This repository contains utility scripts for doing facial detection in images using OpenCV.
Most of these scripts are experiments. The goal is to incorporate these scripts into scripts for a Raspberry Pi facial detection device - see the pi-opencv repository.
Completed tasks:
- Take a photo using a webcam
- Basic face-finding code
- Consistent face-finding across multiple test photographs
- Consistent face-finding and eye-finding (over-sensitive)
- Webcam continuous face-finding script
In-progress tasks:
- Find eyes in a photograph (using test images from internet)
- Find eyes in a webcam photograph (using webcam photos)
- Find a face that may be rotated up to N degrees (using webcam)
- Detect sideways faces using eyes angle
STATUS: DONE
take_photo.py - takes a photo with a webcam
- Imports OpenCV
- Captures an image from the specified camera device
- Transposes the image (rotate right)
- Saves the images to a file
- Uses imshow to show the images on screen
- (Future work) image is a numpy array, so do further processing/exports
STATUS: DONE
basic_face_detection.py - illustrate basic face detection
- Illustrates facial detection in the simplest script possible
- Cascade classifier is sensitive to parameter choices
- Does not generalize well
Expected output:
STATUS: DONE
find_face_image.py - more generalized face detection script
- Open an image on disk using OpenCV or Pillow
- Create cascade classifier to find faces
- Get rectangles containing faces
- Draw rectangles around faces
- Get rectangles containing eyes
- Draw rectangles around eyes
- Show the image of the face with rectangles
This script worked on multiple face photos, including two from the webcam that will be used with the final Raspberry Pi setup (one low-res, one high-res).
STATUS: DONE (OVER-SENSITIVE)
find_face_and_eyes_image.py - generalized face + eyes detection script
Follows the same routine as find_face_image.py:
- Open an image on disk using OpenCV or Pillow
- Create cascade classifier to find faces
- Get rectangles containing faces
- Draw rectangles around faces
- Get rectangles containing eyes
- Draw rectangles around eyes
- Show the image of the face with rectangles
The problem is with eye detection, which is too sensitive to the particular photograph and the parameters used.
Some tips:
- Easy to find eyes if face is well-lit and centered
- Dark/unlit faces make eyes (and face) difficult to detect
- If parameters too coarse, no or one eye detected
- If parameters too fine, mouth corners detected as eyes
- Sometimes a single eye is found twice, with significant overlap
- There are multiple eye detection classifiers, you should probably try them all
- Easiest scenario is to focus on specific camera, specific configuration, specific lighting conditions
STATUS: DONE
webcam_continuous_face.py
Workflow:
- Every N seconds, capture an image from the camera
- Put all images into raw/
- Run face detection algorithm
- If face is found, draw bounding box and put into faces/
- Create a simple index.html file that will display the last image with a found face
$ # Window 1: shell
$ python webcam_continuous_face.py
$ # Window 2: shell
$ ./face_server_run.sh
# Window 3: browser
http://localhost:8080/
Notes:
Notes:
- It's easy to write a script that usually detects faces, or detects one eye, but getting the task to work consistently, and always find a face and two eyes, is a pain.
- The process is extremely sensitive to the parameters used for the cascading classifier.
Each different photo of a face requires different
scaleFactorandminNeighborssettings - Eyes are also difficult to detect without fiddling with settings that are specific to each image.
- This SO question mentions an eye pair Haar cascade file.
- opencv-contrib repo has additional cascade .xml files
- See opencv-contrib modules/face/data/cascades