Face-detection based transformations
On this page
You can detect faces in your images for automatic cropping or blurring those out. Face detection is available in group photos, including photos with small faces.
How it works
/:uuid/detect_faces/
The detect_faces
operation returns the coordinates of faces found in an
input image. The output is similar to the json
operation. The output is a JSON with the additional list of faces
that
holds the coordinates of faces that were detected.
Data for each of the found faces are put into separate lists that look like this:
[x, y, x_size, y_size]
json
Further, lists within faces
contain:
x
,y
— coordinates of the upper-left corner of an area where a face was found.x_size
,y_size
— dimensions of that area.
Note, detect_faces
is not divided from a file UUID by the /-/
separator.
Hence, it can not be piped to other operations.
Example
Run a face-check for the following image on our CDN:
Put detect_faces
into the image URL, separating it with
the forward slash /
from the UUID:
Get the following faces
list in the response JSON:
"faces": [
[45, 142, 207, 207],
[460, 113, 238, 238],
[892, 43, 265, 265]
]
json
detect_faces
uses an algorithm that better detects the fronts of faces rather
than facial profiles. Also, covering important face features with
different objects leads to a decline in detection accuracy.
Technically, the operation detects faces using Haar Cascades. That approach deals with machine learning processes that rely on classifiers holding cascades of features specific to faces, eyes, etc.