L_DicomGetImage

Summary

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

Syntax

L_LTDIC_API L_UINT16 L_DicomGetImage(hDS, pElement, pBitmap, uStructSize, nIndex, nBitsPerPixel, uFlags, pfnCallback, pUserData)

Parameters

HDICOMDS hDS

A DICOM handle.

pDICOMELEMENT pElement

Pointer to a DICOMELEMENT structure within the Data Set.

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the loaded bitmap.

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 get. To get the last image in the Pixel Data element, use ELEMENT_INDEX_MAX

L_INT32 nBitsPerPixel

Resulting bitmap pixel depth. Possible values are:

L_UINT uFlags

Flags which control the behavior of this function. Possible values are:

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

L_DicomGetImage will only update the BITMAPHANDLE structure with data pertaining to the image. Therefore, some fields, such as XResolution and YResolution, will not be updated or will be updated 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 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 only represent values in the range (2048 to 2048). In this case the function will change the high bit inside the bitmap handle to be 12 instead of 11 (bits stored becomes 13), which can represent values in the range (8192 to 8191).

L_DicomGetImage 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:

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, Linux.

See Also

Functions

• L_DicomGetCountImage
• L_DicomGetImageList

Topics

• Working with Data Sets

Example

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

L_INT DicomGetImageExample(L_VOID) 
{ 
   HDICOMDS      hDS; 
   pDICOMELEMENT pElement; 
   BITMAPHANDLE  Bitmap; 
   L_UINT16 nRet; 
 
   hDS = L_DicomCreateDS(NULL); 
 
   nRet = L_DicomLoadDS(hDS, MAKE_IMAGE_PATH(TEXT("Image1.dcm")), 0); 
   if (nRet != DICOM_SUCCESS) 
   { 
      L_DicomFreeDS(hDS); 
      return nRet; 
   } 
 
   pElement = L_DicomFindFirstElement(hDS, NULL, TAG_PIXEL_DATA, FALSE); 
   if (pElement != NULL) 
   { 
      nRet = L_DicomGetImage(hDS, 
         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); 
   } 
 
   L_DicomFreeDS(hDS); 
   return DICOM_SUCCESS; 
}