`image_convert`

Convert between image formats (e.g. PNG to JPEG). Output format is inferred from the output file extension.

Parameters

pathstringone of path or source_key: Input 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_pathstringrequired: Output image path (format inferred from extension)
qualitynumberdefault 85: JPEG quality (1-100), only used for JPEG output
output_keystringdefault "image_convert": Prefix for output values

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>_path — output file path
<output_key>_format — output format (from extension)
<output_key>_success — true on success

Example

local flow = Flow.new("image_convert_demo")

flow:step("convert", nodes.image_convert({
    path = "examples/fixtures/ironflow-sample.png",
    output_path = "output/photo.jpg",
    quality = 90
}))

flow:step("log", nodes.log({
    message = "Converted to: ${ctx.image_convert_path} (${ctx.image_convert_format})"
})):depends_on("convert")

return flow

Resource contract

Image headers and decoded byte requirements are checked before allocation using IRONFLOW_MAX_IMAGE_ENCODED_BYTES (50 MiB), IRONFLOW_MAX_IMAGE_PIXELS (25 million), and IRONFLOW_MAX_IMAGE_DECODE_ALLOCATION_BYTES (128 MiB). JPEG conversion admits the retained source plus RGB conversion buffer. Decode, format conversion, and encode run on a tracked blocking worker with cancellation checkpoints between opaque codec operations. JPEG output is streamed to its destination instead of first accumulating the complete encoded file in memory.