1. Re-arranged html structure, used html5 features. 2. Added multiple images capability, images can be added one-by-one or selecting them with ctrl/cmd from the file dialog. 4. Output for multiple images can be represented by a single byte array or with a byte array for each images, its identifier will be increased with a trailing counter. 3. Added ‘GFXfontBitmap’ support. 4. Other smaller improvement. NOTE: still under testing.
image2cpp
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.
Running the tool
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: http://javl.github.io/image2cpp/
Example Arduino code
You can find a simple Arduino example sketch over here in the repository.
Screen types
I wrote the code with my 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.