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GetImage(DicomElement,int,int,RasterByteOrder,DicomGetImageFlags) Method

Summary
Gets the image of a Pixel Data element.
Syntax
C#
C++/CLI
public RasterImage GetImage( 
   DicomElement element, 
   int index, 
   int bitsPerPixel, 
   RasterByteOrder order, 
   DicomGetImageFlags flags 
) 
public: 
RasterImage^ GetImage(  
   DicomElement^ element, 
   int index, 
   int bitsPerPixel, 
   RasterByteOrder order, 
   DicomGetImageFlags flags 
)

Parameters

element
An item in the Data Set.

index
The zero-based index of the frame to load.

bitsPerPixel
Value that represents the resulting image pixel depth. Possible values are:

Value Meaning
0 Keep the original file's pixel depth (do not convert).
1 to 8 The specified bits per pixel in the resulting image.
12 12 bits per pixel in the resulting image.
16 16 bits per pixel in the resulting image.
24 24 bits per pixel in the resulting image.
32 32 bits per pixel in the resulting image.

order
This value is ignored.

flags
Flags that control the behavior of this method.

Return Value

The image of a Pixel Data element.

Remarks

If element is null, this method will load any image within the file, based on the index parameter. If DicomGetImageFlags.AllowRangeExpansion is set in flag, consider the following example:

If the Data Set has the following attributes:

Bits allocated 16

Bits stored 12

Pixel Range 0 - +4095

Pixel Representation is unsigned (0)

Photometric Interpretation is MONOCHROME2

Rescale Slope 1

Rescale Intercept -1024

After applying the rescale slope and the intercept:

Output minimum pixel value = (0 * 1 +(-1024)) = -1024

Output maximum pixel value = (4095 * 1 + (-1024)) = 3071

The new pixel value range (-1024 to 3071) can not be represented with the current bits stored (12 bits), which can represent values in the range (-2048 to 2048). In this case the method will change the high bit inside the image object to be 12 instead of 11 (bits stored becomes 13), which can represent values in the range (-8192 to 8191).

Please note that the method will not be able to update the high bit and/or low bit if the number of bits stored was already equal to the number of bits allocated.

If the DICOM dataset has a Multi-frame Functional Groups module, some VOI LUT information will be read from the correspondingFrame VOI LUT Sequence, and some Modality LUT information will be read from the corresponding Pixel Value Transformation Sequence. The specific elements that are read is shown below: (0028,9132) Frame VOI LUT Sequence Child Elements

Tag Name
(0028,1050) Window Center
(0028,1051) Window Width
(0028,1055) Window Center & Width Explanation

(0028,9145) Pixel Value Transformation Sequence child elements

Tag Name
(0028,1052) Rescale Intercept
(0028,1053) Rescale Slope
(0028,1054) Rescale Type

For a detailed discussion on Multi-frame Functional Groups see the topic Multi-frame Functional Groups.

Example

This example will read a DICOM dataset and do a number of image related operations such as loading and saving.

C#
using Leadtools; 
using Leadtools.Dicom; 
 
 
public void TestDicomImage() 
{ 
   string dicomFileName = Path.Combine(LEAD_VARS.ImagesDir, "DICOM", "image3.dcm"); 
   //Make sure to initialize the DICOM engine, this needs to be done only once  
   //In the whole application 
   DicomEngine.Startup(); 
   using (DicomDataSet ds = new DicomDataSet()) 
   { 
      //Load DICOM File 
      ds.Load(dicomFileName, DicomDataSetLoadFlags.None); 
 
      DicomElement pixelDataElement = ds.FindFirstElement(null, DicomTag.PixelData, true); 
      if (pixelDataElement == null) 
      { 
         Console.WriteLine("This dataset is missing the pixel data element", "Sample"); 
         return; 
      } 
 
      if (ds.GetImageCount(pixelDataElement) == 0) 
      { 
         Console.WriteLine("Sample: This dataset has no images"); 
         return; 
      } 
 
      DicomImageInformation imageInformation = ds.GetImageInformation(pixelDataElement, 0); 
      if (imageInformation == null) 
      { 
         Console.WriteLine("Sample: Can't retrieve image information"); 
         return; 
      } 
      // Over here we can access the different properties of the DicomImageInformation class to get some 
      // of the image attributes such as bits allocated (DicomImageInformation. BitsAllocated) 
      RasterImage image = ds.GetImage(pixelDataElement, 
         0, 
         0, 
         RasterByteOrder.Gray, 
         DicomGetImageFlags.AllowRangeExpansion | DicomGetImageFlags.AutoApplyModalityLut | DicomGetImageFlags.AutoApplyVoiLut); 
 
      if (image == null) 
      { 
         Console.WriteLine("Sample: Can't retrieve image"); 
         return; 
      } 
 
      //If the image has more than one frame then we can call DicomDataSet.GetImages to get all the frames 
      using (DicomDataSet ds1 = new DicomDataSet()) 
      { 
         ds1.Initialize(DicomClassType.DXImageStoragePresentation, DicomDataSetInitializeType.ExplicitVRLittleEndian); 
         DicomElement pixelDataElement1 = ds1.FindFirstElement(null, DicomTag.PixelData, true); 
         if (pixelDataElement1 != null) 
         { 
            ds1.SetImage(pixelDataElement1, 
               image, 
               DicomImageCompressionType.None, 
               DicomImagePhotometricInterpretationType.Monochrome2, 
               16, 
               2, 
               DicomSetImageFlags.AutoSetVoiLut); 
            //If we have more than one frame then we can call DicomDataSet.SetImages 
 
            //This is an alternative way to set the image, I will first delete the 
            //existing image and then call DicomDataSet.InsertImage 
            ds1.DeleteElement(pixelDataElement1); 
            pixelDataElement1 = ds1.InsertElement(null, false, DicomTag.PixelData, DicomVRType.UN, false, 0); 
            ds1.InsertImage(pixelDataElement1, 
               image, 
               0, 
               DicomImageCompressionType.None, 
               DicomImagePhotometricInterpretationType.Monochrome2, 
               16, 
               2, 
               DicomSetImageFlags.AutoSetVoiLut); 
            //If we have more than one frame then we can call DicomDataSet.InsertImages 
 
            ds1.Save(Path.Combine(LEAD_VARS.ImagesDir, "DICOM", "Test.dcm"), DicomDataSetSaveFlags.None); 
 
         } 
      } 
      //Load DICOM File 
      ds.Load(dicomFileName, DicomDataSetLoadFlags.None); 
   } 
   DicomEngine.Shutdown(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
}
Requirements

Target Platforms

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