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2 Commits

Author SHA1 Message Date
Matt McWilliams 6ae5797ebb Fix sloppy merge 2022-11-14 13:42:44 -05:00
Matt McWilliams ff04b2aa37 Add a few pattern matching algorithms to notes 2022-11-14 13:40:26 -05:00
3 changed files with 137 additions and 11 deletions

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@ -295,9 +295,6 @@ def create_blank (w, h, rgb_color = (255, 255, 255)) :
blank[:] = color blank[:] = color
return blank return blank
def place (bottom, top, x, y) :
return bottom.paste(top, (x, y))
def get_mean_rect (holePunches) : def get_mean_rect (holePunches) :
left = 0 left = 0
right = 0 right = 0
@ -308,7 +305,7 @@ def get_mean_rect (holePunches) :
left += float(hp['x']) left += float(hp['x'])
top += float(hp['y']) top += float(hp['y'])
elif hp['order'] == 2 : elif hp['order'] == 2 :
right += float(hp['y']) right += float(hp['x'])
top += float(hp['y']) top += float(hp['y'])
elif hp['order'] == 3 : elif hp['order'] == 3 :
left += float(hp['x']) left += float(hp['x'])
@ -316,9 +313,9 @@ def get_mean_rect (holePunches) :
elif hp['order'] == 5 : elif hp['order'] == 5 :
right += float(hp['x']) right += float(hp['x'])
bottom += float(hp['y']) bottom += float(hp['y'])
x = round((right / 2.0) - (left / 2.0)) w = round((right / 2.0) - (left / 2.0))
y = round((bottom / 2.0) - (top / 2.0)) h = round((bottom / 2.0) - (top / 2.0))
return (x, y) return (w, h)
def center_within (larger, smaller) : def center_within (larger, smaller) :
@ -328,7 +325,19 @@ def center_within (larger, smaller) :
h2 = smaller[1] h2 = smaller[1]
x = ((w1 - w2) / 2) x = ((w1 - w2) / 2)
y = ((h1 - h2) / 2) y = ((h1 - h2) / 2)
return (x, y) return (int(x), int(y))
# If we consider (0,0) as top left corner of image called
# im with left-to-right as x direction and top-to-bottom
# as y direction. and we have (x1,y1) as the top-left vertex
# and (x2,y2) as the bottom-right vertex of a rectangle
# region within that image, then:
#
# roi = im[y1:y2, x1:x2]
def crop (img, xoffset, yoffset, w, h) :
#crop_img = img[y:y+h, x:x+w].copy()
return im[yoffset:yoffset+w, xoffset:xoffset+w].copy()
if len(sys.argv) < 2: if len(sys.argv) < 2:
print('Please provide path of scan to normalize') print('Please provide path of scan to normalize')
@ -358,6 +367,7 @@ normalHeight = round(float(width) / pageRatio)
holePunches = find_hole_punches(img) holePunches = find_hole_punches(img)
rotated = correct_rotation(img, original, holePunches) rotated = correct_rotation(img, original, holePunches)
rotatedHeight, rotatedWidth = rotated.shape[:2]
holePunches = find_hole_punches(rotated) holePunches = find_hole_punches(rotated)
blank = create_blank(width, normalHeight) blank = create_blank(width, normalHeight)
@ -378,11 +388,13 @@ print(f'Mean rectangle: {meanRect[0]},{meanRect[1]}')
# offset is the position within the new normal image # offset is the position within the new normal image
# the top left hole punch should be centered to # the top left hole punch should be centered to
offset = center_within((width, normalHeight), meanRect) offset = center_within((width, normalHeight), meanRect)
print(f'Offset: {offset[0]},{offset[1]}') print(f'Offset : {offset[0]},{offset[1]}')
print(f'Topleft: {tl["x"]},{tl["y"]}')
print(f'Rotated: {rotatedWidth},{rotatedHeight}')
print(f'Blank : {width},{normalHeight}')
display(img)
#normal = place(blank, rotated, 0, 0) #normal = place(blank, rotated, 0, 0)
#display(normal) display(blank)

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@ -0,0 +1,81 @@
import math
import numpy
import scipy.ndimage
import imagecodecs
import imreg
from matplotlib import pyplot, patches
def brute_force_scale_invariant_template_matching(
template, # grayscale image
search, # scaled and cropped grayscale image
zooms=(1.0, 0.5, 0.25), # sequence of zoom factors to try
size=None, # power-of-two size of square sliding window
delta=None, # advance of sliding windows. default: half window size
min_overlap=0.25, # minimum overlap of search with window
max_diff=0.05, # max average of search - window differences in overlap
max_angle=0.5, # no rotation
):
"""Return yoffset, xoffset, and scale of first match of search in template.
Iterate over scaled versions of the template image in overlapping sliding
windows and run FFT-based algorithm for translation, rotation and
scale-invariant image registration until a match of the search image is
found in the sliding window.
"""
if size is None:
size = int(pow(2, int(math.log(min(search.shape), 2))))
if delta is None:
delta = size // 2
search = search[:size, :size]
for zoom in zooms:
windows = numpy.lib.stride_tricks.sliding_window_view(
scipy.ndimage.zoom(template, zoom), search.shape
)[::delta, ::delta]
for i in range(windows.shape[0]):
for j in range(windows.shape[1]):
print('.', end='')
window = windows[i, j]
im2, scale, angle, (t0, t1) = imreg.similarity(window, search)
diff = numpy.abs(im2 - window)[im2 != 0]
if (
abs(angle) < max_angle
and diff.size / window.size > min_overlap
and numpy.mean(diff) < max_diff
):
return (
(i * delta - t0) / zoom,
(j * delta - t1) / zoom,
1 / scale / zoom,
)
raise ValueError('no match of search image found in template')
def rgb2gray(rgb, scale=None):
"""Return float grayscale image from RGB24 or RGB48 image."""
scale = numpy.iinfo(rgb.dtype).max if scale is None else scale
scale = numpy.array([[[0.299, 0.587, 0.114]]], numpy.float32) / scale
return numpy.sum(rgb * scale, axis=-1)
template = imagecodecs.imread('cw1_IMG_9037.jpg')
search = imagecodecs.imread('cw1_p1_9037_kzw.jpg')
yoffset, xoffset, scale = brute_force_scale_invariant_template_matching(
rgb2gray(template), rgb2gray(search), zooms=(0.5,)
)
print(yoffset, xoffset, scale)
figure, ax = pyplot.subplots()
ax.imshow(template)
rect = patches.Rectangle(
(xoffset, yoffset),
scale * search.shape[1],
scale * search.shape[0],
linewidth=1,
edgecolor='r',
facecolor='none',
)
ax.add_patch(rect)
pyplot.show()

33
fourcell/notes/sift.py Normal file
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@ -0,0 +1,33 @@
# Initiate SIFT detector
sift = cv2.SIFT_create()
# find the keypoints and descriptors with SIFT
# Here img1 and img2 are grayscale images
kp1, des1 = sift.detectAndCompute(img1,None)
kp2, des2 = sift.detectAndCompute(img2,None)
# FLANN parameters
# I literally copy-pasted the defaults
FLANN_INDEX_KDTREE = 1
index_params = dict(algorithm = FLANN_INDEX_KDTREE, trees = 5)
search_params = dict(checks=50) # or pass empty dictionary
# do the matching
flann = cv2.FlannBasedMatcher(index_params,search_params)
matches = flann.knnMatch(des1,des2,k=2)
## OPTIONAL - Show matches ##
# Need to draw only good matches, so create a mask
matchesMask = [[0,0] for i in range(len(matches))]
# ratio test as per Lowe's paper <- this is a criterion for matches selection
for i,(m,n) in enumerate(matches):
if m.distance < 0.7*n.distance:
matchesMask[i]=[1,0]
draw_params = dict(matchColor = (0,255,0),
singlePointColor = (255,0,0),
matchesMask = matchesMask,
flags = cv2.DrawMatchesFlags_DEFAULT)
img3 = cv2.drawMatchesKnn(img1,kp1,img2,kp2,matches,None, **draw_params)
f, ax = plt.subplots(1, figsize=(15,15))
ax.imshow(img3)
plt.show()