PDF to PNG Image

Hi,

We are converting PDF page to PNG image by using below code:

  ASCab config = ASCabNew();

  ASCabPutInt (config, kExtractImgCmdKeyColorSpace, kColorSpaceAuto);
  ASCabPutInt (config, kExtractImgCmdKeyResolution, kImgResolutionAuto);
  ASCabPutBool(config, kExtractImgCmdKeyConfigured,true);
  ASCabPutInt(config, kExtractImgCmdKeyConvFormat, kImgConversionFormatPng); 
  AVConversionStatus bSucceeded = AVConversionConvertFromPDFWithHandler(convFromPDFFilter.handler, config,  kAVConversionNoFlags,
        pdPageDoc, outPath, fileSys, NULL);

But out image file is wrong.(Viewer can't open this picture because the file appears to be demaged, corrupted, or is too large)

Please help us to resolve the problem.

Thanks