Complete OpenCV 4.12.0 changelog:https://github.com/opencv/opencv/wiki/OpenCV-Change-Logs#version4120

Python:

• Added libavif to the package and corresponding image format support on Linux and Mac OS. Windows is in progress.
• Enabled GIF support by default.
• Updated Numpy dependency rules. Packages for Python 3.9+ are built with Numpy 2.x. Packages for older Python version are built with Numpy 1.x.
• Improved libjpeg-turbo performance in Windows builds (added NASM and assembly branches).
• Made DNN, FLANN, G-API modules optional during the package build (bindings generation and typing).