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June 18, 2016 06:31
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OpenCV fake OCR example
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| #https://opencv-python-tutroals.readthedocs.io/en/latest/py_tutorials/py_gui/py_image_display/py_image_display.html#display-image | |
| #http://docs.opencv.org/3.0-beta/modules/imgproc/doc/miscellaneous_transformations.html | |
| #http://docs.opencv.org/2.4/doc/tutorials/imgproc/threshold/threshold.html | |
| import cv2 | |
| # Original image for annotation | |
| img = cv2.imread('CSH-drink-4k.jpg') | |
| # Grayscale image | |
| gray = cv2.imread('CSH-drink-4k.jpg',0) | |
| # Threshold image, save a copy to admire | |
| thresh = cv2.threshold(gray, 243, 255, cv2.THRESH_BINARY_INV)[1] | |
| cv2.imwrite('CSH-drink-4k-thresh.png',thresh) | |
| # The ultimate strategy is to identify all of the contours and find a bounding | |
| # box for them. Then we'll dump all of the ones that don't fit ones and zeroes | |
| # and then identify the ones and zeroes based on the size of the box. | |
| # Find all of the contours in the image. | |
| im2, contours, hierarchy = cv2.findContours(thresh.copy(),cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE) | |
| # Each bounding rectangle is [x,y,w,h]. So rectangle[1] is y and rectangle[3] is height | |
| # Determine if two rectangles are vertically overlapping (on the same line) | |
| def voverlapping(rectangle1, rectangle2): | |
| return not ((rectangle1[1] > (rectangle2[1] + rectangle2[3])) or | |
| ((rectangle1[1] + rectangle1[3]) < rectangle2[1])) | |
| # Each bounding rectangle is [x,y,w,h] | |
| # | |
| # We first map from contours to bounding rectangles, then we filter that based | |
| # on rectangle size criteria, then we sort that based on x, y position left to | |
| # right, top to bottom. The final pile of rectangles should all be ones and | |
| # zeroes, identifiable by size. | |
| boundingRectangles = sorted( | |
| filter( | |
| lambda rectangle: ((rectangle[2] > 20) and (rectangle[3] > 40) and (rectangle[2] < 40) and (rectangle[3] < 60)), | |
| map(lambda contour: cv2.boundingRect(contour), contours) | |
| ), | |
| lambda rectangle1, rectangle2: rectangle1[0] - rectangle2[0] if voverlapping(rectangle1, rectangle2) else rectangle1[1] - rectangle2[1] | |
| ) | |
| # Ones are smaller than zeroes, so make an array of bits with their bounding | |
| # rectangle using the size for identification. | |
| bitsAndRectangles = map(lambda rectangle: ((1 if rectangle[2] < 30 else 0), rectangle), boundingRectangles) | |
| # Convert all the bits to a giant string and print it | |
| bitsString = reduce(lambda finalString, bitAndRectangle: finalString + str(bitAndRectangle[0]), bitsAndRectangles, "") | |
| print bitsString | |
| # Take the original color image and annotate it with the bounding for each bit | |
| # along with our interpretation of the bit value and a circle in the corner for | |
| # bit zero in an eight bit byte. | |
| fontFace = cv2.FONT_HERSHEY_SIMPLEX | |
| fontScale = 1 | |
| fontThickness = 2 | |
| bitcount = 0 | |
| for rectangle in bitsAndRectangles: | |
| [x,y,w,h] = rectangle[1] | |
| # Draw the bounding | |
| cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,0),1) | |
| # Draw our interpretation of the bit value in the lower left | |
| cv2.putText(img,str(rectangle[0]),(x+1,y+h-4), fontFace, fontScale,(0,0,0),fontThickness,cv2.LINE_AA) | |
| # If we are drawing bit zero then draw a filled circle to indicate it | |
| if (bitcount % 8) == 0: | |
| cv2.circle(img,(x + 4 + 2, y + 4 + 2), 4, (0, 0, 0), -1) | |
| bitcount += 1 | |
| # Put the image with annotations | |
| cv2.imwrite('CSH-drink-4k-annotated.png',img) |
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