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File validation and characterisation.
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Incorret JHOVE Error „FocalPlaneResolutionUnit value out of range: 5“ #387

Open rolandsuri opened 5 years ago

rolandsuri commented 5 years ago

Dev Effort

5D

Description

A value of five in the field "FocalPlaneResolutionUnit" is correct, as it follows the latest standard. According to the actual TIFF/EP-specification (ISO 12234-2:2001), the FocalPlaneResolutionUnit is a SHORT with values 1,2,3,4, or 5. In the documentation of Aware Systems, only the values 1,2, or 3 were allowed. The TIFF/EP-specifikation is newer and is referenced in the Module Info of TIF-hul. The TIFF/EP-specification also makes more sense: The 5 stands for Micrometer. As the optical imaging chips became smaller, the imager resolution can also me stated in terms of number of pixels per micrometer.

tledoux commented 5 years ago

In fact, the problem is more complex because there is two specifications !!! The TIFF/EP specifies the tag 37392 (named "FocalPlaneResolutionUnit") with 5 values but the EXIF specifies the tag 41488 (also named "FocalPlaneResolutionUnit") with only 3 values !!!

This fact is very confusing and the files I have seen seem to indicate that many manufacturers don't respect the specifications or fill the tags erroneously... I try to come up with a list of values mostly compatible with the two spec. and consistent with the implementations...

MartinSpeller commented 4 years ago

Incorret JHOVE Error „FocalPlaneResolutionUnit value out of range: 5“ #387 - Assigned to TBA

marhop commented 3 years ago

Just FTR, something has changed here in the meanwhile: I have a TIFF file with a FocalPlaneResolutionUnit value of 4. JHOVE 1.20 complains, JHOVE 1.24 does not. (Also FTR: ExifTool recognizes value 4 in tag ExifIFD:FocalPlaneResolutionUnit (41488) as "mm".)