From 710bc1ad662a83031b2c5ae6df18099b3df6e6fb Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt@pharr.org>
Date: Wed, 9 Oct 2024 16:47:12 -0700
Subject: [PATCH] image.cpp: fix MAE computation

Fixes #442.
---
 src/pbrt/util/image.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pbrt/util/image.cpp b/src/pbrt/util/image.cpp
index 4929bbebe..22b489e94 100644
--- a/src/pbrt/util/image.cpp
+++ b/src/pbrt/util/image.cpp
@@ -557,7 +557,7 @@ ImageChannelValues Image::MAE(const ImageChannelDesc &desc, const Image &ref,
             ImageChannelValues vref = ref.GetChannels({x, y}, refDesc);
 
             for (int c = 0; c < desc.size(); ++c) {
-                double error = double(v[c]) - double(vref[c]);
+                double error = std::abs(double(v[c]) - double(vref[c]));
                 if (IsInf(error))
                     continue;
                 sumError[c] += error;