color_detection.py

import cv2
import numpy as np
import pandas as pd
import argparse

#Creating argument parser to take image path from command line
ap = argparse.ArgumentParser()
ap.add_argument('-i', '--image', required=True, help="Image Path")
args = vars(ap.parse_args())
img_path = args['image']

#Reading the image with opencv
img = cv2.imread(img_path)
imgwidth = img.shape[1]
imgheight = img.shape[0]

#declaring global variables (are used later on)
clicked = False
r = g = b = xpos = ypos = 0

#Reading csv file with pandas and giving names to each column
index=["color","color_name","hex","R","G","B"]
csv = pd.read_csv('pantone.csv', names=index, header=None)

#function to calculate minimum distance from all colors and get the most matching color
def getColorName(R,G,B):
    minimum = 10000
    for i in range(len(csv)):
        d = abs(R- int(csv.loc[i,"R"])) + abs(G- int(csv.loc[i,"G"]))+ abs(B- int(csv.loc[i,"B"]))
        if(d<=minimum):
            minimum = d
            cname = csv.loc[i,"color_name"]
    return cname

# function which converts decimal value to hexadecimal value
def Hex(decimal):
    conversion_table = {0: '0', 1: '1', 2: '2', 3: '3',
                    4: '4', 5: '5', 6: '6', 7: '7',
                    8: '8', 9: '9', 10: 'A', 11: 'B',
                    12: 'C', 13: 'D', 14: 'E', 15: 'F'}
    if(decimal <= 0):
        return ''
    remainder = decimal % 16
    return Hex(decimal//16) + conversion_table[remainder]

#function to get x,y coordinates of mouse double click
def draw_function(event, x,y,flags,param):
    if event == cv2.EVENT_LBUTTONDBLCLK:
        global b,g,r,xpos,ypos, clicked, b, g, r
        clicked = True
        xpos = x
        ypos = y
        b,g,r = img[y,x]
        b = int(b)
        g = int(g)
        r = int(r)
       
cv2.namedWindow('image', cv2.WINDOW_NORMAL)
cv2.setMouseCallback('image',draw_function)

while(1):

    cv2.imshow("image",img)
    if (clicked):
   
        #cv2.rectangle(image, startpoint, endpoint, color, thickness)-1 fills entire rectangle 
        cv2.rectangle(img,(10,20), (885,70), (b,g,r), -1)

        #Creating text string to display( Color name and RGB values )
        bhex = int(b*1)
        ghex = int(g*256)
        rhex = int(r*65536)
        color = int(rhex+ghex+bhex)
        col = Hex(color)
        text = getColorName(r,g,b) + ' R='+ str(r) +  ' G='+ str(g) +  ' B='+ str(b) + ' Hex=#'+ str(col)
        
        #cv2.putText(img,text,start,font(0-7),fontScale,color,thickness,lineType )
        cv2.putText(img, text,(10,55),cv2.FONT_HERSHEY_TRIPLEX,1,(255,255,255),2,cv2.LINE_AA)

        #For very light colours we will display text in black colour
        if(r+g+b>=600):
            cv2.putText(img, text,(10,55),cv2.FONT_HERSHEY_TRIPLEX,1,(0,0,0),2,cv2.LINE_AA)
            
        clicked=False

    #Break the loop when user hits 'esc' key    
    if cv2.waitKey(20) & 0xFF ==27:
        break
    
cv2.destroyAllWindows()