What does the theme copyright cover?

[Phidippides]

I am using a theme that I downloaded from this site.  I'm wondering what the copyright on the theme covers (perhaps just images?).  I'm also guessing that we have free license to modify these themes in any way that we want (I could not find this explicitly mentioned anywhere), except that we must leave the copyright notice on the page.  That said, at what point is the copyright no longer in effect?  Surely, if I modify a theme enough, sooner or later the copyright would no longer cover the theme.  Does anyone know?

[H]

Theme copyright depends on the author.

Obviously the "Powered by SMF" must remain intact

[1MileCrash]

As far as freedome of modifying, unless the author says otherwise, you can modify it to your hearts content. Anything created by them is copyrighted by law...scheme, graphics, layout, everything. No matter how much you modify it, the theme is theirs and protected. You are not allowed to redistribute (unless a theme author says otherwise) a theme, no matter how much it is modified. The copyright must stay (unless a theme author says otherwise) no matter how much it is modifed.

Really it is up to the author. But that is what i go by. They created it- period.

[Harzem]

First, you can't modify the SMF copyright, as you know

About theme copyrights:
Usually designers think (or state) like that: "You can use the images as you want, as long as they are in a SMF environment.". That means, you can use theme images in your site to make your site theme look like your forum theme. But if you are using vBulletin, you usually can't use SMF theme images.

About modifying theme copyright, like "Dilber MC theme by HarzeM":
Authors request you to not remove it. That is ethically incorrect.

You can modify any theme as you want. You can put a "modified (or) redesigned by Phidippides". But you are still requested not to remove the original authors notice.

If you want to have a "totally yours" theme, you can modify the default theme. You are free to modify it as you like and put your name as the designer.

[Phidippides]

Ok, thanks for the help.  Basically I'd like to modify/eliminate some default graphics that are provided in a theme by bloc.  I'm not interested in distribution at all.  There was no license agreement contained in the theme file, so I was curious as to the protocol around here.  I think you all have cleared up my confusion.