Detecting Contours using Python<\/h2>\n\n\n\n
So let’s get started with Detecting Contours for images using the OpenCV library in Python.<\/p>\n\n\n\n
1. Importing Modules<\/h3>\n\n\n\n
First, we import the necessary modules which include OpenCV<\/a> and matplotlib<\/a> to plot the images on the screen.<\/p>\n\n\n The next step includes loading the image from the file directory to our program using the We will plot the images in form of a For better detection of contours, we convert the image to a grayscale image by using Next we convert the image into a binary image as it makes the image processing much much easier as it removes the unnecessary items from the image and focuses on the important objects only.<\/p>\n\n\n\n The code for the same is shown below. We will be plotting the binary image on the third slot on the main plot.<\/p>\n\n\n The final step is to detect contours using the We then plot all the images in the subplot, the code for the same is shown below.<\/p>\n\n\n The final output of the whole procedure explained above is shown below. You can see that the results are very accurate.<\/p>\n\n\n\n I also tried the same code for a different image. The results are displayed below.<\/p>\n\n\n\n Congratulations! Now you are one step closer to detecting objects from images. We learned to detect the proper boundaries of the objects today!<\/p>\n\n\n\n Keep learning! Happy coding!<\/p>\n\n\n\n Thank you for reading!<\/p>\n","protected":false},"excerpt":{"rendered":" Hello fellow learner! Today we will learn about detecting contours in an image. Contours are defined as refined boundaries of objects and can be really helpful in detecting objects. Recommended read: How to detect edges in Python? Detecting Contours using Python So let’s get started with Detecting Contours for images using the OpenCV library in […]<\/p>\n","protected":false},"author":28,"featured_media":17493,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-17492","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-examples"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/posts\/17492","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/users\/28"}],"replies":[{"embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/comments?post=17492"}],"version-history":[{"count":0,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/posts\/17492\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/media\/17493"}],"wp:attachment":[{"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/media?parent=17492"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/categories?post=17492"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.askpython.com\/wp-json\/wp\/v2\/tags?post=17492"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\nimport cv2\nimport matplotlib.pyplot as plt\n<\/pre><\/div>\n\n\n
2. Loading the image into the program<\/h3>\n\n\n\n
imread<\/code> function and then converting the image into RGB<\/code> format.<\/p>\n\n\n\nsubplot<\/code> where the first image is the original loaded image. The code for the same is shown below.<\/p>\n\n\n\nloaded_img = cv2.imread("image.jpg")\nloaded_img = cv2.cvtColor(loaded_img, cv2.COLOR_BGR2RGB)\n\nplt.figure(figsize=(20,20))\n\nplt.subplot(2,2,1)\nplt.title("Original Image")\nplt.imshow(loaded_img)\nplt.axis("off")\n<\/pre><\/div>\n\n\n3. Converting image to GrayScale<\/h3>\n\n\n\n
cvtColor<\/code> function. After converting the image to grayscale we plot it on the second subplot on the main plot.<\/p>\n\n\n\ngray_image = cv2.cvtColor(loaded_img, cv2.COLOR_RGB2GRAY)\nplt.subplot(2,2,2)\nplt.title("Grayscale Image")\nplt.imshow(gray_image,cmap="gray")\nplt.axis("off")\n<\/pre><\/div>\n\n\n4. Getting Binary Image<\/h3>\n\n\n\n
\n_, binary_img = cv2.threshold(gray_image, 225, 255, cv2.THRESH_BINARY_INV)\nplt.subplot(2,2,3)\nplt.title("Binary Image")\nplt.imshow(binary_img,cmap="gray")\nplt.axis("off")\n<\/pre><\/div>\n\n\n5. Detecting Contours<\/h3>\n\n\n\n
findContours<\/code> method of openCV library and then we draw the contours on the image.<\/p>\n\n\n\n\ncontours, hierarchy = cv2.findContours(binary_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)\nfinal_image = cv2.drawContours(loaded_img, contours, -1, (0, 255, 0), 2)\nplt.subplot(2,2,4)\nplt.title("Contours detected Image")\nplt.imshow(final_image,cmap="gray")\nplt.axis("off")\n<\/pre><\/div>\n\n\nThe Output Plot<\/h2>\n\n\n\n
![\"](\"https:\/\/www.askpython.com\/wp-content\/uploads\/2021\/05\/Contour_Detection_output_1.jpg\")
The Final Code for Detecting Contours<\/h2>\n\n\n
\nimport cv2\nimport matplotlib.pyplot as plt\n\nloaded_img = cv2.imread("image1.png")\nloaded_img = cv2.cvtColor(loaded_img, cv2.COLOR_BGR2RGB)\n\nplt.figure(figsize=(20,20))\n\nplt.subplot(2,2,1)\nplt.title("Original Image")\nplt.imshow(loaded_img)\nplt.axis("off")\n\ngray_image = cv2.cvtColor(loaded_img, cv2.COLOR_RGB2GRAY)\nplt.subplot(2,2,2)\nplt.title("Grayscale Image")\nplt.imshow(gray_image,cmap="gray")\nplt.axis("off")\n\n_, binary_img = cv2.threshold(gray_image, 225, 255, cv2.THRESH_BINARY_INV)\nplt.subplot(2,2,3)\nplt.title("Binary Image")\nplt.imshow(binary_img,cmap="gray")\nplt.axis("off")\n\ncontours, hierarchy = cv2.findContours(binary_img, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)\nfinal_image = cv2.drawContours(loaded_img, contours, -1, (0, 255, 0), 2)\nplt.subplot(2,2,4)\nplt.title("Contours detected Image")\nplt.imshow(final_image,cmap="gray")\nplt.axis("off")\n\nplt.savefig('Contour_Detection_output_2.png', dpi = 1000,bbox_inches = 'tight')\nplt.tight_layout()\nplt.show()\n<\/pre><\/div>\n\n\n![\"Contour](\"https:\/\/www.askpython.com\/wp-content\/uploads\/2021\/05\/Contour_Detection_output_2.jpg\")
Conclusion<\/h2>\n\n\n\n