csharp/aiportal/tscamera/RecordCenter/UltraRecord/Server/ImageCompression.cs

ImageCompression.cs
using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Imaging;

namespace bfbd.UltraRecord.Core
{
	static partial clast ImageCompression
	{
		public static Image GrayScale(Image image)
		{
			// Make a new 8-BPP indexed bitmap that is the same size as the source image.
			int Width = image.Width;
			int Height = image.Height;
			int nColors = 256;
			Bitmap bitmap = new Bitmap(Width, Height, PixelFormat.Format8bppIndexed);

			// fill palette
			ColorPalette pal = bitmap.Palette;
			for (int i = 0; i < nColors; i++)
			{
				int Alpha = (i == 0) ? 0x00 : 0xFF;
				int Intensity = i * 0xFF / (nColors - 1);
				pal.Entries[i] = Color.FromArgb(Alpha, Intensity, Intensity, Intensity);
			}

			Rectangle rect = new Rectangle(0, 0, Width, Height);

			BitmapData bitmapData = bitmap.LockBits(rect, ImageLockMode.WriteOnly, PixelFormat.Format8bppIndexed);

			// Write to the temporary buffer that is provided by LockBits.
			// Copy the pixels from the source image in this loop.
			// Because you want an index, convert RGB to the appropriate
			// palette index here.
			IntPtr pixels = bitmapData.Scan0;

			unsafe
			{
				// Get the pointer to the image bits.
				// This is the unsafe operation.
				byte* pBits;
				if (bitmapData.Stride > 0)
					pBits = (byte*)pixels.ToPointer();
				else
					// If the Stide is negative, Scan0 points to the last 
					// scanline in the buffer. To normalize the loop, obtain
					// a pointer to the front of the buffer that is located 
					// (Height-1) scanlines previous.
					pBits = (byte*)pixels.ToPointer() + bitmapData.Stride * (Height - 1);
				uint stride = (uint)Math.Abs(bitmapData.Stride);

				for (uint row = 0; row < Height; ++row)
				{
					for (uint col = 0; col < Width; ++col)
					{
						//Color pixel;    // The source pixel.

						// The destination pixel.
						// The pointer to the color index byte of the
						// destination; this real pointer causes this
						// code to be considered unsafe.
						byte* p8bppPixel = pBits + row * stride + col;

						//pixel = image.GetPixel((int)col, (int)row);

						// Use luminance/chrominance conversion to get grayscale.
						// Basically, turn the image into black and white TV.
						// Do not calculate Cr or Cb because you 
						// discard the color anyway.
						// Y = Red * 0.299 + Green * 0.587 + Blue * 0.114

						// This expression is best as integer math for performance,
						// however, because GetPixel listed earlier is the slowest 
						// part of this loop, the expression is left as 
						// floating point for clarity.

						//double luminance = (pixel.R * 0.299) +
						//    (pixel.G * 0.587) +
						//    (pixel.B * 0.114);

						// Gray scale is an intensity map from black to white.
						// Compute the index to the grayscale entry that
						// approximates the luminance, and then round the index.
						// Also, constrain the index choices by the number of
						// colors to do, and then set that pixel's index to the 
						// byte value.
						//*p8bppPixel = (byte)(luminance * (nColors - 1) / 255 + 0.5);

					} /* end loop for col */
				} /* end loop for row */
			} /* end unsafe */

			// To commit the changes, unlock the portion of the bitmap.  
			bitmap.UnlockBits(bitmapData);

			// Bitmap goes out of scope here and is also marked for
			// garbage collection.
			// Pal is referenced by bitmap and goes away.
			// BmpCopy goes out of scope here and is marked for garbage
			// collection. Force it, because it is probably quite large.
			// The same applies to bitmap.
			bitmap.Dispose();
			return null;
		}

		public static void SaveGrayScale(Image image, string filename, uint nColors, bool fTransparent)
		{

			// GIF codec supports 256 colors maximum, monochrome minimum.
			if (nColors > 256)
				nColors = 256;
			if (nColors < 2)
				nColors = 2;

			// Make a new 8-BPP indexed bitmap that is the same size as the source image.
			int Width = image.Width;
			int Height = image.Height;

			// Always use PixelFormat8bppIndexed because that is the color
			// table-based interface to the GIF codec.
			Bitmap bitmap = new Bitmap(Width,
									Height,
									PixelFormat.Format8bppIndexed);

			// Create a color palette big enough to hold the colors you want.
			ColorPalette pal = GetColorPalette(nColors);

			// Initialize a new color table with entries that are determined
			// by some optimal palette-finding algorithm; for demonstration 
			// purposes, use a grayscale.
			for (uint i = 0; i < nColors; i++)
			{
				uint Alpha = 0xFF;                      // Colors are opaque.
				uint Intensity = i * 0xFF / (nColors - 1);    // Even distribution. 

				// The GIF encoder makes the first entry in the palette
				// that has a ZERO alpha the transparent color in the GIF.
				// Pick the first one arbitrarily, for demonstration purposes.

				if (i == 0 && fTransparent) // Make this color index...
					Alpha = 0;          // Transparent

				// Create a gray scale for demonstration purposes.
				// Otherwise, use your favorite color reduction algorithm
				// and an optimum palette for that algorithm generated here.
				// For example, a color histogram, or a median cut palette.
				pal.Entries[i] = Color.FromArgb((int)Alpha,
												(int)Intensity,
												(int)Intensity,
												(int)Intensity);
			}

			// Set the palette into the new Bitmap object.
			bitmap.Palette = pal;


			// Use GetPixel below to pull out the color data of Image.
			// Because GetPixel isn't defined on an Image, make a copy 
			// in a Bitmap instead. Make a new Bitmap that is the same size as the
			// image that you want to export. Or, try to
			// interpret the native pixel format of the image by using a LockBits
			// call. Use PixelFormat32BppARGB so you can wrap a Graphics  
			// around it.
			Bitmap BmpCopy = new Bitmap(Width,
									Height,
									PixelFormat.Format32bppArgb);
			{
				Graphics g = Graphics.FromImage(BmpCopy);

				g.PageUnit = GraphicsUnit.Pixel;

				// Transfer the Image to the Bitmap
				g.DrawImage(image, 0, 0, Width, Height);

				// g goes out of scope and is marked for garbage collection.
				// Force it, just to keep things clean.
				g.Dispose();
			}

			// Lock a rectangular portion of the bitmap for writing.
			BitmapData bitmapData;
			Rectangle rect = new Rectangle(0, 0, Width, Height);

			bitmapData = bitmap.LockBits(
				rect,
				ImageLockMode.WriteOnly,
				PixelFormat.Format8bppIndexed);

			// Write to the temporary buffer that is provided by LockBits.
			// Copy the pixels from the source image in this loop.
			// Because you want an index, convert RGB to the appropriate
			// palette index here.
			IntPtr pixels = bitmapData.Scan0;

			unsafe
			{
				// Get the pointer to the image bits.
				// This is the unsafe operation.
				byte* pBits;
				if (bitmapData.Stride > 0)
					pBits = (byte*)pixels.ToPointer();
				else
					// If the Stide is negative, Scan0 points to the last 
					// scanline in the buffer. To normalize the loop, obtain
					// a pointer to the front of the buffer that is located 
					// (Height-1) scanlines previous.
					pBits = (byte*)pixels.ToPointer() + bitmapData.Stride * (Height - 1);
				uint stride = (uint)Math.Abs(bitmapData.Stride);

				for (uint row = 0; row < Height; ++row)
				{
					for (uint col = 0; col < Width; ++col)
					{
						// Map palette indexes for a gray scale.
						// If you use some other technique to color convert,
						// put your favorite color reduction algorithm here.
						Color pixel;    // The source pixel.

						// The destination pixel.
						// The pointer to the color index byte of the
						// destination; this real pointer causes this
						// code to be considered unsafe.
						byte* p8bppPixel = pBits + row * stride + col;

						pixel = BmpCopy.GetPixel((int)col, (int)row);

						// Use luminance/chrominance conversion to get grayscale.
						// Basically, turn the image into black and white TV.
						// Do not calculate Cr or Cb because you 
						// discard the color anyway.
						// Y = Red * 0.299 + Green * 0.587 + Blue * 0.114

						// This expression is best as integer math for performance,
						// however, because GetPixel listed earlier is the slowest 
						// part of this loop, the expression is left as 
						// floating point for clarity.

						double luminance = (pixel.R * 0.299) +
							(pixel.G * 0.587) +
							(pixel.B * 0.114);

						// Gray scale is an intensity map from black to white.
						// Compute the index to the grayscale entry that
						// approximates the luminance, and then round the index.
						// Also, constrain the index choices by the number of
						// colors to do, and then set that pixel's index to the 
						// byte value.
						*p8bppPixel = (byte)(luminance * (nColors - 1) / 255 + 0.5);

					} /* end loop for col */
				} /* end loop for row */
			} /* end unsafe */

			// To commit the changes, unlock the portion of the bitmap.  
			bitmap.UnlockBits(bitmapData);

			bitmap.Save(filename, ImageFormat.Png);

			// Bitmap goes out of scope here and is also marked for
			// garbage collection.
			// Pal is referenced by bitmap and goes away.
			// BmpCopy goes out of scope here and is marked for garbage
			// collection. Force it, because it is probably quite large.
			// The same applies to bitmap.
			BmpCopy.Dispose();
			bitmap.Dispose();
		}

		public static Image GrayScaleCompress(Image image)
		{
			uint nColors = 256;
			bool fTransparent = true;

			// Make a new 8-BPP indexed bitmap that is the same size as the source image.
			int Width = image.Width;
			int Height = image.Height;

			// Always use PixelFormat8bppIndexed because that is the color
			// table-based interface to the GIF codec.
			Bitmap bitmap = new Bitmap(Width,
									Height,
									PixelFormat.Format8bppIndexed);

			// Create a color palette big enough to hold the colors you want.
			ColorPalette pal = GetColorPalette(nColors);

			// Initialize a new color table with entries that are determined
			// by some optimal palette-finding algorithm; for demonstration 
			// purposes, use a grayscale.
			for (uint i = 0; i < nColors; i++)
			{
				uint Alpha = 0xFF;                      // Colors are opaque.
				uint Intensity = i * 0xFF / (nColors - 1);    // Even distribution. 

				// The GIF encoder makes the first entry in the palette
				// that has a ZERO alpha the transparent color in the GIF.
				// Pick the first one arbitrarily, for demonstration purposes.

				if (i == 0 && fTransparent) // Make this color index...
					Alpha = 0;          // Transparent

				// Create a gray scale for demonstration purposes.
				// Otherwise, use your favorite color reduction algorithm
				// and an optimum palette for that algorithm generated here.
				// For example, a color histogram, or a median cut palette.
				pal.Entries[i] = Color.FromArgb((int)Alpha,
												(int)Intensity,
												(int)Intensity,
												(int)Intensity);
			}

			// Set the palette into the new Bitmap object.
			bitmap.Palette = pal;


			// Use GetPixel below to pull out the color data of Image.
			// Because GetPixel isn't defined on an Image, make a copy 
			// in a Bitmap instead. Make a new Bitmap that is the same size as the
			// image that you want to export. Or, try to
			// interpret the native pixel format of the image by using a LockBits
			// call. Use PixelFormat32BppARGB so you can wrap a Graphics  
			// around it.
			Bitmap BmpCopy = new Bitmap(Width,
									Height,
									PixelFormat.Format32bppArgb);
			{
				Graphics g = Graphics.FromImage(BmpCopy);

				g.PageUnit = GraphicsUnit.Pixel;

				// Transfer the Image to the Bitmap
				g.DrawImage(image, 0, 0, Width, Height);

				// g goes out of scope and is marked for garbage collection.
				// Force it, just to keep things clean.
				g.Dispose();
			}

			// Lock a rectangular portion of the bitmap for writing.
			BitmapData bitmapData;
			Rectangle rect = new Rectangle(0, 0, Width, Height);

			bitmapData = bitmap.LockBits(
				rect,
				ImageLockMode.WriteOnly,
				PixelFormat.Format8bppIndexed);

			// Write to the temporary buffer that is provided by LockBits.
			// Copy the pixels from the source image in this loop.
			// Because you want an index, convert RGB to the appropriate
			// palette index here.
			IntPtr pixels = bitmapData.Scan0;

			unsafe
			{
				// Get the pointer to the image bits.
				// This is the unsafe operation.
				byte* pBits;
				if (bitmapData.Stride > 0)
					pBits = (byte*)pixels.ToPointer();
				else
					// If the Stide is negative, Scan0 points to the last 
					// scanline in the buffer. To normalize the loop, obtain
					// a pointer to the front of the buffer that is located 
					// (Height-1) scanlines previous.
					pBits = (byte*)pixels.ToPointer() + bitmapData.Stride * (Height - 1);
				uint stride = (uint)Math.Abs(bitmapData.Stride);

				for (uint row = 0; row < Height; ++row)
				{
					for (uint col = 0; col < Width; ++col)
					{
						// Map palette indexes for a gray scale.
						// If you use some other technique to color convert,
						// put your favorite color reduction algorithm here.
						Color pixel;    // The source pixel.

						// The destination pixel.
						// The pointer to the color index byte of the
						// destination; this real pointer causes this
						// code to be considered unsafe.
						byte* p8bppPixel = pBits + row * stride + col;

						pixel = BmpCopy.GetPixel((int)col, (int)row);

						// Use luminance/chrominance conversion to get grayscale.
						// Basically, turn the image into black and white TV.
						// Do not calculate Cr or Cb because you 
						// discard the color anyway.
						// Y = Red * 0.299 + Green * 0.587 + Blue * 0.114

						// This expression is best as integer math for performance,
						// however, because GetPixel listed earlier is the slowest 
						// part of this loop, the expression is left as 
						// floating point for clarity.

						double luminance = (pixel.R * 0.299) +
							(pixel.G * 0.587) +
							(pixel.B * 0.114);

						// Gray scale is an intensity map from black to white.
						// Compute the index to the grayscale entry that
						// approximates the luminance, and then round the index.
						// Also, constrain the index choices by the number of
						// colors to do, and then set that pixel's index to the 
						// byte value.
						*p8bppPixel = (byte)(luminance * (nColors - 1) / 255 + 0.5);

					} /* end loop for col */
				} /* end loop for row */
			} /* end unsafe */

			// To commit the changes, unlock the portion of the bitmap.  
			bitmap.UnlockBits(bitmapData);

			// Bitmap goes out of scope here and is also marked for
			// garbage collection.
			// Pal is referenced by bitmap and goes away.
			// BmpCopy goes out of scope here and is marked for garbage
			// collection. Force it, because it is probably quite large.
			// The same applies to bitmap.
			BmpCopy.Dispose();
			//bitmap.Dispose();
			return bitmap;
		}

		private static ColorPalette GetColorPalette(uint nColors)
		{
			// astume monochrome image.
			PixelFormat bitscolordepth = PixelFormat.Format1bppIndexed;
			ColorPalette palette;    // The Palette we are stealing
			Bitmap bitmap;     // The source of the stolen palette

			// Determine number of colors.
			if (nColors > 2)
				bitscolordepth = PixelFormat.Format4bppIndexed;
			if (nColors > 16)
				bitscolordepth = PixelFormat.Format8bppIndexed;

			// Make a new Bitmap object to get its Palette.
			bitmap = new Bitmap(1, 1, bitscolordepth);

			palette = bitmap.Palette;   // Grab the palette

			bitmap.Dispose();           // cleanup the source Bitmap

			return palette;             // Send the palette back
		}
	}
}