Luminosity Masks

Luminosity Masks is a type of selection in Photoshop . But theywon’t be found in any menu.

When you make an adjustment through a Brights Luminosity Mask, only the brighter areas of the image will be affected while the darker and midtone pixels will be left untouched.

There are a few different ways to create Luminosity Masks . One simplest method is given below :

A : Creating the Brights Luminosity Mask

• The first Luminosity Mask we’ll create is the Brights mask . It targets only the pixels that are considered more than 50% bright. 
• Here , only the brighter areas of the image will be affected while the darker and midtone pixels will be left untouched.

1. Open the image in photoshop 

Picture -1 (Original Picture)

2. Press Ctrl + Click in the RGB thumbnail in the Channels Tab (Window --> Channel).

You can see the selection of some of the areas . 

Picture  - 2  

• Whatever you do with this picture , only the brighter areas of the image will be affected while the darker and midtone pixels will be left untouched.
• The initial selection created by Ctrl+ clicking on the RGB thumbnail targeted every pixel brighter than 50% white. 

3. Save the selection by clicking the Select --> Save selection as channel icon. The selection is now saved as a channel and given the name A1.

4. Double Click the name of your new channel “A1” and you can see channel options like : 

5. Press Ctrl+ D to deselect the selection .
6. Output :

That’s it; you’ve now created your first Luminosity Mask!

B : Creating the Dark Luminosity Mask

Here , the process is almost the same as for Brights one,  but you need to invert the selection:

1. Open the image in photoshop 
2. Press Ctrl + Click in the RGB thumbnail in the Channels Tab (Window --> Channel) 

(Step 1 and 2 are same as above)

     3. Ctrl + Shift + i  (Or, Select --> Inverse) to invert the selection .Then you can see that the inverse selection as,

Picture - 3 

4. Save the selection by clicking the Select --> Save selection as channel icon. The selection is now saved as a channel and given the name A2.

(Notice that A1 is White Luminosity Mask and A2 is Dark Luminosity Mask)

5. Press Ctrl+ D to deselect the selection .

6. Output :

Now you’ve created a Darkst Luminosity Mask!

C : Compare A and B

• The initial selection created by Ctrl+ clicking on the RGB thumbnail targeted every pixel brighter than 50% white. 
• Since we wanted exactly the opposite (everything darker than 50% black), we inverted the selection before saving.
• In the Brights mask, all the bright areas are white or some shade of it, while in the Darks mask all the dark parts are white.

C : Creating the Midtone Luminosity Mask

• We need both Brights one and Dark one to make it.
• Basically, midtones are all the pixels that weren’t selected in Brights one and Dark one . To create the Midtones mask, we’ll take the entire image and just subtract out the brights and darks.

1. Select the entire Image ( Ctrl A)
2. Subtract Bright one (Ctrl+ alt + click on the ‘Bright one’ channel’s thumbnail)

3. Subtract Dark one (Ctrl+ alt + click on the ‘Dark one’ channel’s thumbnail)

4. Save selection and rename the new channel to ‘Midtones 1’.

Let’s recap what just happened: We started by selecting all the pixels, then removing pixels that are brighter than 50% white and then those darker than 50% black. That left us with the first (and narrowest) selection of the Midtones; the mask targets pixels that are neither dark nor bright.

You can activate one by Ctrl+ clicking on its thumbnail.