[Dcmlib] Re: some bugs with 'MONOCHROM1 ' and 'MONOCHROM2 '

[Jean-Pierre Roux]

> Dennis,
>
> 	I am really suspicious. I only know one image that had odd lenght, and
> it was an image written by an old gdcm version. Two options here:
>

--> Mathieu :
Actually, there is a lot of DICOM images with odd length for some fields
(not only old gdcm version written images ...)
Of course, it's a violation of DICOM rules, but who cares about DICOM
rules :-(

> - Can you send me the DICOM image (what are the right on the image,
> license ?)
>
> - If you are not allowed to send this image, please send me the output
> of PrintHeader:

--> Mathieu : I'm afraid the result of PrintHeader will not give very
usefull information, because a recent commit (you did it) returns now an
even length string (when it's odd length on disk) and displays an even
length ...

--> Dennis :
Could you send us (to dcmlib) an image that causes the problem (Well, the
image doesn't cause any problem. gdcm does ...)
You can anonymyse it with any hexadecimal editor, replacing the patient's
name by spaces.
Anyway, I think your suggestion for a 'strong' way of comparing the
strings is a good idea. Thank you.

Jean-Pierre Roux

>
> You have to execute:
> $ ./bin/PrintHeader ~/Creatis/gdcmData/test.acr
>
> Thanks
> Mathieu
>
> derong wrote:
>> Hi, Mathieu
>>
>> It seems i have found a serious bug after i do some testing.
>>
>> In the file gdcmHeader.cxx, there are some codes as follows:
>>
>>  // beware of trailing space at end of string
>>    // DICOM tags are never of odd length
>>    if ( strPhotometricInterpretation == GDCM_UNFOUND   ||
>>         strPhotometricInterpretation == "MONOCHROME1 " ||
>>         strPhotometricInterpretation == "MONOCHROME2 " )
>>    {
>>       return 1;
>>    }
>>
>> there is a space added to the tail of "MONOCHROM1 " and "MONOCHROM2 ".
>> I have read some file that there is no space added the tail, that will
>> cause crash when we set component number to 3.
>>
>> I think that component number is important to read DICOM file, we can
>> not just set it to 3 if we can not identify it.(it is dangerous to
>> do memcpy)
>>
>> And we can compare the string value by following.
>>
>> std:string strPINoSpace(strPhotometricInterpretation, 0,
>> strPhotometricInterpretation.find_first(' '));
>>
>> if ( strPhotometricInterpretation == GDCM_UNFOUND   ||
>>      strPINoSpace  == "MONOCHROME1" ||
>>      strPINoSpace == "MONOCHROME2" )
>>    {
>>       return 1;
>>    }
>>
>> I think that is more robust. maybe that dicom file violates the DICOM
>> conformance."DICOM tags are never of odd length".
>>
>> How do you think about it?
>>
>> thx,
>>
>> Dennis
>>
>>
>
>
>
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