[Dcmlib] Signed Images

[Mathieu Malaterre]

you're the boss ! I don't think opengl is giving you access to the 
scalar range, I believe it always assume texture are [0,1]

Anyway he fastest ever solution would still be reading the value from 
the DICOM tags, by any chance do you have those values in your images ?

Mathieu

On Jun 14, 2005, at 12:07 PM, Aris Basic wrote:

> applying it to the image in fastes possible way :)
> and correspodning formula is why i went towards OpenGL (should allowe 
> me to use GPU to do it)
> dont get how VTK adn some other libraries do it very fast withouth GPU 
> :(
>
>
> Mathieu Malaterre wrote:
>
>> For the window/level is is pretty easy:
>>
>> double range[2];
>> my_function(range, image);
>> // range now contains the pixel value min and pixel value max.
>>
>> level = (range[1]+range[0] )/2
>> window = range[1]-range[0]
>>
>> In theory there is a window/level tag in DICOM but I don't trust them 
>> :P
>>
>> HTH
>> Mathieu
>>
>> On Jun 14, 2005, at 11:38 AM, Aris Basic wrote:
>>
>>> I have some of my images havnot tested it with gdcm provided images 
>>> will probably do it and compare with vtkgdcmViewer.
>>> IM trying to display them with OpenGL (creating and RECT texture 
>>> from pixel data [ opengl supposedly shoudl be able to
>>> deal with signed pixel data , but doesnt look like its doing )
>>> (i tryed too figgure out how is VTK donig the W/L transfomration and 
>>> rest but did not have luck finding that piece of code quickly :)
>>>
>>>
>>> Jean-Pierre Roux wrote:
>>>
>>>> Aris Basic wrote:
>>>>
>>>>> is gdcm doing any conversion on pixel data from signed 
>>>>> (pixelrepresentation == 1) images ?
>>>>> pixelrepresentation == 0 images i can display nicely but 
>>>>> representation 1 they come up strange :(
>>>>
>>>>
>>>>
>>>>
>>>> gdcm doesn't make any transformation for 'signed pixels'.
>>>> It's up to the user to deal with the sign.
>>>> How do you display the image?
>>>> Did you try with vtkgdcmViever? (of course, you need VTK ...)
>>>>
>>>> In our test data set ( gdcmData), there are a few 'signed pixels' 
>>>> images :
>>>>
>>>> MR-MONO2-16-head.dcm CT-MONO2-16-chest.dcm
>>>> CT-MONO2-16-ankle.dcm  CT-MONO2-16-ort.dcm
>>>> CT-MONO2-16-brain.dcm
>>>> GE_RHAPSODE-16-MONO2-JPEG-Fragments.dcm 
>>>> GE_GENESIS-16-MONO2-Uncompressed-UnusualVR.dcm
>>>> GE_GENESIS-16-MONO2-WrongLengthItem.dcm 
>>>> PICKER-16-MONO2-No_DicomV3_Preamble.dcm
>>>> 012345.002.050.dcm
>>>>
>>>> Did you try to display them?
>>>> HTH.
>>>>
>>>> Jean-Pierre
>>>>
>>>>>
>>>>> jsut trying to find a bug :) not pointing fingers
>>>>
>>>>
>>>>
>>>> Thx for reporting it.
>>>> Could you send us one of your images, so we can check 'at home' if 
>>>> there is any problem.
>>>>
>>>>>
>>>>>
>>>>> Aris
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>>>>>
>>>
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>>
>