blob_stats

Builtin index · Images

result = blob_stats(img)

Input: img · Output: result

What it is

img is a Model produced by label_blobs/bwlabel. Per-region area, centroid and bounding box, from a labelled image (identical operation to regionprops above).

Overloads

One call shape — this function is not overloaded.

Code	Input	Output	Description
`result = blob_stats(img)`	`img` Modelnot documented yet	`result` List or Record	Returns a `List` of `Record`s, one per blob.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

m = [255, 255, 0, 0, 0, 0; 255, 255, 0, 255, 0, 0; 0, 0, 0, 0, 0, 0; 0, 255, 0, 0, 0, 0; 0, 0, 0, 0, 255, 255; 0, 0, 0, 0, 255, 255]
binary = image_from_matrix(m)

cleaned = remove_small_blobs(binary, 3)     # drop the two 1-pixel specks

imshow(cleaned)
labeled = label_blobs(cleaned)
stats = blob_stats(labeled)

for i = 1 to labeled.count
    r = stats[i - 1]
    print(r.label, r.area, r.centroid_x, r.centroid_y)
end for

output

1 4 0.5 0.5
2 4 4.5 4.5

from images

How it works

blob_stats(labeled) (alias regionprops) — per-blob geometry from a label_blobs/bwlabel result: a Value::List of one Value::Record per blob (label, area, centroid_x, centroid_y, bbox_x, bbox_y, bbox_width, bbox_height), in label-id order. centroid_x/centroid_y are the real arithmetic mean of that blob's own pixel coordinates (not a bounding-box-center approximation); bbox_* is the tightest axis-aligned rectangle containing every one of that blob's pixels.

From the note above this builtin in the interpreter, where the reasoning was written down as it was built.