ACE Selections and Compositing 2 — Questions and Answers
Question 1: Which blending mode in the Layer Style dialog makes white pixels transparent while preserving dark tones, useful for compositing smoke or fire?
- Multiply
- Screen (Correct answer)
- Overlay
- Luminosity
Correct answer: Screen
Screen blending mode makes white areas transparent and lets darker pixels composite naturally, making it ideal for fire, smoke, and light effects.
Question 2: When using the Polygonal Lasso tool, how do you close a selection without clicking exactly on the starting point?
- Press Shift+Enter
- Double-click (Correct answer)
- Press Ctrl/Cmd+D
- Right-click and choose Close
Correct answer: Double-click
Double-clicking with the Polygonal Lasso tool automatically closes the selection by drawing a straight segment from the current position back to the start point.
Question 3: What does the 'Decontaminate Colors' option in Refine Edge/Select and Mask do?
- Removes color casts from the entire image
- Replaces fringe pixels with colors from nearby edge pixels (Correct answer)
- Converts the selection to a grayscale mask
- Neutralizes the background color before extraction
Correct answer: Replaces fringe pixels with colors from nearby edge pixels
Decontaminate Colors replaces residual background-colored fringe pixels near extracted edges with colors sampled from the foreground subject.
Question 4: In the Channels panel, what is the quickest way to load a saved alpha channel as an active selection?
- Drag the alpha channel onto the canvas
- Ctrl/Cmd+click the alpha channel thumbnail (Correct answer)
- Double-click the alpha channel
- Right-click the alpha channel and choose Load Selection
Correct answer: Ctrl/Cmd+click the alpha channel thumbnail
Ctrl/Cmd+clicking any channel thumbnail instantly loads that channel's luminosity as a selection in one step.
Question 5: What is the effect of holding Alt/Option while clicking a layer mask thumbnail in the Layers panel?
- Deletes the layer mask
- Toggles the mask on and off
- Displays the mask as a grayscale image on the canvas (Correct answer)
- Inverts the mask
Correct answer: Displays the mask as a grayscale image on the canvas
Alt/Option+clicking a layer mask thumbnail switches the canvas view to display the raw grayscale mask, making it easy to paint or inspect its details.
Question 6: Which Select menu command lets you select all pixels on the current layer that fall within a specific color range?
- Select > Focus Area
- Select > Color Range (Correct answer)
- Select > Similar
- Select > Grow
Correct answer: Select > Color Range
Select > Color Range opens a dialog where you sample colors with an eyedropper and adjust Fuzziness to select matching tones across the layer.
Question 7: When compositing a subject shot on a green screen, which Photoshop feature is specifically designed to remove color spill from the subject's edges?
- Hue/Saturation adjustment clipped to the subject layer
- Decontaminate Colors in Select and Mask (Correct answer)
- The Sponge tool set to Desaturate
- Remove Background in the Properties panel
Correct answer: Decontaminate Colors in Select and Mask
Decontaminate Colors in Select and Mask is purpose-built to neutralize green (or blue) spill that bleeds onto subject edges during chroma-key extractions.
ACE Selections and Compositing 2
Which blending mode in the Layer Style dialog makes white pixels transparent while preserving dark tones, useful for compositing smoke or fire?