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How to Draw Colored Lines on Transparent Images with OpenCV in Python

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by vigneshchennai74 dot icon Updated: Feb 17, 2023

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This code demonstrates how to use the OpenCV library in Python to modify a transparent image. It's useful for various applications that require the manipulation of transparent images, such as image editing software or computer vision projects. 


This code imports the cv2 (OpenCV) module, a Python wrapper for the OpenCV library, and the NumPy module, which supports multi-dimensional arrays and matrices. This code prepares the image file for further processing by loading it into a numpy array and obtaining its dimensions. The loaded image can then be modified or processed in various ways, such as resizing, cropping, or applying image filters. 


This code draws a straight line on the image result using the line() function from the cv2 module. These modules can perform various image processing tasks, such as loading, manipulating, and saving images and applying various image processing operations like filtering, thresholding, and segmentation. This code modifies the image result by adding a blue line to it. The resulting array can then be saved as a new image file or used for further image processing. 


Here is an example of how to draw a line in a transparent Image 

Preview of the output that you will get on running this code from your IDE

CODE

In this solution we use the Imread function of the OpenCV.

Drawing a line on PNG image OpenCV2 Python

PythondotLines of Code : 20dotLicense : Strong Copyleft (CC BY-SA 4.0)

Dependent Libraries : 
import cv2
import numpy as np

# load transparent image
img = cv2.imread('blue_circle.png', cv2.IMREAD_UNCHANGED)
hh, ww = img.shape[:2]

# draw colored line as opaque
result = img.copy()
cv2.line(result, (20, 30), (100, 80), (255, 255, 0, 255), 10)

# save result
cv2.imwrite('blue_circle_line.png', result)

# display result, though it won't show transparency
cv2.imshow("IMAGE", img)
cv2.imshow("RESULT", result)
cv2.waitKey(0)
cv2.destroyAllWindows()
  1. Copy the code using the "Copy" button above, and paste it in a Python file in your IDE.
  2. Import open Cv library and Numpy library.
  3. Modify the name, location of the image in the code.
  4. Run the file to draw a line.


I hope you found this useful. I have added the link to dependent libraries, version information in the following sections.


i found this code snippet by searching for "Drawing a line on PNG image OpenCV2 Python' in kandi. You can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions


  1. The solution is created and executed in python version 3.7.15 .
  2. The solution is tested on OpenCV 4.6.0
  3. The solution is tested on numpy 1.21.6


Using this solution, we are going to draw a line in PNG image using the OpenCv library in Python with simple steps. This process also facilities an easy to use, hassle free method to create a hands-on working version of code which would help us draw a line in a image in Python

Dependent Library

numpyby numpy

Python doticonstar image 23755 doticonVersion:v1.25.0rc1doticon
License: Permissive (BSD-3-Clause)

The fundamental package for scientific computing with Python.

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            numpyby numpy

            Python doticon star image 23755 doticonVersion:v1.25.0rc1doticon License: Permissive (BSD-3-Clause)

            The fundamental package for scientific computing with Python.
            Support
              Quality
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                  License
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                      opencvby opencv

                      C++ doticonstar image 69456 doticonVersion:4.7.0doticon
                      License: Permissive (Apache-2.0)

                      Open Source Computer Vision Library

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                                opencvby opencv

                                C++ doticon star image 69456 doticonVersion:4.7.0doticon License: Permissive (Apache-2.0)

                                Open Source Computer Vision Library
                                Support
                                  Quality
                                    Security
                                      License
                                        Reuse

                                          If you do not have OpenCV that is required to run this code, you can install it by clicking on the above link and copying the pip Install command from the OpenCV page in kandi.

                                          You can search for any dependent library on kandi like OpenCV ,numpy

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