recursively walk directory and extract faces

face_extract.rb

require "opencv"
require "fileutils"

include OpenCV

detector = CvHaarClassifierCascade::load("./haarcascade_frontalface_alt.xml")

input_dir = ARGV[0]
output_dir = ARGV[1] || 'output'
FileUtils.mkdir_p(output_dir)

Dir.glob(File.join(input_dir, "**/*")).each_with_index do |image_file, index|
  next unless /\.jpg|\.jpeg|\.png|\.pgm/.match File.extname(image_file)

  image = IplImage.load(image_file, CV_LOAD_IMAGE_GRAYSCALE)
  detector.detect_objects(image).each do |rect|
    output_image = image.sub_rect(rect)
    path = File.join(output_dir, "#{index}_#{File.basename(image_file)}")
    output_image.save_image(path)
    puts "Saved face to: #{path}"
    image.reset_roi
  end
end