LDicomDS::GetImage

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#include "Ltdic.h"

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

pDICOMELEMENT pElement;

/* pointer to a DICOMELEMENT structure */

pBITMAPHANDLE pBitmap;

/* pointer to the image handle */

L_UINT uStructSize;

/* size in bytes, of the structure pointed to by pBitmap */

L_UINT32 nIndex;

/* index value */

L_INT32 nBitsPerPixel;

/* resulting image pixel depth */

L_UINT uFlags;

/* flags */

FILEREADCALLBACK pfnCallback;

/* optional callback function */

L_VOID *pUserData;

/* pointer to more parameters for the callback */

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

Parameter

Description

pElement

Pointer to a DICOMELEMENT structure within the Data Set.

pBitmap

Pointer to the image handle that references the loaded image.

uStructSize

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

nIndex

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

nBitsPerPixel

Resulting image pixel depth. The following are valid values:

 

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

 

uFlags

Flags which control the behaviour of this function:

 

Value

Meaning

 

DICOM_GETIMAGE_AUTO_LOAD_OVERLAYS

[0x0001] If set, the function will automatically extract the overlays included in the dataset and add them to the loaded image.

 

DICOM_GETIMAGE_AUTO_APPLY_MODALITY_LUT

[0x0002] If set, the function will automatically apply the "Modality LUT" when loading the image.

 

DICOM_GETIMAGE_AUTO_APPLY_VOI_LUT

[0x0004] If set, the function will automatically apply the "VOI LUT" when loading the image.

 

DICOM_GETIMAGE_ALLOW_RANGE_EXPANSION

[0x0008] (Deprecated, do not use) If set, the function will adjust the high bit and/or low bit (if possible) inside the image handle in order to hold the range of pixel values after applying the modality LUT.
 

DICOM_GETIMAGE_AUTO_SCALE_MODALITY_LUT

[0x0010] If set, the function will scale the resulting pixel data to fit within the range of 0 to 2^BitsPerPixel-1 if any of the values would exceed that range.
 

DICOM_GETIMAGE_AUTO_SCALE_VOI_LUT

[0x0020] Only used in conjuction with DICOM_GETIMAGE_AUTO_SCALE_MODALITY_LUT. If set, the function will rescale the VOI LUT to match the rescale that was performed by DICOM_GETIMAGE_AUTO_SCALE_MODALITY_LUT.

 

DICOM_GETIMAGE_AUTODETECT_INVALID_RLE_COMPRESSION

[0x0040] For RLE compressed, automatically detects if the MSB and LSB segments are written in the incorrect order.

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.

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

0

SUCCESS

>0

An error occurred. Refer to Return Codes.

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:

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) 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

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 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

Topics:

Working with Data Sets

 

How to Disable the Automatic Loading of the default DICOM IOD Table

Example

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

#define MAKE_IMAGE_PATH(pFileName) TEXT("C:\\Users\\Public\\Documents\\LEADTOOLS Images\\")pFileName
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;
}
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