I was wondering what whether modifying an old public domain cartoon (e.g. to make the sound appear to be stereo, or make a black & white film colour [either with the standard character’s colours, or different colours], or radically re-editing the video or making the sound totally different) would infringe any trademarks on the cartoon characters that appear in the cartoon… ? (Assuming the video had a disclaimer on it stating that the new video didn’t own the trademark to that cartoon character, and whatever other disclaimers might be needed)
I know I could just ask the trademark owner or ask a lawyer, but lawyers probably cost money 
(and this is just an idea at the moment), and I’m trying to avoid asking the trademark owner for now…
You may not just have TM issues but you could also very well have copyright issues:
Let’s think of something easy: if something is in the public domain then it’s yours to do with what you please. However, you cannot then claim a copyright on it (which probably isn’t of your concern). What becomes tricky is if a TM that’s been abandoned comes back into use. Abandonement comes after 2 years of non-use. After 2 years, you can use it as a TM before the original TM-holder can claim rights to it. You’ll still be sued, most likely, but the case should be in your favor. Remember, your TM has to be associated with a good or service in order to qualify for a TM, otherwise, you might have a copyright. You cannot copyright anything from the public domain.
Now, from your fact pattern, let’s assume that there is this public domain, in it contains a cartoon. Someone has a TM of this cartoon character used to sell Widget X. Can you now take TM cartoon character and modify it? Most likely, no, regardless if you got the image out of the library, the a video, a dvd, etc. Someone now has a TM from it (which is what you stated in your fact pattern).
The most obvious law you would be violating is dilution of trademark – where you cause confusion as to of the TM and the goods or services connected to it; or, tarnishment, where the use is unsavory or unwelcome. And, depending on your usage, you’ll probably incur infringement concerns as well.
I know that “Iron” Bil Keane and his henchmen managed to shut down the Dysfunctional Family Circus.
This is the kind of thing I’m talking about:
http://www.toonzone.net/brian/video/dvd/cc-war.html
Here they edited the sound of public domain characters that included some (probably) trademarked characters (superman [see cover], bugs bunny, daffy duck, porky pig). They turned the soundtrack from mono to surround and added extra sound effects.
The DVD got a poor review here mostly because they thought the new sound was “terribly fake” sounding and the original mono sound wasn’t included at all. So perhaps the trademark owners could say that it tarnishes the trademark or something…
The DVD cover (front and back) doesn’t seem to have any mention about those WB characters and Superman being trademarked… perhaps they have a disclaimer when you watch the video or something.
So that appears to be legal… (or maybe the trademark owners aren’t too fussy). But I wonder if radically changing the sound (e.g. making them say different things) would be ok - assuming you had a disclaimer…
On the DVD back cover it did say though that “the pictures on this package are enhanced replications from the actual cartoons contained on this disk”. So I guess it is illegal to draw the trademarked characters from scratch or possibly distort the originals (e.g. distort the colours or make black and white things colour).
The Dysfunctional Family Circus would have been using copyrighted material or at least characters that look like trademarked characters without permission… though I thought it was ok to parody things without permission (like Mad probably does).
Or, if some employees of, oh, some unnamed hostile takeover target were traveling in my area, and had to gas up at one of these convenience stores, might they be upset that their (convenience store’s) logo bears an incredible resemblance to this little chap?
Oh, let me reiterate IANYL, blah blah blah
Adding/enhancing sound may still have a blurring effect, or a tarnishment effect. It depends on the sound. I recognize most of those characters as trademarked, so I think you’re out of luck. Then again, my recognition of a TM is no basis for a TM, do a USPTO search if you’re so inclined. The packaging itself doesn’t necessarily need a TM or a R mark to indicate a property right. The actual product, does, however. Regardless, a lack of mark would have to pretty onerous and the likelihood of knowledge by the alleged infringer would have to be greatly specious in order for the court to excuse the TM-holder’s lack of notice.
You could also put whatever disclaimers you want showing attirbution of the property right, but that’s not going to save you from a dilution or an infringement suit. Depending on how much (or how little) altering, the context it was used, I would be hard-pressed to think of a situation where you could not be hauled off into fed court. It also doesn’t matter what source you used to create your alteration of the TM mark (and like I said, depending on the source, you may have a copyright violation, too). All that matters is the final alteration, and the context in which it is used.
It is, but there’s no bright line of parody, only litigation can settle the boundary between parody or fair use and infringment. Spinn, the creator of the DFC, was all set to fight it, until, as excerpted from here: