Tuturial zum Lab* Farbraum in der c't Fotografie

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cimfine
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Tuturial zum Lab* Farbraum in der c't Fotografie

Post by cimfine » Mon 14 Jul 2014 09:32

Guten Morgen,
in der aktuellen c’t Digitale Fotografie 4/2014 gibt es einen Artikel über die Verwendung des Lab* Farbraums für Farbkorrekturen. Der Artikel ist keine einfache Kost, aber inhaltlich sehr interessant - und war der Grund warum ich mir die Zeitschrift mal wieder gekauft habe (denn ansonsten finde ich 9,90 Euro etwas heftig). Als in Frage kommende Programme werden lediglich Photoshop, Photoline und (mit deutlichen Abstrichen, da nur 8 bit) PhotoPaint genannt. Auch wenn die meisten Screenshots von PS sind, erwähnt der Autor auch einige Stellen, an denen Photoline besser arbeitet als PS. Es wird auch eine Photoline Aktion zum Erstellen einer Sättigungsmaske zur Verfügung gestellt. Der Artikel soll in der nächsten Ausgabe fortgesetzt werden.

Ich habe die beschriebenen Maßnahmen bislang nur kurz ausprobiert, aber ich muss dem Autor recht geben, die Erhöhung der Sättigung etwa funktioniert besser als z.B. in Lightroom.

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Herbert123
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Re: Tuturial zum Lab* Farbraum in der c't Fotografie

Post by Herbert123 » Sat 11 Oct 2014 20:18

Lab mode is awesome - I use it all the time for colour corrections and enhancements, but sadly most users have no idea about the power of Lab. This is understandable, because Lab mode is quite counter-intuitive at first.

If you are interested in becoming acquainted in-depth with the possibilities, and how it can super-charge the quality in your images, check out the books by Dan Margulis - he is pretty much the reference for this type of workflow.

All his techniques can be converted to Photoline, and indeed, most of the time Photoline makes it easier to work with Lab (since we can apply Lab curves without being forced to switch to Lab image mode).

His newest book is great:
http://www.moderncolorworkflow.com/the-book

There are also (paid) video tutorials.
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photoken
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Re: Tuturial zum Lab* Farbraum in der c't Fotografie

Post by photoken » Sun 12 Oct 2014 04:37

Herbert123 wrote:Lab mode is awesome...
Absolutely right. Setting a Curves adjustment on that "L" channel is almost magical. When I see the users in the Photoshop Elements forum or the PaintshopPro forum struggling to achieve a correction that ultimately is much worse than what PL can easily do, I have to laugh....
Ken
Yes, I think it can be eeeeeasily done....
Just take everything out on Highway 61.

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Herbert123
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Re: Tuturial zum Lab* Farbraum in der c't Fotografie

Post by Herbert123 » Sun 12 Oct 2014 06:02

Have you tried this simple trick (basically "vibrance" adjustment):

Before:
before.jpg
After:
after.jpg
Curves (keep the curve centered for the a and b channels, otherwise you'll get a colour cast). If the colours are too strong, reducing the opacity for the adjustment layer will do the trick. Or go beyond 100% (Don't you just love this? I know of no other image editor that allows us to go beyond 100% for a layer's opacity. So convenient!)

Btw, the L adjustment is not really required, but does pop the details more. You should try this a/b move on a sunset photo taken at the beach. Mindblowing how much colour you can get from an initially good looking sunset with this simple technique.

Before you perform this Lab move, make certain you colour corrected the image first - a colour cast will otherwise become much stronger as well, of course. I did have to colour correct this photo a bit for the green and blue channels.
curves.jpg
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photoken
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Re: Tuturial zum Lab* Farbraum in der c't Fotografie

Post by photoken » Sun 12 Oct 2014 06:26

Herbert123 wrote:Have you tried this simple trick (basically "vibrance" adjustment):
Yes, although I prefer to use the HSL or HIS mode for "vibrance" adjustments -- I find it easier to just increase the Saturation for only the less saturated areas using those modes.

As I understand it, the "Vibrance" adjustment in other image editors also has an additional feature in its algorithm to "protect" the pastel red areas. This is so the adjustment doesn't have much effect on Caucasian skin tones, but the surrounding background is enhanced. Not saying that the same effect can't be achieved in PL, but it would definitely take some work....
Ken
Yes, I think it can be eeeeeasily done....
Just take everything out on Highway 61.