From Tai Shimizu:
Gridditor is a new way to quickly and easily edit photos. It makes photo editing faster and more creative by showing you filters in combinations you may not expect.
Gridditor shows you four filters at any given time, one in each cardinal direction with your original image at the center. The farther you go in any direction, the stronger the effect gets. By arranging the previews in a grid, you can see the effect of applying multiple filters at once letting you edit faster, and showing you creative possibilities you may not have considered otherwise.
Filters include 1970s, Black & White (with 3 color filters), Bleach Bypass, Brightness, Contrast, Crumpled, Darkness, Desaturation, Gloom, Highlights, Monochrome, Saturation, Sepia Tone, Shadows, Softness, Split Tone, Toy Camera, Vibrance (Overlay Blur), Vignette, Focused, Focused Color, and Focused Contrast.
Maximum export size is based on Core Image's maximum image size on your device. Full camera resolution is available on iPhone 4S and 5, export on iPhone 4 and 3GS is limited to approximately 2.5 megapixels. Gridditor Requires iOS6.