Tutorials of programming languages, frameworks, libraries, etc.
In this tutorial, I will show you how to convert RGBA images to RGB images in the simplest ways using OpenCV (cv2) and Pillow (PIL). This method simply removes the alpha channel from the RGBA images, the transparency will turn into black (or sometimes noises) in the resulting images. If you want to set the […]
This tutorial will show you how to convert an RGBA image to an RGB image and set the transparent background to white (or any colors). Although it is easy to convert an image from RGBA to RGB by simply removing the alpha channel, sometimes the transparent background turns into black (or even noises/weird artifacts) when […]
This tutorial will show you how to read/open an image from a URL using OpenCV (cv2) and Pillow (PIL). Also, we will show you how to read the image from a URL with request headers. If you want to read them into Base64, you may read Image & Base64. 1. Read From a URL OpenCV […]
This tutorial will show you how to read an image file into base64 format, and convert an image to base64 format (and from base64 to an image) in OpenCV (cv2) and Pillow (PIL). Base64 is a format to represent binary data in text. This is widely used on the web and email to deliver data […]
This tutorial will show you how to warp/transform an image in OpenCV (cv2) and Pillow (PIL), using the perspective transformation technique. OpenCV The vertices of transformation are as follows: Pillow Where pa is the four vertices in the current plane, and pb contains four vertices in the resulting plane. (find_coeffs function, modified from here) Full Example OpenCV Pillow Syntax OpenCV Parameters: […]
In this tutorial, you will learn how to rotate or translate/shift an image with a specified background color. For simple image rotation and translation, please read the previous tutorials: 1. Image Rotation Rotate 45 degrees counterclockwise with a background color RGB(0,0,0) (black). OpenCV Pillow 2. Image Translation Translate the image to the right by 10 […]
This tutorial will show you how to translate/shift an image along the x-axis and y-axis using OpenCV (cv2) and Pillow (PIL). OpenCV Translate the image to the right by 10 pixels and downward by 20 pixels. Pillow Translate the image to the right by 10 pixels and downward by 20 pixels. Note: pil_img.rotate(angle, translate) will do translation […]
In this tutorial, you will learn how to mirror and flip an image using OpenCV (cv2) or Pillow (PIL). OpenCV Pillow Full Example OpenCV Pillow Syntax OpenCV Parameters: Returns: Pillow Parameters: Returns: Parameters: Returns: References
This tutorial will show you how to rotate an image without cutting/cropping the sides of it using OpenCV (cv2) and Pillow (PIL). We also call this “rotation with bounding”. Rotate With Bounding For OpenCV, you need to first install imutils by: pip install imutils. The following code shows the image rotation by 45 degrees counterclockwise. […]
In this tutorial, you will learn how to rotate an image in OpenCV (cv2) and Pillow (PIL). 1. Rotate by 90, 180, or 270 Degrees For OpenCV, the function cv2.rotate lets you rotate the image only by 90, 180, or 270 degrees. 2. Rotate by Any Angle OpenCV Pillow Full Example OpenCV Pillow Syntax OpenCV […]