Reading image pixel values

I am trying to read the pixel values ​​of an image contained in a DICOM file in my simple C ++ application using the Grassroots DICOM library (GDCM). When reading file metadata, I get the following picture information:

 
Bits allocated: 16
Bits Stored: 16
High Bit: 15
Unsigned or signed: 1
Samples pr pixel: 1
Dimensions: 2
Dimension values: 256x256
Pixel Representation: 1
SamplesPerPixel: 1
ScalarType: INT16
PhotometricInterpretation: MONOCHROME2
Pixel buffer length: 131072

Given that the image has a resolution of 256x256 and is of type MONOCHROME2, I expected the pixel buffer length to be 256x256 = 65536 elements, but in reality it is 131072 elements.

If I use MATLAB instead of importing pixel data, I get exactly 65536 values ​​in the range 0 - 850, where 0 is black and 850 is white.

, GDCM ++, pixelbuffer - 131072 , -128 +127, 0- 3. :

Exerpt:    

PixelBuffer[120] = -35
PixelBuffer[121] = 0
PixelBuffer[122] = 51
PixelBuffer[123] = 2
PixelBuffer[124] = 71
PixelBuffer[125] = 2
PixelBuffer[126] = 9
PixelBuffer[127] = 2
PixelBuffer[128] = -80
PixelBuffer[129] = 2
PixelBuffer[130] = 87
PixelBuffer[131] = 3
PixelBuffer[132] = 121
PixelBuffer[133] = 3
PixelBuffer[134] = -27
PixelBuffer[135] = 2
PixelBuffer[136] = 27
PixelBuffer[137] = 2
PixelBuffer[138] = -111
PixelBuffer[139] = 1
PixelBuffer[140] = 75
PixelBuffer[141] = 1
PixelBuffer[142] = 103 

? ? "googeling image pixel structure" , , . - , ?

+4
1

16- MONOCHROME2 Dicom:

byte[] signedData = new byte[2];
        List<int> tempInt = new List<int>();
        List<ushort> returnValue = new List<ushort>();

        for (i = 0; i < PixelBuffer.Length; ++i)
        {
            i1 = i * 2;
            signedData[0] = PixelBuffer[i1];
            signedData[1] = PixelBuffer[i1 + 1];
            short sVal = System.BitConverter.ToInt16(signedData, 0);

            int pixVal = (int)(sVal * rescaleSlope + rescaleIntercept);

            tempInt.Add(pixVal);
        }

        int minPixVal = tempInt.Min();
        SignedImage = false;
        if (minPixVal < 0) SignedImage = true;

        foreach (int pixel in tempInt)
        {
            ushort val;
            if (SignedImage)
                val = (ushort)(pixel - short.MinValue);
            else
            {
                if (pixel > ushort.MaxValue) val = ushort.MaxValue;
                else val = (ushort)(pixel);
            }

            returnValue.Add(val);
        }
+1

Source: https://habr.com/ru/post/1655562/


All Articles