RGB to Grayscale

Turbo Photo provide several ways to turn color image to grayscale in its 'Tone Maker' function.(Enhancement-Tone Maker)

Algorizon	Desc.	Pros.	Cons.
Desaturate	Use L channel in HSL as result	Simple	Contrast loss, noise
Channel Mixer	Mix RGB together to get grayscale	Easy to understand Flexible, user can manage the ratio of each channel Used by most softwares as default way.	Sometime not nature, too dark for red and blue.
Non-Linear Mixer	Consider human eye response for each channel.A professinal way.	Best in most case Flexible, user can manage the ratio of each channel Only in Turbo Photo	May hard to understand

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