Layers and masks are the two concepts that define how Photoshop works for photographers. Layers let you stack edits on top of your original image without changing it. Masks let you control exactly where those edits apply. Together, they make non-destructive editing possible: you can adjust, remove, or rearrange any edit at any time without permanently altering a single pixel of your photograph. Once you understand layers and masks, every other Photoshop skill becomes easier because you have a framework for organizing and controlling your work.
What Layers Are and Why They Matter
Think of layers as transparent sheets stacked on top of your photograph. Each sheet can hold its own content: a tonal adjustment, a color correction, retouching work, sharpening, text, or an entirely different image. You can see through the transparent parts of each layer to the layers below, and the final image is the combined view of all visible layers from top to bottom.
Without layers, every edit you make would permanently alter the pixels of your original file. Change the brightness and you cannot undo it later. Clone out a blemish and the original skin is gone forever. With layers, the original remains untouched at the bottom of the stack, and every edit sits above it on its own independent layer. Toggle a layer off and the edit disappears. Delete it and the edit is gone. Change its settings and the edit updates.
This non-destructive approach is not just a safety net. It is a fundamentally better way to edit because it lets you make decisions iteratively. You can refine a contrast adjustment three weeks after you made it. You can strengthen or weaken a color correction without starting over. You can compare different approaches by toggling layers on and off. Layers turn editing from a one-way, permanent process into a flexible, revisable one.
The Layers Panel
The Layers panel is where you manage everything related to layers. It shows the layer stack from top to bottom, with the topmost layer in the stack being the one that is “on top” of the image. Each layer has a visibility toggle (the eye icon), a name, a thumbnail preview, and controls for opacity and blend mode.
Keep your Layers panel organized. Name every layer descriptively: “Skin healing,” “Curves contrast boost,” “Dodge and burn,” “Output sharpen.” When a file has twenty or more layers (common in complex edits), generic names like “Layer 1 copy” make it impossible to find what you need. Spending two seconds to name a layer saves minutes of confusion later.
Use layer groups (folders) to organize related layers. Put all your retouching layers in a “Retouching” group, all your color adjustments in a “Color” group, and all your output preparation in an “Output” group. Groups can be collapsed to save space, toggled on and off as a unit, and given their own masks.
Types of Layers for Photographers
Photoshop has many layer types, but photographers primarily use five.
The Background Layer
When you open an image in Photoshop, it arrives as the Background layer. This layer is locked by default, which prevents you from accidentally painting on it, moving it, or applying effects directly to it. Keep it locked. Your original pixels live here, and protecting them is the foundation of non-destructive editing.
If you need to work directly on pixels (which you should avoid when possible), duplicate the Background layer first and work on the copy. The Background layer itself should remain pristine throughout your entire editing session.
Pixel Layers
Pixel layers contain actual image data. They are created when you duplicate a layer, paste content, create a new blank layer and paint on it, or stamp visible layers together. Retouching work typically happens on blank pixel layers. You create a new empty layer, select a healing or cloning tool with “Sample All Layers” enabled, and paint your corrections onto this blank layer. The corrections exist independently from the original, making them easy to modify or remove.
A stamped visible layer (Ctrl/Cmd+Alt+Shift+E) creates a new pixel layer that is a flattened composite of all visible layers below. This is useful when you need to apply a filter to the combined result of all your edits without flattening the file. For example, you might stamp visible before applying sharpening so the sharpening sees the final composite image.
Adjustment Layers
Adjustment layers are the primary way photographers apply tonal and color corrections in Photoshop. They apply an effect (Curves, Levels, Hue/Saturation, Color Balance, Black & White, and many others) to all layers below them without modifying any pixels. Every adjustment layer comes with its own mask, which controls where the adjustment is visible.
The key advantage of adjustment layers over direct adjustments (Image > Adjustments menu) is that they are completely re-editable. Double-click an adjustment layer’s thumbnail to reopen its settings and change them at any time. Reduce the opacity to soften the effect. Toggle the visibility to compare before and after. Delete it to remove the effect entirely.
The most important adjustment layers for photographers are:
- Curves: The most powerful and flexible tonal control. It handles contrast, brightness, and per-channel color adjustments. A single Curves layer can replace Levels, Brightness/Contrast, and portions of Color Balance. Learn Curves well and it will handle most of your tonal editing needs. It is the foundation of color grading.
- Levels: A simpler interface for setting black point, white point, and midtone brightness. Useful for quick tonal corrections and for stretching the dynamic range of a flat image.
- Hue/Saturation: Adjust the hue, saturation, and lightness of specific color ranges. Useful for selectively warming or cooling colors, desaturating distracting elements, or shifting a color in one part of the spectrum without affecting others.
- Color Balance: Shift the color of shadows, midtones, and highlights independently. Excellent for creative color grading (for example, pushing shadows toward cool blue and highlights toward warm orange).
- Black & White: Convert the image to black and white with control over how each color translates to a gray tone. Far better than simply desaturating because you can control the relative brightness of reds, oranges, yellows, greens, cyans, and blues independently.
- Selective Color: Fine-tune the CMYK components of individual color ranges. Useful for precise color control that the other adjustment types cannot achieve.
- Vibrance: Increase saturation intelligently, protecting already-saturated colors and skin tones. A safer alternative to global Saturation for photographic work.
Smart Objects
A Smart Object is a layer that wraps its contents in a protective container. When you apply a filter to a Smart Object, the filter becomes a Smart Filter, which is non-destructive and re-editable. Double-click the Smart Filter to change its settings at any time.
For photographers, Smart Objects are essential for three workflows. First, applying sharpening (Unsharp Mask, Smart Sharpen, or High Pass) non-destructively so you can fine-tune the amount later. Second, applying Camera Raw Filter as a Smart Filter, which gives you the full power of Lightroom-style adjustments at any point in your Photoshop workflow. Third, embedding placed images (for compositing) at their original resolution so they can be scaled up and down without quality loss.
The downside of Smart Objects is that you cannot paint directly on them. You cannot use the Clone Stamp, Healing Brush, or any painting tool on a Smart Object layer. For retouching, you need pixel layers. For adjustments and filters, Smart Objects give you non-destructive flexibility.
Fill Layers
Fill layers contain a solid color, gradient, or pattern. Photographers use them primarily for two purposes. A solid gray fill layer set to Soft Light blend mode creates a dodge and burn surface where painting with white lightens and black darkens. A solid color fill layer with reduced opacity and a blend mode like Color or Soft Light creates a color wash effect useful for tinting or color grading.
Gradient fill layers are useful for simulating graduated neutral density filters. A black-to-transparent gradient set to Multiply can darken a bright sky, and the gradient can be repositioned or adjusted at any time because it is a live fill layer rather than a painted effect.
Layer Opacity and Blend Modes
Every layer has an opacity slider and a blend mode setting. These two controls determine how the layer interacts with the layers below it.
Opacity
Opacity controls the layer’s overall transparency. At 100 percent, the layer is fully visible. At 50 percent, it is semi-transparent, and the layers below show through at half strength. At 0 percent, the layer is invisible.
Reducing opacity is the simplest way to soften any effect. If a Curves adjustment is too strong, reduce its opacity to 60 percent instead of reworking the curve. If a retouching layer looks too obvious, lower its opacity until the effect is subtle. This quick-and-dirty approach works for fast adjustments, though masks provide more precise control when you need to soften the effect in specific areas rather than globally.
Blend Modes for Photographers
Blend modes control how a layer’s pixels mathematically interact with the pixels below. There are dozens of blend modes, but photographers regularly use only a handful.
Normal: The default. Pixels on this layer replace pixels below, modulated by opacity. Used for retouching layers and standard pixel layers.
Multiply: Darkens the image. Black stays black, white becomes transparent, and everything in between darkens proportionally. Useful for darkening specific areas (like a bright sky) or adding shadow effects. A Multiply layer can simulate the effect of a graduated ND filter when combined with a gradient mask.
Screen: The opposite of Multiply. It lightens the image. Black becomes transparent, white stays white, and everything in between brightens. Useful for lightening shadows or creating glow effects.
Overlay: Increases contrast by darkening shadows and brightening highlights simultaneously. Midtones (50 percent gray) become transparent. Used for High Pass sharpening (a gray High Pass layer set to Overlay sharpens edges while leaving flat areas unchanged) and for contrast enhancement.
Soft Light: A gentler version of Overlay with a less aggressive contrast boost. This is the preferred blend mode for dodge and burn layers. Fill a layer with 50 percent gray, set it to Soft Light, and paint with white to lighten or black to darken. The gray is invisible, and only your painted adjustments show through.
Luminosity: Applies only the brightness changes from the layer, ignoring any color shifts. Useful when you want a Curves or Levels adjustment to affect contrast without shifting colors. Set the adjustment layer’s blend mode to Luminosity to prevent unwanted saturation changes.
Color: The opposite of Luminosity. Applies only the color from the layer, preserving the luminosity below. Useful for tinting effects and for correcting color casts in specific areas without affecting their brightness.
What Masks Are and How They Work
A mask is a grayscale image attached to a layer that controls the layer’s visibility on a per-pixel basis. Where the mask is white, the layer is fully visible. Where the mask is black, the layer is completely hidden. Where the mask is gray, the layer is partially visible, with the transparency proportional to the shade of gray.
This simple principle gives you precise, flexible control over where any edit applies. Add a Curves adjustment to brighten the image, then paint black on its mask everywhere except the subject’s face, and you have brightened only the face. The rest of the image is unaffected because the mask hides the Curves layer in those areas.
The power of masks over selections or erasing is that masks are non-destructive and infinitely editable. If you erase part of a layer, those pixels are gone. If you hide part of a layer with a mask, you can reveal it again at any time by painting white on the mask. You can blur the mask to soften the transition. You can adjust the mask’s density to make it partially transparent everywhere. Masks give you complete control without destroying anything.
Layer Masks
Layer masks are the most common type of mask. Every adjustment layer comes with one automatically. For other layer types, you add a mask by clicking the “Add layer mask” button at the bottom of the Layers panel.
Creating and Editing Layer Masks
A newly created mask is white by default, meaning the entire layer is visible. To hide parts of the layer, paint on the mask with black. To reveal parts, paint with white. Toggle the foreground and background colors with the X key, which makes it easy to switch between revealing and concealing as you work.
To start with a mask that hides everything (useful when you want to paint in an effect selectively), hold Alt/Option when clicking “Add layer mask.” This creates a black mask, and you paint with white to reveal only the areas where you want the effect to appear.
You can also create a mask from a selection. Make a selection using any selection tool (Quick Selection, Select Subject, Pen tool, Color Range), then click “Add layer mask.” The selection becomes white in the mask, and everything outside the selection becomes black. This is one of the most common workflows: select the area you want to affect, create the adjustment layer (which automatically uses the selection as its mask), then refine the mask with a brush.
Brush Techniques for Masks
When painting masks, your brush settings matter enormously.
Soft brush, low opacity: This is your default for most photographic masking. A soft brush (hardness 0-20 percent) with low opacity (10-30 percent) creates gradual, invisible transitions. Build up the mask gradually rather than trying to paint it perfectly in one stroke. Multiple passes at low opacity create a smoother result than a single pass at high opacity.
Hard brush, high opacity: Use this for areas that need a precise, sharp edge. If you are masking an adjustment that should affect one side of a hard boundary (like a wall or the edge of a building), a hard brush keeps the mask edge clean.
Feathered selections: For large areas with gradual transitions (like masking a sky from a foreground), making a selection with feathering and filling the mask is often faster than painting by hand.
Gradient tool on masks: Dragging a gradient on a mask creates a smooth linear or radial transition from visible to hidden. This is the digital equivalent of a graduated filter and is extremely useful for blending adjustments that should apply to one half of the image and fade into the other half.
Viewing and Refining Masks
Alt/Option-click the mask thumbnail to view the mask as a grayscale image filling the canvas. This lets you see the mask in detail and spot any rough edges, holes, or uneven areas that are hard to notice in the composite view. Alt/Option-click again to return to normal view.
Shift-click the mask thumbnail to disable the mask temporarily. The full layer becomes visible without any masking. This is useful for comparing the masked and unmasked effect.
In the Properties panel, you can adjust two important mask properties. Density reduces the mask’s maximum effect. At 100 percent density, black areas completely hide the layer. At 50 percent density, black areas only hide 50 percent of the layer, making the overall effect lighter. Feather blurs the mask, softening all edges. This is useful for quickly softening a mask that was created from a selection with hard edges.
Clipping Masks
A clipping mask uses the content of one layer to define the visibility of the layer above it. If you clip an adjustment layer to a retouching layer, the adjustment only affects the pixels on the retouching layer, not the entire image. The bottom layer’s transparency becomes the mask for every layer clipped to it.
To create a clipping mask, hold Alt/Option and click on the line between two layers in the Layers panel. Or right-click a layer and choose “Create Clipping Mask.” The clipped layer shows an indent and a downward arrow indicating it is clipped to the layer below.
Photographers use clipping masks when they need an adjustment to affect only a specific layer rather than everything below. For example, if you have composited a new sky as a separate layer, you might clip a Curves adjustment to that sky layer so the Curves only adjusts the sky. Without the clipping mask, the Curves would also affect the foreground. This is particularly useful in HDR compositing and exposure blending workflows where different adjustments apply to different exposure layers.
Luminosity Masks
Luminosity masks are selections (and therefore masks) based on the brightness values in the image. A highlights luminosity mask selects the brightest pixels most strongly, transitions through midtones with partial selection, and leaves the darkest pixels unselected. A shadows mask does the reverse. Midtones masks select the middle range.
For photographers, luminosity masks are transformative because they let you make adjustments that target specific tonal ranges with perfectly smooth, natural-looking transitions. Want to recover detail in just the highlights without affecting the shadows? Apply a Curves darkening adjustment with a highlights luminosity mask. Want to lift just the shadows without washing out the midtones? Use a shadows luminosity mask. The transitions are perfectly smooth because they follow the actual luminosity gradients in the image.
Creating Luminosity Masks
The basic method is to Ctrl/Cmd-click on the RGB channel in the Channels panel. This creates a selection based on the image’s luminosity: bright areas are more selected, dark areas are less selected. This is your basic Highlights selection. To create a Shadows selection, invert it (Ctrl/Cmd+Shift+I). To create increasingly targeted selections (Highlights 2, Highlights 3), intersect the Highlights selection with itself by Ctrl/Cmd+Alt+Shift-clicking the RGB channel again.
Once you have a luminosity selection active, create an adjustment layer. The selection automatically becomes the adjustment layer’s mask. Now the adjustment applies most strongly to the tonal range you selected and fades naturally through the transitions.
Luminosity masks are especially valuable for landscape photographers working with exposure blending and for any photographer who needs to recover highlights or open shadows without affecting the rest of the tonal range. They produce far more natural results than simply dragging a Highlights or Shadows slider because the mask transitions follow the actual image content.
Masks and Selections: Working Together
Selections and masks are two representations of the same thing. A selection is a temporary mask defined by marching ants. A mask is a permanent selection stored as a grayscale channel on a layer. You can freely convert between them.
To convert a selection to a mask: make your selection, then create an adjustment layer or click “Add layer mask.” The selection becomes the mask.
To convert a mask to a selection: Ctrl/Cmd-click the mask thumbnail in the Layers panel. The mask becomes an active selection.
This interchangeability means you can use any selection tool (Quick Selection, Select Subject, Color Range, Select Sky, Pen tool) to create the initial shape of a mask, then refine it with brush painting, Gaussian blur, or Levels adjustments applied directly to the mask. The most efficient workflow usually combines automated selection with manual refinement.
Use Select and Mask (available from any active selection) to refine edges before converting to a mask. The Refine Edge Brush is particularly important for portrait photographers who need clean masks around hair. Paint along the hair edge, and the algorithm separates individual strands from the background, creating a mask that would take hours to paint manually.
Practical Masking Workflows for Photographers
Targeted Exposure Adjustment
Your subject’s face is slightly underexposed while the background is properly exposed. Add a Curves adjustment layer and brighten the midtones. Invert the mask to black (Ctrl/Cmd+I). Paint with a soft white brush at 50 percent opacity over the face, building up the brightness gradually. The Curves brightening now applies only to the face, with a smooth falloff into the surrounding areas.
Selective Color Enhancement
You want to boost the saturation of a sunset sky without affecting the foreground. Add a Hue/Saturation layer and increase saturation. Use Select Sky or a gradient on the mask to limit the effect to just the sky. The foreground retains its natural color while the sky becomes more vivid. This is far more controlled than using a global saturation boost, which would oversaturate skin tones and foliage.
Vignette Effect
Add a Curves layer and darken the midtones. Use a large, soft black brush to paint the center of the mask, creating a radial gradient from full effect at the edges to no effect in the center. Alternatively, use the Elliptical Marquee tool with heavy feathering, invert the selection, and use that as the mask. This creates a darkened edge (vignette) that draws the viewer’s eye toward the center of the frame. The effect is easily adjustable: change the Curves settings to darken or lighten, repaint the mask to reposition the bright center, or adjust the mask’s feather in Properties.
Exposure Blending
Stack a dark exposure (for sky detail) and a bright exposure (for foreground detail) as two layers. Add a mask to the top layer. Use a gradient, luminosity mask, or hand-painted mask to blend the two exposures, revealing the properly exposed portions of each. This manual HDR blending technique gives you complete control over the transition and avoids the artifacts that automated HDR processing sometimes introduces. It is a core technique for landscape photographers dealing with high-contrast scenes where the histogram cannot fit in a single exposure.
Selective Sharpening
Sharpen a Smart Object or stamped layer, then add a mask. Paint black over areas that should not be sharpened: sky, out-of-focus backgrounds, smooth skin. Paint white over areas that benefit from sharpening: eyes, hair, textured surfaces, architectural detail. This selective approach avoids the problem of global sharpening, which amplifies noise in smooth areas and sharpens bokeh in ways that look unnatural.
Background Replacement
Select the subject using Select Subject, refine the edge with Select and Mask (especially the Refine Edge Brush for hair), and output the selection as a layer mask. Place the new background on a layer below the subject. The mask defines the boundary between subject and new background. Fine-tune the mask edge to eliminate fringing, and use a Color Balance or Curves layer clipped to the background to match the lighting between elements. Matching white balance and light direction between the subject and replacement background is the most important step for making the composite look convincing.
Layer Organization and Best Practices
Professional Photoshop files can have dozens of layers. Without organization, the file becomes impossible to navigate. Good habits established early save enormous time as your files grow more complex.
Naming Convention
Double-click a layer name to rename it. Use short, descriptive names: “Blemish removal,” “Curves contrast,” “D&B skin,” “Sky saturation,” “Output sharpen.” When you return to a file months later, or when a collaborator opens it, clear names make the edit understandable at a glance.
Layer Groups
Group related layers into folders. A typical structure for a portrait edit might look like this from bottom to top: Background (locked), Retouching group (healing, clone work, blemish removal), Color & Tone group (Curves, Hue/Saturation, Color Balance), Dodge & Burn group, and Output group (sharpening, resize). Collapse groups you are not currently working in to keep the panel manageable.
Color Coding
Right-click a layer to assign a color label. Use colors consistently: red for retouching, blue for color adjustments, yellow for dodge and burn, green for output preparation. Color coding provides instant visual identification as you scan the Layers panel.
Flattening and Merging
Resist the urge to flatten your file. Flattening merges all layers into a single Background layer, permanently destroying your non-destructive edit structure. Flatten only when exporting the final output file (JPEG for web, flattened TIFF for print). Save your working file as a PSD or layered TIFF with all layers intact.
If you need to reduce file size, consider merging completed layer groups rather than flattening everything. Merge only layers you are completely finished editing. And keep an archived copy of the fully layered file before any merge. This fits into a broader photography workflow where your working files and delivery files are stored separately.
Common Mistakes
Editing directly on the Background layer. This is the most fundamental mistake. Once you paint, clone, or adjust pixels on the Background layer, those changes are permanent. Always work on separate layers above the Background. Lock the Background layer and leave it locked.
Using the Eraser instead of masks. The Eraser permanently deletes pixels. A mask hides them reversibly. There is almost no situation in photographic editing where the Eraser is the right choice. If you are reaching for the Eraser, you should be adding a mask instead.
Using only hard-edged brushes on masks. Hard brush edges create obvious, visible transitions in your adjustments. Unless you specifically need a sharp boundary (like the edge of a building), use soft brushes at low opacity and build up the mask gradually. The difference between amateur and professional masking is almost entirely about edge quality.
Forgetting to select the mask before painting. A common frustration: you try to paint on a mask but the paint appears on the layer content instead. Before painting a mask, click the mask thumbnail in the Layers panel. The bracket indicators around the thumbnail confirm the mask is selected. If you accidentally paint on the layer content, undo immediately and click the mask.
Not viewing the mask to check quality. Masks that look fine in the composite view often have rough edges, holes, or uneven coverage when viewed directly. Alt/Option-click the mask thumbnail regularly to inspect it as a grayscale image. Clean up any problems before moving on.
Flattening too early. Flattening destroys your ability to adjust anything. Once flattened, a Curves layer that was too aggressive can only be corrected by adding another correction on top, not by fixing the original. Keep all layers until you export the final output.
Ignoring layer blend modes. Many photographers use only Normal mode, missing the power of Soft Light for dodge and burn, Luminosity for contrast adjustments that should not shift color, and Multiply/Screen for targeted darkening and lightening. Experimenting with blend modes opens up techniques that are difficult or impossible to achieve with Normal mode alone.
Try This: Practical Exercises
Work through these exercises to build muscle memory with layers and masks. Each one practices a core workflow you will use regularly.
Exercise 1: Build a Basic Layer Stack
Open any photograph. Without making any edits, set up a proper layer structure: lock the Background, add a Curves adjustment layer, add a Hue/Saturation layer, add a blank layer named “Dodge and Burn” (fill with 50 percent gray, set to Soft Light), and add a sharpening layer at the top (stamp visible, convert to Smart Object). Group them into named folders. Save as PSD. This structure is the skeleton of every professional edit and should become automatic.
Exercise 2: Practice Mask Painting
Open a portrait or any image with a clear subject. Add a Hue/Saturation layer and dramatically shift the hue (make it obviously wrong so you can easily see where the mask is working). Now fill the mask with black (Ctrl/Cmd+I) so the effect is completely hidden. Paint with a soft white brush at 30 percent opacity to gradually reveal the hue shift on just the background, carefully keeping the subject unchanged. Practice controlling the brush: build up slowly, toggle between white and black (X key) to fix mistakes, and check the mask directly (Alt/Option-click) to evaluate your painting quality.
Exercise 3: Create a Luminosity Mask
Open a landscape with a bright sky and darker foreground. Go to the Channels panel and Ctrl/Cmd-click the RGB channel to load a highlights selection. Create a Curves adjustment layer (the selection becomes the mask). Darken the Curves to bring down the highlights. Notice how the darkening applies strongest to the brightest areas and fades naturally through the midtones. Alt/Option-click the mask to see the luminosity gradient. This is far more natural than painting a straight-line mask across the horizon. Compare the result to a basic global adjustment where you darken the entire image.
Exercise 4: Blend Two Exposures
Take two exposures of the same scene (one for the sky, one for the foreground) or use two virtual copies from a RAW file processed differently. Stack them in Photoshop, align them, and add a mask to the top layer. Use a large soft gradient, a luminosity mask, or a hand-painted mask to blend the two exposures into a single image with detail in both the sky and the foreground. Toggle the mask on and off to compare the blended result to each individual exposure.
Exercise 5: Selective Color Grading with Masks
Open any photograph. Add a Color Balance layer and create a warm tone in the highlights. Add a second Color Balance layer and create a cool tone in the shadows. On the warm layer’s mask, paint black over the shadow areas so the warm tone only affects the lit areas. On the cool layer’s mask, paint black over the highlight areas so the cool tone only affects the darker areas. The result is a split-toned color grade with warm highlights and cool shadows. This is the foundation of cinematic color grading in Photoshop, and masks are what make it possible to apply different treatments to different tonal ranges.
FAQ
How many layers is too many?
There is no hard limit on the number of layers, but more layers mean larger file sizes and slower performance. Most photographic edits use between 5 and 30 layers. If you have more than that, consolidate by merging finished editing stages. A complex composite might have 50 or more layers, which is fine as long as the file remains manageable. The goal is not to minimize layers but to use them effectively: each layer should serve a clear purpose, and none should be redundant.
What is the difference between a layer mask and a clipping mask?
A layer mask is a grayscale image that you paint or generate to control where a layer is visible. It is the most common and flexible masking method. A clipping mask uses another layer’s transparency as the mask. If you clip Layer B to Layer A, Layer B is only visible where Layer A has pixels. Clipping masks are useful when you want an adjustment to affect only one specific layer rather than everything below it, but they do not give you the painting and gradient control that layer masks provide.
Can I apply a mask to a layer group?
Yes, and this is a powerful technique. Click on a layer group in the Layers panel and add a mask. The mask now controls the visibility of the entire group. This is useful when you have multiple related adjustment layers and want to limit them all to the same area. Instead of painting the same mask on five separate layers, paint it once on the group. Any layer inside the group is affected by the group mask.
My PSD file is enormous. How do I reduce the size?
Large PSD files are a natural consequence of non-destructive editing with many layers. To reduce size: merge layers you are finished editing (but keep an archived copy first), delete any layers that are hidden and no longer needed, flatten unnecessary Smart Objects back to pixel layers, and save with maximum compression. TIFF with LZW compression is lossless and smaller than uncompressed PSD for files with large areas of similar color. If the file is still too large, archive the full layered version and work from a flattened copy for output adjustments.
Should I use layer masks or the Eraser tool?
Layer masks, always. The Eraser permanently deletes pixels. A mask hides them, and you can unhide them at any time by painting white on the mask. Masks can be blurred, adjusted, inverted, duplicated, and refined. The Eraser offers none of these options. The only time the Eraser is acceptable is on a temporary, throwaway layer where you are certain you will never need those pixels again. In practice, this almost never applies to photographic editing.
How do I copy a mask from one layer to another?
Alt/Option-drag the mask thumbnail from one layer to another in the Layers panel. This creates a copy of the mask on the destination layer. If you want to move the mask (removing it from the source), drag without holding Alt/Option. You can also Ctrl/Cmd-click a mask to load it as a selection, then create a new adjustment layer, which will use that selection as its mask. This workflow is useful when you want several layers to share the same masked area.