[Dcmlib] CT-MONO2-16-chest.dcm / Pixel Padding Value

[Mathieu Malaterre]

Hello,

	Could someone comment on the use of Pixel Padding Value ? I don't think 
that gdcm is using it. But if one open CT-MONO2-16-chest.dcm there does 
not seems to be anything wrong...

	What it is supposed to do ?

Thanks,
Mathieu

C.7.5.1.1.2 Pixel Padding Value
Pixel Padding Value (0028,0120) is used to pad non-rectangular images to 
rectangular format.
The native format of some images is not rectangular. It is common for 
devices with this format to
pad the images to the rectangular format required by the DICOM Standard 
with a specific pixel
value that is not contained in the native image. This attribute 
specifies the value of this padding
value.
Notes: 1. When the relationship between pixel value and X-Ray Intensity 
is unknown, it is
recommended that the following values be used to pad with black:
0 if Photometric Interpretation (0028,0004) is MONOCHROME2.
2BitsStored
- 1 if Photometric Interpretation (0028,0004) is MONOCHROME1.
2. When the relationship between pixel value and X-Ray Intensity is 
known (for example as
defined by Pixel Intensity Relationship (0028,1040) and Pixel Intensity 
relationship Sign
(0028,1041)), it is recommended that a value equivalent to air be used.
When modifying equipment changes the pixel padding value in the image, 
it shall change the
value of Pixel Padding Value (0028,0120).


and according to:

http://www.cms-stl.com/products/rtp/dicom/dicom_conform_ver_3_0.htm
If the DICOM header for a 16 bit CT image file defines a pixel padding 
value, XiO will convert all pixels equal to that padding value to the 
minimum pixel value representable by the data type of that image. It is 
assumed that the CT manufacturer has selected a padding pixel value that 
is outside the range of the pixel values that make up the image.