problem with reading MRI image (dicom)

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D C
D C 2012-12-19
回答： abdalla gad 2015-6-24
I use dicomread function and then the matrix seems to be ok(includes numbers >0), but when i want to display image using imshow function matlab always displays black background. I didn't have this problem with CT images. Did you have any problems like that?

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采纳的回答

Matt Kindig
Matt Kindig 2012-12-19
Hi D C,
It's probably just a display issue. When using imshow, try setting the DisplayRange to autoscale, i.e.
imshow( DICOM_Matrix, 'DisplayRange', []);
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D C
D C 2012-12-19
It works! Thank you! But could you explain why this parameter 'DisplayRange' was needed?
Image Analyst
Image Analyst 2012-12-19
It's not - you can use just [] alone. See my answer below.

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更多回答（4 个）

Image Analyst
Image Analyst 2012-12-19
You probably have a uint16 image and are only using a small fraction of the 65535 allowable gray levels. If you don't specify a display range, it will put 0 to 0 on the display, and 65535 to 255 on the display (255 is the most an 8/24/32 bit color display can display). So if your max value is, say, 3000, it will show up as 3000/65535*255 = 12 gray levels and will be very dark - practically invisible. To have it autoscale so that the 3000 will get mapped to 255, use [], like this:
imshow(yourImageArray, []);
This will also work for floating point (single, double) images, which normally will show up as all white because it expects floating point images to be in the range 0-1. Do this and tell me what it says:
whos yourImageArray
max(yourImageArray(:)) % Don't use a semicolon
min(yourImageArray(:))
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D C
D C 2012-12-19
编辑：D C 2012-12-19
MRI has a range 0-50 and CT has a range -2260 to 2467, so I guess I'm unable in this case to compare/fuse images?
Image Analyst
Image Analyst 2012-12-19
Why not? Why can't you just scale them with mat2gray()?

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D C
D C 2012-12-20
I meant I have to convert one of them. Thank you for all your help! That was pretty useful!
Wes
Wes 2013-4-9
Hi there,
It seems like I have a similar problem with reading DICOMs. I have stored T2* maps in DICOM files (it is a long scan, so I have about 240 time points of each map). Matlab reads it in such a strange way, windowing however it's pleased ;-) For me, the important bit is to retain the actual voxel value when I read in images, so absolutely no scaling can be done by Matlab. Any idea how to achieve that?
Thanks!
abdalla gad
abdalla gad 2015-6-24
hi.. plz i want to have code for read 3d mri dicom files

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