`image_resize`

Resize a single image file.

Parameters

pathstringone of path or source_key: Source image path (supports ${ctx.key} interpolation).
source_keystringone of path or source_key: Context key containing a path, artifact URI/descriptor, { artifact = ... }, or an explicit { base64 = "..." } object.
output_pathstringrequired: Destination file path for the resized image.
widthnumber: Target width in px. Required if height is omitted.
heightnumber: Target height in px. Required if width is omitted.
formatstringdefault inferred from output_path or png: Output format: png, jpeg, or jpg.
output_keystringdefault "resized_image": Prefix for the generated context output keys.

If both path and source_key are provided, execution fails. Artifact inputs are opened and SHA-256 verified inside the tracked blocking worker; decoding consumes that same rewound handle rather than a resolved store pathname.

Supported source formats are BMP, Farbfeld, GIF, HDR, ICO, JPEG, PNG, PNM, QOI, TGA, TIFF, and WebP. Output remains restricted to PNG or JPEG.

Context Output

<output_key> — output file path.
<output_key>_width — output width in pixels.
<output_key>_height — output height in pixels.
<output_key>_format — output format ("png" or "jpeg").
<output_key>_success — true on success.

Example

local flow = Flow.new("image_resize_demo")

flow:step("resize", nodes.image_resize({
    path = "examples/fixtures/ironflow-sample.png",
    output_path = "outputs/sample_front_small.png",
    width = 120
}))

flow:step("log", nodes.log({
    message = "Resized to ${ctx.resized_image_width}x${ctx.resized_image_height}"
})):depends_on("resize")

return flow

Resource contract

The encoded source, decoded dimensions/pixels, decoder allocation, and computed output dimensions are checked against IRONFLOW_MAX_IMAGE_ENCODED_BYTES (50 MiB), IRONFLOW_MAX_IMAGE_PIXELS (25 million), and IRONFLOW_MAX_IMAGE_DECODE_ALLOCATION_BYTES (128 MiB) before resize allocation; the allocation check includes the retained source and computed output buffer. Decode, resize, and encode run on a tracked blocking worker; cancellation is observed between opaque codec and transform operations.