Emmanu Emmanu - 1 year ago 124
Python Question

How to find the colour of main object in an fixed image

My aim is to find the color of main object in a frame/image. In my case image is always of same type. For example News reporter(human) in Forest or News reporter in Animal farm.The position of news reporter is also same.What is the simple solution to find out the dominant colour of the main object(News Reporter)

Any help is welcome.Thanks

EDIT Code added

import cv2
from collections import namedtuple
from math import sqrt
import random
import webcolors

import Image
except ImportError:
from PIL import Image

Point = namedtuple('Point', ('coords', 'n', 'ct'))
Cluster = namedtuple('Cluster', ('points', 'center', 'n'))

def get_points(img):
points = []
w, h = img.size
for count, color in img.getcolors(w * h):
points.append(Point(color, 3, count))
return points

rtoh = lambda rgb: '#%s' % ''.join(('%02x' % p for p in rgb))

def colorz(filename, n=3):
img = Image.open(filename)
img.thumbnail((200, 200))
w, h = img.size

points = get_points(img)
clusters = kmeans(points, n, 1)
rgbs = [map(int, c.center.coords) for c in clusters]
return map(rtoh, rgbs)

def euclidean(p1, p2):
return sqrt(sum([
(p1.coords[i] - p2.coords[i]) ** 2 for i in range(p1.n)

def calculate_center(points, n):
vals = [0.0 for i in range(n)]
plen = 0
for p in points:
plen += p.ct
for i in range(n):
vals[i] += (p.coords[i] * p.ct)
return Point([(v / plen) for v in vals], n, 1)

def kmeans(points, k, min_diff):
clusters = [Cluster([p], p, p.n) for p in random.sample(points, k)]

while 1:
plists = [[] for i in range(k)]

for p in points:
smallest_distance = float('Inf')
for i in range(k):
distance = euclidean(p, clusters[i].center)
if distance < smallest_distance:
smallest_distance = distance
idx = i

diff = 0
for i in range(k):
old = clusters[i]
center = calculate_center(plists[i], old.n)
new = Cluster(plists[i], center, old.n)
clusters[i] = new
diff = max(diff, euclidean(old.center, new.center))

if diff < min_diff:

return clusters

def main():

img = cv2.imread('d:/Emmanu/project-data/b1.jpg')
crop_img = res[100:200, 150:250]
cv2.imwrite("d:/Emmanu/project-data/color-test.jpg", crop_img)
g= colorz('d:/Emmanu/project-data/color-test.jpg',1)
print k
print webcolors.rgb_to_name(f, spec='css3')

if __name__ == '__main__':main()

The problem is this returns the major color in the whole image not the main object

Answer Source

If your taking the colour of whole image,in most cases you will get wrong answer since background is more.If your image size is fixed and you are sure about object's position The most simple solution is Crop the image at where you expect the object.In most cases it will work.

In order to crop

import cv2
img = cv2.imread("'d:/Emmanu/project-data/b1.jpg'")
crop_img = img[200:400, 100:300] # Crop from x, y, w, h -> 100, 200, 300, 400
# NOTE: its img[y: y + h, x: x + w] and *not* img[x: x + w, y: y + h]
cv2.imshow("cropped", crop_img)

Now give this crop_image as input to your code.And in most cases it will give correct solution.There is nothing more simple that this.I think this will help.

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