iTextSharp.text.pdf.codec.PngImage.DecodeUpFilter C# (CSharp) Method

        private static void DecodeUpFilter(byte[] curr, byte[] prev,
            int count)
        {
            for (int i = 0; i < count; i++) {
                int raw = curr[i] & 0xff;
                int prior = prev[i] & 0xff;

                curr[i] = (byte)(raw + prior);
            }
        }