added image cropping tool
parent
d94611313c
commit
36faee0258
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# a digital cake knife in the spirit of Hannah Höch
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# cuts out composable contours from the herbarium scans
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import glob
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import os.path
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import sqlite3
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import cv2
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import numpy as np
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from PIL import Image
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BLUR = 3
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CANNY_THRESH_1 = 200
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CANNY_THRESH_2 = 250
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MASK_DILATE_ITER = 40
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MASK_ERODE_ITER = 40
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MASK_COLOR = (0.0,0.0,1.0) # In BGR format
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src_imgs = glob.glob("specimen_img_raw/*")
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db = sqlite3.connect("ratios.db")
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dbc = db.cursor()
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for src in src_imgs:
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img_color = cv2.imread(src)
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scalar = float(1000.0 / img_color.shape[1])
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new_height = int(scalar * img_color.shape[0])
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img_color = cv2.resize(img_color, (1000, new_height))
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img_gray = cv2.imread(src, flags=cv2.IMREAD_GRAYSCALE)
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img_gray = cv2.resize(img_gray, (1000, new_height))
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# add some white around the edges so we have some space to rotate
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img_color = cv2.copyMakeBorder(img_color,10,10,10,10,cv2.BORDER_CONSTANT, value=[255, 255, 255])
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img_gray = cv2.copyMakeBorder(img_gray,10,10,10,10,cv2.BORDER_CONSTANT, value=[255])
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blurred = cv2.GaussianBlur(img_gray, (9, 9), 0)
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aperture = 5 # default is 3 but 5 or 7 are more sensitive
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# most of this is ganked directly from this https://stackoverflow.com/questions/29313667/how-do-i-remove-the-background-from-this-kind-of-image
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#-- Edge detection -------------------------------------------------------------------
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edges = cv2.Canny(blurred, CANNY_THRESH_1, CANNY_THRESH_2, apertureSize=aperture)
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edges = cv2.dilate(edges, None)
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edges = cv2.erode(edges, None)
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#-- Find contours in edges, sort by area ---------------------------------------------
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contour_info = []
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contours, _ = cv2.findContours(edges, cv2.RETR_LIST, cv2.CHAIN_APPROX_NONE)
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for c in contours:
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contour_info.append((
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c,
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cv2.isContourConvex(c),
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cv2.contourArea(c),
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))
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contour_info = sorted(contour_info, key=lambda c: c[2], reverse=True)
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# filter out the accidental box contours - should be less than 85% of pixels
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img_area = img_color.shape[0] * img_color.shape[1]
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for cont in contour_info:
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max_contour = cont
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pixel_ratio = max_contour[2] / img_area
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if pixel_ratio < 0.85:
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test_img = img_color.copy()
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c_rect = cv2.minAreaRect(max_contour[0])
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box = cv2.boxPoints(c_rect)
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box = np.int0(box)
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cv2.drawContours(test_img, [max_contour[0]], -1, (255, 0, 0, 20), 3)
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cv2.drawContours(test_img, [box], -1, (0, 255, 0), 3)
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cv2.imwrite("test.png", test_img)
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test_viewer = Image.open("test.png")
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test_viewer.show()
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if input("contour ok (y/n)?") == "y":
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test_viewer.close()
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break
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test_viewer.close()
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#-- Create empty mask, draw filled polygon on it corresponding to largest contour ----
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# Mask is black, polygon is white
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mask = np.zeros(edges.shape)
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cv2.fillConvexPoly(mask, max_contour[0], (255))
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#-- Smooth mask, then blur it --------------------------------------------------------
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mask = cv2.dilate(mask, None, iterations=MASK_DILATE_ITER)
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mask = cv2.erode(mask, None, iterations=MASK_ERODE_ITER)
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mask = cv2.GaussianBlur(mask, (BLUR, BLUR), 0)
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mask_stack = np.dstack([mask]*3) # Create 3-channel alpha mask
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#-- Blend masked img into MASK_COLOR background --------------------------------------
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mask_stack = mask_stack.astype('float32') / 255.0 # Use float matrices,
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img_color = img_color.astype('float32') / 255.0 # for easy blending
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# split image into channels
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try:
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c_red, c_green, c_blue = cv2.split(img_color)
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except ValueError:
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print("seems to be greyscale already...")
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img_color = cv2.cvtColor(img_color, cv2.COLOR_GRAY2BGR)
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c_red, c_green, c_blue = cv2.split(img_color)
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# merge with mask got on one of a previous steps
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img_a = cv2.merge((c_red, c_green, c_blue, mask.astype('float32') / 255.0))
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# find bounding minimum bounding rect as that's what we want to rotate & save
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rect = cv2.minAreaRect(max_contour[0])
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box = cv2.boxPoints(rect)
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box = np.int0(box)
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width = int(rect[1][0])
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height = int(rect[1][1])
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# set up a new destination exactly the size of our ROI
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src_pts = box.astype("float32")
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dst_pts = np.array([[0, height-1],
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[0, 0],
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[width-1, 0],
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[width-1, height-1]], dtype="float32")
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# now rotate using warp which is more efficient and preserves pixels
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M = cv2.getPerspectiveTransform(src_pts, dst_pts)
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warped = cv2.warpPerspective(img_a, M, (width, height))
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# save to disk
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basename, ext = os.path.splitext(os.path.basename(src))
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out_path = os.path.join("specimen_cutout", basename + ".png")
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print("saving cropped cutout", out_path)
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cv2.imwrite(out_path, warped*255)
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# add to database
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if height > width:
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ratio = float(height) / width
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else:
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ratio = float(width) / height
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try:
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dbc.execute("INSERT INTO images VALUES (?, ?, ?, ?)", (ratio, width, height, out_path))
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except sqlite3.IntegrityError as err:
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print(err)
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print("Trying db update instead.")
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dbc.execute("UPDATE images SET (ratio, width, height) = (?, ?, ?) WHERE img_path = ?",
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(ratio, width, height, out_path))
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db.commit()
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db.close()
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