message: fix png error
diff: @@ -48,7 +48,7 @@ CompressPNG::CompressPNG(const Params &parameters) : Operator("png", parameters)
  }
  size_t CompressPNG::Compress(const void *dataIn, const Dims &dimensions,
  - DataType /*type*/, void *bufferOut,
  + DataType type, void *bufferOut,
  const Params &parameters, Params &info)
  {
  auto lf_Write = [](png_structp png_ptr, png_bytep data, png_size_t length) {
  @@ -129,8 +129,9 @@ size_t CompressPNG::Compress(const void *dataIn, const Dims &dimensions,
  nullptr, nullptr, nullptr);
  png_infop pngInfo = png_create_info_struct(pngWrite);
  - const uint32_t bytesPerPixel =
  - ndims == 3 ? static_cast<uint32_t>(dimensions[2]) : elementSize;
  + const uint32_t bytesPerPixel = ndims == 3
  + ? static_cast<uint32_t>(dimensions[2])
  + : helper::GetDataTypeSize(type);
  const uint32_t width = static_cast<uint32_t>(dimensions[1]);
  const uint32_t height = static_cast<uint32_t>(dimensions[0]);
  