Re: C# SaveJPEG example

msjuniorc · ‎11-11-2008

Hi all,
I am looking for help in resolving an issue I have when saving a Bitmap to JPEG.
I am using a minimally adapted code extracted from the tippi.cs example delivered with the samples in version 6.

The problem here is that every third or fourth image turns out completely gray. I have also verified that the same behaviour is present in the unmodified version of the example. Any help or further c# example will be greatly apreciated.

TIA,

msjuniorc

PS some background: I am collecting about 15fps at 1280x1024, processing the frames and then creating an MJPEG stream of cropped frames.

[c-sharp]

unsafe public static void SaveJPEG(string filename)
      {
              IppiSize roi;
              // JSS sampling = JSS.JS_OTHER;
              JSS sampling = JSS.JS_411;
              // JSS sampling = JSS.JS_422;
              // JSS sampling = JSS.JS_444;
              
              JCOLOR in_color = JCOLOR.JC_BGR;
              JCOLOR out_color = JCOLOR.JC_YCBCR;
              

              int JPEGSize;
              byte[] pJPEG;
              JERRCODE jerr;
              JPEGEncoder encoder = new JPEGEncoder();

              roi = new IppiSize(bmpdst.Width, bmpdst.Height);
              
              //01// Console.WriteLine("Width: {0} Height: {1}", bmpdst.Width, bmpdst.Height);
              JPEGSize = roi.width * roi.height * nChannels;
              
              //01// Console.WriteLine("JPEGSize: {0}", JPEGSize);
              // just for too small images
              if (JPEGSize < 1024)
              {
                  JPEGSize = 4096;
              }
              pJPEG = new byte[JPEGSize];
              switch (nChannels)
              {
                  case 1:
                      in_color = JCOLOR.JC_GRAY;
                      out_color = JCOLOR.JC_GRAY;
                      sampling = JSS.JS_444;
                      break;
                  case 3:
                      in_color = JCOLOR.JC_BGR;
                      out_color = JCOLOR.JC_YCBCR;
                      break;
                  case 4:
                      in_color = JCOLOR.JC_CMYK;
                      out_color = JCOLOR.JC_YCCK;
                      break;
                  default:
                      break;
              }
              // This saves whithout issues.
              // bmpdst.Save(@"R:OutputImage.bmp");
              BitmapData dstdata = getBmpData(bmpdst);
              
              encoder.SetSource((byte*)dstdata.Scan0, dstdata.Stride, roi, nChannels, in_color);
              int qualityJPEG = 50;
              encoder.SetDestination(ref pJPEG, JPEGSize, qualityJPEG, sampling, out_color, JMODE.JPEG_BASELINE, 0);
              // encoder.SetDestination(ref pJPEG, JPEGSize, qualityJPEG, sampling, out_color, JMODE.JPEG_PROGRESSIVE, 0);
              if (in_color == JCOLOR.JC_CMYK)
              {
                  BGRA_to_RGBA((byte*)dstdata.Scan0, width, height, dstdata.Stride);
              }
              int size = JPEGSize;
              jerr = encoder.WriteImageBaseline(ref size);
              // jerr = encoder.WriteImageProgressive(ref size);
              // Console.WriteLine("jerr> {0}", jerr);
              if (JERRCODE.JPEG_OK == jerr)
              {
                  FileStream fs = new FileStream(filename, FileMode.Create, FileAccess.Write);
                  BinaryWriter bw = new BinaryWriter(fs);
                  bw.Write(pJPEG, 0, size);
                  bw.Close();
                  fs.Close();
                  bmpdst.UnlockBits(dstdata);
              }

      }
[/c-sharp]

msjuniorc · ‎11-14-2008

The solution to the problem can be found at thread:

http://software.intel.com/en-us/forums/showthread.php?t=61729

lee_step provided a modified version of encoder.cs and solved the problem.

msjuniorc