Merge branch 'master' into filter-heuristics

src/interlace.rs

@@ -135,6 +135,19 @@ pub fn deinterlace_image(png: &PngImage) -> PngImage {
             if current_pass == 3 && png.ihdr.height <= 4 {
                 current_pass += 1;
             }
+            if current_pass == 4 && png.ihdr.width <= 2 {
+                current_pass += 1;
+            }
+            if current_pass == 5 && png.ihdr.height <= 2 {
+                current_pass += 1;
+            }
+            if current_pass == 6 && png.ihdr.width == 1 {
+                current_pass += 1;
+            }
+            if current_pass == 7 && png.ihdr.height == 1 {
+                break;
+            }
+
             pass_constants = interlaced_constants(current_pass);
             current_y = pass_constants.y_shift as usize;
         }

src/reduction/alpha.rs

@@ -16,7 +16,10 @@ pub(crate) fn try_alpha_reductions(
     alphas: &HashSet<AlphaOptim>,
     eval: &Evaluator,
 ) {
-    assert!(!alphas.is_empty());
+    if alphas.is_empty() {
+        return;
+    }
+
     let alphas = alphas.iter().collect::<Vec<_>>();
     let alphas_iter = alphas.par_iter().with_max_len(1);
     alphas_iter

tests/regression.rs

@@ -634,4 +634,20 @@ fn issue_175() {
         ColorType::Grayscale,
         BitDepth::One,
     );
-}
+}
+
+#[test]
+fn issue_182() {
+    let input = "tests/files/issue-175.png";
+    let (output, mut opts) = get_opts(Path::new(input));
+    opts.interlace = Some(0);
+
+    test_it_converts(
+        input,
+        Some((output, opts)),
+        ColorType::Grayscale,
+        BitDepth::One,
+        ColorType::Grayscale,
+        BitDepth::One,
+    );
+}