[Dcmlib] PixelPaddingValue

[Aris Basic]

It coudl be also that im reading this wrong :)
what i would like to have is the pixels with padding value to become 0 
(black) ;)
maybe im expecting wrong things :(


Aris Basic wrote:

> Dono i just think it would be probably easier for gdcm lib to do the 
> chanegs like pixelpadding and conversion from signed to unsigned pixel 
> data this is what i ment with std (Notes):
>
> 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.
>
> btw when newer gdcm give out message that pixeldata has to bin 
> downshift what actualy happens ?
> (was looking at gdcm code but i all i've seen is the printing of the 
> Warn message).
> (i noticed that with JPEG Lossless compresed 12bit images (packed in 
> 16) i personaly have to multiply each pixel value with 256 (16*16)
> and for LEI images its enoigh to multiply it by 16 (in order to adjust 
> its 12bit range value in 16bit space)
> (at least that gives me results (on display) comparable to other dicom 
> viewer [efilm,...] ))
>
> Aris
>
>
> Jean-Pierre Roux wrote:
>
>> Aris Basic wrote:
>>
>>> Just a question shouldnt  gdcm replace PixelPadding value with the 
>>> either black or something else (according do DICOM std) ?
>>
>>
>>
>> Hi, Aris.
>> What do you mean by "according do DICOM std"?
>>
>> The PPV (0028,0120) is used mostly to fill in the corners of round 
>> images , just to tell the user no to loose time making computations 
>> on those meaningless pixels . Any pixels in the image that have this 
>> value are not to be treated as meaningful objects - but as background 
>> color.
>>
>> It's up to the user to deal with this information, don't you think so?
>>
>> Well ...
>> Probabely 'vtkgdcmViewer' doesn't deal with it, that can be a problem 
>> if the PPV is a  very high value (image will be displayed very dark, 
>> the first time)
>> But vtkgdcmViewer is just a little (*very* usefull, but little) tool 
>> , side of gdcm.
>>
>> Jean-Pierre
>>
>>>
>>> Aris
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>
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