image-match/python/opencv/doc/tutorials/app/animations.markdown

Handling Animated Image Files {#tutorial_animations}

@tableofcontents

| | | | -: | :- | | Original author | Suleyman Turkmen (with help of ChatGPT) | | Compatibility | OpenCV >= 4.11 |

Goal

In this tutorial, you will learn how to:

• Use cv::imreadanimation to load frames from animated image files.
• Understand the structure and parameters of the cv::Animation structure.
• Display individual frames from an animation.
• Use cv::imwriteanimation to write cv::Animation to a file.

Source Code

@add_toggle_cpp

• Downloadable code: Click here

• Code at a glance: @include samples/cpp/tutorial_code/imgcodecs/animations.cpp @end_toggle

@add_toggle_python

• Downloadable code: Click here

• Code at a glance: @include samples/python/tutorial_code/imgcodecs/animations.py @end_toggle

Explanation

Initializing the Animation Structure

Initialize a cv::Animation structure to hold the frames from the animated image file.

@add_toggle_cpp @snippet cpp/tutorial_code/imgcodecs/animations.cpp init_animation @end_toggle

@add_toggle_python @snippet python/tutorial_code/imgcodecs/animations.py init_animation @end_toggle

Loading Frames

Use cv::imreadanimation to load frames from the specified file. Here, we load all frames from an animated WebP image.

@add_toggle_cpp @snippet cpp/tutorial_code/imgcodecs/animations.cpp read_animation @end_toggle

@add_toggle_python @snippet python/tutorial_code/imgcodecs/animations.py read_animation @end_toggle

Displaying Frames

Each frame in the animation.frames vector can be displayed as a standalone image. This loop iterates through each frame, displaying it in a window with a short delay to simulate the animation.

Note: Frame durations in cv::Animation are expressed in milliseconds. When displaying frames manually using cv::waitKey, make sure to use the corresponding duration value to preserve the original animation timing.

@add_toggle_cpp @snippet cpp/tutorial_code/imgcodecs/animations.cpp show_animation @end_toggle

@add_toggle_python @snippet python/tutorial_code/imgcodecs/animations.py show_animation @end_toggle

Saving Animation

@add_toggle_cpp @snippet cpp/tutorial_code/imgcodecs/animations.cpp write_animation @end_toggle

@add_toggle_python @snippet python/tutorial_code/imgcodecs/animations.py write_animation @end_toggle

Summary

The cv::imreadanimation and cv::imwriteanimation functions make it easy to work with animated image files by loading frames into a cv::Animation structure, allowing frame-by-frame processing. With these functions, you can load, process, and save frames from animated image files like GIF, AVIF, APNG, and WebP.