At 13:46 2003-06-29 +1000, Merv Leeding wrote:
>I wouldn't throw away the scanner. Chances are that the images will need
>some improvement that can be done by a scanner in ways that are not
>possible with a camera, short of a professional studio, and post-capture
>editing is also very likely.
I recently finished scanning an album of my grandmother's (photos dating ca. 1912-1920), and determined that, while about 1/3 of the pictures produced acceptable scans, another 1/3 required considerable massaging, and the final 1/3 will have to be re-shot using a copy stand (which just arrived from an eBay auction yesterday).
There are several types of problems. One of the most common is "mirroring" or "silvering-out", where some of the silver salts in the darker areas of the photo migrate to the surface of the emulsion and turn back into tiny grains of silver over time. They produce a sort of haze over the photo which is very hard to get rid of.
Using a copy stand and polarizing filter(s), it's possible to reduce this to a minimum. Or so I understand (have seen examples). Sometimes scanning the same photo twice or even four times and recombining the scans (tricky, since it's hard to keep the angles of rotation identical) can help. This technique can also be useful on the next problem: lumpy glue.
All the photos in this particular album were stuck in with library paste or mucilage, evidently. I don't know if photo corners had been invented yet ... In many cases, especially where the photo paper is very lightweight, the surface is bumpy (more likely library paste than mucilage, I expect). Sometimes a double (or quad) scan and superimposing the pictures - and here you may have to fool around with various blending modes - will result in an almost perfect picture. But not always, or at least I haven't had 100% good results with this.
On a copystand, the angles of the lights can be adjusted to reduce or eliminate the shadows from the bumps. Sometimes a polarizing filter helps here too (or so I understand - I have only just put my stand together and haven't had a chance to use it yet).
Other problems include severely faded photos. Manipulating them in Photoshop or whatever often helps. Copying through colored filters can also help, and can be used to remove stains too. Sometimes even just with Photoshop (or whatever you use) you can bring out details in very dark prints as well. No technique seems to be universal, however. It's a matter of cut and try, starting with an educated guess.
It's much more of an art than a science.
One thing I've found to be nearly universal: scan everything in color. Use 16-bit-per-channel color if available. Generally, I manipulate the picture until it's as good as I can get it before converting back to black and white (greyscale). But not always. Use the "Channels" window (if you have it), and sometimes one channel (often red) will leap out as being far better than the other two. In that case, I convert that to greyscale immediately (16-bit). Sometimes the improvement is so dramatic that nothing more needs doing. Usually, however, I find a bit of tweaking on the brightness and contrast is advisable.
When I am satisfied, or when I need to use a technique not available in 16-bit mode, I convert the picture to 8 bits for storage. As someone else pointed out, always store in a lossless format like .tif.
I've done very little so far with color photos, except for 50-60 old Polaroids; there I found that PS's auto-color enhancement worked almost flawlessly in most cases. Not to say that the pictures are perfect yet, but very much better than the originals.
That's just an overview. I could say a lot more, but my fingers are getting tired ;-) ...
Check this URL for some very useful information on restoration:
Hope that helps,