orthanc: OrthancFramework/Sources/Images/ImageProcessing.cpp comparison

ImageProcessing::ConvertJpegYCbCrToRgb()

author	Sebastien Jodogne <s.jodogne@gmail.com>
date	Tue, 12 Jan 2021 13:07:15 +0100
parents	d9473bd5ed43
children	19e8540064d8

comparison

equal deleted inserted replaced

-:f77ee6e6cf47
+:fd958175c5b9
 Copy(region, *resized);
 }
 return target.release();
 }
+void ImageProcessing::ConvertJpegYCbCrToRgb(ImageAccessor& image)
+{
+// http://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_C.7.6.3.html#sect_C.7.6.3.1.2
+// https://en.wikipedia.org/wiki/YCbCr#JPEG_conversion
+// TODO - Check out the outcome of Mathieu's discussion about
+// truncation of YCbCr-to-RGB conversion:
+// https://groups.google.com/forum/#!msg/comp.protocols.dicom/JHuGeyWbTz8/ARoTWrJzAQAJ
+const unsigned int width = image.GetWidth();
+const unsigned int height = image.GetHeight();
+const unsigned int pitch = image.GetPitch();
+uint8_t* buffer = reinterpret_cast<uint8_t*>(image.GetBuffer());
+if (image.GetFormat() != PixelFormat_RGB24 ||
+pitch < 3 * width)
+{
+throw OrthancException(ErrorCode_IncompatibleImageFormat);
+}
+for (unsigned int y = 0; y < height; y++)
+{
+uint8_t* p = buffer + y * pitch;
+for (unsigned int x = 0; x < width; x++, p += 3)
+{
+const float Y  = p[0];
+const float Cb = p[1];
+const float Cr = p[2];
+const float result[3] = {
+Y                             + 1.402f    * (Cr - 128.0f),
+Y - 0.344136f * (Cb - 128.0f) - 0.714136f * (Cr - 128.0f),
+Y + 1.772f    * (Cb - 128.0f)
+};
+for (uint8_t i = 0; i < 3 ; i++)
+{
+if (result[i] < 0)
+{
+p[i] = 0;
+}
+else if (result[i] > 255)
+{
+p[i] = 255;
+}
+else
+{
+p[i] = static_cast<uint8_t>(result[i]);
+}
+}
+}
+}
+}
 }

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