From 9be8654e854753235143d328d7ed3d0d4eb0190d Mon Sep 17 00:00:00 2001
From: Matthew McCormick <matt@mmmccormick.com>
Date: Thu, 26 Jun 2025 13:26:37 -0400
Subject: [PATCH] WIP: fix(downsample): set output offset for center pixel
 shift

Fixes #1409
---
 packages/downsample/downsample-label-image.cxx | 2 +-
 packages/downsample/downsample.cxx             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/downsample/downsample-label-image.cxx b/packages/downsample/downsample-label-image.cxx
index 75c359ccf..d236ecbf9 100644
--- a/packages/downsample/downsample-label-image.cxx
+++ b/packages/downsample/downsample-label-image.cxx
@@ -67,7 +67,7 @@ class PipelineFunctor
     {
       const double cropRadiusValue = cropRadius.size() ? cropRadius[i] : 0.0;
 
-      outputOrigin[i] = inputOrigin[i] + cropRadiusValue * inputSpacing[i];
+      outputOrigin[i] = inputOrigin[i] + cropRadiusValue * inputSpacing[i] + 0.5 * (shrinkFactors[i] - 1) * inputSpacing[i];
       outputSpacing[i] = inputSpacing[i] * shrinkFactors[i];
       outputSize[i] = std::max<itk::SizeValueType>(0, (inputSize[i] - 2 * cropRadiusValue) / shrinkFactors[i]);
     }
diff --git a/packages/downsample/downsample.cxx b/packages/downsample/downsample.cxx
index 8980a73e3..506d9536d 100644
--- a/packages/downsample/downsample.cxx
+++ b/packages/downsample/downsample.cxx
@@ -80,7 +80,7 @@ class PipelineFunctor
     {
       const double cropRadiusValue = cropRadius.size() ? cropRadius[i] : 0.0;
 
-      outputOrigin[i] = inputOrigin[i] + cropRadiusValue * inputSpacing[i];
+      outputOrigin[i] = inputOrigin[i] + cropRadiusValue * inputSpacing[i] + 0.5 * (shrinkFactors[i] - 1) * inputSpacing[i];
       outputSpacing[i] = inputSpacing[i] * shrinkFactors[i];
       outputSize[i] = std::max<itk::SizeValueType>(0, (inputSize[i] - 2 * cropRadiusValue) / shrinkFactors[i]);
     }