This section of the panel is extremely powerful, but it has been designed to be simple to use at all levels of expertise. 

There are three main ways this section can be used. 

  • Preview Mode OFF
  • Preview Mode ON
  • Preview Mode ON with Add & Subtract Enabled

Loading Luminosity Selections the FAST way with Preview Turned OFF

The simplest way to use this section is to load luminosity selections with the preview button switched to OFF. 

By clicking one of the buttons 5-4-3-2-1-0-1-2-3-4-5, a selection will be loaded that is based on the luminosity of the image. 

From “Shadows” on the left, to “Highlights” on the right, the numbers correspond to how deep into the shadows or highlights you want to isolate with your selection.

For example, clicking 5 on the left side (“Shadows 5”) will load a selection that isolates the deepest shadows within the image. 

Clicking 1 on the left side (“Shadows 1”) will load a selection that isolates the entire shadow half of the histogram.

Likewise clicking 5 on the right side (“Highlights 5”) will load a selection that isolates the brightest highlights in the image. 

The 0 button is a little different in that it loads a mid-tone selection. The range of this mid-tone selection is quite broad as it covers virtually the entire histogram except for the brightest highlights and the deepest shadows. 

The selections each button creates are the same regardless whether preview mode is on or off so to visualise the selections each button creates, it’s useful to review the next section regarding Preview being turned ON. 

Loading Luminosity Selections with Preview Turned ON

As mentioned above, the selections each button creates is the same whether preview is turned off or on. But with preview mode ON, you get to see a visual representation of the selection before deciding you want to use it. 

Below is a range of images that show the portion of the histogram that each button will select for the example image, next to the preview of that selection which displays the selected parts of the image in white (or grey). 

So in the top example, the light parts of the preview are the darkest parts of the image because Shadows 5 has been used. The light parts of the bottom example are the brightest highlights in the image because Highlights 5 has been used. 

How To Create Luminosity Selections Using Preview Mode ON – Step By Step

Here is the general flow you should follow when creating/loading selections with a preview:

  • Step 1: Turn Preview Mode On (If not already)
  • Step 2: Press one of the selection buttons to load your desired selection (this makes the preview visible in the main window).
  • Step 3 (Optional): Modify and tweak your selection using the tools available in the “Build and Modify Mask” section of the panel
  • Step 4: Press the Use Mask button to load the previewed selection as an actual selection and remove the preview from view. Or if you want to cancel and start over, press the Cancel Mask button

Once you complete step 4 in this process, you’ll see marching ants across the image indicating that your selection is now active. From here you can use this selection in any way you like.

Adding Or Subtracting Selections From One Another

The third and final “Mode” the Luminosity Selections section of the panel can be used in is Adding or Subtracting.

To add or subtract a selection from another selection is best explained using simple shape selections.

Lets say we use the rectangular marquee tool to create a square selection:

Then we ADD another square selection to the top corner of the existing selection, with some overlap. The resulting selection becomes:

The Add and Subtract checkboxes only become active when Preview is turned ON.

Or, we could SUBTRACT that same second selection from the first, and the result would be something like:

Luminosity Selections can be added and subtracted from each other in the same exact way. The only difference is that the marching ants are not the best way to visualise what’s happening…

For luminosity selections, it is much easier to visualise what’s happening by using the selection previews!

Take the following example where I have started out by turning Preview ON and pressing the “Highlights 1” button on the selection bar. The preview looks like this:

In this preview, the light half of the image (according to the histogram) is shown light grey to white, and the dark half of the image is shown dark grey to black.

Think of it as if we are “selecting the light half of the image”… (Because that’s exactly what we are doing)

Now… What happens if we SUBTRACT the very brightest brights from this “selection”?

Lets see…

With the preview still active, we check the “Sub” box.

Then we choose which selection to subtract from the current preview… In this example we want the brightest highlights, so we press the Highlights 5 button… The preview then changes to show us the preview of the selection we are about to subtract from the original one…

In this preview, only the brightest slivers of the image are shown in light grey to white.

Now, to actually subtract the above selection from the originally loaded one, we press the Apply button… And the preview updates again to show us the result:

The highlights in this selection preview have now been turned from bright greys and whites, to duller greys telling us those highlights have been “subtracted” from the original selection preview.

Next, to load this preview as a selection that we can use we simply press the “Use Mask” button.

How To Add Or Subtract Selections To Or From One Another – Step By Step

To summarise, here are the steps you should follow to add or subtract one selection from another:

  • Step 1: Turn Preview Mode On (If not on already)
  • Step 2: Press one of the buttons on the selections bar to load a preview of your “starting” selection
  • Step 3: Put a check in the “Add” or “Sub” box according to whether you want to add or subtract a selection from the one you loaded in step 2
  • Step 4: Press one of the buttons on the selections bar to load a preview of the selection you will add to or subtract from the original selection previewed in step 2
  • Step 5: Press the “Apply” button to perform the addition or subtraction
  • Step 6: Press the Use Mask button to load the previewed selection as an actual selection and remove the preview from view. Or if you want to cancel and start over, press the Cancel Mask button