OpenCV Basics

Want to combine two images using just a line of code? Or wanna blur an image? Lets find out how!

In this Article (Click to skip to that topic):

• [Blend images: What is it?]
• [Code to Blend]
• [Methods to Blur an Image ]
• [Code to Blur Image]

Blend images: What is it?

Blending images in opencv, is combining to images of same size. So we have to remember to resize those two images to same size(which will be shown in the code later).

Using this, we can make pretty cool posters, wallpapers, beautiful creations in your imaginations and many more…

So lets learn how to do it in a simple way

bigarr=np.arange(0, 10).reshape((2,5))
bigarr

#'arange' gives an array withn values from 0 to 9, 'reshapes' converts into a matrix of 2x5

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Output:

array([[0, 1, 2, 3, 4],
[5, 6, 7, 8, 9]])

bigarr[:, 2]

#Here only column 2 is considered but not row as colon(:) is mentioned

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Output:

array([2, 7])

For more practice on Numpy visit

 https://numpy.org/devdocs/user/quickstart.html

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## Display Image in Opencv using Numpy

Now,how to open or show an image using our numpy knowledge:

We use libraries

• PIL(Python Imaging Library)

• Matplotlib( For visualization) and import Image from PIL

Image.open(image file path)       

# Opens and identifies the given image file

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Each pixel has a shape.

For Eg:(1080,1080,3)which is (pixel height,pixel width,color channels)
The 3 color channels are red,green and blue(RGB).

plt.imshow                         

# Displays the image

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Example

import numpy as np
import matplotlib.pyplot as plt 
%matplotlib inline
from PIL import Image

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img=Image.open(r'C:\Desktop\image.jpg') 

# Opens Image

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img

#To Preview Image

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Each pixel has a shape.

For Eg:(1080,1080,3) which is (pixel height,pixel width,color channels).

The 3 color channels are red,green and blue(RGB).

plt.imshow             

# Displays the image

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Example:

img_array=np.asarray(img)

# Converting image into array of values

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img_array.shape

# Displaying the shape of the array

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Output:

(1080,1920,3)

plt.imshow(img_array)

# Displaying array into Image  

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What if only one channel is used in displaying image instead all 3 in RGB?

plt.imshow(array[:,:,0])           # Displays image with only Red channel.

plt.imshow(array[:,:,1])           # Displays image with only Green channel.

plt.imshow(array[:,:,2])           # Displays image with only Blue channel.

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## Gray Image using Numpy

What if we want a gray image like in old movies?

The parameter cmap=’gray’ is used to convert color images into a gray image.

plt.imshow(array[:,:,0],cmap=’gray’) 

# Displays image with grayscale values.

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Example

plt.imshow(img_array[:,:,0])

#Displaying only RED channel in RGB. Replace 0 with 1 for Green and 2 for Blue Channel. 

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plt.imshow(img_array[:,:,0],cmap='gray')

#Converting the color image into grayscale using cmap

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For more code on fliping, resizing etc visit the blog, follow the Instagram page mentioned below

If you are building a project or wanna upgrade your skills for the job or just excited to build cool stuff, learn opencv easily and quickly from Instagram page code_voyager:

https://www.instagram.com/p/B_5ey22pLu_/?igshid=1t6k2adh9a9zk

Or more detailed version feel free to visit :
https://jayachandrika.com/computer-vision-images

Looking forward for you to join us!

原文链接：OpenCV Basics