`image_metadata`

Extract metadata from an image file (dimensions, format, color type).

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 source path, artifact URI/descriptor, { artifact = ... }, or explicit Base64 object
output_keystringdefault "image_metadata": Prefix for output values

Artifact inputs are opened and SHA-256 verified inside the tracked blocking worker; header inspection 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. AVIF and OpenEXR are not supported.

Context Output

<output_key>_width — image width in pixels
<output_key>_height — image height in pixels
<output_key>_format — format detected from the image header (e.g. png, jpeg); artifact files do not need an extension
<output_key>_color_type — color type (e.g. Rgb8, Rgba8)

Example

local flow = Flow.new("image_metadata_demo")

flow:step("meta", nodes.image_metadata({
    path = "examples/fixtures/ironflow-sample.png",
    output_key = "img"
}))

flow:step("log", nodes.log({
    message = "Image: ${ctx.img_width}x${ctx.img_height} (${ctx.img_format})"
})):depends_on("meta")

return flow

Resource contract

Metadata inspection sniffs the image header on a tracked blocking worker and does not allocate a decoded pixel buffer. It still rejects encoded sources over IRONFLOW_MAX_IMAGE_ENCODED_BYTES (50 MiB), dimensions over IRONFLOW_MAX_IMAGE_PIXELS (25 million), or a decoder-reported byte requirement over IRONFLOW_MAX_IMAGE_DECODE_ALLOCATION_BYTES (128 MiB).