Differences
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| Both sides previous revisionPrevious revision | Last revisionBoth sides next revision | ||
| isp:brightness [2023/09/10 20:56] – [Algorithm] Igor Yefmov | isp:brightness [2023/09/10 21:01] – [Calculation reference] Igor Yefmov | ||
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| 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 30: | Line 37: | ||
| \] | \] | ||
| - | Brightness adjustment is a trivial addition, clamping | + | Finding |
| + | \[ | ||
| + | R = | ||
| + | \begin{cases} | ||
| + | k_R * 2047 & \text{if} \; L \leq 2047 \\ | ||
| + | 255 - k_R * 2047 & \text{if} \; L > 2047 | ||
| + | \end{cases} | ||
| + | \] | ||
| + | If we are crossing the middle luma boundary as the result of this adjustment - flip the slope: | ||
| \[ | \[ | ||
| - | L` = L + br \\ | + | k_R = 2 - k_R |
| - | L` \in [0..4095] | + | |
| \] | \] | ||