blog - Page 14 of 15

Morphological transformation – OpenCV 3.4 with python 3 Tutorial 17

Source code Images transformation: [python] import cv2 import numpy as np img = cv2.imread("balls.jpg", cv2.IMREAD_GRAYSCALE) _, mask = cv2.threshold(img, 250, 255, cv2.THRESH_BINARY_INV) kernel = np.ones((5, 5), np.uint8) dilation = cv2.dilate(mask, kernel) erosion = cv2.erode(mask, kernel, iterations=6) cv2.imshow("Image", img) cv2.imshow("Mask", mask) cv2.imshow("Dilation", dilation) cv2.imshow("Erosion", erosion) cv2.waitKey(0) cv2.destroyAllWindows() [/python] Real Time Video Morphological transformation: [python] import […]

Smoothing images – OpenCV 3.4 with python 3 Tutorial 16

[python] import cv2 import numpy as np img = cv2.imread("early_1800.jpg") averaging = cv2.blur(img, (21, 21)) gaussian = cv2.GaussianBlur(img, (21, 21), 0) median = cv2.medianBlur(img, 5) bilateral = cv2.bilateralFilter(img, 9, 350, 350) cv2.imshow("Original image", img) cv2.imshow("Averaging", averaging) cv2.imshow("Gaussian", gaussian) cv2.imshow("Median", median) cv2.imshow("Bilateral", bilateral) cv2.waitKey(0) cv2.destroyAllWindows() [/python] Files: early_1800.jpg balloons_noisy.png carpet.jpg lake.jpg

Adaptive thresholding – OpenCV 3.4 with python 3 Tutorial 15

[python] import cv2 import numpy as np img = cv2.imread("book_page.jpg") _, threshold = cv2.threshold(img, 155, 255, cv2.THRESH_BINARY) img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) mean_c = cv2.adaptiveThreshold(img_gray, 255, cv2.ADAPTIVE_THRESH_MEAN_C, cv2.THRESH_BINARY, 15, 12) gaus = cv2.adaptiveThreshold(img_gray, 255, cv2.ADAPTIVE_THRESH_GAUSSIAN_C, cv2.THRESH_BINARY, 91, 12) cv2.imshow("Img", img) cv2.imshow("Binary threshold", threshold) cv2.imshow("Mean C", mean_c) cv2.imshow("Gaussian", gaus) cv2.waitKey(0) cv2.destroyAllWindows() [/python] Files: book_page.jpg

Affine transformation – OpenCV 3.4 with python 3 Tutorial 14

[python] import cv2 import numpy as np img = cv2.imread("grid.jpg") rows, cols, ch = img.shape cv2.circle(img, (83, 90), 5, (0, 0, 255), -1) cv2.circle(img, (447, 90), 5, (0, 0, 255), -1) cv2.circle(img, (83, 472), 5, (0, 0, 255), -1) pts1 = np.float32([[83, 90], [447, 90], [83, 472]]) pts2 = np.float32([[0, 0], [447, 90], [150, 472]]) […]

Perspective transformation – OpenCV 3.4 with python 3 Tutorial 13

The Perspective Transformation is that operation that we use when we want to change the perspective of an object. In simpler words, let’s say for example that we have a sheet of paper on the table and we’re capturing it with a camera. As you can clearly see on the picture above, the part of […]

Basic geometric transformations – OpenCV 3.4 with python 3 Tutorial 12

[python] import cv2 import numpy as np img = cv2.imread("red_panda.jpg") rows, cols, ch = img.shape print("Height: ", rows) print("Width: ", cols) scaled_img = cv2.resize(img, None, fx=1/2, fy=1/2) matrix_t = np.float32([[1, 0, -100], [0, 1, -30]]) translated_img = cv2.warpAffine(img, matrix_t, (cols, rows)) matrix_r = cv2.getRotationMatrix2D((cols/2, rows/2), 90, 0.5) rotated_img = cv2.warpAffine(img, matrix_r, (cols, rows)) cv2.imshow("Original image", […]

Histograms – OpenCV 3.4 with python 3 Tutorial 11

Source code: [python] import cv2 import numpy as np from matplotlib import pyplot as plt img = cv2.imread("sea_beach.jpg") b, g, r = cv2.split(img) cv2.imshow("img", img) cv2.imshow("b", b) cv2.imshow("g", g) cv2.imshow("r", r) plt.hist(b.ravel(), 256, [0, 256]) plt.hist(g.ravel(), 256, [0, 256]) plt.hist(r.ravel(), 256, [0, 256]) plt.show() [/python] Files: sea.jpg sea_beach.jpg

Basic Thresholding – OpenCV 3.4 with python 3 Tutorial 10

Threshold: [python] import cv2 import numpy as np img = cv2.imread("black_to_white.jpeg", cv2.IMREAD_GRAYSCALE) _, threshold_binary = cv2.threshold(img, 128, 255, cv2.THRESH_BINARY) _, threshold_binary_inv = cv2.threshold(img, 128, 255, cv2.THRESH_BINARY_INV) _, threshold_trunc = cv2.threshold(img, 128, 255, cv2.THRESH_TRUNC) _, threshold_to_zero = cv2.threshold(img, 12, 255, cv2.THRESH_TOZERO) cv2.imshow("Image", img) cv2.imshow("th binary", threshold_binary) cv2.imshow("th binary inv", threshold_binary_inv) cv2.imshow("th trunc", threshold_trunc) cv2.imshow("th to zero", […]

Object detection using HSV Color space – OpenCV 3.4 with python 3 Tutorial 9

color.py (python file)Download What we will learn in this tutorial: What is HSV How to object recognition by color works What is HSV HSV (Hue Saturation Value) is a color format that describes colors in terms of their shade (saturation) and brightness (value). How to object recognition by color works In this tutorial I explained […]

Trackbars – OpenCV 3.4 with python 3 Tutorial 8

Source code: [python] import cv2 import numpy as np def nothing(x): pass cap = cv2.VideoCapture(0) cv2.namedWindow("frame") cv2.createTrackbar("test", "frame", 50, 500, nothing) cv2.createTrackbar("color/gray", "frame", 0, 1, nothing) while True: _, frame = cap.read() test = cv2.getTrackbarPos("test", "frame") font = cv2.FONT_HERSHEY_COMPLEX cv2.putText(frame, str(test), (50, 150), font, 4, (0, 0, 255)) s = cv2.getTrackbarPos("color/gray", "frame") if s == […]