Inputs

• Two or more absolute paths to local input images
• Optional output path; default to an explicit collage.png in the current working directory
• Optional canvas size (--width, --height), default 1920×1200
• Optional --seed for deterministic layout

Prepare Instructions

Resolve credentials in this order:

• Shell environment variables
• The current working directory .env only
• ~/.transloadit/credentials

If your .env lives in a parent directory, export the variables into the shell first.

Run

npx -y @transloadit/node image merge \
  --input ./photo-a.jpg \
  --input ./photo-b.jpg \
  --input ./photo-c.jpg \
  --input ./photo-d.jpg \
  --input ./photo-e.jpg \
  --input ./photo-f.jpg \
  --effect polaroid-stack \
  --width 1920 \
  --height 1200 \
  --format png \
  --output ./collage.png

After the command finishes, confirm the image exists at the expected output path.

Tuning

• --background '#eee5d3' picks a warm beige canvas (default). Hex codes or named colors both work.
• --background none (with --format png or --format webp) produces a transparent canvas.
• --coverage 1.5 is the default. Use 2.0–2.5 for bigger, more overlapping photos; 1.0 or below for smaller, more widely spaced polaroids.
• --seed 42 makes the layout deterministic — rerun with the same inputs to reproduce the same output.
• --shuffle lets the Robot reorder inputs before laying them out.

Debug If It Fails

npx -y @transloadit/node assemblies get <assemblyIdOrUrl> -j

Notes:

• Repeated --input values are bundled into a single /image/merge assembly.
• The polaroid-stack effect works best with 4–12 inputs. Fewer than four tends to look sparse; more than a dozen starts to occlude heavily.
• Each input is cropped to a square inside its polaroid frame — portrait or landscape originals both work.
• Prefer an explicit output filename (e.g. ./collage.png or ./collage.jpg) over a directory output so the extension is deterministic.