Flourish - Color Photo Editor

Flourish is a histogram-based photo editing app where you manipulate the histogram itself to change the image. Don't know what a histogram is? Flourish will teach you.

Flourish puts colors front and center. The histogram becomes your tool not just for passive visualization but the way you change your images. Push it to the right to brighten the image, center it and your exposure is balanced. It's that simple. Need more control? Expand it into red, green, blue, and luminance channels and tweak colors individually, even in black and white.

EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/