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OpenCV 3.x with Python By Example

You're reading from   OpenCV 3.x with Python By Example Make the most of OpenCV and Python to build applications for object recognition and augmented reality

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Product type Paperback
Published in Jan 2018
Publisher Packt
ISBN-13 9781788396905
Length 268 pages
Edition 2nd Edition
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Authors (2):
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Gabriel Garrido Calvo Gabriel Garrido Calvo
Author Profile Icon Gabriel Garrido Calvo
Gabriel Garrido Calvo
Prateek Joshi Prateek Joshi
Author Profile Icon Prateek Joshi
Prateek Joshi
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Table of Contents (17) Chapters Close

Title Page
Copyright and Credits
Contributors
Packt Upsell
Preface
1. Applying Geometric Transformations to Images FREE CHAPTER 2. Detecting Edges and Applying Image Filters 3. Cartoonizing an Image 4. Detecting and Tracking Different Body Parts 5. Extracting Features from an Image 6. Seam Carving 7. Detecting Shapes and Segmenting an Image 8. Object Tracking 9. Object Recognition 10. Augmented Reality 11. Machine Learning by an Artificial Neural Network 1. Other Books You May Enjoy

Can we expand an image?


We know that we can use seam carving to reduce the width of an image without deteriorating the interesting regions. So, naturally, we need to ask ourselves if we can expand an image without deteriorating the interesting regions. As it turns out, we can do it using the same logic. When we compute the seams, we just need to add a column instead of deleting one.

If we expand the image of the ducks naively, it will look something like this:

If we do it in a smarter way—that is, by using seam carving—it will look something like this:

As you can see, the width of the image has increased and the ducks don't look stretched. The following is the code to do it:

import sys 
import cv2 
import numpy as np 

# Add a vertical seam to the image 
def add_vertical_seam(img, seam, num_iter): 
    seam = seam + num_iter 
    rows, cols = img.shape[:2] 
    zero_col_mat = np.zeros((rows,1,3), dtype=np.uint8) 
    img_extended = np.hstack((img, zero_col_mat)) 

    for row in range(rows)...
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