$ git clone --recursive https://github.com/Yohannfra/lvgl_batch_image_converter.git
Edit the variables CF and FORMAT in run_batch.py to fit your needs.
# run on all directory (only .png, .jpg and .bmp will be converted)
./run_batch.py directory_with_images
# run on files
./run_batch.py file1.png file2.png file3.png ...