请看下面的示例,它预先计算了查找表(LUT)并使用它来转换每个像素。这个版本涵盖了12位的情况;对于8位的情况,代码非常相似,但很难在像素格式上进行泛化。
从12位GS到有效的8位GS的转换将会丢失数据。但是,您可以调整LUT表以便更好地对焦于输入值范围更小、对比度更好的值(例如
DICOM窗口中心/窗口宽度)。
class Program
{
static void Main( string[] args )
{
int width = 4095;
int height = 1200;
int bits = 12;
byte[] wedge = Wedge( width, height, bits );
Bitmap bmp = Convert( wedge, width, height, bits );
string file = "wedge.png";
bmp.Save( file );
Process.Start( file );
}
static Bitmap Convert( byte[] input, int width, int height, int bits )
{
var bitmap = new Bitmap( width, height, PixelFormat.Format32bppArgb );
var rect = new Rectangle( 0, 0, width, height );
var lut = CreateLut( bits );
var bitmap_data = bitmap.LockBits( rect, ImageLockMode.WriteOnly, bitmap.PixelFormat );
ConvertCore( width, height, bits, input, bitmap_data, lut );
bitmap.UnlockBits( bitmap_data );
return bitmap;
}
static unsafe void ConvertCore( int width, int height, int bits, byte[] input, BitmapData output, uint[] 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 )
{
int max_input = 1 << bits;
uint[] lut = new uint[ max_input ];
for ( int i = 0; i < max_input; i++ )
{
byte intensity = (byte)( ( i * 0xFF ) / max_input );
lut[ i ] = (uint)( 0xFF000000L | ( intensity * 0x00010101L ) );
}
return lut;
}
static byte[] Wedge( int width, int height, int bits )
{
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;
}
}