I have a piece of code like this:
<figure>
<img title="An amazing image that I forgot to specify a url for"/>
<figcaption>An amazing image that I forgot to specify a url for</figcaption>
</figure>
Is it necessary for me to specify the title
attribute in addition to the figcaption
element, and will not doing so result in SEO problems?
Figcaption is enough. But you may need to specify title if you have to apply microformats like vCard: http://www.rachaelmoore.name/web-design/microformats/marking-up-contact-information-semantic-using-html5-microformat/
Title attribute is mainly for providing a tooltip about what is that image or link about. Usually a the target's title.
In the images, using figcaption should be enough to overcome title attribute, hence you have a specific markup for describing the resource. Howver consider always using ALT attribute, even with figcaption.
This is because you can have more than one image in a figure.
For example, using 3 images for ilustrating progress on a process.