static size_t WritePSDChannels(const PSDInfo *psd_info,
  const ImageInfo *image_info,Image *image,Image *next_image,
  MagickOffsetType size_offset,const MagickBooleanType separate,
  ExceptionInfo *exception)
{
  CompressionType
    compression;

  Image
    *mask;

  MagickOffsetType
    rows_offset;

  size_t
    channels,
    count,
    length,
    offset_length;

  unsigned char
    *compact_pixels;

  count=0;
  offset_length=0;
  rows_offset=0;
  compact_pixels=(unsigned char *) NULL;
  compression=next_image->compression;
  if (image_info->compression != UndefinedCompression)
    compression=image_info->compression;
  if (compression == RLECompression)
    {
      compact_pixels=AcquireCompactPixels(next_image,exception);
      if (compact_pixels == (unsigned char *) NULL)
        return(0);
    }
  channels=1;
  if (separate == MagickFalse)
    {
      if (next_image->storage_class != PseudoClass)
        {
          if (IsImageGray(next_image) == MagickFalse)
            channels=next_image->colorspace == CMYKColorspace ? 4 : 3;
          if (next_image->alpha_trait != UndefinedPixelTrait)
            channels++;
        }
      rows_offset=TellBlob(image)+2;
      count+=WriteCompressionStart(psd_info,image,next_image,compression,
        channels);
      offset_length=(next_image->rows*(psd_info->version == 1 ? 2 : 4));
    }
  size_offset+=2;
  if (next_image->storage_class == PseudoClass)
    {
      length=WritePSDChannel(psd_info,image_info,image,next_image,
        IndexQuantum,compact_pixels,rows_offset,separate,compression,
        exception);
      if (separate != MagickFalse)
        size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
      else
        rows_offset+=offset_length;
      count+=length;
    }
  else
    {
      if (IsImageGray(next_image) != MagickFalse)
        {
          length=WritePSDChannel(psd_info,image_info,image,next_image,
            GrayQuantum,compact_pixels,rows_offset,separate,compression,
            exception);
          if (separate != MagickFalse)
            size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
          else
            rows_offset+=offset_length;
          count+=length;
        }
      else
        {
          if (next_image->colorspace == CMYKColorspace)
            (void) NegateCMYK(next_image,exception);

          length=WritePSDChannel(psd_info,image_info,image,next_image,
            RedQuantum,compact_pixels,rows_offset,separate,compression,
            exception);
          if (separate != MagickFalse)
            size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
          else
            rows_offset+=offset_length;
          count+=length;

          length=WritePSDChannel(psd_info,image_info,image,next_image,
            GreenQuantum,compact_pixels,rows_offset,separate,compression,
            exception);
          if (separate != MagickFalse)
            size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
          else
            rows_offset+=offset_length;
          count+=length;

          length=WritePSDChannel(psd_info,image_info,image,next_image,
            BlueQuantum,compact_pixels,rows_offset,separate,compression,
            exception);
          if (separate != MagickFalse)
            size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
          else
            rows_offset+=offset_length;
          count+=length;

          if (next_image->colorspace == CMYKColorspace)
            {
              length=WritePSDChannel(psd_info,image_info,image,next_image,
                BlackQuantum,compact_pixels,rows_offset,separate,compression,
                exception);
              if (separate != MagickFalse)
                size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
              else
                rows_offset+=offset_length;
              count+=length;
            }
        }
      if (next_image->alpha_trait != UndefinedPixelTrait)
        {
          length=WritePSDChannel(psd_info,image_info,image,next_image,
            AlphaQuantum,compact_pixels,rows_offset,separate,compression,
            exception);
          if (separate != MagickFalse)
            size_offset+=WritePSDSize(psd_info,image,length,size_offset)+2;
          else
            rows_offset+=offset_length;
          count+=length;
        }
    }
  compact_pixels=(unsigned char *) RelinquishMagickMemory(compact_pixels);
  if (next_image->colorspace == CMYKColorspace)
    (void) NegateCMYK(next_image,exception);
  if (separate != MagickFalse)
    {
      const char
        *property;

      property=GetImageArtifact(next_image,"psd:opacity-mask");
      if (property != (const char *) NULL)
        {
          mask=(Image *) GetImageRegistry(ImageRegistryType,property,
            exception);
          if (mask != (Image *) NULL)
            {
              if (compression == RLECompression)
                {
                  compact_pixels=AcquireCompactPixels(mask,exception);
                  if (compact_pixels == (unsigned char *) NULL)
                    return(0);
                }
              length=WritePSDChannel(psd_info,image_info,image,mask,
                RedQuantum,compact_pixels,rows_offset,MagickTrue,compression,
                exception);
              (void) WritePSDSize(psd_info,image,length,size_offset);
              count+=length;
              compact_pixels=(unsigned char *) RelinquishMagickMemory(
                compact_pixels);
            }
        }
    }
  return(count);
}