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Scanning old prints, getting rid of the red cast?
Redfax
Registered Users Posts: 27 Big grins
So my sister started digging into the photo cupboard of her husband's family, and since i'm staying at their place and am the resident (comparative) photo geek I decided to pitch in and help with the scanning and editing.
So far they're all prints, and some of them have the weird '70s "bumpy" finish. Luckily its the regular type, so I've found a convenient workflow to get rid of it using fast fourier transforms, which are way cool http://www.skeller.ch/ps/fft_action.php
The prints are obviously completely f'd up color wise, with the typical red cast. I'm doing my best to try to centre things around neutral gray, but its not clearing up all the way, at all (even when a suitably gray object is in the frame). Does anybody have any tricks, or is it normal after all these years?
Incidentally i was thinking, if i had the prints AND the negative for the same shot, could i recontruct the full color profile? The same pigments would be washed away in both, but of course they would be representing opposite ends of the spectrum! I haven't found any negatives so far, but I thought it would be an interesting hypothetical.
So far they're all prints, and some of them have the weird '70s "bumpy" finish. Luckily its the regular type, so I've found a convenient workflow to get rid of it using fast fourier transforms, which are way cool http://www.skeller.ch/ps/fft_action.php
The prints are obviously completely f'd up color wise, with the typical red cast. I'm doing my best to try to centre things around neutral gray, but its not clearing up all the way, at all (even when a suitably gray object is in the frame). Does anybody have any tricks, or is it normal after all these years?
Incidentally i was thinking, if i had the prints AND the negative for the same shot, could i recontruct the full color profile? The same pigments would be washed away in both, but of course they would be representing opposite ends of the spectrum! I haven't found any negatives so far, but I thought it would be an interesting hypothetical.
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Do you mean that there's a red cast in the digital version after you've scanned them? I don't think I've ever had that problem with prints I've scanned. I try to scan the negatives wherever possible (one less generation, so better signal to noise ratio)
Why would you want to scan both print and negative? Doesn't make sense somehow… I must be missing something here…
BTW Welcome to DGPF!!
- Wil
Here's why I think scanning both print AND negative would be advantageous. The red cast is casued by certain pigments being more durable than others. In this case its the cyan which is decomposing too soon. Now, assuming the negative has the same pigments as the print paper, the same cyan dye would also be decomposing too soon BUT in the NEGATIVE the cyan dye is actually coding for the Red channel, which is preserved just fine in the print. So in theory there should be a way of recombining the information from both sources to get vivid color!
Granted this is a fairly limited applicability set, and it isnt my case, but i still think it would be pretty cool
I don't know if that would really work, while I don't know for sure I doubt that the dyes in the negative and the paper are similar enough that you could easily do a 1:1 flip to get the red out. Also, if the prints and negatives were stored under different conditions and materials, they may have faded at different rates even if they were the same dyes.
I guess some people deal with this by editing the channels themselves, like playing with the Red channel curve of an RGB image. Also, some scanning software has a fade compensation feature which presumably models common fade scenarios and reverses them; my copy of VueScan does, I'm just saying if yours has that it might be something to try.
Using both a print and a negative can be useful in understanding the original colors, but normally the negative will provide much greater dynamic range and negatives are often not as exposed to the elements of light and handling so they may have held up better overall. It's not unusual to find that negatives have suffered other types of degradation and scratches are a usual problem as well as blotchy regions caused by poor fixation and/or poor rinsing.
Moderator of the Cameras and Accessories forums
To learn the tweaks that Ansel Adams performed to alter the image in the print process.
This seems like a fine answer in its own right, but the real point is to remember that custom prints may have different information than the negative. Even choices of paper are "custom", as papers may vary in contrast and color as well as dynamic range (which has already been mentioned).
Dale B. Dalrymple
...with apology to Archimedies
I wrote about using a cyan or a green filter here - http://www.dgrin.com/showthread.php?t=49659&highlight=green+filter+nuclear
Moderator of the Technique Forum and Finishing School on Dgrin
I'm not an expert on this, but...
Photographic negatives and prints use different sets of chemicals in their emulsions. Those in the negatives seem to be a bit more robust than those in prints, and when I have taken old negatives to be printed, the new prints typically looked brand-new. Granted, I've only printed negatives about 15 years old (pics taken in 1990 reprinted in about 2004-2005), but I was pleasantly surprised at the quality of the prints.
It's a moot point in your case, of course, since you haven't found any negatives, but if you should find any, you may just find that they're in far better condition than the prints, and scans of the negs may not have any major color cast at all (aside from any exposure problems they may have from the original exposure).