Generate placeholder image with text overlay

overlay_text.sh

#!/usr/bin/env bash
set -euo pipefail

if [ $# -eq 0 ]; then
    echo "Usage: $0 \"Your text here\""
    exit 1
fi

TEXT="$*"
FILENAME=$(echo "$TEXT" | sed 's/\\n/_/g; s/[^A-Za-z0-9]/_/g; s/__*/_/g').jpg

# Convert literal \n to actual newlines
TEXT="${TEXT//\\n/$'\n'}"
TMPIMG=$(mktemp /tmp/loremflickr_XXXXXX.jpg)
trap 'rm -f "$TMPIMG"' EXIT

# Download a random nature image from Lorem Flickr (1300x900)
echo "Downloading image..."
curl -sL -o "$TMPIMG" "https://loremflickr.com/1300/900/nature"

# Determine average brightness of the image (0-255 scale)
BRIGHTNESS=$(magick "$TMPIMG" -colorspace Gray -resize 1x1! -format "%[fx:int(mean*255)]" info:)
echo "Image average brightness: $BRIGHTNESS"

# Choose text and stroke colors that contrast with the image
if [ "$BRIGHTNESS" -gt 128 ]; then
    TEXT_COLOR="black"
    STROKE_COLOR="white"
else
    TEXT_COLOR="white"
    STROKE_COLOR="black"
fi
echo "Using $TEXT_COLOR text with $STROKE_COLOR outline"

# Overlay text centered on the image with Arial Black, wrapping long lines
magick "$TMPIMG" \
    \( -background none \
       -font "/System/Library/Fonts/Supplemental/Arial Black.ttf" \
       -fill "$TEXT_COLOR" \
       -stroke "$STROKE_COLOR" \
       -strokewidth 2 \
       -size 1260x860 \
       -gravity center \
       caption:"$TEXT" \) \
    -gravity center \
    -composite \
    "$FILENAME"

echo "Saved: $FILENAME"