Use Local Adjustments to make edits that are only applied to a selected area of the picture. This selected area is called a “mask.”
Work with Masks
To create a mask, click on one of the masking tools. This adds a Mask # item to the right panel. The masking tool used is shown below it. The left part of the mask has a thumbnail that illustrates the final mask’s specific appearance in black and white. Black indicates the parts of the picture that are not included in the mask, while white indicates the parts that are included.
Masking Tools
Several tools for defining a mask are available.
Subject
This creates a mask automatically using artificial intelligence. ZPS analyzes the picture, assesses which elements are its main subject, and includes these in the mask.
Background
This creates a mask automatically using artificial intelligence. Just as with the Subject mask, ZPS assesses which elements in the picture are its main subject, but it then includes everything else in the mask. The same effect can be achieved by inverting the Subject mask.
Sky
This creates a mask automatically using artificial intelligence. ZPS analyzes the picture to find the sky area within it and includes it in the mask.
Object
Use this to mask an object in the picture. Draw a rectangle around the object, and ZPS will find the main subject within this rectangle using artificial intelligence and include it in the mask.
Brush
Use this to “brush on” any desired mask using a circular brush. This brush has two modes: 
Add to Mask and 
Remove from Mask. Use the four settings available here to adjust the brush parameters.
Radius – sets the brush size. This setting can also be adjusted using the mouse: press [Shift] and turn the mouse wheel.
Opacity – this adjusts the brush transparency. The default value is 100%.
Density – this sets how strongly the effect is applied in one mouse click.
Blur – this adjusts the smoothness of the transition between the area being adjusted and its surroundings.
Brush-based masks can also be added using the presets under Tool Actions. These presets are available:
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Brush – Dodge & Burn Brushes
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Brush – Brush for Iris Brightening
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Brush – Tooth Brightening
Radial Gradient
Use Radial Gradient to add a mask in the shape of a circle or ellipse. To add the mask, click and drag in the picture. A radial mask is placed in the spot where you clicked. If the photo contains a human face, you can also add a mask using presets. In the Actions category within the Presets section, some presets utilizing AI technology are available:
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AI Radial Filter – Lighten Faces
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AI Radial Filter – Brighten Eyes
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AI Radial Filter – Enhance Mouth
Using one of these presets makes ZPS seek out all the faces, eyes, or mouths in the picture and create a separate mask for each one.
To reposition a mask, click and drag the node that is shown in the middle of each mask. On the top, bottom, left, and right edges of a mask, there are nodes that can be clicked and dragged to stretch or shrink the mask. A dashed line runs through the middle node of the in-preview controls; this line defines the mask’s angle. Hovering the mouse cursor by this line shows an icon: 
. Click and drag this icon to change the mask’s angle.
Linear Gradient
Use Linear Gradient to add a mask with a gradient defined by a straight line. To finish adding the mask, click and drag in the picture. The direction in which you drag defines the gradient’s rotation, while the distance that you drag defines its width. Both values can be changed later.
Color Range
Use this tool to set the range of colors to which changes are applied. To set the color range, activate the eyedropper 
, and then click a spot with the desired color in the photo. The selected color range is shown as a section of a radial color graph. Move the white points in this graph to adjust the color range so that it only includes selected details in the picture.
Stretch – use this to adjust the edges of the mask area, fine-tuning your selection.
Blur – use this to adjust the smoothness of the transition between the mask and the rest of the photo.
Luminance Range
Use this to set the range of luminance (brightness) levels to which the changes are applied. To select the luminance range, activate the eyedropper , and then click a spot with the desired luminance level in the photo. The selected range is indicated on a graph. Move the white dots in the graph to adjust the luminance range so that it only includes selected details in the picture.
Stretch – use this to adjust the edges of the mask area, fine-tuning your selection.
Blur – use this to adjust the smoothness of the transition between the mask and the rest of the photo.
Combining the Masking Tools
Long-press in the right panel over a mask to see three extra options: 
Add, 
Subtract, and 
Intersection. Each one lets you choose the same masking tool or a different one and adjust the existing mask using that tool.
Add – the new and original selected areas are added together.
Subtract – the new selected area is subtracted from the original area.
Intersection – the resulting mask contains the areas that are present in both the new and original masks.
An icon next to each mask indicates the way in which it interacts with other masks. Left-click an icon to change the corresponding mask’s mode.
Other Operations
Long-pressing on a mask also shows other options besides the mask modes.
Invert – click this to make the mask include everything that was not selected before and exclude everything that was selected before.
Duplicate – this creates another mask with an identical shape, position, and settings.
Remove – this removes the entire mask and all changes to the mask’s settings.
Hide – when this is active, the mask and any adjustments to it are preserved, but they are not reflected in the edited photo’s preview.
Menu – contains the options listed above. The menu for Mask also contains a Default Settings option, which removes all the adjustments made to a picture. The menu for a masking tool in use also contains a list of mask modes.
To rename a mask, double-click its name.
If you’ve created multiple masks, selection areas can be moved among them. Click and drag an area to assign it to a different mask.
Show Selection
Clicking the arrow next to the button displays these options: Normal, Inverted, Mask Only, Desaturate, and Show When Editing. With default (normal) settings, the Inverted option is active, alongside Desaturate and Show When Editing..
Normal – Everything that is not included in the selection is covered in a transparent red.
Inverted – Everything that is included in the selection is covered in blue.
Mask Only – everything that is not included in the selection is covered in an opaque red, and everything that is included in the selection is covered in an opaque white.
Desaturate – if this option is active, everything that is not included in the selection is displayed in black and white when the Normal or Inverse option is being used.
Show When Editing – if this option is active, the selection display options are only shown when you are changing the mask’s shape, position, and rotation, or when you are hovering the mouse over a mask’s name. If this is not checked, and is not active as well, the selection is not displayed at all. If it is not checked, but the icon is active, the selection will continue to be displayed.