Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
isp:brightness [2023/09/10 20:56] – [Algorithm] Igor Yefmov | isp:brightness [2023/09/10 21:49] (current) – [Calculation reference] Igor Yefmov | ||
---|---|---|---|
Line 20: | Line 20: | ||
To calculate luminosity we just find the max and min of the triplet and get a simple average: | To calculate luminosity we just find the max and min of the triplet and get a simple average: | ||
\[L = \frac{min(R, | \[L = \frac{min(R, | ||
+ | |||
+ | Brightness adjustment is a trivial addition, clamping the value to its proper limits: | ||
+ | |||
+ | \[ | ||
+ | L` = L + br \\ | ||
+ | L` \in [0..4095] | ||
+ | \] | ||
The slope \(k_R\) for the red component calculation depends on whether \(L\) is above or below the middle: | The slope \(k_R\) for the red component calculation depends on whether \(L\) is above or below the middle: | ||
Line 26: | Line 33: | ||
\begin{cases} | \begin{cases} | ||
R / L & \text{if} \; L \leq 2047 \\ | R / L & \text{if} \; L \leq 2047 \\ | ||
- | \frac{R - 2047}{L - 2047} & \text{if} \; L > 2047 | + | \frac{R - 4095}{L - 4095} & \text{if} \; L > 2047 |
\end{cases} | \end{cases} | ||
\] | \] | ||
- | Brightness adjustment is a trivial addition, clamping | + | Finding |
+ | \[ | ||
+ | R = | ||
+ | \begin{cases} | ||
+ | k_R * 2047 & \text{if} \; L \leq 2047 \\ | ||
+ | 4095 - k_R * 2047 & \text{if} \; L > 2047 | ||
+ | \end{cases} | ||
+ | \] | ||
+ | If we are crossing the middle luma boundary as the result of this adjustment - flip the slope: | ||
\[ | \[ | ||
- | L` = L + br \\ | + | k_R = 2 - k_R |
- | L` \in [0..4095] | + | |
\] | \] | ||