From 8da44fc45cf154c837d290a0c6917b1755467ccb Mon Sep 17 00:00:00 2001
From: Andrew <andrew@digerati.co.nz>
Date: Wed, 27 Nov 2024 20:13:08 +1300
Subject: [PATCH] Assume None if the line is all zeros

---
 src/png/mod.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/png/mod.rs b/src/png/mod.rs
index df695973..cd2d605b 100644
--- a/src/png/mod.rs
+++ b/src/png/mod.rs
@@ -360,6 +360,15 @@ impl PngImage {
                 prev_line = line_data;
             } else {
                 // Heuristic filter selection strategies
+
+                if line_data.iter().all(|&x| x == 0) {
+                    // Assume None if the line is all zeros
+                    filtered.push(RowFilter::None as u8);
+                    filtered.extend_from_slice(&line_data);
+                    prev_line = line_data;
+                    continue;
+                }
+
                 let mut best_line = Vec::new();
                 let mut best_line_raw = Vec::new();
                 // Avoid vertical filtering on first line of each interlacing pass