I use the previously described Perfect Resize but an excellent free program for changing image resolution is FastStone Rhoto Resizer. I would recommend the Lanczos 3 algorithm for enlarging. Stepwise enlarging as others have described will probably get the best results
As the person above explained quite well the only way to have a decent result in increasing size is too do it by increment ( you can use a photoshop action that increases ten times 110% back to back or use specialty plugins like mentioned from On one ... Vertus also has a good one and alien slin too. I understand that you just wanted a couple bigger and that you have picasa but do you know like from what starting size to what desired size you need? If it's only a couple and they are easily accessible I am willing to help you out if you dont feel like getting proper software good luck
Sure you can. That's what enlargers exist for. Mine's a Beseler. You should rephrase that and say that you can't make something bigger and maintain or improve the quality. Even then it isn't quite true, but it would take an unbelievable amount of work, editing the whole photo one pixel at a time, and it would absolutely not be worth it. You'd be sick to death of that photo, and might die of old age, before it was done.
Depends on your skill level. I know a guy who restores old damaged photos. I'm pretty good at things like spot toning and blemish removal, I don't need a computer to do it, and you can't find what I did even if you look for it with a loupe. I'm pretty good at editing with a computer too, and I don't need much of an editing program to do it, but he can do stuff that is unbelievable. He could probably do it.
You’re damn right about that. I once had to take a bad scan of an offset printed image of a CEO that was about half an inch square and blow it up to lifesize. Took me three days. I didn’t try to go for photo-realism, but made it look more like an oil painting. The eye details were the worst. Made quite a bit of money, though.
Worst one I ever had to do took me a little over a month. That was just getting rid of artifacts from a bad scan. Unfortunately, I was going for realism. I didn't have a serious image editing program at the time and had to do it in paint.