Image Editing Software | Applying Color Filters on Image

 Hello friends! Welcome to the last post on Image Editing Software. In this post, you will be learning how to apply color filters to an image. We will be doing this using the OpenCV library package. You can also check out the video below. 

So let's get started. We will start by importing Opencv and Numpy to our code. 

import cv2
import numpy as np

And now we will start writing the callback methods for applying filters. Let us start with the yellowButton_callback() method. 

def yellowButton_callback():
    opencvImage = cv2.cvtColor(np.array(originalImage), cv2.COLOR_RGB2BGR)
    opencvImage[:, :, 0] = 20
    global outputImage
    outputImage = Image.fromarray(cv2.cvtColor(opencvImage, cv2.COLOR_BGR2RGB))
    dispayImage(outputImage)

Alright. Let us understand the above code line by line. To apply a color filter I have to manipulate the image array. So I need the image in an array form. np.array(originalImage) converts the image that we read using the PIL library into a 3D array. Now, since OpenCV reads images in BGR form, I had to convert them from RGB(PIL uses RGB format) to BGR using cv2.COLOR_RGB2BGR. Thus opencvImage holds the image data in array form and in BGR format.

Now, let's go to the second line. Here I have just assigned a constant value to channel 0(Blue channel) of the image. But why 20? Well, I got that value by experimenting with the image array. You are free to assign whichever value you want. You will see different kinds of color filters being applied to the image. 

Then we define the outputImage variable to store the image that will be displayed on the GUI window and for saving purposes. Now, remember we are using PIL to display and save images. So we have to convert back this opencvImage into PIL compatible format. For that, we have to convert the opencvImage from BGR to RGB format using cv2.COLOR_BGR2RGB method. And again convert the image array into PIL compatible format using Image.fromarray() method. At last displayImage() method is called to display the image on the GUI window. 

Similarly, you can write other color filter callback methods. Only the array manipulation line will change. Below are all the callback methods for your reference. 

def blueButton_callback():
    opencvImage = cv2.cvtColor(np.array(originalImage), cv2.COLOR_RGB2BGR)
    opencvImage[:, :, 2] = 100
    global outputImage
    outputImage = Image.fromarray(cv2.cvtColor(opencvImage, cv2.COLOR_BGR2RGB))
    dispayImage(outputImage)

def pinkButton_callback():
    opencvImage = cv2.cvtColor(np.array(originalImage), cv2.COLOR_RGB2BGR)
    opencvImage[:, :, 1] = 100
    global outputImage
    outputImage = Image.fromarray(cv2.cvtColor(opencvImage, cv2.COLOR_BGR2RGB))
    dispayImage(outputImage)

def orangeButton_callback():
    opencvImage = cv2.cvtColor(np.array(originalImage), cv2.COLOR_RGB2BGR)
    opencvImage[:, :, 2] = 200
    global outputImage
    outputImage = Image.fromarray(cv2.cvtColor(opencvImage, cv2.COLOR_BGR2RGB))
    dispayImage(outputImage)

def noneButton_callback():
    pass

The Image Editing Software is now complete.

Now, You can run this code and use this basic level Image Editing Software. You can also try to add more features to this software. 

Enjoy Coding.....!!!

For full code click here.