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Author Topic: Slide scans color-balance by PS?  (Read 581 times)

Eric Myrvaagnes

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Slide scans color-balance by PS?
« on: June 19, 2020, 11:48:42 am »

Dave (Isle of Skye) suggested a possible way of automatically getting PhotoShop to correct the color balance of some scanned Kodachromes from the Canadian Rockies I posted recently over in the Landscape Showcase thread ("Re: Looking back part 3: Canadian Rockies (1977-...)
« Reply #31 on: June 17, 2020, 01:37:50 pm »".)

My bad color vision has prevented me from making appropriate adjustments myself. So I chose a few scans that my wife (with good color vision) has complained about and tried Dave's suggested method. Here, and in the next three posts, I show before and after versions of four of the slides, and I invite comments on which member of each pair is better, and whether the better looks at all convincing.

The first pair is looking down on Lake O'Hara, and the second pair is the rock wall behind Floe Lake.
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #1 on: June 19, 2020, 12:05:06 pm »

Floe Lake Rock Wall:
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #2 on: June 19, 2020, 12:08:05 pm »

View north from Yuma Pass (near Floe Lake):
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #3 on: June 19, 2020, 12:09:12 pm »

Mountain goat, near Twin Falls:
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KLaban

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Re: Slide scans color-balance by PS?
« Reply #4 on: June 19, 2020, 12:50:58 pm »

Eric, I'm looking at these on my workhorse editing desktop system which has everything including the cat's arse profiled and calibrated and the second version of all four are much improved.

As for convincing, well compared to the first version of each, a resounding yes!
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schertz

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Re: Slide scans color-balance by PS?
« Reply #5 on: June 19, 2020, 02:12:49 pm »

Hi Eric,
When I viewed your images in the original post, I didn’t realize you had colour vision challenges. I just assumed you wished to keep your slides the way they were previously edited (you had also mentioned some film processing mishaps). With this new info, many of the original images had a strong magenta tint throughout, and especially in the highlights. This new processing you have done is great and looks far more realistic. Love the new editing process!
The content of the photographs remains outstanding.
Cheers,
Mike
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #6 on: June 19, 2020, 04:07:10 pm »

Thank you Keith and Mike.
I will now go ahead and try the PS almost-automated procedure on all of my old slide scans.

I had an exhibit several years ago at a local library, and I brought a photographer friend to see it, and he remarked that my blue skies looked a bit magenta. They just looked blue yo my eyes, so i couldn't see how to fix them.

My one safety technique since then is that I never touch the color balance slider in LightRoom unless the image is sufficiently abstract that I don't care about color accuracy.

Mike's suggested technique is simple enough that I should be able to make a PS action to do it quickly. By the way, I am still using PS 6 (wno rental fees) and this works for me.

-Eric
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John R

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Re: Slide scans color-balance by PS?
« Reply #7 on: June 19, 2020, 05:21:30 pm »

These are much more natural, Eric. Thank you to Mike for the great tutorial on creating or fixing colour balance.

I gave up on Kodachrome and got swept away by the Fujifilm tide of 'pop' colours. As I learned more, I tried to choose film with characteristics that best suited the subject. Green scenery definitely benefited from Fuji. But Ilfachrome was better for more pastel like colours, and so on.

JR

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schertz

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Re: Slide scans color-balance by PS?
« Reply #8 on: June 19, 2020, 09:36:39 pm »

Just to clarify: it was Dave (Isle of Skye) who made the processing suggestions that you employed here. I deserve no credit.
Cheers,
Mike
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John R

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Re: Slide scans color-balance by PS?
« Reply #9 on: June 19, 2020, 10:03:34 pm »

Just to clarify: it was Dave (Isle of Skye) who made the processing suggestions that you employed here. I deserve no credit.
Cheers,
Mike
Ok. Thank you Dave (Isle of Skye)!
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Rajan Parrikar

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Re: Slide scans color-balance by PS?
« Reply #10 on: June 20, 2020, 04:58:48 am »


As for convincing, well compared to the first version of each, a resounding yes!

+1

kers

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Re: Slide scans color-balance by PS?
« Reply #11 on: June 20, 2020, 05:35:54 am »

I just made scans of over 10.000 slides, mostly from the 1980-2000
Some started to change colour already, others looked perfect.
It is a lot of work sometimes to get the colours right.
in this case the colours look more natural after the photoshop treatment.
I still have a lot of work to do.
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #12 on: June 20, 2020, 01:28:42 pm »

Just to clarify: it was Dave (Isle of Skye) who made the processing suggestions that you employed here. I deserve no credit.
Cheers,
Mike
Oops! My bad.
Thanks so much Dave!!
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #13 on: June 23, 2020, 01:32:17 pm »

Update: I have now replaced all of my Canadian Rockies images (in the Landscape Showcase forum) with ones reprocessed using an action built on Dave's suggestion. I have also added four more images that I forgot to include the first time.

Enjoy!

-Eric
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rabanito

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Re: Slide scans color-balance by PS?
« Reply #14 on: June 24, 2020, 09:58:48 am »

I'm still curious on how this works.
I've always used the eyedropper of White Balance in Lightroom when necessary. I assume that clicking on a neutral gray pixel this tells LR that that is "gray" and then LR corrects all other colours.
Now I tried this Ctrl+Shift+B thingy in PS and it does something, but the result is  different.
In LR I'm telling the program what "gray is". I imagine that I can understand how it works.
In PS I'm just pressing keys, PS does everything for me. I don't know what criteria it uses.
Can anybody explain a little?
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #15 on: June 24, 2020, 10:12:07 am »

That's a good question.
For me, with defective color vision, I can't be sure what gray might be neutral in a photo, unless I had included a neutral gray card when taking the photo.

I think Dave's explanation was roughly that PS looks at the brightest and darkest points in an image and assumes that they are white and black, and adjusts from there.

That suggests an experiment I might try: I'll set up a scene where the brightest is non-white (say, really light green, for example) and the darkest is a dark version of the same color. What will PS do to that? When I get around to doing that, I'll post the results here.
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RSL

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Re: Slide scans color-balance by PS?
« Reply #16 on: June 24, 2020, 10:38:47 am »

The ability of digital cameras and of Photoshop (Camera Raw or Lightroom, which has Camera Raw built in) to handle white balance has improved almost beyond belief since I started doing digital 20 years ago. In most cases it's right on. Occasionally you need to instruct it with the eyedropper.
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Eric Myrvaagnes

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Re: Slide scans color-balance by PS?
« Reply #17 on: June 24, 2020, 02:13:59 pm »

But the eyedropper isn't reliable for those of us with deficient color vision. If I pick a spot that looks neutral to me, it may well have considerable magenta that I don't see.

I should carry the gray card with me more often...
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RSL

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Re: Slide scans color-balance by PS?
« Reply #18 on: June 24, 2020, 02:37:00 pm »

The other thing you can do, Eric, is pick a spot you know is white. Usually there are more of those than spots that are middle gray.
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rabanito

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Re: Slide scans color-balance by PS?
« Reply #19 on: June 24, 2020, 03:31:53 pm »

I photographed a gray card (visitor unasked for  :) )

I got the following readings in PS (Info RGB)

Photo 1 As Shot
Gray Card      155 157 175
White Wall     239 239 244

Photo 2 In PS Camera Raw - Eyedropper on gray card
Gray Card      175 175 175
White Wall     249 249 249

Photo 3 with Ctrl+Alt + B
Gray Card      159 159 174
White Wall     252 252 252

Photo 2 seems to be right
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