Draw Shapes,Text,Polygons,Blend,Blur images | Using OpenCV With Python | Easy code

In this Article lets learn:

• [Blend: How to Combine 2 Images?]
• [Draw Shapes & Text on Image]
• [Draw a Polygon]
• [Blur an image]

Pre Requesites: Jupyter or any python editor

Blend: How to Combine 2 Images?

Blending in OpenCV is joining two images of same size into each other.

We can make cool posters, blend your loved ones picture with their favourite character on background and gift them, bring out your creativity and what not!

Lets begin the magic!

    import cv2  #opencv library     import matplotlib.pyplot as plt # Matplotlib used for visualization     %matplotlib inline

    # Reading the jpeg formmatted image from its path to img1     img1=cv2.imread(r'./img/hp.JPG')

    # Reading the jpeg formatted image from its path to img2     img2=cv2.imread(r'./img/doc.JPG')

    # Converting from BGR(blue,green,red) color space to RGB using cvtColor     img1=cv2.cvtColor(img1,cv2.COLOR_BGR2RGB)
    img2=cv2.cvtColor(img2,cv2.COLOR_BGR2RGB)

    # Displaying the image 1     plt.imshow(img1)

    # Displaying the image 2     plt.imshow(img2)

Output:

    #'1' Flips image to left side, '0' to upside down and '-1' to combination of both 0 and 1     flip_img=cv2.flip(img1,1)

    # Showing flipped image     plt.imshow(flip_img)

Output:

    # Gives the shape (height,width, no.of color channels(RGB)) of image1     flip_img.shape

Output:

(2093, 2652, 3)

    # Gives the shape (height,width, no.of color channels(RGB)) of image2     img2.shape

Output:

(2127, 3840, 3)

    # Both images should be of same size to blend.     flip_img=cv2.resize(flip_img,(2652,2093))
    img2=cv2.resize(img2,(2652,2093))

    # Increase in alpha increases img1 weightage,beta for img2     blended=cv2.addWeighted(src1=flip_img,alpha=0.9,src2=img2,beta=0.9,gamma=0)

Output:

    # Saves the blended img under the name blended.JPG     cv2.imwrite('blended_img.png',blended)

Output:

True

Draw Shapes on Image

Different shapes can be drawn on an image, to mark an object or create a figure etc.

• Rectangles
• Hollow circles
• Solid Circles
• Lines

and many more can be drawn using OpenCV.

    import cv2 # opencv library     import numpy as np
    # Matplotlib used for visualization purpose     import matplotlib.pyplot as plt
    %matplotlib inline

    # Array of size 512x512 filled with zero as values,     # to create an image with black color.     img=np.zeros(shape=(512,512,3),dtype=np.int16)

    # Displays the shape(Height,width,no.of color channels(RGB))     img.shape

Output:

(512, 512, 3)

    # To display the image     plt.imshow(img)

    # cv2.rectangle(image, start_point, end_point, color, thickness)     cv2.rectangle(img,pt1=(0,0),pt2=(100,100),color=(0,0,255),thickness=10)

Output:

array([[[ 0, 0, 255],
[ 0, 0, 255],
[ 0, 0, 255],
...,
[ 0, 0, 0],
[ 0, 0, 0],
[ 0, 0, 0]],..

    plt.imshow(img)

    # cv2.circle(image, center_coordinates, radius, color, thickness)     cv2.circle(img,center=(150,150),radius=100,color=(255,0,0),thickness=10)

Output:

array([[[ 0, 0, 255],
[ 0, 0, 255],
[ 0, 0, 255],
...,
[ 0, 0, 0],
[ 0, 0, 0],
[ 0, 0, 0]],
[[ 0, 0, 255],
[ 0, 0, 255],
[ 0, 0, 255],
...,

    plt.imshow(img)

    # Negative values for thickness results in filled/solid circles     cv2.circle(img,center=(200,200),radius=100,color=(255,255,0),thickness=-10)

Output:

array([[[ 0, 0, 255],
[ 0, 0, 255],
[ 0, 0, 255],
...,
[ 0, 0, 0],
[ 0, 0, 0],
[ 0, 0, 0]],

plt.imshow(img)

    # cv2.line(image, start_point, end_point, color, thickness)     cv2.line(img,pt1=(275,275),pt2=(512,512),color=(0,255,0),thickness=10)

Output:

array([[[ 0, 0, 255],
[ 0, 0, 255],
[ 0, 0, 255],
...,
[ 0, 0, 0],
[ 0, 0, 0],
[ 0, 0, 0]],

   plt.imshow(img)

    # Font of the text     text_style=cv2.FONT_ITALIC

    # Syntax     #cv2.putText(image, text, org, font, fontScale, color[, thickness[, lineType[, bottomLeftOrigin]]]) 
    cv2.putText(img,text='HAKUNA MATATA',org=(10,200),fontFace=text_style,fontScale=2,color=(0,0,255),thickness=3,lineType=cv2.LINE_AA)

Output

array([[[0, 0, 0],
[0, 0, 0],
[0, 0, 0],
...,
[0, 0, 0],
[0, 0, 0],
[0, 0, 0]],..

   plt.imshow(img)

Draw a Polygon

    import cv2
    import numpy as np

    # Matplotlib used for visualization purpose     import matplotlib.pyplot as plt
    %matplotlib inline

    # Array of size 512x512 filled with zero as values,     # to create an image with black color.     img=np.zeros(shape=(512,512,3),dtype=np.int16)

    # Assigning vertices to polygon     poly=np.array([[100,200],[200,100],[400,300],[200,400]],dtype=np.int32)
    poly.shape

Output:

    (4, 2)

    # Reshaping according to opencv format     poly_new=poly.reshape((-1,1,2))
    poly_new.shape

Output:

(4, 1, 2)

    # cv2.polylines(img, pts, isClosed, color[, thickness[, lineType[, shift]]])     cv2.polylines(img,[poly_new],isClosed=True,color=(0,255,0),thickness=10)

Output:

array([[[0, 0, 0],
[0, 0, 0],
[0, 0, 0],
...,

    plt.imshow(img)

Blur an image

There are plenty of blurring techniques available.Some of the methods are:

• Default Blurring Technique
• Gaussian Blurring Technique
• Smoothing Technique
• Median Blurring Technique
• Bilateral Filter Blurring Technique

Lets explore each one of them:

     import cv2  # opencv library 
    # Matplotlib used for visualization     import matplotlib.pyplot as plt
    %matplotlib inline
    import numpy as np

    img=cv2.imread(r'./img/image.JPG')
    img=cv2.cvtColor(img,cv2.COLOR_BGR2RGB)
    plt.imshow(img)

    kernel=np.ones((5,5),np.float)/25

    # Default Blurring Technique     plt.imshow(cv2.blur(img,ksize=(5,5)))

    # Gaussian Blurring Technique     plt.imshow(cv2.GaussianBlur(img,(5,5),0))

    # Smoothing Technique     plt.imshow(cv2.filter2D(img,-1,kernel))

    # Median Blurring Technique     # Reduces unwanted noise     plt.imshow(cv2.medianBlur(img,5))

    # Bilateral Filter Blurring Technique     # Reduces unwanted noise with sharp edges but slow     plt.imshow(cv2.bilateralFilter(img,9,75,75))

Try out all these and feel free to ask me doubts via gmail at: jayachandrika56@gmail.com

Now you can follow us to explore more interesting topics, in Instagram at: @code_voyager

Hope you had fun experimenting with the code.
Have an amazing day!

原文链接：Draw Shapes,Text,Polygons,Blend,Blur images | Using OpenCV With Python | Easy code