I have this original image:
then I have applied the following code to
Converted the Original image to HSV image
Then using cv2.findContours() I have made a list containing all the contours.
Then i have removed all the contours of area less than 30.
Then I got the following image:
What I want is to remove the boundary from the resulting image it is of no use (outer boundary of leaf).I only need the inner patches of the leaf.
This is the code i used.
import cv2
import numpy as np
img = cv2.imread('Apple___Blackrot30.JPG')
hsv = cv2.cvtColor(img,cv2.COLOR_BGR2HSV)
lower_gr = np.array([25,0,0])
upper_gr = np.array([90,255,255])
mask = cv2.inRange(hsv,lower_gr,upper_gr)
mask=~mask
res = cv2.bitwise_and(img,img,mask = mask)
blur = cv2.bilateralFilter(res,9,75,75)
im2,cont,_ = cv2.findContours(mask,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
areas = [cv2.contourArea(each_conts) for each_conts in cont]
cont_counter = 0
for each_conts in areas:
if each_conts < 30:
cv2.fillPoly(im2, pts =[cont[cont_counter]], color=(0,0,0))
if each_conts > 1024:
cv2.drawContours(mask, cont[cont_counter], 0, (255,255,255), -1)
cont_counter+=1
cv2.imshow('cn',im2)
You can use the concept of hierarchy of contours to solve this problem. But there is a caveat, all your images must be the same as the one in the question.
I just added some additional stuff to your code.
Code:
img2 = img.copy()
im2, cont, hierarchy = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
l = []
for e, h in enumerate(hierarchy[0]):
#print (e, h[3])
if h[3] == -1:
l.append(e)
for i in l:
if cv2.contourArea(cont[i]) < 1000:
cv2.drawContours(img2, [cont[i]], -1, (0, 255, 255), 2)
cv2.imshow('img2', img2)
Result:
hierarchy returns an array expressing the parent-child relationship of contours. As per the documentation link,
it as an array of four values : [Next, Previous, First_Child, Parent].
In the hierarchy array I scanned the Parent column (4th column) to see whether it has no parent contours (-1) and drew them
I assume you only need the inner spots inside a leaf.
Segment using the otsu algorithm
apply the flood-fill operation to ensure you capture all leaf pixels
Extract only the inner contour
All can simply be done using opencv below are the codes:
import cv2
import numpy as np
def flood_fill_binary(binary):
hh = binary.shape[0]
ww = binary.shape[1]
xx = 10
yy = 10
black = [0,0,0]
binary = cv2.copyMakeBorder(binary,10,10,10,10,cv2.BORDER_CONSTANT,value=black)
im_floodfill = binary.copy()
h, w = binary.shape[:2]
mask = np.zeros((h+2, w+2), np.uint8)
cv2.floodFill(im_floodfill, mask, (0,0), 255)
im_floodfill_inv = cv2.bitwise_not(im_floodfill)
im_out = binary | im_floodfill_inv
crop_og = im_out[yy:yy+hh,xx:xx+ww]
return crop_og
def leaf_spots_detector(image):
image = image.astype('uint8')
hh = image.shape[0]
ww = image.shape[1]
xx = 10
yy = 10
#kernel = np.ones((3,3),np.uint8)
grayed_image = cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
_, segmented = cv2.threshold(grayed_image,0, 255,
cv2.THRESH_BINARY+cv2.THRESH_OTSU)
segmented = flood_fill_binary(segmented)
segmented = cv2.copyMakeBorder(segmented,xx,xx,yy,yy,cv2.BORDER_CONSTANT,value=
[0,0,0])
major = cv2.__version__.split('.')[0]
if major == '3':
ret, contours, hierarchy = cv2.findContours(segmented, cv2.RETR_TREE,
cv2.CHAIN_APPROX_SIMPLE)
else:
contours, hierarchy = cv2.findContours(segmented, cv2.RETR_TREE,
cv2.CHAIN_APPROX_SIMPLE)
print(hierarchy.shape)
image_external = np.zeros(segmented.shape, segmented.dtype)
for i in range(1,len(contours)):
#if hierarchy[0][i][3] == -1:
cv2.drawContours(image_external, contours, i,(225,255,255), -1)
image_external = image_external[yy:yy+hh,xx:xx+ww]
#image_external = cv2.dilate(image_external,kernel,iterations = 1)
return image_external
image = cv2.imread('image/path.png')
leaf_spots = leaf_spots_detector(image)
cv2.imshow("detected spots", leaf_spots)
cv2.waitKey(0)
cv2.destroyAllWindow()
Related
I'm having an image and i want to crop only the number inside with out the lines bounding around image. Here is the sample image:
As you can see there is 2 lines on the right and bottom of the image, i want to crop only number 8, if nothing inside, i will return None for the result, but with my code, it also return the area which include these line. So is there anyway to fix this?
Result i got:
Or with empty image, i got:
Here is my code:
import cv2
def process(image, readFile=True, returnType='binary'):
out_gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# Performing OTSU threshold
ret, thresh1 = cv2.threshold(out_gray, 220, 255, cv2.THRESH_OTSU + cv2.THRESH_BINARY_INV)
# Specify structure shape and kernel size.
# Kernel size increases or decreases the area
# of the rectangle to be detected.
# A smaller value like (10, 10) will detect
# each word instead of a sentence.
rect_kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (8,8))
# Appplying dilation on the threshold image
dilation = cv2.dilate(thresh1, rect_kernel, iterations = 1)
# Finding contours
contours, hierarchy = cv2.findContours(dilation, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
if len(contours) <= 0:
return False
contours, boundingBoxes = sort_contours(contours, 'left-to-right')
# Creating a copy of image
im2 = img.copy()
idata = 0
# Looping through the identified contours
# Then rectangular part is cropped and passed on
# to pytesseract for extracting text from it
# Extracted text is then written into the text file
i = 1
minHeight = 10
minWidth = 10
result = []
for cnt in contours:
x, y, w, h = cv2.boundingRect(cnt)
# Drawing a rectangle on copied image
rect = cv2.rectangle(im2, (x, (y-1)), (x + w, y + h + 1), (0, 255, 0), 1)
cv2.imwrite(f'{constant.__RESULT_PATH}/cutted123withbounding.png', im2)
# Cropping the text block for giving input to OCR
cropped = im2[y:y + h, x:x + w]
if w >= minWidth and h >= minHeight:
result.append(thresh1)
i = i + 1
return result
I am using pytessearct to extract the text from images. But it doesn't work on images which are inclined. Consider the image given below:
Here is the code to extract text, which is working fine on images which are not inclined.
img = cv2.imread(<path_to_image>)
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (5,5),0)
ret3, thresh = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
def findSignificantContours (img, edgeImg):
contours, heirarchy = cv2.findContours(edgeImg, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)
# Find level 1 contours
level1 = []
for i, tupl in enumerate(heirarchy[0]):
# Each array is in format (Next, Prev, First child, Parent)
# Filter the ones without parent
if tupl[3] == -1:
tupl = np.insert(tupl, 0, [i])
level1.append(tupl)
significant = []
tooSmall = edgeImg.size * 5 / 100 # If contour isn't covering 5% of total area of image then it probably is too small
for tupl in level1:
contour = contours[tupl[0]];
area = cv2.contourArea(contour)
if area > tooSmall:
significant.append([contour, area])
# Draw the contour on the original image
cv2.drawContours(img, [contour], 0, (0,255,0),2, cv2.LINE_AA, maxLevel=1)
significant.sort(key=lambda x: x[1])
#print ([x[1] for x in significant]);
mx = (0,0,0,0) # biggest bounding box so far
mx_area = 0
for cont in contours:
x,y,w,h = cv2.boundingRect(cont)
area = w*h
if area > mx_area:
mx = x,y,w,h
mx_area = area
x,y,w,h = mx
# Output to files
roi = img[y:y+h,x:x+w]
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (5,5),0)
ret3, thresh = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
cv2_imshow(thresh)
text = pytesseract.image_to_string(roi);
print(text); print("\n"); print(pytesseract.image_to_string(thresh));
print("\n")
return [x[0] for x in significant];
edgeImg_8u = np.asarray(thresh, np.uint8)
# Find contours
significant = findSignificantContours(img, edgeImg_8u)
mask = thresh.copy()
mask[mask > 0] = 0
cv2.fillPoly(mask, significant, 255)
# Invert mask
mask = np.logical_not(mask)
#Finally remove the background
img[mask] = 0;
Tesseract can't extract the text from this image. Is there a way I can rotate it to align the text perfectly and then feed it to pytesseract? Please let me know if my question require any more clarity.
Here's a simple approach:
Obtain binary image. Load image, convert to grayscale,
Gaussian blur, then Otsu's threshold.
Find contours and sort for largest contour. We find contours then filter using contour area with cv2.contourArea() to isolate the rectangular contour.
Perform perspective transform. Next we perform contour approximation with cv2.contourArea() to obtain the rectangular contour. Finally we utilize imutils.perspective.four_point_transform to actually obtain the bird's eye view of the image.
Binary image
Result
To actually extract the text, take a look at
Use pytesseract OCR to recognize text from an image
Cleaning image for OCR
Detect text area in an image using python and opencv
Code
from imutils.perspective import four_point_transform
import cv2
import numpy
# Load image, grayscale, Gaussian blur, Otsu's threshold
image = cv2.imread("1.jpg")
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
blur = cv2.GaussianBlur(gray, (7,7), 0)
thresh = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]
# Find contours and sort for largest contour
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]
cnts = sorted(cnts, key=cv2.contourArea, reverse=True)
displayCnt = None
for c in cnts:
# Perform contour approximation
peri = cv2.arcLength(c, True)
approx = cv2.approxPolyDP(c, 0.02 * peri, True)
if len(approx) == 4:
displayCnt = approx
break
# Obtain birds' eye view of image
warped = four_point_transform(image, displayCnt.reshape(4, 2))
cv2.imshow("thresh", thresh)
cv2.imshow("warped", warped)
cv2.waitKey()
To Solve this problem you can also use minAreaRect api in opencv which will give you a minimum area rotated rectangle with an angle of rotation. You can then get the rotation matrix and apply warpAffine for the image to straighten it. I have also attached a colab notebook which you can play around on.
Colab notebook : https://colab.research.google.com/drive/1SKxrWJBOHhGjEgbR2ALKxl-dD1sXIf4h?usp=sharing
import cv2
from google.colab.patches import cv2_imshow
import numpy as np
def rotate_image(image, angle):
image_center = tuple(np.array(image.shape[1::-1]) / 2)
rot_mat = cv2.getRotationMatrix2D(image_center, angle, 1.0)
result = cv2.warpAffine(image, rot_mat, image.shape[1::-1], flags=cv2.INTER_LINEAR)
return result
img = cv2.imread("/content/sxJzw.jpg")
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
mask = np.zeros((img.shape[0], img.shape[1]))
blur = cv2.GaussianBlur(gray, (5,5),0)
ret, thresh = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
cv2_imshow(thresh)
contours, _ = cv2.findContours(thresh, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
largest_countour = max(contours, key = cv2.contourArea)
binary_mask = cv2.drawContours(mask, [largest_countour], 0, 1, -1)
new_img = img * np.dstack((binary_mask, binary_mask, binary_mask))
minRect = cv2.minAreaRect(largest_countour)
rotate_angle = minRect[-1] if minRect[-1] < 0 else -minRect[-1]
new_img = rotate_image(new_img, rotate_angle)
cv2_imshow(new_img)
I need to extract the 12 oval shapes from the image and store them in separate variables say 1 to 12.
The original image was as follows
Original Image:
Output image:
Can someone help me extract all those oval shapes into different variables ?
my code is
import cv2
import numpy as np
path = r'/home/parallels/Desktop/Opencv/data/test.JPG'
i = cv2.imread(path, -1)
img_rgb = cv2.resize(i, (1280,720))
cv2.namedWindow("Original Image",cv2.WINDOW_NORMAL)
img = cv2.cvtColor(img_rgb, cv2.COLOR_RGB2HSV)
img = cv2.bilateralFilter(img,9,105,105)
r,g,b=cv2.split(img)
equalize1= cv2.equalizeHist(r)
equalize2= cv2.equalizeHist(g)
equalize3= cv2.equalizeHist(b)
equalize=cv2.merge((r,g,b))
equalize = cv2.cvtColor(equalize,cv2.COLOR_RGB2GRAY)
ret,thresh_image = cv2.threshold(equalize,0,255,cv2.THRESH_OTSU+cv2.THRESH_BINARY)
equalize= cv2.equalizeHist(thresh_image)
canny_image = cv2.Canny(equalize,250,255)
canny_image = cv2.convertScaleAbs(canny_image)
kernel = np.ones((3,3), np.uint8)
dilated_image = cv2.dilate(canny_image,kernel,iterations=1)
contours, hierarchy = cv2.findContours(dilated_image, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
contours= sorted(contours, key = cv2.contourArea, reverse = True)[:10]
c=contours[0]
print(cv2.contourArea(c))
final = cv2.drawContours(img, [c], -1, (255,0, 0), 3)
mask = np.zeros(img_rgb.shape,np.uint8)
new_image = cv2.drawContours(mask,[c],0,255,-1,)
new_image = cv2.bitwise_and(img_rgb, img_rgb, mask=equalize)
cv2.namedWindow("new",cv2.WINDOW_NORMAL)
cv2.imshow("new",new_image)
cv2.waitKey(0)
You're on the right track. After obtaining your binary image, you can perform contour area + aspect ratio filtering. We can sort the contours in order from left-to-right using imutils.contours.sort_contours(). We find contours then filter using cv2.contourArea
and aspect ratio with cv2.approxPolyDP + cv2.arcLength. If they pass this filter, we draw the contours and append it to a oval list to keep track of the contours. Here's the results:
Filtered mask
Results
Isolated ovals
Output from oval list
Oval contours: 12
Code
import cv2
import numpy as np
from imutils import contours
# Load image, resize, convert to HSV, bilaterial filter
image = cv2.imread('1.jpg')
resize = cv2.resize(image, (1280,720))
original = resize.copy()
mask = np.zeros(resize.shape[:2], dtype=np.uint8)
hsv = cv2.cvtColor(resize, cv2.COLOR_RGB2HSV)
hsv = cv2.bilateralFilter(hsv,9,105,105)
# Split into channels and equalize
r,g,b=cv2.split(hsv)
equalize1 = cv2.equalizeHist(r)
equalize2 = cv2.equalizeHist(g)
equalize3 = cv2.equalizeHist(b)
equalize = cv2.merge((r,g,b))
equalize = cv2.cvtColor(equalize,cv2.COLOR_RGB2GRAY)
# Blur and threshold for binary image
blur = cv2.GaussianBlur(equalize, (3,3), 0)
thresh = cv2.threshold(blur, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]
# Find contours, sort from left-to-right
# Filter using contour area and aspect ratio filtering
ovals = []
num = 0
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if len(cnts) == 2 else cnts[1]
(cnts, _) = contours.sort_contours(cnts, method="left-to-right")
for c in cnts:
area = cv2.contourArea(c)
x,y,w,h = cv2.boundingRect(c)
ar = w / float(h)
if area > 1000 and ar < .8:
cv2.drawContours(resize, [c], -1, (36,255,12), 3)
cv2.drawContours(mask, [c], -1, (255,255,255), -1)
cv2.putText(resize, str(num), (x,y - 5), cv2.FONT_HERSHEY_SIMPLEX, 0.7, (36,55,12), 2)
ovals.append(c)
num += 1
result = cv2.bitwise_and(original, original, mask=mask)
result[mask==0] = (255,255,255)
print('Oval contours: {}'.format(len(ovals)))
cv2.imshow('equalize', equalize)
cv2.imshow('thresh', thresh)
cv2.imshow('resize', resize)
cv2.imshow('result', result)
cv2.imshow('mask', mask)
cv2.waitKey()
Today I am trying to identify the edge of an object.
I got a great result by doing this.
import cv2
img = cv2.imread("0.png")
img2 = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
img2 = cv2.equalizeHist(img2)
img2 = cv2.GaussianBlur(img2, (7, 7), 0)
edges = cv2.Canny(img2, 180, 300)
im2, contours, hierarchy = cv2.findContours(edges, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
cv2.drawContours(img, contours, -1, (0, 255, 0), 1)
cv2.imshow('img', img)
cv2.waitKey(0)
cv2.destroyAllWindows()
and the image looks like: (it's a welding's x-ray)
My ultimate goal is to find the center line between the edges,
(the collection of (MaxY+MinY)/2 on each X)
the ideal result should look like this: (sorry for the bad hand drawing)
Could anyone let me know how should I do this?
Thank you very much.
First of all you should prepare your image so that you can found your one contour (threshold, histogram equalization etc.). The contour returns you a set of (x,y) coordinates that represent the contour so for the first step you should seperate the upper edge from the bottom (split it on half). In my example I made it complementary to momements of the contour but note that this will not work for curved lines! You will have to make an algorithm to divide upper side and down side. Once you have done this you can make two list, containing one element per x coordinate. Then simply calculate the midle and make a point on the image.
Example code:
import cv2
import numpy as np
img = cv2.imread('centerline.png')
mask = np.zeros((img.shape[:2]), np.uint8)
h2, w2 = img.shape[:2]
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
equ = cv2.equalizeHist(gray)
_, thresh = cv2.threshold(equ,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
kernel = np.ones((5,5),np.uint8)
opening = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kernel)
_, contours, hierarchy = cv2.findContours(opening,cv2.RETR_TREE,cv2.CHAIN_APPROX_NONE)
for cnt in contours:
x,y,w,h = cv2.boundingRect(cnt)
print(h, w)
if h < 30 and w > 270:
cv2.drawContours(mask, [cnt], 0, (255,255,255), -1)
res = cv2.bitwise_and(img, img, mask=mask)
gray = cv2.cvtColor(res,cv2.COLOR_BGR2GRAY)
_, thresh = cv2.threshold(gray,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
blur = cv2.GaussianBlur(thresh,(5,5),0)
_, contours, hierarchy = cv2.findContours(blur,cv2.RETR_TREE,cv2.CHAIN_APPROX_NONE)
cnt = max(contours, key=cv2.contourArea)
M = cv2.moments(cnt)
cy = int(M['m01']/M['m00'])
mask = np.zeros((img.shape[:2]), np.uint8)
cv2.drawContours(mask, [cnt], 0, (255,255,255), -1)
up = []
down = []
for i in cnt:
x = i[0][0]
y = i[0][1]
if x == 0:
pass
elif x == w2:
pass
else:
if y > cy:
down.append(tuple([x,y]))
elif y < cy:
up.append(tuple([x,y]))
else:
pass
up.sort(key = lambda x: x[0])
down.sort(key = lambda x: x[0])
up_1 = []
down_1 = []
for i in range(0, len(up)-1):
if up[i][0] != up[i+1][0]:
up_1.append(up[i])
else:
pass
for i in range(0, len(down)-1):
if down[i][0] != down[i+1][0]:
down_1.append(down[i])
else:
pass
lines = zip(up_1, down_1)
for i in lines:
x1 = i[0][0]
y1 = i[0][1]
x2 = i[1][0]
y2 = i[1][1]
middle = np.sqrt(((x2-x1)**2)+((y2-y1)**2))
cv2.circle(img, (x1, y1+int(middle/2)), 1, (0,0,255), -1)
cv2.imshow('img', img)
Result:
I followed along at http://www.pyimagesearch.com/2016/10/03/bubble-sheet-multiple-choice-scanner-and-test-grader-using-omr-python-and-opencv/
now I am trying to make this function in real time. My end goal is to detect a solid colored circle so this looked like a good start.
My crash:
~/py:.python test_grader.py
Traceback (most recent call last):
File "test_grader.py", line 82, in <module>
questionCnts = contours.sort_contours(questionCnts,
AttributeError: 'list' object has no attribute 'sort_contours'
questionCnts = contours.sort_contours(questionCnts,
method="top-to-bottom")[0] << line 82 crashing
questionCnts is defined as [].. I dont understand how appending the contour is supposed to add this method.
Full source
from imutils.perspective import four_point_transform
from imutils import contours
import numpy as np
import argparse
import imutils
import cv2
import copy
cap = cv2.VideoCapture(0)
ANSWER_KEY = {0: 1, 1: 4, 2: 0, 3: 3, 4: 1}
while(True):
ret, image = cap.read()
clone = copy.copy(image)
gray = cv2.cvtColor(clone, cv2.COLOR_BGR2GRAY)
blurred = cv2.GaussianBlur(gray, (5, 5), 0)
edged = cv2.Canny(blurred, 75, 200)
ret, thresh = cv2.threshold(gray,127,255,1) #only black squares?
contours, h = cv2.findContours(thresh,1,1) #was 2
# find contours in the edge map, then initialize
# the contour that corresponds to the document
cnts = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
# cnts = cv2.findContours(edged.copy(), cv2.RETR_EXTERNAL,
# cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if imutils.is_cv2() else cnts[1]
docCnt = None
# ensure that at least one contour was found
if len(cnts) > 0:
# sort the contours according to their size in
# descending order
cnts = sorted(cnts, key=cv2.contourArea, reverse=True)
# loop over the sorted contours
for c in cnts:
# approximate the contour
peri = cv2.arcLength(c, True)
approx = cv2.approxPolyDP(c, 0.02 * peri, True)
# if our approximated contour has four points,
# then we can assume we have found the paper
if len(approx) == 4:
docCnt = approx
break
# apply a four point perspective transform to both the
# original image and grayscale image to obtain a top-down
# birds eye view of the paper
paper = four_point_transform(image, docCnt.reshape(4, 2))
warped = four_point_transform(gray, docCnt.reshape(4, 2))
# apply Otsu's thresholding method to binarize the warped
# piece of paper
thresh = cv2.threshold(warped, 0, 255,
cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)[1]
# find contours in the thresholded image, then initialize
# the list of contours that correspond to questions
cnts = cv2.findContours(thresh.copy(), cv2.RETR_EXTERNAL,
cv2.CHAIN_APPROX_SIMPLE)
cnts = cnts[0] if imutils.is_cv2() else cnts[1]
questionCnts = []
# loop over the contours
for c in cnts:
# compute the bounding box of the contour, then use the
# bounding box to derive the aspect ratio
(x, y, w, h) = cv2.boundingRect(c)
ar = w / float(h)
# in order to label the contour as a question, region
# should be sufficiently wide, sufficiently tall, and
# have an aspect ratio approximately equal to 1
if w >= 20 and h >= 20 and ar >= 0.9 and ar <= 1.1:
questionCnts.append(c)
# sort the question contours top-to-bottom, then initialize
# the total number of correct answers
questionCnts = contours.sort_contours(questionCnts,
method="top-to-bottom")[0]
correct = 0
# each question has 5 possible answers, to loop over the
# question in batches of 5
for (q, i) in enumerate(np.arange(0, len(questionCnts), 5)):
# sort the contours for the current question from
# left to right, then initialize the index of the
# bubbled answer
cnts = contours.sort_contours(questionCnts[i:i + 5])[0]
bubbled = None
# loop over the sorted contours
for (j, c) in enumerate(cnts):
# construct a mask that reveals only the current
# "bubble" for the question
mask = np.zeros(thresh.shape, dtype="uint8")
cv2.drawContours(mask, [c], -1, 255, -1)
# apply the mask to the thresholded image, then
# count the number of non-zero pixels in the
# bubble area
mask = cv2.bitwise_and(thresh, thresh, mask=mask)
total = cv2.countNonZero(mask)
# if the current total has a larger number of total
# non-zero pixels, then we are examining the currently
# bubbled-in answer
if bubbled is None or total > bubbled[0]:
bubbled = (total, j)
# initialize the contour color and the index of the
# *correct* answer
color = (0, 0, 255)
k = ANSWER_KEY[q]
# check to see if the bubbled answer is correct
if k == bubbled[1]:
color = (0, 255, 0)
correct += 1
# draw the outline of the correct answer on the test
cv2.drawContours(paper, [cnts[k]], -1, color, 3)
# grab the test taker
score = (correct / 5.0) * 100
print("[INFO] score: {:.2f}%".format(score))
cv2.putText(paper, "{:.2f}%".format(score), (10, 30),
cv2.FONT_HERSHEY_SIMPLEX, 0.9, (0, 0, 255), 2)
cv2.imshow("Original", image)
cv2.imshow("Exam", paper)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cv2.waitKey(0)