Snapseed

 Snapseed is a Google image editing app that provides you with top-notch filters and photo editing effects right from your smartphone. For all practical purposes and uses (at least as far as amateur photographers are concerned) it covers all your basic needs. 

• 29 Tools and Filters, including: Healing, Brush, Structure, HDR, Perspective (see list below)

• Opens JPG and RAW files

• Save your personal looks and apply them to new photos later

• Selective filter brush

• All styles can be tweaked with fine, precise control

Brush – selectively retouch exposure, saturation, brightness or warmth

• Selective – the renown “Control Point” technology: Position up to 8 points on the image and assign enhancements, the algorithm does the rest magically

• Healing – remove the uninvited neighbor from a group picture

• Vignette – add a soft darkness around the corners like a beautiful, wide-aperture would do