Files on an SD Card, hard drive or USB stick are just blocks of data. If you know how that data is stored you can decode the file to get the contents.

With an LCD screen and SD card reader attached to your Arduino you've got everything you need to display images. All you have to do is work out how to translate the image file into pixels.

Ready made libraries are the easy option. But with a bit of thought you can actually write your own image handler from scratch.

Let me show you how to take a bitmap image file, decode its structure, read in its data and then write its pixel information to your LCD panel. You'll find out how to work with byte level file handling and image manipulation. After this tutorial you'll have all the skills to read and write any file type, or even create your own.

For all the circuit diagrams and to download the code and sketches please visit my website page for this tutorial.

https://bytesnbits.co.uk/bitmap-image-handling-arduino

Videos for setting up the hardware
SD Card : https://youtu.be/FI7yXDi-fKA
LCD panel : https://youtu.be/4DtuOeeYHys