Dicomread changes pixel values!
in [Matlab]
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From: Saman on 1 Jun 2010 19:02 "Ida Haggstrom" <ida_haggstrom(a)yahoo.se> wrote in message <gcv0j1$rjg$1(a)fred.mathworks.com>... > Hi! > I have a problem with DICOMREAD. I have a dynamic PET data set (medical), with pixel values above 16 bit. When I read the DICOM file into Matlab, using DICOMREAD, this changes the pixel values of the images, probably because it can't handle pixel values above 2^16. If I study one pixels value dynamically, the intensity as a function of time is completely different from what it should be! > Has anyone encountered this problem, and found out how to get around it? Is there another way to read DICOM images into Matlab without using DICOMREAD? Thanks! > /Ida Hi Ida, Did you by any chance figure out why dicomread changes the pixel values and what to do about it? Thanks, Saman
From: Jeff Mather on 2 Jun 2010 14:22 Saman wrote: > "Ida Haggstrom" <ida_haggstrom(a)yahoo.se> wrote in message > <gcv0j1$rjg$1(a)fred.mathworks.com>... >> Hi! >> I have a problem with DICOMREAD. I have a dynamic PET data set >> (medical), with pixel values above 16 bit. When I read the DICOM file >> into Matlab, using DICOMREAD, this changes the pixel values of the >> images, probably because it can't handle pixel values above 2^16. If I >> study one pixels value dynamically, the intensity as a function of >> time is completely different from what it should be! Has anyone >> encountered this problem, and found out how to get around it? Is there >> another way to read DICOM images into Matlab without using DICOMREAD? >> Thanks! >> /Ida > > Hi Ida, > > Did you by any chance figure out why dicomread changes the pixel values > and what to do about it? > > Thanks, > Saman Saman and Ida, I don't think this is the intended behavior of DICOMREAD, which is supposed to give back the data exactly as it's stored in the Pixel/Instance Data field of the DICOM file. If one of you are able to send me a file containing data that you feel is read incorrectly, I will investigate it. Jeff
From: Saman on 2 Jun 2010 19:30
Jeff Mather <jeff.mather(a)mathworks.com> wrote in message <4C06A168.6030609(a)mathworks.com>... > Saman wrote: > > "Ida Haggstrom" <ida_haggstrom(a)yahoo.se> wrote in message > > <gcv0j1$rjg$1(a)fred.mathworks.com>... > >> Hi! > >> I have a problem with DICOMREAD. I have a dynamic PET data set > >> (medical), with pixel values above 16 bit. When I read the DICOM file > >> into Matlab, using DICOMREAD, this changes the pixel values of the > >> images, probably because it can't handle pixel values above 2^16. If I > >> study one pixels value dynamically, the intensity as a function of > >> time is completely different from what it should be! Has anyone > >> encountered this problem, and found out how to get around it? Is there > >> another way to read DICOM images into Matlab without using DICOMREAD? > >> Thanks! > >> /Ida > > > > Hi Ida, > > > > Did you by any chance figure out why dicomread changes the pixel values > > and what to do about it? > > > > Thanks, > > Saman > > > Saman and Ida, > > I don't think this is the intended behavior of DICOMREAD, which is > supposed to give back the data exactly as it's stored in the > Pixel/Instance Data field of the DICOM file. > > If one of you are able to send me a file containing data that you feel > is read incorrectly, I will investigate it. > > Jeff Thank you so much Jeff for your help. Here is the solution (for everyone's benefit): X = dicomread('the file name'); meta = dicominfo('the file name'); Y = X * meta.RescaleSlope + meta.RescaleIntercept; Y will now have the scaled pixel values. Thanks again. Saman |