These are my max settings. I'm pretty sure the image has to be square so it can load it into texture memory correctly. EX: 128^2, 256^2, 512^2, 1024^2. Load your images into photoshop and first change "canvas size" to be equal to the width/height. Then scale the image to 512 or 1024. I always round up because there is no…
Another tip... make sure your image is a power of 2 (1024x1024 is usually good). The video card eats this for breakfast, so you get faster frame rates whilst working than if you did 1024x1010, for example. I also suggest darkening your guide image to mid grey and dropping the contrast a little... it will help your eyes…