opaque. Personally I've no experience with DICOM images.
I don't think that you have to guess. You have to find out how your data
> Greetings,
>
> Thanks, but why is this being done? And more importantly how am I supposed to
> get the raw stored value in the DICOM dataset?
>
> Note: the positive values in both the signed and unsigned integers are
> logically and physically the same, i.e., no conversion. The negative signed
> values are physically the same as the large positive (>32768) unsigned values,
> conversion depends on why the logical and physical representations are
> different. In the case of MRI DICOM the values are positive and <10K, so no
> conversion (either signed/unsigned), thus no header values for conversion.
>
> The way the status line displays these values suggests to me that the raw and
> converted values are known to ImageJ. I'd prefer not to have to guess as to
> how the voxel values were manipulated.
>
> Thanks,
>
> Fred
>
> On Mon, August 6, 2018 2:25 am, Herbie wrote:
>> Good day Fred,
>>
>> this effect maybe due to signed and unsigned 16bit gray-scale.
>>
>> 2^15 = 32768;
>> 32768 + 4691 = 37359;
>>
>> HTH
>>
>> Herbie
>>
>> ::::::::::::::::::::::::::::::::::::::::
>> Am 06.08.18 um 05:51 schrieb Fred Damen:
>>> Greetings,
>>>
>>> When dealing with MRI DICOM datasets I am getting what I consider to be an
>>> incorrect value when fetching the voxel value using Java methods
>>> ImageProcessor::get(x,y) or getf(x,y). Case in point, when the status line
>>> on
>>> the main ImageJ window reads "... value = 4691.00 (37459)", the value
>>> returned
>>> by get/getf is 37459 and not the correct value of 4691.
>>>
>>> What is this second value and how do I fetch the correct value?
>>>
>>> These DICOM datasets should not contain voxel intensity scaling, and, the
>>> list
>>> of tag/values produced on the 'Info' page for one of the slices does not
>>> contain the tags: Rescale intercept, (0028|1052), and rescale slope
>>> (0028|1053). The raw data stored in the files are 16 bit signed integers:
>>> 0028,0100 Bits Allocated: 16
>>> 0028,0101 Bits Stored: 16
>>> 0028,0102 High Bit: 15
>>> 0028,0103 Pixel Representation: 1
>>> The values are always below 10K.
>>>
>>> The ImageJ image summary incorrectly indicates that the dataset is scaled:
>>> Calibration function: y = a+bx
>>> a: -32768.000000
>>> b: 1.000000
>>>
>>> but this scaling would not produce the second value on the status line given
>>> the correct value.
>>>
>>> Thanks in advance,
>>>
>>> Fred
>>>
>>> --
>>> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>>>
>>
>> --
>> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>>
>
>