TIPS & TRICKS BLOG

Hello Guys, In this tutorial, I will discuss the color map in OpenCV. Color Map is used to show different color temperatures. And this can also be used to generate some cool image filters.  OpenCV comes with thirteen built-in color maps. So in this tutorial, I will show you how to use color maps.  Let’s get started List of Color Maps COLORMAP_AUTUMN COLORMAP_BONE COLORMAP_JET COLORMAP_WINTER COLORMAP_RAINBOW COLORMAP_OCEAN COLORMAP_SUMMER COLORMAP_SPRING COLORMAP_COOL COLORMAP_HSV COLORMAP_PINK COLORMAP_HOT COLORMAP_PARULA To apply color map first we need to convert an image to grayscale. So I will use  img = cv.imread("nature.jpg",cv.IMREAD_GRAYSCALE) If you are not aware of this function then please check my previous tutorial  http://techievaibhav.in/2019/01/10/reading-an-image-using-opencv/ To apply color maps, OpenCV comes with a function called applyColorMap() . This function takes two parameters. Gray Scale image Color Map Autumn Bone Cool Hot HSV Jet Ocean Parula Pink ...

In this tutorial, I will show you how to draw a circle in OpenCV. OpenCV comes with lots of built-in functions that make our life easier especially when we are working on image processing .  And there is a function called circle in OpenCV which is used to draw a circle. This function takes following parameters: 1. Image : Takes an image object 2. Center : Center point coordinates 3. Radius : Radius of the circle 4. Color : Takes color in BGR format 5. Thickness : By default set to 1 (optional) 6. Line Type : By default set to 8-connected.It can also be  LINE_AA  or  4-connected  (Optional) 7. Shift:  Shifts fractional bits in the point coordinates of center and radius (Optional) Especially when we are creating closed shapes. Thickness plays an important role. Here if the negative thickness is passed in this function or any other function which creates a closed shape(rectangle, polygon, etc). Then it creates a filled shape (filled with color). Negative Thickness Filled Circle Positive ...

Hello Guys, In this tutorial, I will show you how to draw a line in OpenCV. OpenCV comes with lots of built-in functions that make our life easier especially when we are working on image processing .  And there is a function called line  in OpenCV which is used to draw a line. This function takes the following parameters: 1. Image: Takes image object 2. Point 1: Point 1 X and Y  Coordinates 3. Point 2:  Point 2 X and Y  Coordinates 4. Color: Takes color in BGR format 5. Thickness: By default set to 1  (optional) 6. Line Type: By default set to 8-connected .It can also be LINE_AA  or 4-connected  (Optional) 7. Shift: Shifts fractional bits in the point coordinates (Optional) Well it is recommended to use line LINE_AA ( Anti Aliased) as line type. Line Without LINE_AA  (Anti Aliased) You can observe the right and left ends of the line . You will notice curves are showing in a zigzag pattern.  Line With LINE_AA  (Anti Aliased) Now in this image you can observe the curv...

Hi Guyz, In this tutorial, I will discuss the video properties and how to view the video properties of any video file using OpenCV.  A video file contains different types of properties like width, height, frames, etc. Sometimes it is required to take out these basic video details. In order to make this work, easy OpenCV comes with built-in properties to ease out the work for developers. video = cv.VideoCapture("video.mp4")video.get(0) OpenCV has a function named get(propId). Which takes property Identifier as an argument. There are total 22 property identifiers that OpenCV supports.  List of Property Identifiers One can also modify the properties of video file using set function. This function takes two arguments.  1. Index  2. Property Identifier In case, You want to modify the width and height of the video file. video.set(3,320) # Width video.set(4,480) # Height Program #import cv2 moduleimport cv2 as cv#This function shows the properties of a video filedef showProper...

Hello Guys, In this tutorial, I will show you how to play a video file using OpenCV. To play a video file or to stream a webcam OpenCV has a function named  VideoCapture.  This function takes only one argument. If you want to play the video you need to pass the file name with extension. Ex:  nature.mp4. Similarly, If you want to stream your webcam you need to pass a number or device index. Which simply means which webcam you want to access. Just in case, If you have more than one webcam. If you have only one webcam then you have to pass 0 or else if you have two web cameras then for accessing the second web camera you have to pass 1  and so on.  Once we have initialized the video object by calling the VideoCapture function. Then we will use an infinite while loop which will iterate till video.read() method returns true. read() function returns two parameters  1. Boolean – If True video still playing or False if the video is ended.  2. Frame – Here frame is simpl...

Hello Guys, In this article, I will discuss about how to write images in OpenCV. For writing images, Opencv has the function named “ imwrite “. This function takes two arguments.  1. Image name with extension  2. Image object This function returns a boolean . If it writes the file successfully then it returns True, otherwise False . # Import cv2 moduleimport cv2 as cv#reading an using imread function without passing any parameter# By default it loads the image in color formatcolored_image= cv.imread("nature.jpg") #imwrite returns True if it writes the file successfully otherwise #returns Falseresult = cv.imwrite("nature.png",colored_image)if result: png_img = cv.imread("nature.png") cv.imshow("Png Image",png_img) cv.waitKey(0) cv.destroyAllWindows()else: print("Error in writing file") Also don’t forget to check my previous OpenCV tutorials.  http://techievaibhav.in/category/programming/opencv/

Hello Guys, In this tutorial, I will discuss how to display an image using OpenCV.  OpenCV comes with the function named imshow  which is used to display images.  imshow function takes two arguments    1. Window name  2. Image object We can show show any number of windows . But the name of each window must be different. # Import cv2 moduleimport cv2 as cv#reading an using imread function without passing any parameter#by default it loads image in color format (BGR format)colored_image= cv.imread("nature.jpg") # loads image in gray formatgray_image= cv.imread("nature.jpg",cv.IMREAD_GRAYSCALE)#Code to display single imagecv.imshow("Colored Image",colored_image)#Passing zero means it will open till you press any key #to close the window. It takes time in milliseconds . So if 500 will be #passed then it will be opened for 500 ms and then it will be closed #automatically.cv.waitKey(0) # This is used to close all opened windowscv.destroyAllWindows() #code to dis...

Hi Guyz, In this tutorial, I will discuss how to read an image in OpenCV using python . OpenCV has the function called imread for reading an image. This imread function reads the image in BGR format. BGR stands for Blue Green Red. This function takes two argument. Image path Flag  There are three types of flags which this function takes. IMREAD_COLOR  IMREAD_GRAYSCALE IMREAD_UNCHANGED IMREAD_COLOR : This is the default flag which this function takes automatically. So if you want to read an image in the color format then you don’t have pass any flag. Or you can also pass 0 .  IMREAD_GRAYSCALE : When using this flag it read an image in grayscale format. Or you can also pass  1.   IMREAD_UNCHANGED : Loads an image with transparency (Alpha channel). Or you can also pass -1 . import cv2 as cv """ Reading Colored Image """colored_image= cv.imread("nature.jpg") #Same statement can also be written as colored_image= cv.imread("nature.jpg",cv...