{"id":1940,"date":"2016-06-24T19:06:02","date_gmt":"2016-06-24T10:06:02","guid":{"rendered":"http:\/\/avinton.com\/?page_id=1940"},"modified":"2023-11-21T18:38:23","modified_gmt":"2023-11-21T09:38:23","slug":"opencv-simple-exercise","status":"publish","type":"page","link":"https:\/\/avinton.com\/en\/academy\/opencv-simple-exercise\/","title":{"rendered":"OpenCV Simple Exercise"},"content":{"rendered":"

OpenCV Exercise<\/h1>\n

Make sure we are in our home directory<\/p>\n

\ncd ~\n<\/pre>\n
Create a new directory for this exercise<\/p>\n
\nmkdir pytest\ncd pytest\n<\/pre>\n
Download the image below to this new directory<\/p>\n
\"\"<\/p>\n
Copy the following code:<\/div>\n
<\/div>\n
\n
<\/div>\n
\n
# import the necessary packages<\/code><\/span><\/div>\n
import<\/code><\/span> numpy <\/code><\/span>as<\/code><\/span> np<\/code><\/span><\/div>\n
import<\/code><\/span> cv2<\/code><\/span><\/div>\n
\u00a0<\/code><\/div>\n
# load the games image<\/code><\/span><\/div>\n
image<\/code><\/span> =<\/code><\/span> cv2<\/code><\/span>.<\/code><\/span>imread<\/code><\/span>(<\/code><\/span>\"test.png\"<\/code><\/span>)<\/code><\/span><\/div>\n
\u00a0<\/code><\/div>\n
# find the red color game in the image<\/code><\/span><\/div>\n
upper<\/code><\/span> =<\/code><\/span> np<\/code><\/span>.<\/code><\/span>array<\/code><\/span>(<\/code><\/span>[<\/code><\/span>65<\/code><\/span>,<\/code><\/span> 65<\/code><\/span>,<\/code><\/span> 255<\/code><\/span>]<\/code><\/span>)<\/code><\/span><\/div>\n
lower<\/code><\/span> =<\/code><\/span> np<\/code><\/span>.<\/code><\/span>array<\/code><\/span>(<\/code><\/span>[<\/code><\/span>0<\/code><\/span>,<\/code><\/span> 0<\/code><\/span>,<\/code><\/span> 200<\/code><\/span>]<\/code><\/span>)<\/code><\/span><\/div>\n
mask<\/code><\/span> =<\/code><\/span> cv2<\/code><\/span>.<\/code><\/span>inRange<\/code><\/span>(<\/code><\/span>image<\/code><\/span>,<\/code><\/span> lower<\/code><\/span>,<\/code><\/span> upper<\/code><\/span>)<\/code><\/span><\/div>\n
\u00a0<\/code><\/div>\n
# find contours in the masked image and keep the largest one<\/code><\/span><\/div>\n
(<\/code><\/span>_<\/code><\/span>,<\/code><\/span> cnts<\/code><\/span>,<\/code><\/span> _<\/code><\/span>)<\/code><\/span> =<\/code><\/span> cv2<\/code><\/span>.<\/code><\/span>findContours<\/code><\/span>(<\/code><\/span>mask<\/code><\/span>.<\/code><\/span>copy<\/code><\/span>(<\/code><\/span>)<\/code><\/span>,<\/code><\/span> cv2<\/code><\/span>.<\/code><\/span>RETR_EXTERNAL<\/code><\/span>,<\/code><\/span><\/div>\n
cv2<\/code><\/span>.<\/code><\/span>CHAIN_APPROX_SIMPLE<\/code><\/span>)<\/code><\/span><\/div>\n
c<\/code><\/span> =<\/code><\/span> max<\/code><\/span>(<\/code><\/span>cnts<\/code><\/span>,<\/code><\/span> key<\/code><\/span>=<\/code><\/span>cv2<\/code><\/span>.<\/code><\/span>contourArea<\/code><\/span>)<\/code><\/span><\/div>\n
\u00a0<\/code><\/div>\n
# approximate the contour<\/code><\/span><\/div>\n
peri<\/code><\/span> =<\/code><\/span> cv2<\/code><\/span>.<\/code><\/span>arcLength<\/code><\/span>(<\/code><\/span>c<\/code><\/span>,<\/code><\/span> True<\/code><\/span>)<\/code><\/span><\/div>\n
approx<\/code><\/span> =<\/code><\/span> cv2<\/code><\/span>.<\/code><\/span>approxPolyDP<\/code><\/span>(<\/code><\/span>c<\/code><\/span>,<\/code><\/span> 0.05<\/code><\/span> *<\/code><\/span> peri<\/code><\/span>,<\/code><\/span> True<\/code><\/span>)<\/code><\/span><\/div>\n
\u00a0<\/code><\/div>\n
# draw a green bounding box surrounding the red game<\/code><\/span><\/div>\n
cv2<\/code><\/span>.<\/code><\/span>drawContours<\/code><\/span>(<\/code><\/span>image<\/code><\/span>,<\/code><\/span> [<\/code><\/span>approx<\/code><\/span>]<\/code><\/span>,<\/code><\/span> -<\/code><\/span>1<\/code><\/span>,<\/code><\/span> (<\/code><\/span>0<\/code><\/span>,<\/code><\/span> 255<\/code><\/span>,<\/code><\/span> 0<\/code><\/span>)<\/code><\/span>,<\/code><\/span> 4<\/code><\/span>)<\/code><\/span><\/div>\n
cv2<\/code><\/span>.<\/code><\/span>imshow<\/code><\/span>(<\/code><\/span>\"Image\"<\/code><\/span>,<\/code><\/span> image<\/code><\/span>)<\/code><\/span><\/div>\n
cv2<\/code><\/span>.<\/code><\/span>waitKey<\/code><\/span>(<\/code><\/span>0<\/code><\/span>)<\/code><\/span><\/div>\n<\/div>\n<\/div>\n
Paste the code into a file called pytest.py<\/p>\n
\nvi pytest.py\n<\/pre>\n
Paste then save and exit vi<\/p>\n
Run the python program<\/p>\n
\npython pytest.py\n<\/pre>\n
Now it should make a green square around the red logo box.<\/p>\n
The exercise is to make it make the square around the blue logo box (middle one).<\/p>\n
Email me<\/a> back the result<\/p>\n","protected":false},"excerpt":{"rendered":"
OpenCV Exercise Make sure we are in our home directory cd ~ Create a new directory for this exercise mkdir pytest cd pytest Download the image below to this new directory Copy the following code: # import the necessary packages import numpy as np import cv2 \u00a0 # load the games image image = cv2.imread(“test.png”)
Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"parent":1906,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-1940","page","type-page","status-publish","hentry"],"yoast_head":"\nOpenCV Simple Exercise - Avinton Japan<\/title>\n<meta name=\"description\" content=\"OpenCV Exercise Make sure we are in our home directory cd ~ Create a new directory for this exercise mkdir pytest cd pytest Download the image below to\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/avinton.com\/en\/academy\/opencv-simple-exercise\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"OpenCV Simple Exercise - Avinton Japan\" \/>\n<meta property=\"og:description\" content=\"OpenCV Exercise Make sure we are in our home directory cd ~ Create a new directory for this exercise mkdir pytest cd pytest Download the image below to\" \/>\n<meta property=\"og:url\" content=\"https:\/\/avinton.com\/en\/academy\/opencv-simple-exercise\/\" \/>\n<meta property=\"og:site_name\" content=\"Avinton Japan\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/Avintons\/\" \/>\n<meta property=\"article:modified_time\" content=\"2023-11-21T09:38:23+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/avinton.com\/wp-content\/uploads\/2023\/11\/avintonAcademyOpenCVSimpleExercise-300x109.jpg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:site\" content=\"@AvintonJapan\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/avinton.com\/en\/academy\/opencv-simple-exercise\/\",\"url\":\"https:\/\/avinton.com\/en\/academy\/opencv-simple-exercise\/\",\"name\":\"OpenCV Simple Exercise - 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