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());
}
