EncoderParameters ep = new EncoderParameters(3);
if (this.pbMain.Image.PixelFormat == PixelFormat.Format1bppIndexed) //by hxq, 黑白用G4压缩
{
ep.Param[0] = new EncoderParameter(Encoder.Compression, (long)EncoderValue.CompressionCCITT4);
ep.Param[1] = new EncoderParameter(Encoder.Quality, 0L);
ep.Param[2] = new EncoderParameter(Encoder.ColorDepth, 1L);
}