focal_length_repartition.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
import pylab
import glob
from collections import Counter
 
from PIL import Image
from PIL.ExifTags import TAGS
 
 
DIRECTORY = "/home/cedric/vienna/*.JPG"
 
 
def get_exif(fn):
    ret = {}
    i = Image.open(fn)
    info = i._getexif()
    if info is not None:
        for tag, value in info.items():
            decoded = TAGS.get(tag, tag)
            ret[decoded] = value
    return ret
 
 
 
if __name__ == "__main__":
    cnt = Counter()
    pictures = glob.glob(DIRECTORY)
    focal = Counter()
    for picture in pictures:
        exif = get_exif(picture)
        if exif != {}:
            focal[exif['FocalLength'][0]] += 1
 
    if focal:
        length = len(focal)
        ind = pylab.arange(length)
        width = 0.35 # bars width
 
        focal_list = [elem for elem in focal.keys()]
        focal_count = [elem for elem in focal.values()]
        max_focal_count = max(focal_count)  # max focal_count
 
        p = pylab.bar(ind, focal_count, width, color='r')
 
        pylab.ylabel("Number of shots")
        pylab.xlabel("Focal length")
        pylab.title("Focal length repartition for " + str(sum(focal_count)) + " pictures")
        pylab.xticks(ind + (width / 2), focal_list)
        pylab.xlim(-width, len(ind))
 
        # changing the ordinate scale according to the max.
        if max_focal_count <= 100:
            pylab.ylim(0, max_focal_count + 5)
            pylab.yticks(pylab.arange(0, max_focal_count + 5, 5))
        elif max_focal_count <= 200:
            pylab.ylim(0, max_focal_count + 10)
            pylab.yticks(pylab.arange(0, max_focal_count + 10, 10))
        elif max_focal_count <= 600:
            pylab.ylim(0, max_focal_count + 25)
            pylab.yticks(pylab.arange(0, max_focal_count + 25, 25))
        elif max_focal_count <= 800:
            pylab.ylim(0, max_focal_count + 50)
            pylab.yticks(pylab.arange(0, max_focal_count + 50, 50))
 
 
        for rect in p:
            height = rect.get_height()
            pylab.text(rect.get_x()+rect.get_width()/2., 1.05*height, '%d'%int(height),
                    ha='center', va='bottom')
 
 
        pylab.show()
    else:
        print "No result."