I'm trying to work with CT DICOM images and would like my images to show HU. At the moment its showing intensities from 0-2099, however it says that the 'rescale type' is HU. Air should be a negative number so how can I rectify this situation?

The image definitely has air in it, therefore it should be in the negatives? I'm not sure what's wrong with this. Is there a way I can convert it so that imtool shows the proper HU values? Any help is greatly appreciated thanks!!

[Walter Roberson]

You should be multiplying the values by the RescaleSlope, and then adding the RescaleIntercept. The slope is 1 so that leaves the values unchanged, by the intercept is -1024 which can lead to negative values.

[Jamie Szabo]

info = dicominfo('File 60.dcm');
disp(info);
Y = dicomread(info);
b = info.RescaleIntercept;
m = info.RescaleSlope;
HU = m.*Y+b;
disp(HU);
% %Shows it with the toolbar
imtool(Y,[]);

This is what my code begins with. The values wont go below zero, however they do go higher if i alter the equation. Is there something im missing? Thanks for your help!

[Walter Roberson]

don't forget to double(Y) as it might be uint16

[Jamie Szabo]

Oh yes, thanks walter! How can I replace these values with the new ones for 260 different dicom images?

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F