Categories vs IPTC/XMP Metadata

[strawbale]

Following up from viewtopic.php?f=82&t=40215
and after having read https://www.xnview.com/download/XnViewM ... inners.pdf

it seems that the next step (for me) before starting to catalogue my photos is chosing between using Categories or adding/editing the IPTC-IIM/XMP metadata.

What are the pros and cons of each method?
Is IPTC-IIM/XMP metadata transferable to another programme (if need be in the future) and Categories are not?

I tested the Categories feature and it seems straight forward (and useful to me).

However, when I choose Tools > Metadata > Edit IPTC-IIM/XMP for one of the (few) photos I assigned Categories to I don't see anything under the Categories tab - why?

[strawbale]

In addition, when I choose Tools > Metadata > Edit IPTC-IIM/XMP for a photo I have NOT assigned a Category to, I see some Categories mentioned under the Keywords tab - why? (eventhough the 2CV is blue, it's not a Bird nor a Blue Tit...)

[strawbale]

Another set of questions related to categorizing is about adding/editing comment:
- is that information transferable to/readable in (some) other applications?
- what's the differnce between Description and Embedded comment?

[michel038]

For the first questions :
"Catergories" in XnViewMP is a tool to make easy entering keywords in photos. (IPTC or XMP depending on Settings, Metadata)
At the same time, XnViewMP builds a database that allows you to filter photos in "Category filter" pane . (use Ctrl key to select more categories, Alt key to exclude categories) and offers quick search features.

Edit IPTC/XMP Window :
In this window, you can enter other metadata (Caption, Title, Copyright, City, State etc ...) in IPTC or XMP metadata depending on setting you choose in the last tab (Options)
IPTC Category is an old IPTC metadata, which no one currently uses. You can forget this metadata.
I think it's more time loosing to enter keywords in this window than using categories tool.

IPTC is a well known method , most softwares can read IPTC data.
Since 10 years, XMP seems to replace xmp. I'm using both iptc and xmp (see that cat)

Second question
Description is not a metadata, this function creates a text file named descript.ion , containing a comment. Some old softwares can read this file.
Embedded comment was used when neither iptc nor xmp were created. This comment is written in EXIF field.
Almost all exif fields are technical informations, currently written by cameras when shooting (you can also enter your exif copyright in some cameras)

[strawbale]

For the first questions :
"Catergories" in XnViewMP is a tool to make easy entering keywords in photos. (IPTC or XMP depending on Settings, Metadata)
At the same time, XnViewMP builds a database that allows you to filter photos in "Category filter" pane . (use Ctrl key to select more categories, Alt key to exclude categories) and offers quick search features.

Edit IPTC/XMP Window :
In this window, you can enter other metadata (Caption, Title, Copyright, City, State etc ...) in IPTC or XMP metadata depending on setting you choose in the last tab (Options)
IPTC Category is an old IPTC metadata, which no one currently uses. You can forget this metadata.
I think it's more time loosing to enter keywords in this window than using categories tool.

IPTC is a well known method , most softwares can read IPTC data.
Since 10 years, XMP seems to replace xmp. I'm using both iptc and xmp (see that cat)

Second question
Description is not a metadata, this function creates a text file named descript.ion , containing a comment. Some old softwares can read this file.
Embedded comment was used when neither iptc nor xmp were created. This comment is written in EXIF field.
Almost all exif fields are technical informations, currently written by cameras when shooting (you can also enter your exif copyright in some cameras)

Thanks a lot, again, for your detailed response.

However, I'm still not sure how to go about it - sorry, I'm a real beginner:
Add one or more Categories to one or more photos by placing ticks in the Category window, and in Preferences > Metadata tick 'Export DB Category to XMP Subject and IPTC Keyword' ? (plus tick Create XMP data or Create IPTC data or tick both ?)

Or the other way around (add Keywords and or Categories in the Edit IPTC/XMP Window) and in Preferences > Metadata tick 'Import XMP subject or IPTC keyword to DB Categories' ?

Additionally, should I also tick 'Update or create XMP Sidecar' ?
and, maybe, 'Read hierarchical keywords' ?

Edit: re-reading your answer again ("I think it's more time loosing to enter keywords in this window than using categories tool") you suggest to do my first method. Also you suggest to tick both 'Create XMP data' and 'Create IPTC data'

[michel038]

En français, c'est plus simple ?

Et avec une bonne dose de courage, le tuto dont le lien est là-dessous, dans ma signature ...

[strawbale]

En français, c'est plus simple ?

Et avec une bonne dose de courage, le tuto dont le lien est là-dessous, dans ma signature ...

Je vais l'essayer, mais le français n'est pas ma langue maternelle (du tout...)