image browser and JPEG comments

N Chosechu chosechu at
Mon Nov 7 16:44:19 UTC 2005

> All I have are more questions. Are the comments stored in the EXIF
> tags, or is this completely outside the realm of exif? How do you get
> the comments in the image to begin with?

% wrjpgcom -comment text filename

Quoting the man page:

The JPEG standard allows "comment" (COM) blocks to occur within a JPEG
file. Although the standard doesn't actually define what COM blocks
are for, they are widely used to hold user-supplied text strings. This
lets you add annotations, titles, index terms, etc to your JPEG files,
and later retrieve them as text. COM blocks do not interfere with the
image stored in the JPEG file. The maximum size of a COM block is 64K,
but you can have as many of them as you like in one JPEG file.

If I understood correctly, EXIF data are meant to store ancillary data
to the acquisition. While you can certainly tweak EXIF into accepting
it seems a better idea to use JPEG comments for what they were made for.

I just tried Konqueror, it displays some informations about JPEG files when
hovering the mouse over, but unfortunately no JPEG comments.

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