {
            for ( int x = 0; x < width; x++ )
            {
                int pixel = x % max;

                int addr = ( ( y * width ) + x ) * 2;

                pixels[ addr + 1 ] = (byte)( ( pixel & 0xFF00 ) >> 8 );
                pixels[ addr + 0 ] = (byte)( ( pixel & 0x00FF ) );
            }
        }

        return pixels;
    }
}