Thomas Singh January 10, 2018 Share January 10, 2018 Does an log image have linear gamma? Is that the same as a linear line that can be seen on a ramp from black to white? What happens when you apply an s-curve to this linear line, is the gamma curve then re-defined? Link to comment Share on other sites
Frank Wylie January 10, 2018 Share January 10, 2018 I'll dodge your question directly and send you to Mr. Art Adams! https://www.provideocoalition.com/the_not_so_technical_guide_to_s_log_and_log_gamma_curves/ 1 Link to comment Share on other sites
Cary Knoop January 11, 2018 Share January 11, 2018 (edited) On 1/10/2018 at 2:38 AM, Thomas Singh said: Does an log image have linear gamma? Is that the same as a linear line that can be seen on a ramp from black to white? What happens when you apply an s-curve to this linear line, is the gamma curve then re-defined? It all boils down to semantics as gamma is in the video world often used to describe any kind of curve. Technically gamma refers to the exponent (or the reciprocal value) of a function and defines how much a linear function is "pulled up or down". For instance below is a graph with various gammas, starting with the red line which is x to the power of 1 thus a gamma of 1, then going upwards with a gamma of 2, 2.2, 2.4 and 2.6 (or the reciprocal values). So for instance x to the power of 0.45 is a gamma of 0.45 (or 1/0.45 = 2.22). A log curve is something different and based on the log function, below is a graph with Rec709 (using a gamma of 2.22 or 0.45) and Panasonic's V-Log as an example. By the way Rec709 is not a complete gamma curve as it is linear at the bottom. Edited January 11, 2018 by Cary Knoop 1 Link to comment Share on other sites
Thomas Singh January 12, 2018 Author Share January 12, 2018 It's a bit hard for me to grasp, but do you call a straight line (black to white on a ramp) linear gamma? What do you call it when it's bended in a bezier shape? Link to comment Share on other sites
cameronrad January 12, 2018 Share January 12, 2018 Check out these resources: Cinematic_Color_VES.pdf https://www.cambridgeincolour.com/tutorials/gamma-correction.htm 1 Link to comment Share on other sites
