Inspiring

Question

Luminosity

Forum|Forum|7 years ago
July 25, 2018
8 replies
2855 views

Hi folks.

I've done the usual Google and YouTube search, but can't find a good tutorial on Photoshop Luminosity that isn't a platform for selling another piece of software.

Can anyone recommend a good tutorial, even on Adobe site?

[Moderator edited title to fix typo.]

This topic has been closed for replies.

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BigDingusAuthor

Inspiring

When I first posted here, it was to learn about Luminosity. I knew absolutely nothing. However your discussions between you are revealing loads for me to soak up like a sponge. Excellent.

Ussnorway7605025

Legend

in my book the best use for them is turning summer photos into winter

here is one that covers the basics but the trick is as old as Photoshop itself and there are many fine-tune options so look around

Summer To Winter - Snow Photoshop Tutorial - YouTube

Stephen Marsh

Community Expert

I would suggest that Luminosity (RGB) and Lightness (L of Lab) are indeed different, however in practice they are similar in how they are used.

D Fosse

Community Expert

Stephen_A_Marsh wrote
I would suggest that Luminosity (RGB) and Lightness (L of Lab) are indeed different, however in practice they are similar in how they are used.

It should be easy enough to test. In my own limited testing I have found them to be identical. And it would be the logical way to do it, since the Lab version is always present in the background. Those data are easily pulled up.

Note, however, that if you display a luminosity mask as a single-channel grayscale image, it will be displayed according to your working gray. Your working gray is assigned.

So you need to keep gamma identical. In practice that means you must test with Adobe RGB and Gray Gamma 2.2 as working gray. All other combinations will change the tone response curve in the mask representation on screen.

Stephen Marsh

Community Expert

Replying To:

D Fosse “It should be easy enough to test. In my own limited testing I have found them to be identical. And it would be the logical way to do it, since the Lab version is always present in the background. Those data are easily pulled up.

Note, however, that if you display a luminosity mask as a single-channel grayscale image, it will be displayed according to your working gray. Your working gray is assigned.So you need to keep gamma identical. In practice that means you must test with Adobe RGB and Gray Gamma 2.2 as working gray. All other combinations will change the tone response curve in the mask representation on screen.”

____________

It is easy to test – and test results with confirm my previous statement. As I said they are not exactly the same thing. They are even called different things, the L in Lab is lightness and the L in RGB Luminosity is not exactly the same as Lab lightness. The HSL L(ightness) value is also not exactly the same thing as the L(ightness) value in Lab.

If the RGB luminosity and the Lab Lightness were exactly the same thing, you could paste the L channel from Lab over the same RGB image and blend it in luminosity mode without any visible change to the underlying RGB image.

Conversely if they were the same thing, the luminosity component of an RGB file could be pasted into the L channel of the same file in Lab mode and there would be no visible change to the image.

In both cases this is not so, there is a visible change.

As I said, people use the term loosely and interchangeably to indicate a method of editing that separates colour edits from tonal edits – however technically they are not the same data and they can’t simply be swapped.

Norman Sanders

Legend

If your objective is altering and controlling luminosity (discrete from color), consider switching to Lab Color Mode where the L channel (luminosity) is separate from the magenta/green and yellow/blue channels that build the image. An excellent book devoted to Lab Color is "Photoshop LAB Color" by Dan Margulis. For starters I recommend the 2006 edition.

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BigDingusAuthor

Inspiring

Thanks for that Norman

D Fosse

Community Expert

Photoshop Luminosity is identical to the Lab L channel. You don't need to switch to Lab mode just for that.

Lab is always at work in the background in Photoshop. Color management in Photoshop uses Lab as Profile Connection Space, so Lab values are always readily available. This is what Luminosity blends and selections are based on. When you load a luminosity selection, you get Lab L, and not a desaturated RGB version, which is different.

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BigDingusAuthor

Inspiring

Axel, been looking at your links. You found better ones than I did. Thanks

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BigDingusAuthor

Inspiring

Thanks Axel. I too found loads on YouTube but they then go into how to use their own addons etc.

Trevor if I was wanting to use their sofetware I would deffinately reward them. However, all I want is the knowledge to do it myself and not have someone use an underhand method of selling their software by pretending to help.

Trevor.Dennis

Community Expert

BigDingus wrote
Hi folks.
I've done the usual Google and YouTube search, but can't find a good tutorial on Photoshop Luminosity that isn't a platform for selling another piece of software.
Can anyone recommend a good tutorial, even on Adobe site?

Can you give us some context?

Are you asking what it is, or how to use it?

Are you thinking of masks, or blend modes?

If you don't feel that the work people put into developing useful software is worth rewarding, then Sven Stork's Luminosity Mask extension is free unless you want to make a small donation.

https://svenstork.com/interactive-luminosity-masks/

https://www.adobeexchange.com/creativecloud.details.12307.html

AxelMatt

Community Expert

I've searched with Google and Youtube and found tons of tutorials.

A Simple But Effective Way to Create Luminosity Masks in Photoshop - YouTube

How To Create Luminosity Masks In Photoshop - YouTube

Creating luminosity masks in Photoshop | Photo Tools Weekly | lynda.com - YouTube

Understanding Luminosity Selections and Luminosity Masks Basics - YouTube

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