Merge pull request #25268 from gursimarsingh:samples_cleanup_python

Removed obsolete python samples #25268

Clean Samples #25006 
This PR removes 36 obsolete python samples from the project, as part of an effort to keep the codebase clean and focused on current best practices. Some of these samples will be updated with latest algorithms or will be combined with other existing samples. 

Removed Samples:

> browse.py
camshift.py
coherence.py
color_histogram.py
contours.py
deconvolution.py
dft.py
dis_opt_flow.py
distrans.py
edge.py
feature_homography.py
find_obj.py
fitline.py
gabor_threads.py
hist.py
houghcircles.py
houghlines.py
inpaint.py
kalman.py
kmeans.py
laplace.py
lk_homography.py
lk_track.py
logpolar.py
mosse.py
mser.py
opt_flow.py
plane_ar.py
squares.py
stitching.py
text_skewness_correction.py
texture_flow.py
turing.py
video_threaded.py
video_v4l2.py
watershed.py

These changes aim to improve the repository's clarity and usability by removing examples that are no longer relevant or have been superseded by more up-to-date techniques.

samples/python/snippets/opt_flow.py

@@ -0,0 +1,104 @@
+#!/usr/bin/env python
+
+'''
+example to show optical flow
+
+USAGE: opt_flow.py [<video_source>]
+
+Keys:
+ 1 - toggle HSV flow visualization
+ 2 - toggle glitch
+
+Keys:
+    ESC    - exit
+'''
+
+# Python 2/3 compatibility
+from __future__ import print_function
+
+import numpy as np
+import cv2 as cv
+
+import video
+
+
+def draw_flow(img, flow, step=16):
+    h, w = img.shape[:2]
+    y, x = np.mgrid[step/2:h:step, step/2:w:step].reshape(2,-1).astype(int)
+    fx, fy = flow[y,x].T
+    lines = np.vstack([x, y, x+fx, y+fy]).T.reshape(-1, 2, 2)
+    lines = np.int32(lines + 0.5)
+    vis = cv.cvtColor(img, cv.COLOR_GRAY2BGR)
+    cv.polylines(vis, lines, 0, (0, 255, 0))
+    for (x1, y1), (_x2, _y2) in lines:
+        cv.circle(vis, (x1, y1), 1, (0, 255, 0), -1)
+    return vis
+
+
+def draw_hsv(flow):
+    h, w = flow.shape[:2]
+    fx, fy = flow[:,:,0], flow[:,:,1]
+    ang = np.arctan2(fy, fx) + np.pi
+    v = np.sqrt(fx*fx+fy*fy)
+    hsv = np.zeros((h, w, 3), np.uint8)
+    hsv[...,0] = ang*(180/np.pi/2)
+    hsv[...,1] = 255
+    hsv[...,2] = np.minimum(v*4, 255)
+    bgr = cv.cvtColor(hsv, cv.COLOR_HSV2BGR)
+    return bgr
+
+
+def warp_flow(img, flow):
+    h, w = flow.shape[:2]
+    flow = -flow
+    flow[:,:,0] += np.arange(w)
+    flow[:,:,1] += np.arange(h)[:,np.newaxis]
+    res = cv.remap(img, flow, None, cv.INTER_LINEAR)
+    return res
+
+def main():
+    import sys
+    try:
+        fn = sys.argv[1]
+    except IndexError:
+        fn = 0
+
+    cam = video.create_capture(fn)
+    _ret, prev = cam.read()
+    prevgray = cv.cvtColor(prev, cv.COLOR_BGR2GRAY)
+    show_hsv = False
+    show_glitch = False
+    cur_glitch = prev.copy()
+
+    while True:
+        _ret, img = cam.read()
+        gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
+        flow = cv.calcOpticalFlowFarneback(prevgray, gray, None, 0.5, 3, 15, 3, 5, 1.2, 0)
+        prevgray = gray
+
+        cv.imshow('flow', draw_flow(gray, flow))
+        if show_hsv:
+            cv.imshow('flow HSV', draw_hsv(flow))
+        if show_glitch:
+            cur_glitch = warp_flow(cur_glitch, flow)
+            cv.imshow('glitch', cur_glitch)
+
+        ch = cv.waitKey(5)
+        if ch == 27:
+            break
+        if ch == ord('1'):
+            show_hsv = not show_hsv
+            print('HSV flow visualization is', ['off', 'on'][show_hsv])
+        if ch == ord('2'):
+            show_glitch = not show_glitch
+            if show_glitch:
+                cur_glitch = img.copy()
+            print('glitch is', ['off', 'on'][show_glitch])
+
+    print('Done')
+
+
+if __name__ == '__main__':
+    print(__doc__)
+    main()
+    cv.destroyAllWindows()