From 6f159755ac8cfdcfd764438f2b1b753b3491c1ec Mon Sep 17 00:00:00 2001
From: Andrew <andrew@digerati.co.nz>
Date: Mon, 31 Oct 2022 18:09:15 +1300
Subject: [PATCH] Improve performance of up

---
 src/reduction/alpha.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/reduction/alpha.rs b/src/reduction/alpha.rs
index 145f7fe4..06df0676 100644
--- a/src/reduction/alpha.rs
+++ b/src/reduction/alpha.rs
@@ -117,8 +117,8 @@ fn reduced_alpha_to_up(png: &PngImage, bpc: usize, bpp: usize) -> Vec<u8> {
                         reduced[offset..(offset + bpp - bpc)]
                             .copy_from_slice(&pixel[..(bpp - bpc)]);
                     }
-                    transparent[col] = 0;
                 }
+                transparent[col] = i32::MIN; // Prevent copying upwards again
                 reduced.extend_from_slice(pixel);
                 line_transparent = false;
             }