Picmatic is the best photo posterize tool with amazing photo editing capabilities and complete Apple Watch features.

~ Great posterize effect
~ Focus Tool
~ Tons of fun stickers
~ One-tap auto enhance
~ Sharpen and blur
~ Cosmetic tools: fix redeye, remove blemishes and whiten teeth
~ Draw and add text
~ Vertical Flip, Horizontal Flip, Mix Flip
~ Gorgeous photo effects
~ Share on Facebook, Twitter, Mail
~ Create your own memes
~ Adjust brightness, contrast, and saturation
~ Adjustable flip grid
~ Crop, rotate, and straighten your photos