Image segment (GrabCut)

POST /api/image-segment5 quota units per call · cache hits free

Cut a foreground subject out of an image using OpenCV's GrabCut algorithm. Supply a rough bounding box and the algorithm refines the alpha matte iteratively.

Foreground / background segmentation with OpenCV's GrabCut algorithm. You provide a rough bounding box around the subject; GrabCut runs a graph-cut + Gaussian-mixture-model refinement and returns an alpha-cut image with the background made transparent. Useful for: - Cutting out a product photo for a catalog. - Pre-processing for image-replace-background. - Quick subject extraction without an ML matting model. Inputs are the bounding box (`x`, `y`, `width`, `height` — pixel coordinates) plus the number of refinement iterations (`iters`). Higher `iters` gives a cleaner mask at the cost of more CPU. **Output:** PNG with alpha when `format=png`; JPEG with the background filled solid `bgColor` when `format=jpeg`. This is classical CV — for hair-fine matte refinement use a neural matting model (`image-remove-bg`), which calls a hosted ONNX network.

Inputs

Name	Type	Default	Description
image*	file	—	Input image bytes.
x*	number	—	Bounding-box left edge in pixels.
y*	number	—	Bounding-box top edge in pixels.
width*	number	—	Bounding-box width in pixels.
height*	number	—	Bounding-box height in pixels.
iters	number (1…10)	3	GrabCut refinement iterations. Higher = cleaner mask, slower.
format	enum (png \| jpeg)	"png"	Output format. PNG preserves the alpha cut-out; JPEG fills the background.
bgColor	string	"#ffffff"	Background fill colour (JPEG only). Hex like #ffffff or a named colour.

Response

Modes: binary, stream, json. Cache: yes (24h TTL).

Large outputs stream: responses over the 4 MiB cache limit are piped through as they are produced instead of buffered. They carry x-cache-skip: size and are never cached — identical follow-up calls recompute.

Every response carries x-cache (HIT / MISS / BYPASS), x-cache-signature (stable across identical inputs), and the rate-limit headers listed below.

Quota & limits

Cost per call	5 units against the 10,000-unit monthly quota. Cache hits are free — only cache misses decrement.
Burst limit	200 requests per rolling minute, shared across all tools.
Max request size	`10 MiB` (base64 inflates file payloads ~33% — the limit applies to the decoded bytes).
Max response size	`25 MiB`
Timeout	30s wall clock.
Rate-limit headers	`X-RateLimit-Limit`, `X-RateLimit-Remaining`, `X-RateLimit-Burst-Limit` on every response; `X-Quota-Warning` once 80% of the monthly quota is spent; `Retry-After` on 429s.

Errors

Errors are JSON with an error string; schema failures add a details object (Zod's flattened field errors).

Status	When	Body
400	Input fails the tool's schema (wrong type, missing required field, malformed base64) or the file bytes can't be parsed as the expected format.	{ "error": "invalid inputs", "details": { "fieldErrors": { … } } }
401	Missing or invalid X-Api-Key / X-Account-Id headers (or no session when called from the browser).	{ "error": "unauthorized" }
404	Unknown tool id, or calling /api/* on the website hostname instead of api.xtract.bot.	{ "error": "not found" }
413	Request body over the tool's max request size, or an image header declaring more megapixels than the tool's pixel budget.	{ "error": "…exceeds maxRequestBytes…" }
415	Content-Type isn't application/json on the json-body transport.	{ "error": "unsupported content-type; expected application/json" }
429	Monthly quota or the 200/min burst limit exhausted. Check Retry-After and the X-RateLimit-* headers.	{ "error": "monthly quota exceeded", "monthRemaining": 0, … }
5xx	Conversion engine failure. Safe to retry; if it persists, the input is hitting a bug — please report it.	{ "error": "…" }

Code samples

Built from the default example.

# Download or substitute the example input:
#   curl -O https://xtract.bot/examples/face-fixtures/face-small.png
IMAGE=$(base64 -w0 < face-small.png)

curl -X POST https://api.xtract.bot/api/image-segment \
  -H "Content-Type: application/json" \
  -H "Accept: application/octet-stream" \
  -H "X-Account-Id: $XTRACT_ACCOUNT_ID" \
  -H "X-Api-Key: $XTRACT_API_KEY" \
  -d '{
  "x": 80,
  "y": 40,
  "width": 240,
  "height": 240,
  "iters": 3,
  "format": "png",
  "image": "'"$IMAGE"'"
}'