I've gotten pretty close I think. Problem is, that I'm pretty sure that the signal getting sent to Processing isn't quite the same as what's printed in the serial monitor back in Arduino.
You're not trying to do both at once, are you?
count = count + 1;
Have you ever wondered why the language used to program the Arduino is not called C=C+1?
And is there any easier way to just send the variable "count" from arduino to processing?
Easier than the one line of code you are using? No.
I also get the error "Could not find a method to load ImageSequence.02 and .03 and .04 and so on with every click of the rotary encoder. What's the story behind this?
What is the first image called?
img = loadImage("ImageSequence_01.png");
So, why do the other images use extensions like .01, .02, etc?
loadImage("ImageSequence_" + val);
Are you missing the .png extension?
How are the files actually numbered? The Arduino is sending '1', 2', '3', ..., '10', '11', etc. You seem to be expecting '01', '02', ..., '10', etc.