macOS Quick Action that adds a random gradient background + drop shadow to images. Supports batch processing — just select multiple files in Finder, right-click, and go. Requires ImageMagick.

gistfile1.txt

#!/bin/zsh

# Add Random Gradient Background + Drop Shadow - macOS Quick Action Script
# Requires: ImageMagick (brew install imagemagick)

export PATH="/opt/homebrew/bin:/usr/local/bin:$PATH"

for INPUT_FILE in "$@"; do
    FILENAME=$(basename "$INPUT_FILE")
    DIRNAME=$(dirname "$INPUT_FILE")
    EXTENSION="${FILENAME##*.}"
    BASENAME="${FILENAME%.*}"
    OUTPUT_FILE="${DIRNAME}/${BASENAME}_gradient.${EXTENSION}"

    # Get image dimensions
    WIDTH=$(magick identify -format "%w" "$INPUT_FILE")
    HEIGHT=$(magick identify -format "%h" "$INPUT_FILE")

    # Generate random colors (hex), avoid near-white (brightness < 200)
    MAX_BRIGHTNESS=200

    while true; do
        R1=$((RANDOM % 256)); G1=$((RANDOM % 256)); B1=$((RANDOM % 256))
        BRIGHTNESS1=$(( (R1 + G1 + B1) / 3 ))
        [[ $BRIGHTNESS1 -lt $MAX_BRIGHTNESS ]] && break
    done

    while true; do
        R2=$((RANDOM % 256)); G2=$((RANDOM % 256)); B2=$((RANDOM % 256))
        BRIGHTNESS2=$(( (R2 + G2 + B2) / 3 ))
        [[ $BRIGHTNESS2 -lt $MAX_BRIGHTNESS ]] && break
    done

    COLOR1=$(printf '#%02X%02X%02X' $R1 $G1 $B1)
    COLOR2=$(printf '#%02X%02X%02X' $R2 $G2 $B2)

    # Random gradient direction
    DIRECTIONS=("0" "45" "90" "135" "180" "225" "270" "315")
    ANGLE=${DIRECTIONS[$((RANDOM % ${#DIRECTIONS[@]}))]}

    # Settings
    PADDING=80         # space around image
    SHADOW_OFFSET=12   # shadow offset in px
    SHADOW_BLUR=18     # shadow softness
    SHADOW_OPACITY=70  # shadow darkness (0-100)

    CANVAS_W=$((WIDTH + PADDING * 2))
    CANVAS_H=$((HEIGHT + PADDING * 2))

    # Create gradient → add shadow to image → composite on gradient
    magick \
        -size "${CANVAS_W}x${CANVAS_H}" \
        "gradient:${COLOR1}-${COLOR2}" \
        -define gradient:angle="${ANGLE}" \
        \( "$INPUT_FILE" \
            \( +clone \
                -background "rgba(0,0,0,${SHADOW_OPACITY})" \
                -shadow "${SHADOW_OPACITY}x${SHADOW_BLUR}+${SHADOW_OFFSET}+${SHADOW_OFFSET}" \
            \) \
            +swap \
            -background none \
            -layers merge \
        \) \
        -gravity center \
        -composite \
        "$OUTPUT_FILE"

    echo "✅ Saved: $OUTPUT_FILE"
    echo "   Gradient: $COLOR1 → $COLOR2 | Angle: ${ANGLE}° | Shadow: offset=${SHADOW_OFFSET}px blur=${SHADOW_BLUR}px"
done