LDicomDS::GetImage

Summary

Loads the image of a Pixel Data element into a BITMAPHANDLE.

Syntax

L_UINT16 LDicomDS::GetImage(pElement, pBitmap, uStructSize, nIndex, nBitsPerPixel, uFlags, pfnCallback, pUserData)

Parameters

pDICOMELEMENT pElement

Pointer to a DICOMELEMENT structure within the Data Set.

pBITMAPHANDLE pBitmap

Pointer to the image handle that references the loaded image.

L_UINT uStructSize

Size in bytes, of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE).

L_UINT32 nIndex

Index value that indicates which frame in a Pixel Data element to load.

L_INT32 nBitsPerPixel

Resulting image pixel depth. The following are valid values:

L_UINT uFlags

Flags which control the behavior of this function:

FILEREADCALLBACK pfnCallback

Optional callback function for additional processing. If you do not provide a callback function, use NULL as the value of this parameter. If you do provide a callback function, use the function pointer as the value of this parameter.

The callback function must adhere to the function prototype described in FILEREADCALLBACK Function.

L_VOID *pUserData

Void pointer that you can use to pass one or more additional parameters that the callback function needs.

To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID  *. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure. If the additional parameters are not needed, you can pass NULL in this parameter.

Returns

Comments

Updates the BITMAPHANDLE structure with ONLY data pertaining to the image.  This means that fields such as XResolution and YResolution, will not be updated or will be set with default values.

If pElement is NULL, this function will load any image within the file, based on the nIndex parameter.

If DICOM_GETIMAGE_ALLOW_RANGE_EXPANSION is set in uFlags, note the following example:

For the following dataset attributes:

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) cannot be represented with the current bits stored (12 bits), which can represent values in the range (2048 to 2048). In this case the function will change the high bit inside the image handle to be 12 instead of 11 (bits stored becomes 13), which can represent values in the range (8192 to 8191).

The function cannot update the high bit and/or low bit if the number of bits stored is 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:

(0028,9145) Pixel Value Transformation Sequence Child Elements:

For a detailed discussion on Multi-frame Functional Groups and how the DICOM_SET_IMAGE_MFG flags are used, see the topic Multi-frame Functional Groups.

Required DLLs and Libraries

• LTDIC
• For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application

Platforms

Win32, x64

See Also

Functions

• LDicomDS::GetCountImage
• LDicomDS::GetImageList
• LDicomDS::GetLoadFileFlags
• LDicomDS::SetLoadFileFlags

Topics

• Working with Data Sets
• How to Disable the Automatic Loading of the default DICOM IOD Table

Example

This example fills a bitmap with an image from the Data Set.

L_INT LDicomDS_GetImageExample() 
{ 
   L_INT          nRet; 
   LDicomDS      *pDS; 
   pDICOMELEMENT  pElement; 
   BITMAPHANDLE   Bitmap; 
 
   pDS = new LDicomDS(NULL); 
 
   nRet = pDS->LoadDS(MAKE_IMAGE_PATH(TEXT("image1.dcm")), 0); 
   if(nRet != DICOM_SUCCESS) 
      return nRet; 
 
   pElement = pDS->FindFirstElement(NULL, TAG_PIXEL_DATA, FALSE); 
   if (pElement != NULL) 
   { 
      nRet = pDS->GetImage(pElement, &Bitmap, sizeof(BITMAPHANDLE), 0, 0, DICOM_GETIMAGE_AUTO_APPLY_MODALITY_LUT| 
         DICOM_GETIMAGE_AUTO_APPLY_VOI_LUT, NULL, NULL); 
      if(nRet != DICOM_SUCCESS) 
         return nRet; 
 
      L_FreeBitmap(&Bitmap); 
   } 
 
   delete pDS; 
 
   return DICOM_SUCCESS; 
}