How to change the splash image of Lenovo Tab M10 (TB-X505X)?

I have a Lenovo Tab M10 tablet. I successfully rooted it and changed its booting animation. Now I want to change its splash picture. I extract splash.img from /dev/block/by-name/splash with the following command: dd if=/dev/block/by-name/splash of=/mnt/sdcard/ But can't get the image out of splash.img. I use the following commands to get images out: ffmpeg -hide_banner -f rawvideo -vcodec rawvideo -pix_fmt rgb24 -s 1280x800 -i splash.img -vframes 1 -y output_splash.png and ffmpeg -hide_banner -f rawvideo -vcodec rawvideo -pix_fmt rgb565 -s 1280x800 -i splash.img -vframes 1 -y output_splash.png And other commands that I found on the internet. But in all cases, the output image is wrong. I want to get the image out to check whether the extracted partition is correct or not. However, a complete guide to changing the splash image is accepted.