I have a question about understanding the default values for ExifIFD:ComponentsConfiguration when creating the ExifIFD group.
The following default values are specified in the DC-008-Translation-2019-E (Page 44): 4 5 6 0 for RGB uncompressed and 1 2 3 0 (other cases).
I have tested the creation of the ExifIFD with default values for a TIFF and JPEG and it seems that the values 1 2 3 0 are always used.
Shouldn't the RGB uncompressed value be written for an uncompressed TIFF and the other value for a JPEG, for example? Or is that unnecessary? Or what else does RGB uncompressed mean?
exiftool -s -G1 test.tif
[ExifTool] ExifToolVersion : 12.15
[System] FileName : test.tif
[System] Directory : .
[System] FileSize : 220 bytes
[System] FileModifyDate : 2021:01:18 18:52:43+01:00
[System] FileAccessDate : 2021:01:18 18:52:43+01:00
[System] FileCreateDate : 2021:01:18 17:59:05+01:00
[System] FilePermissions : rw-rw-rw-
[File] FileType : TIFF
[File] FileTypeExtension : tif
[File] MIMEType : image/tiff
[File] ExifByteOrder : Little-endian (Intel, II)
[IFD0] SubfileType : Full-resolution image
[IFD0] ImageWidth : 1
[IFD0] ImageHeight : 1
[IFD0] BitsPerSample : 8 8 8
[IFD0] Compression : Uncompressed
[IFD0] PhotometricInterpretation : RGB
[IFD0] StripOffsets : 216
[IFD0] Orientation : Horizontal (normal)
[IFD0] SamplesPerPixel : 3
[IFD0] RowsPerStrip : 1
[IFD0] StripByteCounts : 3
[IFD0] XResolution : 300
[IFD0] YResolution : 300
[IFD0] PlanarConfiguration : Chunky
[IFD0] ResolutionUnit : inches
[Composite] ImageSize : 1x1
[Composite] Megapixels : 0.000001
exiftool -v3 "-ExifIFD:DateTimeOriginal<filecreatedate" test.tif
======== test.tif
Setting new values from test.tif
Writing ExifIFD:DateTimeOriginal
Rewriting test.tif...
Editing tags in: ExifIFD IFD0 TIFF
Creating tags in: ExifIFD IFD0 TIFF
FileType = TIFF
FileTypeExtension = TIF
MIMEType = image/tiff
Rewriting IFD0
Creating ExifIFD
+ ExifIFD:ExifVersion = '0232' (mandatory)
+ ExifIFD:DateTimeOriginal = '2021:01:18 17:59:05'
+ ExifIFD:ComponentsConfiguration = '1 2 3 0' (mandatory)
+ ExifIFD:FlashpixVersion = '0100' (mandatory)
+ ExifIFD:ColorSpace = '65535' (mandatory)
Thanks
You're probably right. I should look into this.
The whole idea of mandatory tags is a bit unfortunate. I don't like that idea the ExifTool is forced to write something that you didn't tell it to.
- Phil
Sorry Phil, but I checked the forum before I asked my question, but I missed that the topic had come up on github recently <https://github.com/exiftool/exiftool/issues/53 (https://github.com/exiftool/exiftool/issues/53)>.
In addition to what has already been said there, I found the LOC page on TIFF <https://www.loc.gov/preservation/digital/formats/content/tiff_tags.shtml (https://www.loc.gov/preservation/digital/formats/content/tiff_tags.shtml)>.
There only ExifVersion, FlashpixVersion and ColorSpace are noted as mandatory, so maybe even one of those unpopular tags (i. e. ComponentsConfiguration) can be omitted.