In This Topic ▼

LDicomDS::GetWindow

Summary

Retrieves the attributes that describe window center and window width.

Syntax

#include "ltdic.h"

L_UINT16 LDicomDS::GetWindow(uFrameIndex, uWindowIndex, pWindowAttributes, uStructSize, uFlags)

Parameters

L_UINT32 uFrameIndex

A zero-based index that identifies the frame number in the dataset. If the dataset does not support Multi-frames, this parameter is ignored.

L_UINT uWindowIndex

Index to the window center, window width value to be retrieved. According to the DICOM standard if multiple values are present for the window center and window width, both attributes shall have the same number of values and shall be considered as pairs. This index is zero-based.

pDICOMWINDOWATTRIBS pWindowAttributes

Pointer to a structure to be updated with the window-related attributes.

L_UINT uStructSize

Size of the DICOMWINDOWATTRIBS structure. Pass sizeof(DICOMWINDOWATTRIBS).

L_UINT uFlags

Reserved for future use. Pass 0.

Returns

Value	Meaning
0	The function was successful.
> 0	An error occurred. Refer to Return Codes.

Comments

This function will retrieve the attributes that describe window center and window width and store their values in the structure pointed to by pWindowAttributes.

pWindowAttributes->uStructSize will be set to the value of the parameter uStructSize.

"Window Center" (0028,1050) and "Window Width" (0028,1051) specify a linear conversion from stored pixel values (after any modality LUT or rescale slope and intercept specified in the IOD have been applied) to values to be displayed. Please see "VOI LUT Module Attributes" in the DICOM standard for more details.

This function will fail and return DICOM_ERROR_PARAMETER if the window count (number of values under the window center element) equals 0 or if uWindowIndex is greater or equal to the window count.

uWindowIndex is zero-based, if you pass 0 for example this function will populate pWindowAttributes->fWindowCenter with the first value under the "Window Center" (0028,1050) element, pWindowAttributes-> fWindowWidth with the first value under the "Window Width" (0028,1051) element and pWindowAttributes->pszWindowCWExplanation with "Window Center & Width Explanation" (0028,1055) element if it exists.

The Multi-frame Functional Groups module may have a Shared Functional Groups Sequence item, and/or a Per-frame Functional Groups Sequence item. Either of these items may have a Frame VOI LUT Sequence (0028,9132) item. If the following elements are not found at the top level in the dataset, this function looks in the Shared Functional Groups Sequence item and the Per-frame Functional Groups Sequence items.

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

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.