MacOS Quick Action that adds a random gradient background + drop shadow to images

A macOS Quick Action script that adds a random gradient background + drop shadow to any image (or batch of images) directly from Finder's right-click menu. Powered by ImageMagick.

What it does

• Generates two random colors for the gradient (never near-white)
• Picks a random gradient angle (0°, 45°, 90°… 315°)
• Adds a soft drop shadow behind your image
• Saves the output as a new file (yourfile_gradient.jpg) — original is untouched
• Works on a single file or multiple files at once

Requirements

• macOS (tested on Ventura / Sonoma)
• Homebrew
• ImageMagick

Step 1 — Install ImageMagick

Open Terminal and run:

brew install imagemagick

Verify it's working:

magick --version

Step 2 — Create the Quick Action in Automator

1. Open Automator (use Spotlight: ⌘ Space → type Automator)
2. Click New Document
3. Choose Quick Action as the document type
4. At the top of the workflow, set:

• Workflow receives current → image files
• in → Finder

1. In the search bar on the left, search for Run Shell Script
2. Drag it into the workflow area on the right
3. In the action settings:

• Shell → /bin/zsh
• Pass input → as arguments

1. Paste the script above into the text area

Step 3 — Save the Quick Action

1. Press ⌘ S to save
2. Name it: Add Gradient Background
3. Close Automator

Step 4 — Use it in Finder

1. Select one or more image files in Finder
2. Right-click → Quick Actions → Add Gradient Background
3. Done! A new file named yourimage_gradient.jpg will appear in the same folder

Batch processing works out of the box — select as many images as you want, they'll each get their own unique random gradient.

Customization

You can tweak these four variables inside the script:

| Variable | Default | What it controls |

| PADDING | 80 | Border size around the image (px) |

| SHADOW_OFFSET | 12 | How far the shadow is offset (px) |

| SHADOW_BLUR | 18 | Shadow softness / spread |

| SHADOW_OPACITY | 70 | Shadow darkness (0 = none, 100 = solid black) |

| MAX_BRIGHTNESS | 200 | Max brightness to allow for gradient colors (lower = darker colors only) |

Troubleshooting

Quick Action doesn't appear in Finder

• Make sure you set "Workflow receives current → image files in Finder" in Automator
• Try logging out and back in, or restart Finder: killall Finder

magick: command not found

• The PATH line at the top of the script should fix this, but double-check ImageMagick is installed: brew install imagemagick
• Also confirm the shell in Automator is set to /bin/zsh

Test it in Terminal first

zsh /path/to/add_gradient_background.sh /path/to/image.jpg

This shows the exact error if something goes wrong.

Output example

✅ Saved: /Users/you/Desktop/photo_gradient.jpg
   Gradient: #3A1F8C → #C04A22 | Angle: 135° | Shadow: offset=12px blur=18px