The game runs smoothly, but the quality of the image is poor. How do I make it look better? It seems quite blurry, and I know ps2 graphics weren't great but I don't remember it looking this bad
Increase internal res, and use FXAA.
but keep in mind it will need a good GPU
Set 2x or 3x native resolution . Enable shade boost put all three sliders to 60%.
Sorry jesalvein didnt see your post.
Myself, I just disable texture filtering and put a different resolution. For 4:3 games I use 1024x768, for 16:9 games or 4:3 games with 16:9 hacks I use 1024x600. Some games I've noticed will actually take advantage of higher resolutions than the PS2's native resolution, such as Odin Sphere.
use post processing shaders.
SweetFX or this
GSdx Shader makes the image look more eyecandy.