Confusion between "Comment" and "UserComment"

[Chris C.]

I am managing a huge collection of very old photographs that took months to scan, clean and process and in the course of this work I have discovered I could easily add a comment into a JPEG using FastStone Image Viewer.

The problem is, these comments aren't recognized by Windows Explorer and get destroyed whenever processing pictures in Photoshop and they can only be seen in FastStone and Exifer, which recognizes both comment fields as totally separate entities.

So my question is, what's the deal with having TWO fields for comments, why all the confusion? I did discover by myself after lengthy research that Exiftool does recognize the FastStone and Exifer visible "JPEG Comment" as a "Comment" whereas the ones visible by Windows Explorer (as prop:System.Comment) and context menu InfoTip are "UserComment"s .

In the meantime, to accommodate the cacophony working with Comments, I have found that the command
   exiftool "-UserComment<$Comment" *.jpg
will transfer all the FastStone Editable "JPEG Comments" into the EXIF Data Image Comment Field, visible to Windows Explorer, untouched by Photoshop, which otherwise destroys the JPEG Comment (called a "Comment" in Exiftool)

Of course after Photoshop processing if you want to update the existing UserComment as a JPEG Comment in FastStone, you have to use the command
   exiftool "-Comment<$UserComment" *.jpg
and back after again as previously explained after you are finished commenting.

A lot of unnecessary complications and workarounds if you ask me!

I'd appreciate any comments you may have on this along with any tips on how I could edit the UserComment field directly from an image browser interface.

Thank You!

Chris C.

[StarGeek]

Comment is the very old jpeg COM block.  It dates back to the beginning of the jpeg format and is not part of any other standard.  It is very fragile, as some programs will overwrite it to place the name of the program.  For example, Photoshop used to write "File written by Adobe Photoshop" there, overwriting anything that used to be there.  IMO, using it should avoided.

UserComment is part of the EXIF standard.  Very few programs use it and it's very unlikely to be overwritten.  It's usually set manually through the camera at the time the image is take.  At least that's the case on my old Nikon.  Not many programs read it, though.

So my question is, what's the deal with having TWO fields for comments, why all the confusion?

You don't even want to look into the mess that is video metadata, where the exact same tag can appear in three different places.  Thanks Apple!

I did discover by myself after lengthy research that Exiftool does recognize the FastStone and Exifer visible "JPEG Comment" as a "Comment" whereas the ones visible by Windows Explorer (as prop:System.Comment) and context menu InfoTip are "UserComment"s .

I've done some work on documenting what tags Windows will read here, though it needs updating.

A lot of unnecessary complications and workarounds if you ask me!

You might want to look into more modern programs.  Especially Digital Asset Manager (DAM) programs, such as Digikam, Darktable (both free), Imatch, ACDSee, or Lightroom (all commercial).  They allow you to edit a files metadata according to the more modern standards.  That means your data is more future proof.

I'd appreciate any comments you may have on this along with any tips on how I could edit the UserComment field directly from an image browser interface.

I'd suggest skipping UserComment, as it's not widely supported in most software. The XMP:Description tag is a better location. If you don't want to use a DAM, then at the very least use something like hvdwolf jExifToolGUI (which uses exiftool on the back end) or  Adobe Bridge, both of which are free.  Such programs hide all the very complex mess that is metadata in an easier to use interface.

[Chris C.]

Wow! Thank You StarGeek, what a wealth of information there. I'll try these modern apps right away 👍