image2cpp is a simple tool to change images into byte arrays to use with (monochrome) displays suchs as OLEDs, like those from Adafruit or Sparkfun. While searching for a way to generate these arrays, I mostly found links to a piece of Windows software. Both the flakey results and the hassle of having to boot a virtual machine just to convert an image lead to me writing this pure html + javascript solution.
Alternatively you can also enter a byte array as input to turn it back into an image. This might be useful for debugging, or when you want to write the byte array yourself. I don't know.
You don't need any special dependencies / internet connection; all the necessary parts sit in a single .html file. So just open this index.html page in a (recent) browser to run the tool. Or you can use the online version at: https://wiredolphin.github.io/tools/image2cpp/index.html
You can find a simple Arduino example sketch over here in the repository.
Code is written with 128x64 pixel monochrome OLED display in mind, but it should work with most similar displays. You might need to change some export settings; those are explained in the tool.
Initial code by javl , with aditional code by wiredolphin. The example sketch was made by Adafruit.