/// <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); }