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--- isp:contrast [2023/09/05 05:01] – Igor Yefmov
+++ isp:contrast [2023/09/10 21:53] (current) – [Integer arithmetic] Igor Yefmov
@@ Line 7: / Line 7: @@
 ===== In RGB color space =====
+Each component's contrast adjustment is based on its value and the adjustment itself is calculated as
+\[
+component = (component' - 0.5) * k^2 + 0.5 \\
+component' \in [0..1.0] \\
+contrast \in ]0..2.0]%%
+\]
+==== Integer arithmetic ====
+Of course, much like in [[isp::brightness]] case, we'd like to not use floating point arithmetic, so for the 12-bit pixel components and taking into account that the \(contrast\) is in range \([0..2047]\), the math looks like the following:
+\[
+\frac{
+\left(\begin{bmatrix}
+R  \\
+G  \\
+B
+\end{bmatrix}
+-
+\begin{bmatrix}
+\\
+\\
+\end{bmatrix} \right) \times contrast^2
+}{1024*1024} +
+\begin{bmatrix}
+\\
+\\
+\end{bmatrix}
+\]
 ===== In HSL color space =====

SUB2r