/// <summary>
/// FreeImage method
/// </summary>
/// <param name="bmp"></param>
/*
* public static void FI_ConvertSave(Bitmap bmp)
* {
* if (bmp != null)
* {
* using (FreeImageAPI.FreeImageBitmap fiBitmap = FreeImageAPI.FreeImageBitmap.FromHbitmap(bmp.GetHbitmap()))
* {
* if (fiBitmap.ColorDepth > 24)
* {
* fiBitmap.ConvertColorDepth(FreeImageAPI.FREE_IMAGE_COLOR_DEPTH.FICD_08_BPP);
* }
* for (int i = 16; i < 256; i++)
* fiBitmap.Palette.Data[i] = new FreeImageAPI.RGBQUAD(Color.White);
*
* FreeImageAPI.Palette pl = new FreeImageAPI.Palette(256);
* pl.CreateGrayscalePalette();
* //quantize using the NeuQuant neural-net quantization algorithm
* fiBitmap.Quantize(FreeImageAPI.FREE_IMAGE_QUANTIZE.FIQ_NNQUANT, 16, pl);
*
*
*
* fiBitmap.Save("test_FreeImageOutput.png", FreeImageAPI.FREE_IMAGE_FORMAT.FIF_PNG, FreeImageAPI.FREE_IMAGE_SAVE_FLAGS.PNG_Z_BEST_COMPRESSION);
* //bmp = fiBitmap.ToBitmap();
* //ms = new MemoryStream();
* //fiBitmap.Save(ms, FreeImageAPI.FREE_IMAGE_FORMAT.FIF_PNG, FreeImageAPI.FREE_IMAGE_SAVE_FLAGS.PNG_Z_DEFAULT_COMPRESSION);
* }
* bmp.Dispose();
* }
* }
*/
// From wischik.com
static Bitmap CopyToBpp(System.Drawing.Bitmap b, int bpp)
{
if (bpp != 1 && bpp != 8)
{
throw new System.ArgumentException("1 or 8", "bpp");
}
// Plan: built into Windows GDI is the ability to convert
// bitmaps from one format to another. Most of the time, this
// job is actually done by the graphics hardware accelerator card
// and so is extremely fast. The rest of the time, the job is done by
// very fast native code.
// We will call into this GDI functionality from C#. Our plan:
// (1) Convert our Bitmap into a GDI hbitmap (ie. copy unmanaged->managed)
// (2) Create a GDI monochrome hbitmap
// (3) Use GDI "BitBlt" function to copy from hbitmap into monochrome (as above)
// (4) Convert the monochrone hbitmap into a Bitmap (ie. copy unmanaged->managed)
int w = b.Width;
int h = b.Height;
IntPtr hbm = b.GetHbitmap(); // this is step (1)
//
// Step (2): create the monochrome bitmap.
// "BITMAPINFO" is an interop-struct which we define below.
// In GDI terms, it's a BITMAPHEADERINFO followed by an array of two RGBQUADs
GDI32.BITMAPINFOHEADER bmi = new GDI32.BITMAPINFOHEADER();
bmi.biSize = 40; // the size of the BITMAPHEADERINFO struct
bmi.biWidth = w;
bmi.biHeight = h;
bmi.biPlanes = 1; // "planes" are confusing. We always use just 1. Read MSDN for more info.
bmi.biBitCount = (ushort)bpp; // ie. 1bpp or 8bpp
bmi.biCompression = (uint)GdiFlags.BI_RGB; // ie. the pixels in our RGBQUAD table are stored as RGBs, not palette indexes
bmi.biSizeImage = (uint)(((w + 7) & 0xFFFFFFF8) * h / 8);
bmi.biXPelsPerMeter = 1000000; // not really important
bmi.biYPelsPerMeter = 1000000; // not really important
// Now for the colour table.
uint ncols = (uint)1 << bpp; // 2 colours for 1bpp; 256 colours for 8bpp
bmi.biClrUsed = ncols;
bmi.biClrImportant = ncols;
bmi.cols = new uint[256]; // The structure always has fixed size 256, even if we end up using fewer colours
if (bpp == 1)
{
bmi.cols[0] = GDI32.MAKERGB(0, 0, 0); bmi.cols[1] = GDI32.MAKERGB(255, 255, 255);
}
else
{
for (int i = 0; i < ncols; i++)
{
bmi.cols[i] = GDI32.MAKERGB(i, i, i);
}
}
// For 8bpp we've created an palette with just greyscale colours.
// You can set up any palette you want here. Here are some possibilities:
// greyscale: for (int i=0; i<256; i++) bmi.cols[i]=MAKERGB(i,i,i);
bmi.biClrUsed = 216; bmi.biClrImportant = 216; int[] colv = new int[6] {
0, 51, 102, 153, 204, 255
};
for (int i = 0; i < 216; i++)
{
bmi.cols[i] = GDI32.MAKERGB(colv[i / 36], colv[(i / 6) % 6], colv[i % 6]);
}
// rainbow: bmi.biClrUsed=216; bmi.biClrImportant=216; int[] colv=new int[6]{0,51,102,153,204,255};
// for (int i=0; i<216; i++) bmi.cols[i]=GDI32.MAKERGB(colv[i/36],colv[(i/6)%6],colv[i%6]);
// optimal: a difficult topic: http://en.wikipedia.org/wiki/Color_quantization
//
// Now create the indexed bitmap "hbm0"
IntPtr bits0; // not used for our purposes. It returns a pointer to the raw bits that make up the bitmap.
IntPtr hbm0 = GDI32.CreateDIBSection(IntPtr.Zero, ref bmi, (uint)GdiFlags.DIB_RGB_COLORS, out bits0, IntPtr.Zero, 0);
//
// Step (3): use GDI's BitBlt function to copy from original hbitmap into monocrhome bitmap
// GDI programming is kind of confusing... nb. The GDI equivalent of "Graphics" is called a "DC".
IntPtr sdc = USER32.GetDC(IntPtr.Zero); // First we obtain the DC for the screen
// Next, create a DC for the original hbitmap
IntPtr hdc = GDI32.CreateCompatibleDC(sdc);
GDI32.SelectObject(hdc, hbm);
// and create a DC for the monochrome hbitmap
IntPtr hdc0 = GDI32.CreateCompatibleDC(sdc);
GDI32.SelectObject(hdc0, hbm0);
// Now we can do the BitBlt:
GDI32.BitBlt(hdc0, 0, 0, w, h, hdc, 0, 0, TernaryRasterOperations.SRCCOPY);
// Step (4): convert this monochrome hbitmap back into a Bitmap:
System.Drawing.Bitmap b0 = System.Drawing.Bitmap.FromHbitmap(hbm0);
//
// Finally some cleanup.
GDI32.DeleteDC(hdc);
GDI32.DeleteDC(hdc0);
USER32.ReleaseDC(IntPtr.Zero, sdc);
GDI32.DeleteObject(hbm);
GDI32.DeleteObject(hbm0);
//
return(b0);
}