public static void DecreaseRed(String origFilename, String destFilename) { if (origFilename.Equals(destFilename)) { throw new PngjException("input and output file cannot coincide"); } PngReader pngr = FileHelper.CreatePngReader(origFilename); PngWriter pngw = FileHelper.CreatePngWriter(destFilename, pngr.ImgInfo, true); Console.WriteLine(pngr.ToString()); int chunkBehav = ChunkCopyBehaviour.COPY_ALL_SAFE; // copy all 'safe' chunks // this can copy some metadata from reader pngw.CopyChunksFirst(pngr, chunkBehav); int channels = pngr.ImgInfo.Channels; if (channels < 3) { throw new Exception("This method is for RGB/RGBA images"); } for (int row = 0; row < pngr.ImgInfo.Rows; row++) { ImageLine l1 = pngr.ReadRow(row); for (int j = 0; j < pngr.ImgInfo.Cols; j++) { l1.Scanline[j * channels] /= 2; } pngw.WriteRow(l1, row); } // just in case some new metadata has been read after the image pngw.CopyChunksLast(pngr, chunkBehav); pngw.End(); }
public static void showChunks(String file) { PngReader pngr = FileHelper.CreatePngReader(file); pngr.MaxTotalBytesRead = 1024 * 1024 * 1024L * 3; // 3Gb! pngr.ReadSkippingAllRows(); Console.Out.WriteLine(pngr.ToString()); Console.Out.WriteLine(pngr.GetChunksList().ToStringFull()); }