cucina allows you to create Android splash image (splash.img) and logo.rle image. Currently it supports Gnu/Linux. You could try any bash+x86_64 capable OS.
git clone git@github.com:dronixdevteam/cucina.git
git checkout -t origin/develop
chmod +x menu
splash.img can be created from .png or .jpg image files. Image file size is your Android screen resolution: i.e. 4Geek Horus is 480x800 pixels. Bulk creation is available.
Put images into images/ folder, then run
./menu
Choose menu #1. Follow instructions. Converted images will be into images/ folder.
Flash one of them using fastboot, according to device's partition table, i.e.:
# fastboot flash splash splash.img
logo.rle can be created from .png or .jpg image files. Image file size is your Android screen resolution: i.e. 4Geek Horus is 480x800 pixels. Bulk creation is available.
Put images into images/ folder, then run
./menu
Choose menu #2. Follow instructions. Converted images will be into images/ folder.
Rename .rle file to logo.rle and put it in your boot.img
DroniX Dev Team's 'cucina' is GPL v3 software