SUMMARY I noticed that when I add a tag to a picture, several Metadata are changed, and I don't understand why. For example, for a picture to which I added the Subject Party: Original Updated Composite:HyperfocalDistance 3.22 m 3.24 m Composite:ScaleFactor35efl 4.4 4.3 ExifIFD:BrightnessValue -5.454663662 -5.454663633 ExifIFD:ComponentsConfiguration Y, Cb, Cr, - ExifIFD:FlashpixVersion 100 ExifIFD:LensInfo 2.220000029-5.960000038mm f/1.6-2.2 2.220000029-5.96mm f/1.6-2.2 IFD0:YCbCrPositioning Centered QuickTime:MediaDataSize 1774314 1772898 System:FileModifyDate 2025:08:19 21:02:43+02:00 2025:08:21 18:11:09+02:00 System:FileName IMG_2437_2.HEIC IMG_2437.HEIC System:FileSize 1810 kB 1809 kB XMP-dc:Subject Party XMP-mwg-rs:RegionAppliedToDimensionsH 3024 XMP-mwg-rs:RegionAppliedToDimensionsUnit pixel XMP-mwg-rs:RegionAppliedToDimensionsW 4032 XMP-mwg-rs:RegionAreaH 0.142523383 XMP-mwg-rs:RegionAreaUnit normalized XMP-mwg-rs:RegionAreaW 0.106892535 XMP-mwg-rs:RegionAreaX 0.853608981 XMP-mwg-rs:RegionAreaY 0.546550853 XMP-mwg-rs:RegionExtensionsAngleInfoRoll 370 XMP-mwg-rs:RegionExtensionsAngleInfoYaw -41 XMP-mwg-rs:RegionExtensionsConfidenceLevel 0 XMP-mwg-rs:RegionExtensionsFaceID 1 XMP-mwg-rs:RegionType Face Discussing with the Exiftool team, it seems that this should not happen if using Exiftool update command simply. STEPS TO REPRODUCE 1. Export metadata of a picture that was never manipulated using "exifTool -args -G1" command 2. Add a tag to a picture 3. Export metadata of a picture that was never manipulated using "exifTool -args -G1" command - notice all metadata that differ OBSERVED RESULT Several metadata related to the camera (lens, brightness...) are updated, while only a tag was added EXPECTED RESULT Only the tag should be added, other metadata should not change SOFTWARE/OS VERSIONS Windows: X ADDITIONAL INFORMATION
I can't reproduce it with a quick test here, using a JPG and HEIF file. What are your exact metadata settings regarding reading and writing with ExifTool? Please note that we're still working with Exiv2 and ExifTool uses a so-called EXV container for writing, so more metadata may be written than if you just add a keyword. Reading with Exiv2 may result in a different interpretation/rounding of the values, which may then lead to changed Exif values when writing back. Maik
Created attachment 184822 [details] Configuration
Hi Maik, I have added a screenshot of my configuration and I have Exiftool 13.04 installed. Here is the link to the picture I'm using for tests: https://we.tl/t-JJLqzkWryv Thanks for your help ! Nice day, C
Hi Maik, Did you get the shared testing file from comment #3 ? File is not online anymore... Gilles
Hi Gilles, The problem can sometimes be reproduced with any file, depending on certain metadata in the Rational format. Exiv2 rounds fractions differently than Exiftool. Since we write all the Exif metadata back using the EXV container, slight changes occur at the rounding level. I don't see it as a critical issue. The only solution would be to write the metadata completely natively using Exiftool, writing only the changes that were actually made. I already have some ideas on how we could add this step by step for specific metadata. Maik
*** This bug has been marked as a duplicate of bug 481755 ***