<div>Hi Kajetan, </div>
<div> </div>
<div>You were right. I did find that the range is not from - 16686 (MRIcro histogram came up with this value, not sure why). Looking through the data I see that its actually [-1000, 3000]. However, reading directly from DICOM series, I still got [0, 4094], but reading Analyze file (converted by MRIcro) gave the correct value.
<br> </div>
<div>What is HU scale? Maybe I should use this information to render the images.</div>
<div> </div>
<div>Thanks a lot, that's very helpful.</div>
<div> </div>
<div>- xin<br> </div>
<div><span class="gmail_quote">On 8/14/06, <b class="gmail_sendername">Kajetan Berlinger</b> <<a href="mailto:kaje@kaje.info">kaje@kaje.info</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hi Xin,<br><br>On Monday 14 August 2006 08:05, Xin Guan wrote:<br>> Hi,<br>><br>> I'm using ITK image IO to read images. MRI images are okay, but CT images
<br>> -- no matter it's DICOM or converted Analyze files -- always gave some<br>> weird images. The actual pixel value range is -16330 to 3000, but the<br>> loaded image has a range of 0 to 4094.<br><br>A range from -16330 to 3000 ist not possible, as the intensity value of a CT
<br>voxel is represented by 12 bit. That is from 0 to 4095 or with respect to<br>the HU scale -1023 to 3072.<br>How do you come to this -16330 to 3000 value range?<br>Is there perhaps a pixel padding value defined?<br>This value is stored in DicomTag (0028,0120).
<br>If the image is non-rectangular, this value marks pixels used to pad to<br>rectangular format.<br><br>> It seems that part of the negative<br>> values were simply negated to positive. The error remains the same<br>
> regardless of the pixel type specified -- signed short or float.<br>><br>> I followed ITK example DicomSeriesReadSeriesWrite and Image2 (<br>> itk::ImageFileReader).<br>><br>> I'd appreciate any help on this. Thanks in advance.
<br>><br>> - xin<br><br>cu<br>kaj<br>_______________________________________________<br>Insight-users mailing list<br><a href="mailto:Insight-users@itk.org">Insight-users@itk.org</a><br><a href="http://www.itk.org/mailman/listinfo/insight-users">
http://www.itk.org/mailman/listinfo/insight-users</a><br></blockquote></div><br>