Commenting on a photo which was taken a few years back:
Is this you?
Should I reply:
Yes, this is a few years back.
Yes, this was a few years back.
Which of the above is correct: is or was?
All of them are correct, and all are used. One has a choice of past or present when dealing with images.
While making reference to the whole photo (which is always going to be taken in the past), I'd rather say:
But if I'm spotting myself in the picture amongst other people, I'd say:
At least, it makes sense to me this way.