TYPO3 Core

Please not!
alt text is meant as a substitute for information which is give by the image contents. If there is a caption there is no sense in doubling it as an alt text.
No additional information is given and it is very anoying to screenreader users - the get all the text read twice!

If there is a constant (I dont't think its needed) default should be 'false'!

Alt image would boost the ranking on search engines.

There would be no doubling of information if feature #0002424 is implemented, too.

This can already be done in TYPO3 4.0, since processing of alt/title/caption are all controlled through TypoScript (cObject and stdWrap). For example this is the cObject that will get added in the altText element for each image:

tt_content.image.20.1.altText

just try something like "isEmpty" property to attach the (splitted) caption at that part if its empty. I think some TypoScript wizard will be able to produce some bright TS-code to do that.

As this feature is already possible as Ernesto showed, I'm closing this bug report now.