[转]DICOM图像显示时文件里的VOILUT和WINDOWCENTER/WIDH同用户手工调节窗宽窗位之间的关系

IHE Radiology
Technical Framework Volume 2

4.16.4.2.2.1 Display of Digital X-Ray, Mammo and Intra-Oral
Images

For the “For Presentation” variant of the Digital X-Ray Image, the
Digital Mammography

Image, and the Digital Intra-oral X-Ray Image, the Image Display or
Imaging Document

Consumer actor shall have both the capability to apply all the
transformations specified by the

VOI LUT Sequence (0028,3010) and the capability to apply all the
transformations specified by

the Window Width (0028,1051)/Window Center (0028,1050)/VOI LUT
Function (0028,1056)

attributes in the DX Image Module as selected by the user from the
choices available (e.g.,

guided by Window Center/Width Explanation (0028,1055) or LUT
Explanation(0028,3003).

If VOI LUT Function (0028,1056) is absent, then Window Width
(0028,1051)/Window Center

(0028,1050) shall be assumed to be the parameters of a linear
window operation. VOI LUT

Function (0028,1056) values of “SIGMOID” and “LINEAR” shall be
supported.

The Image Display or Imaging Document Consumer shall support the
application of LUT Data

(0028,3006) in items of the VOI LUT Sequence (0028,3010) regardless
of the Value

Representation (i.e., the DICOM standard allows either OW or US
Value Representation).

The Image Display or Imaging Document Consumer actor must also
support pixel rendering

according to the Grayscale Standard Display Function (GSDF) defined
in DICOM 2009 PS 3.14,

because the output values of these images are always
P-Values.

If the DICOM image is referenced by other DICOM composite objects,
such as Grayscale

Softcopy Presentation States, it is optional for the Image Display
or Imaging Document

Consumer to actually retrieve and display/apply these objects.

4.16.4.2.2.1.1.4 Image Contrast Adjustment

As described in 4.16.4.2.2.1 Display of Digital X-Ray, Mammography
and Intra-Oral Images,

the Image Display shall provide the user with the ability to select
amongst the available window

and VOI LUT choices available in the image object.

Subsequent to the initial application of the chosen contrast
transformation, the Image Display

actor shall allow the user to adjust the contrast without reverting
to a purely linear

transformation:

　　If the chosen
contrast transformation is a lookup table, then the Image Display
shall allow the

input value of the lookup table to be stretched and translated so
as to give the affect of

adjusting contrast and brightness whilst applying the same general
shape as the curve

encoded in the lookup table. To provide feedback to the user, the
“window width” can be

reported as the adjusted range of input values to the LUT, and the
“window center” can be

reported as the center value of that range.

　　If the chosen contrast
transformation is a sigmoid shaped VOI LUT Function
parameterized

by the window center and width, then the Image Display shall allow
the window center and

width values to be adjusted and a sigmoid function reapplied.

If a Pixel Padding Value (0028,0120) only is present in the image
then image contrast

manipulations shall be not be applied to those pixels with the
value specified in Pixel Padding

Value (0028,0120).

If both Pixel Padding Value (0028,0120) and Pixel Padding Range
Limit (0028,0121) are present

in the image then image contrast manipulations shall not be applied
to those pixels with values in

the range between the values of Pixel Padding Value (0028,0120) and
Pixel Padding Range

Limit (0028,0121), inclusive.