Can it be done?

Boomtat

Hi all,

In my work at a museum, it's my job to digitise negs and trannies, duplicate the originals in Photoshop, and store the files.
We get a lot of Kodachrome slides from the 60s that have degraded to the extent that they are mostly magenta and green.
Does anyone know of a method that will reduce magenta without enhancing green?

Cheers
Boomtat

gus

My version but there may well be a better way.

1/ Open image in Photoshop
2/ Select image from the top header & choose adjustments
3/ Choose 'replace colour'
4/ Use the little 'eye dropper' tool that is now sitting there & put it on the colour you wish to reduce/enhance & click
5/ Now use the slider bar that is named 'saturation' to lower/increase

wxwax

Boomtat

Thanks, Gus
I tried your method but found that the eyedropper only selected a certain magenta saturation - it was too specific. The result was patchy (at least the way I did it) so it wasn't the Magic Button I was hoping for.
Many thanks for your time and interest.

Boomtat

Nikolai

Can you post a sample?
I may have some ideas, but it would be much easier to give a recommendation based on a real image..
No need to go hires, 800x600 (or even 640x480) should be plenty.

Richard

Boomtat wrote:

I tried your method but found that the eyedropper only selected a certain magenta saturation - it was too specific. The result was patchy (at least the way I did it) so it wasn't the Magic Button I was hoping for.
Many thanks for your time and interest.

Boomtat

You can increase the selected range by using the fuzziness slider. Also, you can add additional values to the selection by clicking the middle dropper button then clicking on different areas with the dropper. You are right that it's not a magic button, though, and needs to be combined with other tricks to avoid abrupt color changes at the edges. LAB color curve adjustments are more powerful. You might want to have a look at Photoshop LAB Color by Dan Margulis or search for a very good series of tutorials that Rutt and others did here on Dgrin a while back.

Cheers,

Dee

Look at this site:
Applied Science Fiction Digital ROC Professional plug-in (Set for Brightness 25, Black Clip .5%, White Clip .5%, Digital Camera input), followed by an Auto Color Balance in Photoshop. The Digital ROC plug-in is designed to restore the original colors from time-faded color films.

http://www.californiacoastline.org/

About the 1970s imagery (on the left)

Hope this helps...

Jeanne Marie

I'd like to help, but I would need to see the scan results. Maybe adjusting curves after changing mode cmyk. If you could post a link to the image, I wouldn't mind messing with it and posting the results with the steps.

edgework

Boomtat wrote:

Hi all,

In my work at a museum, it's my job to digitise negs and trannies, duplicate the originals in Photoshop, and store the files.
We get a lot of Kodachrome slides from the 60s that have degraded to the extent that they are mostly magenta and green.
Does anyone know of a method that will reduce magenta without enhancing green?

Cheers
Boomtat

Excess magenta and green translates nicely into LAB terms. Your a channel is dominating. Try a color boost to the b channel by dragging the endpoints of the curve each an equal distance towards the center.

Duffy Pratt

edgework wrote:

Excess magenta and green translates nicely into LAB terms. Your a channel is dominating. Try a color boost to the b channel by dragging the endpoints of the curve each an equal distance towards the center.

Yes, and if you want to boost the magenta without changing the green, you can lock down the green with some control points on the A curve, say at 0,0 and -5,-5 and this should let you increase the slope on the positive side without moving the negative (green) side of the curve.

Also, you could do what you want in LAB changing the magenta side to what you want without worrying about the green, and then use the blend if sliders to limit the changes only to the neutral to magenta areas.

Duffy

Boomtat

Nikolai wrote:

I may have some ideas, but it would be much easier to give a recommendation based on a real image..
No need to go hires, 800x600 (or even 640x480) should be plenty.

Here's a scan of the sort we have to deal with. I hope the size is OK.
I'll try out the tips and methods you folks have suggested.

Thanks
Boomtat

rutt

I know how to do a lot with this shot without hand "colorizing" it. Perhaps it can be taken ever farther, but I think you'll have to do some pretty serious painting to get there. Of course I could be wrong.

1. Gotta do something about that horrible magenta/blue cast. I tried LAB curves, but the cast is just too complex. I ending up using the A-bomb of cast fixing: blending the green channel into the blue in multiply mode 70% opacity. Think about it. We want about at least as much yellow as magenta in the flesh. If we just duplicated the green channel into the blue, magenta and yellow would be equal everywhere. That's not quite what we want here; we want the vegetation to be green, for example. So I chose a blending mode that would accentuate the yellow that was already there. There is probably room to fine tune this step.
2. Convert to LAB, steepen the A+B curves to restore some color variation and make an L curve that brings out some contrast. Green side of A curve a little steeper to make the vegetation green.
3. Fix blown yellow hair by painting over in a color blend layer.
4. Sharpen the L channel.

Duffy Pratt

Rutt's excellent work inspired me to give this a shot on my own.

First thing I did was copy the background layer, set to luminosity, and apply the green channel to the image on normal.

Then I made another copy of the background layer, set to color, and applied the green channel to the blue channel in darken mode at about 75-80%. This had a similar effect to what Rutt did with the multiply, and it got rid of the worst of the cast, but left a flat image.

Then I added an adjustment curve, and picked out the truck tire as black, and the tape on the box in the foreground as neutral close to white. I set the tire to 10,10,10 and the box tape to 225s (I think). This was getting there, but there was still too much blue, especially in the plants in the background. So I steepened the blue curve by lowering it to a quarter point until the plants started showing some yellow in them as opposed to blue.

From there, I switched to LAB, steepened the A and B curves trying to get the greens to turn green while keeping the skin tones reasonable.

Then did a Hiraloam sharpen on the L.

I left out the painting in on the blown hair highlights.

I think Rutts is better. It looks a bit more natural, but color faded, which is fine for a picture from that era, I think. My version has more color variation, but it feels harsher to me for some reason I can't put my finger on. (Edit: I went back in and reduced the steepness on the green side of the curve, and like the result better. I had made the picture about the greenery, instead of the soldiers. I think its a little better now.)

rutt

Yeah, mine kinda has the "Munich" look without the warm cast. I tried to get less faded colors but it looked wrong whatever I did. I wanted GREEN vegetation. I wanted brown dirt. I wanted properly balanced flesh tones. I wanted green uniforms. I didn't want green or blue in the hair. Once I got those things and proper black and white points, I tried for bright colors, but couldn't get there. So I declared victory and retreated.

There are people out there who are really good at this kind of repair. But in my experience it usually requires some pretty serious local retouching. In this particular image, perhaps burning/dodging the A and/or B channels would be a start. There is also LAB blends like overlaying the A and/or B channel into the L and the like. I didn't get there.

Nikolai

Nice work, John!

rutt wrote:

... I ending up using the A-bomb of cast fixing: blending the green channel into the blue in multiply mode 70% opacity...

I have a few things to learn in this area of color correction...

rutt

Nikolai wrote:

I have a few things to learn in this area of color correction...

I don't think there is anyone out there who doesn't. The very best, Dan Margulis, for example, are always reevaluating their technique and exploring new ideas. I've been beta reading Professional Photoshop, 5th edition, and it's remarkable how different it is from the 4th edition and even the Canyon book.

Nikolai

Nice!

rutt wrote:

I've been beta reading Professional Photoshop, 5th edition, and it's remarkable how different it is from the 4th edition and even the Canyon book.

Really? This is great news!
BTW, how do I sign up for beta? I'd love to...

rutt

Nikolai wrote:

Really? This is great news!
BTW, how do I sign up for beta? I'd love to...

Sorry, Dan chose a small group (about 10) of beta readers in the spring. The process is closed now. The good news: Dan seems to be on track to publish in the fall.

Duffy Pratt

That's good news about his new book. I have learned probably 90% of what I know about color correction from the 4th edition of Professional Photoshop and the LAB Canyon Conundrum book.

I fooled with Elements for a bit, and learned some from a Kelby book on Elements for digital photographers. When I saw Canyon Conundrum in the store, I knew I had to get photoshop, and have since been through the LAB book 3 times, and am on my second go round of Professional Photoshop, and I'm still learning a ton from these two books.

I've thought about getting some other books too, but as long as there is more to mine from these, I can't really see the point.

Duffy

rutt

Compared to Dan's books, the other books on image enhancement and color correction are greasy kid stuff. Dan teaches his readers (and the students of his 3 day courses) how to think about improving their photos, not just how to follow recipes. I've found great satisfaction in knowing the theory as well as knowing how to apply it.

One thing you can do if you want to get more of Dan's style of image enhancement is to tune into his mailing list. See: http://groups.yahoo.com/group/colortheory/

Duffy Pratt wrote:

That's good news about his new book. I have learned probably 90% of what I know about color correction from the 4th edition of Professional Photoshop and the LAB Canyon Conundrum book....
Duffy

rutt

I gave this another shot. Nothing that different except I finished up with a trip to CMYK to make better shadows. Much better, I think, but still looks like an old photograph. I think something has to happen to the background vegetation to get it to be greener than the green parts of the uniform. Actually, both are a lot more yellow than green, at least LAB green. There is a trick for that which I'm trying to remember...

rutt

I recovered the trick for fixing flat greenery by asking on Dan's yahoo group: http://groups.yahoo.com/colortheory Use the channel mixer to add green and remove blue from the greens. Make sure to subtract as much blue as you add green. This gets the yellow out. Take to LAB if need be and use the blend-if sliders to control eliminate unwanted areas from the blend. The difference isn't as dramatic as the CMYK shadow move, but it takes it a step closer:

Nikolai

Very cool, John!

rutt wrote:

I recovered the trick for fixing flat greenery by asking on Dan's yahoo group: http://groups.yahoo.com/colortheory Use the channel mixer to add green and remove blue from the greens. Make sure to subtract as much blue as you add green. This gets the yellow out. Take to LAB if need be and use the blend-if sliders to control eliminate unwanted areas from the blend. The difference isn't as dramatic as the CMYK shadow move, but it takes it a step closer:

It's great to see your approach to this task in action!

nokout3839

A quick go
Hi All,

Saw this and reminded me of going through our family's 800 slides from back in the day. I found the quckest method to get to a workable image was curves. It will depend on the use of the image (being for a muesem you might want better results than this) but for me I found it to be a great starting point and on some of the more promising photos more work was done.

Its simple, open image->adjustments->curves. once curves dialog is open click on the black eyedropper tool and choose a point that looks to be black in the photos. Do the same with white and if possible the middle eyedropper is for a 50% grey point.

In the end I think you would get better results from the methods used above but for a quick initial step I like simple curves.

Result:

edgework

rutt wrote:

I know how to do a lot with this shot without hand "colorizing" it. Perhaps it can be taken ever farther, but I think you'll have to do some pretty serious painting to get there. Of course I could be wrong.

1. Gotta do something about that horrible magenta/blue cast. I tried LAB curves, but the cast is just too complex. I ending up using the A-bomb of cast fixing: blending the green channel into the blue in multiply mode 70% opacity. Think about it. We want about at least as much yellow as magenta in the flesh. If we just duplicated the green channel into the blue, magenta and yellow would be equal everywhere. That's not quite what we want here; we want the vegetation to be green, for example. So I chose a blending mode that would accentuate the yellow that was already there. There is probably room to fine tune this step.
2. Convert to LAB, steepen the A+B curves to restore some color variation and make an L curve that brings out some contrast. Green side of A curve a little steeper to make the vegetation green.
3. Fix blown yellow hair by painting over in a color blend layer.
4. Sharpen the L channel.

I tried a similar move but kept everything in LAB. I blended 40% of the b channel into the a channel in normal mode. That took care of the purple cast but traded it for a bluish cast. But steepening the a and focusing on the yellow at the expense of the blue dispatched that problem. One thing I noticed, reading back over Rutt's steps: working in LAB kept the hair from blowing out, for the same reason that his color channel retouch works. Very light colors can still contain tone in LAB.

A contrast move brought things into a resonable facsimile of the real world.

Boomtat

Hi guys,

I appreciate the effort you've all put in over my image.

Here at the museum, we have to do battle with the curators who want to preserve the artifacts "as is". I had already "corrected" this image using curves, levels and hue/saturation, and I've included it here. It's down and dirty.... but war is hell, anyway!
The curators are happy with this result, and it took about 10 min to do.
How long did you guys spend on the image? Because we only do low end manipulations, our methods have to be on the quick side.
It was great to see the different approaches you all took.

Thanks again
Boomtat

rutt

I worked on this a lot more than 10 minutes. Hours in fact. But my attitude is that if I'm learning something it's an investment which will pay off next time. Once you solve the puzzle, it only takes a few minutes to do the actual adjustments.