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Creating luminosity masks step by step

Luminosity masks are a way of making advanced selections in Photoshop based on the luminance level of each pixel. Luminosity masks make it possible to control every tone in a picture. The technique are suitable for tone mapping in HDR photos and in all other photos too. To describe the masks I create, I refere to the zones in the Zone System.
What We do are to save selections as Alpha Channels and make it possible to activate the selections in any photo via Actions.
Action in Photoshop make it possible to record what You do in one photo and do the same thing in another photo via Play.

Zone system as luminosity masks
The photo shows luminosity masks I have saved as Channels. In the tutorial I will show how I created the luminosity masks on basis of the zone system step by step. The luminosity masks corespond to the zones: 0-1, 2-3, 4, 4-6, 6, 6-7, 7-8, 8-9, 9-10 and 10.
More about Channels.


First I will demonstrate the use of the luminosity masks

Here is a photo where pixels coresponding to zone 2 and 3 are selected via Alpha Channel named Zone 2-3. The Alpha Channels with the selections are recorded as Actions and can be activated in every photo via Play.
Choose Images/Adjustments/Curves. The Curves is a powerful editing tool.
The selected tones can be modified via the curve. Down will darken the array and up will lighten the array. A S-curve as shown will increase the contrast in the selected array. Selection via the Channel have a lot of feathering. More than the selected are influenced by the change. But the effect are strongest in the selected array. There will never bee a sharp borden araund the selected array.

How to create luminosity masks with Photoshop CC Alpha channels and save them as Action Sets. - First creating masks for the dark array.



I am using a Windows based compuser. The coresponding Mac OS short cuts are shown in the table.



Mac OS

Ctrl + a Select all Command + a
Ctrl + d Clear selection Command + d
Alt – click the New Channel button Create an alpha channel mask and set options Option – click the New Channel button
Shift + Ctrl + Alt and select the channel Decrease pixels selectet Shift + Command + Option and select the channel
Ctrl + Alt and select channel Subtract the channels selection from existing selection Command + Option and select channel
Ctrl and select channel Opens saved channels selection Command and select channel
IZone system chart
Zone system chart. I have created a zone system chart I use for creating luminosity masks. You can download the chart in tiff format by clicking the picture. The chart are cropped in the tutorial.
Open the Actions menu. Create new Action Set with name Zones.
Create new Action and name it Darks. Push Record.
Red dot shows that recording have started.
Open the Channels Menu. Left click with mouse on button with marching ants. Pixels that are more than 50% light are selectet.
Left mouse click on the symbol with the red arrow will save the selection as a Alpha Channel
Hold down 3 keyes Shift, Ctrl and Alt and left click with mouse on symbol for the Alpha Channel. The selection will change from zones 6-10 to zones 7-10.
Now choose Select/inverse and the selection will change to Zone 0-6.
Save the selection as a Alpha Channel. Double left click with the mouse on the symbol for the Alpha Channel and change the name to 0-6.
Hold down 3 keyes Shift, Ctrl and Alt and left click with mouse on the symbol for the Alpha Channel 0-6. The selection will change from zones 0-6 to zones 0-5. Save the selection as an Alpha Channel and name it 0-5.
Continue the same way until only Zone 0-1 are selectet. Save the selection as Alpha Channel and name it Zone 0-1.

Create new selections by subtracting selections

The rest of the luminosity masks are created by subtracting selections from selections. It is not possible to split the selection up in single zones, So go for selections of 2 zones. Somtimes You will end up with one zone.
Hold down the Ctrl key, left mouse klick on the Alpha Channel 0-3.The 0-3 channel are activated and zones 0-3 are selected.
Now hold down 2 keyes Ctrl and Alt, and left klick on the synbol for 0-1 channel. The 0-1 channel selection are now subtracted from the 0-3 channel selections. Zone 2-3 are now selected.
Save the Zone 2-3 selection as a new Alpha Channel and name it Zone 2-3.
Proceed the same way until You have created the desired channels.
Hold down the Shift key and mark the Channels that are not to be saved. Click on the wastebasket . Hold down Ctrl key and d to remove any selection before the recording are stoped.
Now left mouse click on the square to stop the recording.
Now You can use the the Action on every picture You open in Photoshop. Start the Action by marking the Action Darks and push play.
Do you have some questions or suggestions for a better description, please send an email.





About, Bird photography, Landscape and Seascape, Macro and extreme macro photography, Surreal trick photography