Update gainmap documentation.
Fix formula for W.
Update names in the comments to match Android names.
Remove references to HDR base images (didn't make the cut).
Bug: 266628247
Change-Id: Ice5250dd18ed8255503f1b4c9b6d933d2472990e
diff --git a/graphics/java/android/graphics/Gainmap.java b/graphics/java/android/graphics/Gainmap.java
index a7c508c..feedb7d 100644
--- a/graphics/java/android/graphics/Gainmap.java
+++ b/graphics/java/android/graphics/Gainmap.java
@@ -63,20 +63,20 @@
* as follows:
*
* First, let W be a weight parameter determining how much the gainmap will be applied.
- * W = clamp((log(H) - log(displayRatioHdr)) /
- * (log(displayRatioHdr) - log(displayRatioSdr), 0, 1)
+ * W = clamp((log(H) - log(minDisplayRatioForHdrTransition)) /
+ * (log(displayRatioForFullHdr) - log(minDisplayRatioForHdrTransition), 0, 1)
*
* Next, let L be the gainmap value in log space. We compute this from the value G that was
* sampled from the texture as follows:
- * L = mix(log(gainmapRatioMin), log(gainmapRatioMax), pow(G, gainmapGamma))
+ * L = mix(log(ratioMin), log(ratioMax), pow(G, gamma))
*
* Finally, apply the gainmap to compute D, the displayed pixel. If the base image is SDR then
* compute:
* D = (B + epsilonSdr) * exp(L * W) - epsilonHdr
- * If the base image is HDR then compute:
- * D = (B + epsilonHdr) * exp(L * (W - 1)) - epsilonSdr
*
- * In the above math, log() is a natural logarithm and exp() is natural exponentiation.
+ * In the above math, log() is a natural logarithm and exp() is natural exponentiation. The base
+ * for these functions cancels out and does not affect the result, so other bases may be used
+ * if preferred.
*/
public final class Gainmap implements Parcelable {