I have some public-domain photos of Barrack Obama in JPG format which I'm planning on revamping in different artistic styles for a future store of mine and I want to know if I need to resize them or not before converting them into PNG format?

You don't need to no.. unless you want them bigger.

First, make sure that the image really is public domain. There has been a lot of confusion on what is, a lot of people putting up illegal images saying that they are public domain. There have been many Obama take-downs for these errors.

Next, probably, yes you will have to enlarge. In general, most images available on the web are too small for satisfactory quality printing on garments, posters etc. You probably already know that enlarging an image reduces image quality. Adding artistic effects is one way of minimizing the adverse effects of enlargement. If you want to cover the maximum allowed image area on t-shirts then you should make sure your canvas is at least 2400 x 2400 pixels. Anything smaller will result in reduced image size on the Plus dark apparel. Avoid enlargement if you can. If you can get correctly sized images to start with you are far ahead of the game.

Deciding whether to do your enlargement before, after or both before and after applying artistic effects is a matter of experience. If you plan to use the art on dark apparel you will want to be sure to trim along the edges to avoid a white hallo effect caused by the blurred edges of enlargement.

Understanding the dark apparel process can help you
http://www.tutortanith.com/designtips2.htm
and understanding image sizing is also useful
http://www.tutortanith.com/#imagesize

I see... I thought I needed to make them bigger for things like say, a T-Shirt design.

One example of one of the pictures I hope to use is this one:

http://i6.photobucket.com/albu...s-pages-photo-pr.jpg

That image is 768 pixels high. Most dark apparel requires a minimum of 200 pixels per inch (for all practical purposes ppi and dpi can be treated as the same thing). So 768 pixels / 200 pixels per inch = 3.84 inches high. If you want an image that is about 3 3/4 inches high then you don't need to do anything to enlarge it.

My recommendation is to find a legal picture that is larger. If you can't, then enlarge it so that it is at least 2400 pixels high and use your artistic effects to mask the degrading caused by the enlargement. There is specialized software that can enlarge an image like that without detectable degrading if you are up to paying for that kind of specialized software.

Actually that one is not public domain. One would think it was but from what I understand it was "re-done" by a pro and copyrighted.

Finding a public domain pic of Obama seems to be virtually impossible.

I thought there were supposed to be public-domain photos available of Obama, places like the official Whitehouse website, for example?

BTW, how did you know that the pic in my link wasn't in the public domain?

Cuz I tried to use it. And it is available in hi res. I have it at 2800x4073 at 400 dpi.

I can only assume that it's on purpose. Seems he had all his gov pics redone by a pro and copyrighted so there was none available for public use. Probably so the anti obama folks had nothing to work with.

I've tried a half dozen pics, reworked them, changed tie color, reversed them, posterized them, shrunk his ears, changed the background, removed his smile... nothing. Gave up as a lost cause. Just spent too much time for nothing.

But if you do come up with something, I'm sure a few thousand shop keepers would love to hear about it!

If I do find any at decent sizes, I'll be sure to let everybody know here...

Rather than go nuts with pics, just try making a button or something out of a smaller one and give it a day or two to see if it gets pulled. Really no sense spending hours on dressing something up to find it can't be used anyway. I pretty much gave up on him.

BTW, I believe that pic is his senate pic. I think I googled US senators and came up with a list with pics somewhere. Maybe wiki. But it is out there at hi resolution.

Keep in mind, just because it is available for media to use freely doesn't necessarily mean it is available for us to use to sell and make a profit. The photographer may have released the photo rights for everything except commercial use. This may be the case with a lot of the photos available on the government sites.

I don't do anything with politics so I can't speak 100% on them. But as a photographer, I have researched a lot regarding ways to market my photography and such.

Yeah, generally media shots are copyrighted by the media organization that took them.

As far as the gov, tho, it's always been that the shots of senators etc. were taken by gov employees "for the record". Therefore they were all public domain since we pay the employees with our taxes. We essentially paid for them.
However, in Obama's case, he had them re-done and submitted them to the gov, therefore retaining all rights to them. It's pretty much unprecedented. (not to mention annoying!)