I wrote in my last blog that I was restoring old photographs, so I thought I'd give some tips on the most common problem there - scratches. Old photographs and negatives are usually replete with scratches. Start the repair with a high quality scan. You want to scan your images at a high resolution and save the scan as a TIF file to give yourself lots of pixels to bend to your will as you go about fixing these things. Here is a sample of a simple portrait with a scratch problem.
When you are surveying your photo for scratches inside Photoshop, you should do it methodically, starting at the top left corner, at 200-300% zoom, and moving down the image. This can be tedious work and, if your workflow is interrupted, you want to know where you left your repair. These scratches are relatively easy to fix. They're small and aren't destroying any major portions of the image. I take these into Photoshop and fix these flaws before I do any other work that may be necessary, like color fading. There are several helpful tools in Photoshop, and you should try all of them, since different flaws may require different tools. The ones I use most often are the Healing Brush Tool, Spot Healing Brush Tool, and Clone Stamp Tool.
I find the best method is to create a blank layer and make my changes there. If you make mistakes on the new layer, you have not harmed the original scan. You should also ensure that you keep the original scan even after you've made the corrections. As programs improve their tools, you may be able to rework some of your corrections. The Content Aware feature in Photoshop CS5 has made a huge contribution to fixing scratches. Without too much effort, you can repair the image.
One of the more complex scratch problems you'll find on old negatives is film reticulation. We used to cause reticulation purposely as a special effect in the old film days. The uniform fractures made for an interesting effect. The problem here is with regular negatives that have aged in storage conditions that varied in temperature and humidity. This reticulation occurs when the old film is starting to deteriorate and micro-cracks appear on the film. It looks like this.
When you see this, you know you're in for a long repair session. These will be hard to see if you don't zoom in, but will show up in your prints. You use the same techniques to fix these flaws, but the reticulation usually occurs throughout the entire negative. This is no time to do an incomplete job - take your time and move through the image.
This might not be the most fun you'll ever have in photography, but saving old photographs for your family and clients has its own rewards.