Just for fun... You can make an ascii watermark! The steps are:
1. Convert an image into ascii, e.g. using an online generator.
2. Split the ascii into strings that are no more than 4096 characters (pinescript limit).
3. Stack them together as cells on a table (as shown in the script).
I use code generation for step 2, by splitting the ascii file into chunks, then joining each line with a plus sign to make a large string concatenation statement, which I manually copy/paste into pine. Ideally, you could make this whole script into a template with a couple parameters.
Unfortunately, Pinescript doesn't use a monospaced font, so there will be some distortion. Feature request!