[Insight-users] Problem with pixel representation type

[soumend at magnum.barc.ernet.in]

HI !!!!!

I have developed a dicom image viewer which will read the dicom image using 
ITK and displayed through VTK. Still I have some dought in this regard.will 
anybody help me out? 

i) Though the pixel representation field of CT image shows 0 (i.e unsigned 
char),the image is properly displayed when pixel type is taken as signed char. 
Whereas PET image has pixel representation 1 behaves good with signed char 
pixel type as it should be. Why the discrepency is there for CT image?

ii) In the DICOMApphelper the pixel is read as unsigned char for CT image and 
as float in the case of PET image (due to rescale slope and offset values). 
But in my program i have defined  the pixel type of input image as signed 
char. My question ....though the pixel values are read differently still 
images get displayed doesnt matter what is the input pixel type. Why is it so?

iii) the range of pixel value is different for CT and Pet images ...now to 
read from a single interface how can i set the pixel range dynamically in the 
look up table(it is VTK related qs ..still)?
(resaolution of CT images are much better than PET images) 
    


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