COCO Types

SUMMARY

Shared segmentation and return types used by the COCO datatypes. Reference this page from datatypes that accept or return these types.

Segmentation Types

COCORLESegmentation

TypedDict. Canonical COCO RLE segmentation: an encoded Run-Length Encoding using the COCO representation, with size as [height, width] and counts as a UTF-8 string. This compressed form is always used for output and internal storage.

Field	Type	Description
size	list[int]	Segmentation mask size as [height, width].
counts	str	Compressed COCO RLE counts encoded as a UTF-8 string.

COCOUncompressedRLESegmentation

TypedDict. Uncompressed COCO RLE segmentation: the same representation with counts as raw run lengths instead of a compressed string. Accepted as input and automatically compressed to COCORLESegmentation.

Field	Type	Description
size	list[int]	Segmentation mask size as [height, width].
counts	list[int]	Uncompressed COCO RLE counts as non-negative integers.

COCORLESegmentationLike

Type alias: COCORLESegmentation | COCOUncompressedRLESegmentation. Accepted input form for a segmentation/segmentations constructor parameter — either RLE variant is normalized to the canonical compressed COCORLESegmentation form on construction.

COCOPolygonSegmentation

Type alias: list[list[float]]. One or more polygons, each a flattened [x1, y1, x2, y2, ...] list of at least 3 points. This is the canonical, normalized polygon form returned by as_polygon()/as_polygons() and stored internally.

COCOPolygonSegmentationLike

Type alias: Sequence[Sequence[float] | np.ndarray]. Accepted input form for a segmentation/segmentations constructor parameter — a looser container (list, tuple, or np.ndarray) of polygons, each itself a list, tuple, or np.ndarray of coordinates, normalized to COCOPolygonSegmentation on construction.

Result Representations

COCOObjectDetectionResultAsMask

TypedDict. Return type of COCOObjectDetectionResult.as_mask().

Field	Type	Description
image_id	int	Source image id.
category_id	int	Category id.
image_height	int	Source image height.
image_width	int	Source image width.
score	float	Detection confidence score.
bbox	np.ndarray | None	(4,) float32 box in [x, y, w, h] format, or None.
segmentation	np.ndarray | None	Segmentation rasterized to an (image_height, image_width) uint8 binary mask, or None if absent.

COCOObjectDetectionResultAsPolygon

TypedDict. Return type of COCOObjectDetectionResult.as_polygon().

Field	Type	Description
image_id	int	Source image id.
category_id	int	Category id.
image_height	int	Source image height.
image_width	int	Source image width.
score	float	Detection confidence score.
bbox	np.ndarray | None	(4,) float32 box in [x, y, w, h] format, or None.
segmentation	COCOPolygonSegmentation | None	Segmentation extracted as polygon contours, or None if absent.

COCOObjectDetectionResultsAsMasks

TypedDict. Return type of COCOObjectDetectionResults.as_masks().

Field	Type	Description
image_ids	np.ndarray	(N,) source image ids.
category_ids	np.ndarray	(N,) category ids.
image_heights	np.ndarray	(N,) source image heights.
image_widths	np.ndarray	(N,) source image widths.
scores	np.ndarray	(N,) detection confidence scores.
bboxes	np.ndarray | None	(N, 4) float32 boxes in [x, y, w, h] format, or None.
segmentations	list[np.ndarray | None]	Length-N list of uint8 binary masks, or None per entry without a segmentation.

COCOObjectDetectionResultsAsPolygons

TypedDict. Return type of COCOObjectDetectionResults.as_polygons().

Field	Type	Description
image_ids	np.ndarray	(N,) source image ids.
category_ids	np.ndarray	(N,) category ids.
image_heights	np.ndarray	(N,) source image heights.
image_widths	np.ndarray	(N,) source image widths.
scores	np.ndarray	(N,) detection confidence scores.
bboxes	np.ndarray | None	(N, 4) float32 boxes in [x, y, w, h] format, or None.
segmentations	list[COCOPolygonSegmentation | None]	Length-N list of polygon contours, or None per entry without a segmentation.

Annotation Representations

COCOObjectDetectionAnnotationAsMask

TypedDict. Return type of COCOObjectDetectionAnnotation.as_mask().

Field	Type	Description
id	int	Annotation id.
image_id	int	Source image id.
category_id	int	Category id.
bbox	np.ndarray	(4,) float32 box in [x, y, w, h] format.
area	float	Annotation area, >= 0.
iscrowd	bool	Crowd flag; selected the rasterization path.
segmentation	np.ndarray | None	Segmentation rasterized to a binary mask, or None if absent.

COCOObjectDetectionAnnotationsAsMasks

TypedDict. Return type of COCOObjectDetectionAnnotations.as_masks().

Field	Type	Description
ids	np.ndarray	(N,) annotation ids.
image_ids	np.ndarray	(N,) source image ids.
category_ids	np.ndarray	(N,) category ids.
bboxes	np.ndarray	(N, 4) float32 boxes in [x, y, w, h] format.
areas	np.ndarray	(N,) annotation areas, each >= 0.
iscrowds	np.ndarray	(N,) crowd flags; selected each entry's rasterization path.
segmentations	list[np.ndarray | None]	Length-N list of binary masks, or None per entry without a segmentation.