[Dcmlib] Image conversion

[Jean-Pierre Roux]

olivier.stern at swing.be wrote:

>
> Hello,
>
>  
>
> I have a little trouble converting images. I got DICOM images with 16 
> bits allocated, 12 bits stored and 11 as high bit. I'd like to change 
> them to 8 bits allocated, 8 bits stored and 7 as high bit.
>
>  
>
> What I've done first was taking the highest value of pixels on one 
> image and the lowest, and made a conversion to value between 0 and 255 
> (thanks to Jean-Perre Roux). But this conversion wasn't the same from 
> one image to another because the highest value and the lowest change.
>
You have first to retrieve the maximum maximorum and the minimum 
minimorum for the whole serie, and use those *two* values to rescale 
*all* the images.

> What I need is a constant conversion so what I 've done is: as the 
> highest theoric value that a file with 12 bits stored can take is 4095
>
Probabely, the actual maximum pixel value is much less than 4095 (that's 
the highest possible value on 12 bits, not the max value held in the images)
Jean-Pierre.

> and a file with 8 bits stored is 255, all pixels of the original 
> images were devised by 16 (4096/256 = 16). But the output image was 
> very dark, either deleting 0x0028,0x1050 and 0x0028,0x1051. If I 
> devise by 4 I get a relatively good result but I can't say why. Could 
> anyone explain me if what I m doing is correct?
>
> Olivier
>
>  
>
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Dcmlib mailing list
>Dcmlib at creatis.insa-lyon.fr
>http://www.creatis.insa-lyon.fr/mailman/listinfo/dcmlib
>