On 13/02/2020 10:59, J. P. Gilliver (John) wrote:

For .jpg image files, I can add text notes to them very easily: in
IrfanView, I just (open the image and then) type I (info) then C (comment).

This doesn't work for the .png file format.

_Does_ the .png format _have_ a metadata text field? If so, what utility
lets you see it, and ideally edit it?

(I'm talking about text that _becomes part of the file_, not that is
attached to it in some "album" type management system: such that it
remains part of the file even if the file is renamed, moved, or even
emailed.)

I think it depends not just on whether the Portable Network Graphics
format can contain metadata, but also whether you want the metadata to
be available under, say, File or rt-click, Properties, Details in
Explorer. The answer to the first seems to be yes, the second seems to
be no. As a test I have just added some information to a *.png file
using Paint Shop Pro, and it is remembered if the program is closed and
then reopened and the same file loaded, and examination of the binary
contents of the file shows the strings added to be there. However, they
are not shown by the default Windows Image Viewer program, nor under the
File, Properties in Explorer.