Character limits

[nmf]

Can you tell me what the character limits in the various fields in the IPTC Captioning dialog are please ?

I have found some old posts which give partial details but they are a couple of years old, so it is possible the situation has changed, and the one with the most details refers to octets rather than characters. I assume, from what Denis wrote, that each character may use a different numbers of octets but, it would be useful to have at least a mental idea of how long the contents of each field can be for when I am bashing out a caption on deadline as the fields appear to accept what is typed whether they will ultimately be saved intact or not.

Thank you for your help.

(Mac 10.5.5 / Photo Mechanic 4.6.2 and Windows XP / Photo Mechanic 4.6.1)

[Kirk Baker]

Can you tell me what the character limits in the various fields in the IPTC Captioning dialog are please ?

I have found some old posts which give partial details but they are a couple of years old, so it is possible the situation has changed, and the one with the most details refers to octets rather than characters. I assume, from what Denis wrote, that each character may use a different numbers of octets but, it would be useful to have at least a mental idea of how long the contents of each field can be for when I am bashing out a caption on deadline as the fields appear to accept what is typed whether they will ultimately be saved intact or not.

Photo Mechanic will always save everything you type into a field, even if it exceeds the 'specified character limits' of the IPTC standard.  Other programs may have issues with long Caption fields or long Category fields.  For instance the Caption field is 'limited' to 2000 octets.  I put 'limited' in quotes because the limitation is artificial since IPTC data is formatted with a length parameter that can easily hold over 65 thousand characters.  The Category field is 'limited' to three octets but PM does not enforce that limit as it will allow you to type as long a string of characters as you like.

I hope that answers your question, but if it doesn't, please feel free to ask further questions.

-Kirk

[nmf]

Sorry, but I'm still a bit confused.

Can I take it that an octet equals a standard letter or number (eg a b c A B C 1 2 3 ( . % ) in most cases ?

If so can it be assumed that a Caption containing no more than 2000 characters will be visible in most mainstream software that can view IPTC data ?

You say "For instance the Caption field is 'limited' to 2000 octets". Do you have any other such advised limits for the other fields please ? (I appreciate that you can't give a 100% guaranteed answer but you have more knowledge of how such fields will be viewed by other software)

The reason for my questions are to ensure that I am doing everything I can to be certain that the captions, object names, Special Instructions and Rights Usage Terms I insert are all visible in full to any client.

Thanks for your help.

[sidewinder]

An octet is 8 bits. So he means the "limit" is 2000 characters if you are using Roman text.

Look at his definition of "limited" again.

Scott

[Kirk Baker]

Sorry, but I'm still a bit confused.

Can I take it that an octet equals a standard letter or number (eg a b c A B C 1 2 3 ( . % ) in most cases ?

Yes, in general.  It depends on what encoding you're using and whether you're using characters outside of the 7-bit ASCII standard character set.

If so can it be assumed that a Caption containing no more than 2000 characters will be visible in most mainstream software that can view IPTC data ?

Yes, in general though depending on your encoding choice things can get a bit fuzzy.  IPTC is an old standard and is interpreted differently by different applications.  XMP data does not suffer from the same problems, but it isn't as widely supported as IPTC.

You say "For instance the Caption field is 'limited' to 2000 octets". Do you have any other such advised limits for the other fields please ? (I appreciate that you can't give a 100% guaranteed answer but you have more knowledge of how such fields will be viewed by other software)

The reason for my questions are to ensure that I am doing everything I can to be certain that the captions, object names, Special Instructions and Rights Usage Terms I insert are all visible in full to any client.

Caption: 2000 octets
Object Name: 64 octets
Special Instructions: 256 octets
Rights Usage Terms: (it is only in XMP and as far as I know has no defined limits)

HTH,

-Kirk

[nmf]

Thanks Kirk and Scott.

My reason for asking the extra questions was as I didn't know what affects how many octets were used per character the 2000 octet limit didn't mean anything. Knowing in general if I am using Roman text that an octet equals a character helps immensely. Maybe as you say it isn't always accurate but most likely is in the average scenario.

Thanks again for your help.