I saw you do something or I saw you did something?

I guess both are incorrect, because he post the photo before you have seen it.

I saw you post a photo on the web.
I saw you posting a photo on the web.

These are both correct if you witnessed the action of posting the photo taking place. Is this what you mean?

Your first example might be possible in a different context, but it is not a natural expression.

clee62I saw you posted a photo on the web.

I noticed that you (had) posted a photo on the web.

clee62I saw you post a photo on the web

I witnessed the posting.

Hi,

Thanks everyone. Regarding what I meant, I meant not the action but the status. You know what i mean. I was not there when she/he posted the picture but I saw it was posted on the web a few days ago maybe.

Is it clearer to say,"I saw you had a photo posted on the web the other night." Is it the same as "I saw you posted/had posted a photo on the web?"

thanks

I saw the photo you posted on the web.