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@skypanther skypanther/slider.py
Created Oct 17, 2018

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Trackbars (sliders) in OpenCV
'''
slider.py - Demonstrating a user of trackbars on OpenCV windows
Author: Tim Poulsen, github.com/skypanther
License: MIT
2018-10-15
Example usage:
python3 slider.py -i path/to/image.jpg
'''
import argparse
import cv2
import imutils
import os
def main():
min_val = 200
max_val = 300
aperture_size = 3
ap = argparse.ArgumentParser()
ap.add_argument('-i', '--image', default='',
help='Image to use for edge detection')
args = vars(ap.parse_args())
file_name = args['image']
if os.path.isfile(file_name) is False:
print('Cannot open image, quitting...')
exit()
image = cv2.imread(file_name)
image = imutils.resize(image, height=480)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv2.namedWindow('Original')
cv2.createTrackbar('Min', 'Original', 0, 800, no_op)
cv2.createTrackbar('Max', 'Original', 100, 800, no_op)
cv2.imshow('Original', image)
while True:
min_val = int(cv2.getTrackbarPos('Min', 'Original'))
max_val = int(cv2.getTrackbarPos('Max', 'Original'))
print('Min: {}'.format(min_val))
print('Max: {}'.format(max_val))
edges = cv2.Canny(gray, min_val, max_val, aperture_size)
cv2.imshow('Edges', imutils.resize(edges, height=480))
if cv2.waitKey(1) & 0xFF == ord("q"):
cv2.destroyAllWindows()
exit()
def no_op(new_val):
pass
if __name__ == '__main__':
main()
'''
slider2.py - Demonstrating a user of trackbars on OpenCV windows
Author: Tim Poulsen, github.com/skypanther
License: MIT
2018-10-15
Example usage:
python3 slider2.py -i path/to/image.jpg
'''
import argparse
import cv2
import imutils
import os
edge_params = {
'min_val': 200,
'max_val': 300,
'aperture_size': 3
}
gray = None
def main():
global edge_params, gray
ap = argparse.ArgumentParser()
ap.add_argument('-i', '--image', default='',
help='Image to use for edge detection')
args = vars(ap.parse_args())
file_name = args['image']
if os.path.isfile(file_name) is False:
print('Cannot open image, quitting...')
exit()
image = cv2.imread(file_name)
image = imutils.resize(image, height=480)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv2.namedWindow('Original')
cv2.createTrackbar('Min', 'Original', 0, 800, min_change)
cv2.createTrackbar('Max', 'Original', 100, 800, max_change)
cv2.imshow('Original', image)
redraw_edges()
while True:
if cv2.waitKey(1) & 0xFF == ord("q"):
cv2.destroyAllWindows()
exit()
def min_change(new_val):
change_params('min_val', new_val)
def max_change(new_val):
change_params('max_val', new_val)
def change_params(name, value):
global edge_params
edge_params[name] = value
print(edge_params)
redraw_edges()
def redraw_edges():
edges = cv2.Canny(gray,
edge_params['min_val'],
edge_params['max_val'],
edge_params['aperture_size'])
cv2.imshow('Edges', imutils.resize(edges, height=480))
if __name__ == '__main__':
main()
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