Assuming there is no perspective distortion, a reliable method to differentiate between children and adults in an image is by using head-to-body proportions, a technique often learned in human sketching. If you perform a web image search for "children vs adult proportions," you will see that, relative to body size, a child's head is significantly larger than an adult's.
With this understanding, you can implement this logic in MATLAB. The following resources may provide guidance on calculating head and body lengths in an image-
- Head detection and bounding box: https://www.mathworks.com/matlabcentral/fileexchange/70426-persons-counting-by-head-detection-in-real-time.
- Human pose detection, for extracting skeleton keypoints data: https://www.mathworks.com/help/releases/R2021b/deeplearning/ug/estimate-body-pose-using-deep-learning.html.
