From b7dd1de9332a030f7bda21a1b895995063c3fce4 Mon Sep 17 00:00:00 2001
From: Soumick Chatterjee <soumick@live.com>
Date: Wed, 8 Dec 2021 16:09:03 +0100
Subject: [PATCH 1/2] nonnegative_ssim added for MS_SSIM

nonnegative_ssim added for MS_SSIM with True as default, so there won't be any change in the default behaviour.
---
 pytorch_msssim/ssim.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pytorch_msssim/ssim.py b/pytorch_msssim/ssim.py
index c4cbec8..5d117be 100644
--- a/pytorch_msssim/ssim.py
+++ b/pytorch_msssim/ssim.py
@@ -156,7 +156,7 @@ def ssim(
 
 
 def ms_ssim(
-    X, Y, data_range=255, size_average=True, win_size=11, win_sigma=1.5, win=None, weights=None, K=(0.01, 0.03)
+    X, Y, data_range=255, size_average=True, win_size=11, win_sigma=1.5, win=None, weights=None, K=(0.01, 0.03), nonnegative_ssim=False,
 ):
 
     r""" interface of ms-ssim
@@ -220,7 +220,8 @@ def ms_ssim(
             X = avg_pool(X, kernel_size=2, padding=padding)
             Y = avg_pool(Y, kernel_size=2, padding=padding)
 
-    ssim_per_channel = torch.relu(ssim_per_channel)  # (batch, channel)
+    if nonnegative_ssim:
+        ssim_per_channel = torch.relu(ssim_per_channel)  # (batch, channel)
     mcs_and_ssim = torch.stack(mcs + [ssim_per_channel], dim=0)  # (level, batch, channel)
     ms_ssim_val = torch.prod(mcs_and_ssim ** weights.view(-1, 1, 1), dim=0)
 
@@ -284,6 +285,7 @@ def __init__(
         spatial_dims=2,
         weights=None,
         K=(0.01, 0.03),
+        nonnegative_ssim=True,
     ):
         r""" class for ms-ssim
         Args:
@@ -303,6 +305,7 @@ def __init__(
         self.data_range = data_range
         self.weights = weights
         self.K = K
+        self.nonnegative_ssim = nonnegative_ssim
 
     def forward(self, X, Y):
         return ms_ssim(
@@ -313,4 +316,5 @@ def forward(self, X, Y):
             win=self.win,
             weights=self.weights,
             K=self.K,
+            nonnegative_ssim=self.nonnegative_ssim,
         )

From 66997b00fa1a5994893f548a576ad0ab7a5b8a92 Mon Sep 17 00:00:00 2001
From: "Soumick Chatterjee, PhD" <soumick@live.com>
Date: Fri, 27 Jan 2023 14:43:15 +0100
Subject: [PATCH 2/2] up version

---
 setup.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/setup.py b/setup.py
index cf44fc1..0b129bf 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="pytorch_msssim",
-    version="0.2.1",
+    version="0.2.2",
     author="Gongfan Fang",
     author_email="fgf@zju.edu.cn",
     description="Fast and differentiable MS-SSIM and SSIM for pytorch.",
@@ -19,4 +19,4 @@
         "Operating System :: OS Independent",
     ],
     install_requires=['torch']
-)
\ No newline at end of file
+)