From 1a664f1dfaf5c39e9eddf5fdb71d086f951bf72f Mon Sep 17 00:00:00 2001 From: TimothyLottes Date: Wed, 9 Nov 2016 19:21:07 -0500 Subject: [PATCH] Add files via upload --- 20160721.html | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ index.html | 1 + 2 files changed, 52 insertions(+) create mode 100644 20160721.html diff --git a/20160721.html b/20160721.html new file mode 100644 index 0000000..ec51a82 --- /dev/null +++ b/20160721.html @@ -0,0 +1,51 @@ +
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20160721 - Why Motion Blur Trivially Breaks Tone-Mapping - Part 1

+
+ + +Some food for visual thought ... +
+
+You have a scene with a bunch of High Dynamic Range (HDR) light sources, or bright secondary reflections. +Average Picture Level (APL) of the scene as displayed is relatively low, which is standard practice and expected behavior for displayed HDR scenes. +Because the display cannot output the full dynamic range of the scene, the scene is tone-mapped before display, +and thus the groups of pixels representing highlights appear not as bright as they should. +
+
+Now the camera moves, and the scene gets motion blur applied in engine prior to tone-mapping. +All the sudden the scene gets brighter. +The APL increases. +In fact the larger the motion, the brighter the scene gets. +
+
+You, yes you the reader, have seen this before in many games. And technically speaking the game engine isn't doing anything wrong. +
+
+What is happening is those small bright areas of the scene, get blurred, +distributing their energy over more pixels. +Each of these blurred pixels have less intensity than the original source. +As the intensity lowers, it falls more away from the aggressive areas of highlight compression, +approaching tonality which can be reproduced by the display. +So the APL increases, because less of the scene's output energy is getting limited by the tone-mapper. +
+
+The irony in this situation is that as motion and motion blur increases, +the scene is actually getting closer to it's correct energy conserving visual representation as displayed. +
+
+Note the same effect applies as more of the scene gets out of focus during application of Depth of Field. + + + + + + + + + + + +
+ + + diff --git a/index.html b/index.html index b72794a..2fdba1c 100644 --- a/index.html +++ b/index.html @@ -68,6 +68,7 @@ Below this is active random migration (456 prior posts still to filter through) 20160726 - On Killing WIN32?
20160724 - Simplified Vulkan Rapid Prototyping
20160723 - Why Motion Blur Trivially Breaks Tone-Mapping - Part 2
+20160721 - Why Motion Blur Trivially Breaks Tone-Mapping - Part 1
20160715 - LED Displays
20160127 - Temporal AA Neighborhood Clamp