Erik

Lately I've been testing a few "jpg artifacts reducers". Up to now, the winner seems to be DFine by nic.
Yet not one is really perfect.

I usually (you know me, so you know what will follow) go to LAB mode where I have a separation of brightness on one hand, and thwo colour channels on the other. With some selectioning and a lot of patience I get acceptable results.

But I wonder how you work.
What do you do to make enlargements of jpg's that suffer as little as possible from the usual artifacts?

LAB makes very clear that the different apps that reduce filesize when jaypegging follow different methods. I once had a very good article on this, but I have to look it up...
Some jpegs don't suffer in the lightness channel. This makes it easy to blur the colour channels a and b to get acceptable results. But some jpg's have badly damaged lightness channels as well as chroma noise. These are quite difficult to mend.

Just some ideas I throw on the fire here.

Let's have a chautauqua on this...

theKeeper

Well... it's simple... i don't upsize images. That's generally a 'no-no' in Photoshop anyway.

BUT... should one absolutely have to do this... here's one fun method i like to play with...

Grab the Blur tool and, using varying strength and (soft) brush size settings, manually soften the effected areas. Being very careful of course not to smooth out any detail lines in the photo. [righton]

This can sometimes turn out to be hours of the most horrific fun you'll ever have. [stuned] But it works.

Moth

You can sometimes use the median filter then follow up with unsharp mask to get something not too horrible. Just be sure to do this on a duplicate layer not on the original. Mark's makeover tutorial can also work sometimes. But the entire enterprise is often a lot of work for little payoff.

nitrobutler

Now for something off the wall....
Have anyone experimented with HELP>RESIZE IMAGE?
So far I've only experimented with Web resize and all I usually have to correct is a little sharpening, but it does the trick [slick]

C9Mouse

I use the JPEG Repair tools that come with Alien Skin's Image Doctor http://www.alienskin.com/idoc/idoc_main.html

I highly recommend this filter. I've been using it now for about a year and it does wonders on JPEGs.

Erik

Well, I also use that blur tool, or even Gaussian Blur combined with masks, edge masks, inverted edge masks, etc etc etc...and it is a kind of Siberian Stalag indeed.

I prefer LAB as it separates the lighness from the colour info, which is what JPG also does.

Still looking for that article...

Thanks Doug for that link. Be shure I'll try it out...NeatImage and DFine do the job partially (I'm not expereinced with them), but AlienSkin does have a good reputation.