[iMore.com]

Histogram, sharpen, definition, noise reduction, vignette, white balance, and levels can all be added to your photo adjustment options.
That elevates Photos for OS X from a basic photo editing tool to something more advanced. The histogram, for example, lets you see the distribution of light and dark, red, blue, and green pixels within your image. Sharpen and definition can help make the blurry more clear. Vignette darkens images around the edges, and white balance and levels let you change casts, crush blacks, and more. All you have to do is turn them on!

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