Project in Python – Colour Detection using Pandas & OpenCV

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Python Project on Color Detection

Today’s project will be exciting and fun to build. We will be working with colors and you will get to learn about many concepts throughout this project. Colour detection is necessary to recognize objects, it is also used as a tool in various image editing and drawing apps.

This is the 10th project in the DataFlair’s series of 20 Python projects. I suggest you to bookmark the previous projects:

  1. Fake News Detection Python Project
  2. Parkinson’s Disease Detection Python Project
  3. Color Detection Python Project
  4. Speech Emotion Recognition Python Project
  5. Breast Cancer Classification Python Project
  6. Age and Gender Detection Python Project
  7. Handwritten Digit Recognition Python Project
  8. Chatbot Python Project
  9. Driver Drowsiness Detection Python Project
  10. Traffic Signs Recognition Python Project
  11. Image Caption Generator Python Project

What is Colour Detection?

Colour detection is the process of detecting the name of any color. Simple isn’t it? Well, for humans this is an extremely easy task but for computers, it is not straightforward. Human eyes and brains work together to translate light into color. Light receptors that are present in our eyes transmit the signal to the brain. Our brain then recognizes the color. Since childhood, we have mapped certain lights with their color names. We will be using the somewhat same strategy to detect color names.

color detection project in python

About the Python Project

In this color detection Python project, we are going to build an application through which you can automatically get the name of the color by clicking on them. So for this, we will have a data file that contains the color name and its values. Then we will calculate the distance from each color and find the shortest one.

The Dataset

Colors are made up of 3 primary colors; red, green, and blue. In computers, we define each color value within a range of 0 to 255. So in how many ways we can define a color? The answer is 256*256*256 = 16,581,375. There are approximately 16.5 million different ways to represent a color. In our dataset, we need to map each color’s values with their corresponding names. But don’t worry, we don’t need to map all the values. We will be using a dataset that contains RGB values with their corresponding names. The CSV file for our dataset has been taken from this link:

Colors Dataset

The colors.csv file includes 865 color names along with their RGB and hex values.

Prerequisites

Before starting with this Python project with source code, you should be familiar with the computer vision library of Python that is OpenCV and Pandas.

OpenCV, Pandas, and numpy are the Python packages that are necessary for this project in Python. To install them, simply run this pip command in your terminal:

pip install opencv-python numpy pandas

Steps for Building a Project in Python – Color Detection

Here are the steps to build an application in Python that can detect colors:

1. Download and unzip the zip file

Color Detection Zip File

The project folder contains 3 files:

  • Color_detection.py – main source code of our project.
  • Colorpic.jpg – sample image for experimenting.
  • Colors.csv – a file that contains our dataset.

2. Taking an image from the user

We are using argparse library to create an argument parser. We can directly give an image path from the command prompt:

import argparse

ap = argparse.ArgumentParser()
ap.add_argument('-i', '--image', required=True, help="Image Path")
args = vars(ap.parse_args())
img_path = args['image']
#Reading image with opencv
img = cv2.imread(img_path)

3. Next, we read the CSV file with pandas

The pandas library is very useful when we need to perform various operations on data files like CSV. pd.read_csv() reads the CSV file and loads it into the pandas DataFrame. We have assigned each column with a name for easy accessing.

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

4. Set a mouse callback event on a window

First, we created a window in which the input image will display. Then, we set a callback function which will be called when a mouse event happens.

cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_function)

With these lines, we named our window as ‘image’ and set a callback function which will call the draw_function() whenever a mouse event occurs.

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5. Create the draw_function

It will calculate the rgb values of the pixel which we double click. The function parameters have the event name, (x,y) coordinates of the mouse position, etc. In the function, we check if the event is double-clicked then we calculate and set the r,g,b values along with x,y positions of the mouse.

def draw_function(event, x,y,flags,param):
    if event == cv2.EVENT_LBUTTONDBLCLK:
        global b,g,r,xpos,ypos, clicked
        clicked = True
        xpos = x
        ypos = y
        b,g,r = img[y,x]
        b = int(b)
        g = int(g)
        r = int(r)

6. Calculate distance to get color name

We have the r,g and b values. Now, we need another function which will return us the color name from RGB values. To get the color name, we calculate a distance(d) which tells us how close we are to color and choose the one having minimum distance.

Our distance is calculated by this formula:

d = abs(Red – ithRedColor) + (Green – ithGreenColor) + (Blue – ithBlueColor)

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

7. Display image on the window

Whenever a double click event occurs, it will update the color name and RGB values on the window.

Using the cv2.imshow() function, we draw the image on the window. When the user double clicks the window, we draw a rectangle and get the color name to draw text on the window using cv2.rectangle and cv2.putText() functions.

while(1):
    cv2.imshow("image",img)
    if (clicked):
        #cv2.rectangle(image, startpoint, endpoint, color, thickness) -1 thickness fills rectangle entirely
        cv2.rectangle(img,(20,20), (750,60), (b,g,r), -1)

        #Creating text string to display ( Color name and RGB values )
        text = getColorName(r,g,b) + ' R='+ str(r) + ' G='+ str(g) + ' B='+ str(b)

        #cv2.putText(img,text,start,font(0-7), fontScale, color, thickness, lineType, (optional bottomLeft bool) )
        cv2.putText(img, text,(50,50),2,0.8,(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,(50,50),2,0.8,(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()

8. Run Python File

The beginner Python project is now complete, you can run the Python file from the command prompt. Make sure to give an image path using ‘-i’ argument. If the image is in another directory, then you need to give full path of the image:

python color_detection.py -i <add your image path here>

running python mini project

Screenshots:

import cv2 - python mini project

def getColorName - project in python

while (1) python data science project

Output:

Double click on the window to know the name of the pixel color

red color detection - python mini project

yellow color detection - python project with source code

blue color detection - python mini project

Summary

In this Python project with source code, we learned about colors and how we can extract color RGB values and the color name of a pixel. We learned how to handle events like double-clicking on the window and saw how to read CSV files with pandas and perform operations on data. This is used in numerous image editing and drawing apps.

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Hope you enjoyed building this project and keep visiting for more cool projects.

84 Responses

  1. Akshay says:

    File “colorrecog.py”, line 15, in
    csv=pd.read_csv(‘color.csv’ ,names=index,header=None)
    File “C:\Users\SMITHAANIL\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\io\parsers.py”, line 676, in parser_f
    return _read(filepath_or_buffer, kwds)
    File “C:\Users\SMITHAANIL\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\io\parsers.py”, line 448, in _read
    parser = TextFileReader(fp_or_buf, **kwds)
    File “C:\Users\SMITHAANIL\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\io\parsers.py”, line 880, in __init__
    self._make_engine(self.engine)
    File “C:\Users\SMITHAANIL\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\io\parsers.py”, line 1114, in _make_engine
    self._engine = CParserWrapper(self.f, **self.options)
    File “C:\Users\SMITHAANIL\AppData\Local\Programs\Python\Python38-32\lib\site-packages\pandas\io\parsers.py”, line 1891, in __init__
    self._reader = parsers.TextReader(src, **kwds)
    File “pandas\_libs\parsers.pyx”, line 374, in pandas._libs.parsers.TextReader.__cinit__
    File “pandas\_libs\parsers.pyx”, line 674, in pandas._libs.parsers.TextReader._setup_parser_source
    FileNotFoundError: [Errno 2] File color.csv does not exist: ‘color.csv’

    got this error ….please help

  2. Alex says:

    In the line-
    cv2.rectangle(img,(20,20), (750,60), (b,g,r), -1)

    why are the starting and ending points are-(20,20) and (750,60)

  3. anr says:

    File “detect_colors.py”, line 45, in
    cv2.setMouseCallback(‘image’, draw_function())
    TypeError: draw_function() missing 5 required positional arguments: ‘event’, ‘x’, ‘y’, ‘flags’, and ‘param’

    I have this eror please help

    • varun says:

      u dont metion draw_function(),bcz it searches for empty parameter function.so only use keyword just

      (‘image’,draw_function)

  4. Kommuri Lokesh says:

    can we add other image less than 35kb

  5. Tarang Garg says:

    usage: code.py [-h] -i IMAGE
    code.py: error: the following arguments are required: -i/–image

  6. aa says:

    256*256*256 = 16777216

  7. Ivanshi says:

    I have got this error .Please help to execute it further.When i m executing 52nd line .Here is the error:
    [
    error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\highgui\src\window.cpp:376: error: (-215:Assertion failed) size.width>0 && size.height>0 in function ‘cv::imshow’ ]

    Thanks

  8. Ivanshi says:

    This is the error I am getting while executing the code.It comes when while loop is executed.Please help the error is as follows:

    error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\highgui\src\window.cpp:376: error: (-215:Assertion failed) size.width>0 && size.height>0 in function ‘cv::imshow’

  9. kirana shree says:

    hi in the second step i get some error like this
    usage: ipykernel_launcher.py [-h] -i IMAGE
    ipykernel_launcher.py: error: the following arguments are required: -i/–image
    can you plz help me plzzzzz

  10. kirana shree says:

    in the second step
    import argparse
    ap = argparse.ArgumentParser()
    ap.add_argument(‘-i’, ‘–colorpic.jpg’, required=True, help=”D:\python-project-color-detection>python color_detection.py -i/–colorpic.jpg”)
    args = vars(ap.parse_args())
    img_path = args[‘–colorpic.jpg’]
    #Reading image with opencv
    img = cv2.imread(‘D:\python-project-color-detection>python color_detection.py -i colorpic.jpg’)
    i’ll give path like this,but i get error like this
    usage: ipykernel_launcher.py [-h] -i COLORPIC.JPG
    ipykernel_launcher.py: error: the following arguments are required: -i/–colorpic.jpg

  11. Adarsh says:

    Sir which code is corrosponds to which file it is confusing

    • GoRaj says:

      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’, ‘colorpic.jpg’, required=True, help=”Image Path”)
      args = vars(ap.parse_args())
      img_path = args[‘image’]”””

      #Reading the image with opencv
      img = cv2.imread(r”C:\Desktop\python-project-color-detection\colorpic.jpg”)

      #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(‘colors.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=600):
      cv2.putText(img, text,(50,50),2,0.8,(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()

      #download file on desktop location and then run the color python file

  12. charint4 says:

    Does this project use train and test dataset or not?

  13. john vincent raj says:

    i am having this error,

    usage: color_detection.py [-h] -i IMAGE
    color_detection.py: error: the following arguments are required: -i/–image

  14. AHumanBeing says:

    I’m just copying and pasting most of this stuff but what worked for me is removing the required=TRUE.

  15. Mitheel Sankhe says:

    usage: color_detection.py [-h] -i IMAGE
    color_detection.py: error: the following arguments are required: -i/–image

  16. Maliya SL mafia says:

    cant train the system again. its getting errors. why ?

  17. AditiN says:

    How can we close the image window? Why is it recursive? Can anybody please help?

  18. varun says:

    i think you have given wrong input name of the image or image type.

    just check whether the image is there in the current directory where u are executing python and give image name and format correct

  19. Shreya says:

    i am getting this error
    usage: ipykernel_launcher.py [-h] -i IMAGE
    ipykernel_launcher.py: error: the following arguments are required: -i/–image
    An exception has occurred, use %tb to see the full traceback.

    SystemExit: 2

  20. ivan mendes says:

    Color_detection.py [-h] -i IMAGE
    Color_detection.py: error: the following arguments are required: -i/–image

    Error

  21. nawshirwan mah says:

    i have an error please help me
    thanks
    usage: color_detection.py [-h] -i IMAGE
    color_detection.py: error: the following arguments are required: -i/–image

    when coding is
    ap.add_argument(‘-i’, ‘–image’, required=True, help=”Image Path”)

  22. Fiona Le says:

    You should go to the cofiguration tab at the top right corner, then add “-i colorpic.jpg” in Parameter box. Then click Apply and Run. Remember to include ” “.

  23. Pranav Sharma says:

    same error man
    have u got the solution??
    can u help me plssssss

  24. Rakesh Kuchana says:

    Hey, I want to run this code in Jupyter Notebook, but I can’t run. Can you explain steps briefly?

  25. Satabdi Sundaray says:

    are you using k means of clustering?

  26. m11 says:

    use “cv2.destroyAllWindow()” function it will work

  27. Kartik says:

    How I solve this error
    usage: ipykernel_launcher.py [-h] -i IMAGE
    ipykernel_launcher.py: error: the following arguments are required: -i/–image
    An exception has occurred, use %tb to see the full traceback.

    SystemExit: 2

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