[ITK] Color lookup table from dicom metadata

[Konrad Werys]

Hi Dženan,

This is exactly the information I needed, thank you very much!

Kind regards,
Konrad




On 5 January 2018 at 14:56, Dženan Zukić <dzenanz at gmail.com> wrote:

> Hi Konrad,
>
> the binary values in meta-data dictionary are encoded using base64 scheme.
> Once you fetch them from the dictionary, you should decode them. Here
> <https://stackoverflow.com/questions/43328520/base64-decoding-in-itk-4-7-for-dicom>
> is a similar question.
>
> Regards,
> Dženan
>
> On Fri, Jan 5, 2018 at 6:34 AM, Konrad Werys <konradwerys at gmail.com>
> wrote:
>
>> Hi,
>>
>> I need help in getting the Palette Color Lookup Table Data from dicom
>> using ITK and preferably GDCM.
>>
>> I want an array of values of PaletteColorLookupTableData from dicom (tags
>> 0028,1201 0028,1202 0028,1203 for red, green, blue, see
>> http://dicom.nema.org/medical/dicom/2016a/output/chtml/
>> part03/sect_C.7.9.html). The fields are OW type and are described by
>> Palette Color Lookup Table Descriptor (tags 0028,1101 0028,1102 0028,1103
>>  for red, green, blue) each with 3 pieces of information: how many entries
>> are in the field/what is the first value mapped/how many bits per entry (
>> http://dicom.nema.org/medical/dicom/2016a/output/chtml/part
>> 03/sect_C.7.6.3.html#sect_C.7.6.3.1.5).
>>
>> In dicom files I am working with, Red Palette Color Lookup Table
>> Descriptor 0028,1101 field equals to 4096/0/16, I can also correctly read
>> the Red Palette Color Lookup Table Data 0028,1201 in matlab and it has 4096
>> entries.
>>
>> I am reading Red Palette Color Lookup Table Data 0028,1201 as in the itk
>> example https://itk.org/Doxygen/html/Examples_2IO_2DicomImag
>> eReadPrintTags_8cxx-example.html
>> The length of the result string is 10924. The only explanation of this
>> length that I can think of is that the dicom field is of OW type (just like
>> pixel data), and the BitsAllocated 0028,0100 field is 16
>> and BitsStored 0028,0101 is 12. So 10924*12/16 = 8193 which is close to the
>> number of bytes I would expect. But when I try to decode the values this
>> way I am getting completely different numbers than the numbers from matlab.
>>
>> How can I get a nice array of values from Palette Color Lookup Table Data?
>>
>> All help will be appreciated.
>> Kind regards,
>>
>> --
>> Konrad Werys
>> http://mrkonrad.github.io <http://mrkonrad.github.io/MRKonrad/>
>>
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>


-- 
Konrad Werys
http://mrkonrad.github.io <http://mrkonrad.github.io/MRKonrad/>
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