diff --git a/benches/filters.rs b/benches/filters.rs
index 7e048307..27a330b8 100644
--- a/benches/filters.rs
+++ b/benches/filters.rs
@@ -13,7 +13,7 @@ fn filters_16_bits_filter_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(0);
+        png.raw.filter_image(0);
     });
 }
 
@@ -23,7 +23,7 @@ fn filters_8_bits_filter_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(0);
+        png.raw.filter_image(0);
     });
 }
 
@@ -35,7 +35,7 @@ fn filters_4_bits_filter_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(0);
+        png.raw.filter_image(0);
     });
 }
 
@@ -47,7 +47,7 @@ fn filters_2_bits_filter_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(0);
+        png.raw.filter_image(0);
     });
 }
 
@@ -59,7 +59,7 @@ fn filters_1_bits_filter_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(0);
+        png.raw.filter_image(0);
     });
 }
 
@@ -69,7 +69,7 @@ fn filters_16_bits_filter_1(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(1);
+        png.raw.filter_image(1);
     });
 }
 
@@ -79,7 +79,7 @@ fn filters_8_bits_filter_1(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(1);
+        png.raw.filter_image(1);
     });
 }
 
@@ -91,7 +91,7 @@ fn filters_4_bits_filter_1(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(1);
+        png.raw.filter_image(1);
     });
 }
 
@@ -103,7 +103,7 @@ fn filters_2_bits_filter_1(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(1);
+        png.raw.filter_image(1);
     });
 }
 
@@ -115,7 +115,7 @@ fn filters_1_bits_filter_1(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(1);
+        png.raw.filter_image(1);
     });
 }
 
@@ -125,7 +125,7 @@ fn filters_16_bits_filter_2(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(2);
+        png.raw.filter_image(2);
     });
 }
 
@@ -135,7 +135,7 @@ fn filters_8_bits_filter_2(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(2);
+        png.raw.filter_image(2);
     });
 }
 
@@ -147,7 +147,7 @@ fn filters_4_bits_filter_2(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(2);
+        png.raw.filter_image(2);
     });
 }
 
@@ -159,7 +159,7 @@ fn filters_2_bits_filter_2(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(2);
+        png.raw.filter_image(2);
     });
 }
 
@@ -171,7 +171,7 @@ fn filters_1_bits_filter_2(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(2);
+        png.raw.filter_image(2);
     });
 }
 
@@ -181,7 +181,7 @@ fn filters_16_bits_filter_3(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(3);
+        png.raw.filter_image(3);
     });
 }
 
@@ -191,7 +191,7 @@ fn filters_8_bits_filter_3(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(3);
+        png.raw.filter_image(3);
     });
 }
 
@@ -203,7 +203,7 @@ fn filters_4_bits_filter_3(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(3);
+        png.raw.filter_image(3);
     });
 }
 
@@ -215,7 +215,7 @@ fn filters_2_bits_filter_3(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(3);
+        png.raw.filter_image(3);
     });
 }
 
@@ -227,7 +227,7 @@ fn filters_1_bits_filter_3(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(3);
+        png.raw.filter_image(3);
     });
 }
 
@@ -237,7 +237,7 @@ fn filters_16_bits_filter_4(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(4);
+        png.raw.filter_image(4);
     });
 }
 
@@ -247,7 +247,7 @@ fn filters_8_bits_filter_4(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(4);
+        png.raw.filter_image(4);
     });
 }
 
@@ -259,7 +259,7 @@ fn filters_4_bits_filter_4(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(4);
+        png.raw.filter_image(4);
     });
 }
 
@@ -271,7 +271,7 @@ fn filters_2_bits_filter_4(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(4);
+        png.raw.filter_image(4);
     });
 }
 
@@ -283,7 +283,7 @@ fn filters_1_bits_filter_4(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(4);
+        png.raw.filter_image(4);
     });
 }
 
@@ -293,7 +293,7 @@ fn filters_16_bits_filter_5(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(5);
+        png.raw.filter_image(5);
     });
 }
 
@@ -303,7 +303,7 @@ fn filters_8_bits_filter_5(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(5);
+        png.raw.filter_image(5);
     });
 }
 
@@ -315,7 +315,7 @@ fn filters_4_bits_filter_5(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(5);
+        png.raw.filter_image(5);
     });
 }
 
@@ -327,7 +327,7 @@ fn filters_2_bits_filter_5(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(5);
+        png.raw.filter_image(5);
     });
 }
 
@@ -339,6 +339,6 @@ fn filters_1_bits_filter_5(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        png.filter_image(5);
+        png.raw.filter_image(5);
     });
 }
diff --git a/benches/interlacing.rs b/benches/interlacing.rs
index 26d93da7..4288fe93 100644
--- a/benches/interlacing.rs
+++ b/benches/interlacing.rs
@@ -12,10 +12,7 @@ fn interlacing_16_bits(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgb_16_should_be_rgb_16.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(1)
-    });
+    b.iter(|| png.raw.change_interlacing(1));
 }
 
 #[bench]
@@ -23,10 +20,7 @@ fn interlacing_8_bits(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgb_8_should_be_rgb_8.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(1)
-    });
+    b.iter(|| png.raw.change_interlacing(1));
 }
 
 #[bench]
@@ -36,10 +30,7 @@ fn interlacing_4_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(1)
-    });
+    b.iter(|| png.raw.change_interlacing(1));
 }
 
 #[bench]
@@ -49,10 +40,7 @@ fn interlacing_2_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(1)
-    });
+    b.iter(|| png.raw.change_interlacing(1));
 }
 
 #[bench]
@@ -62,10 +50,7 @@ fn interlacing_1_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(1)
-    });
+    b.iter(|| png.raw.change_interlacing(1));
 }
 
 #[bench]
@@ -75,10 +60,7 @@ fn deinterlacing_16_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(0)
-    });
+    b.iter(|| png.raw.change_interlacing(0));
 }
 
 #[bench]
@@ -88,10 +70,7 @@ fn deinterlacing_8_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(0)
-    });
+    b.iter(|| png.raw.change_interlacing(0));
 }
 
 #[bench]
@@ -101,10 +80,7 @@ fn deinterlacing_4_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(0)
-    });
+    b.iter(|| png.raw.change_interlacing(0));
 }
 
 #[bench]
@@ -114,10 +90,7 @@ fn deinterlacing_2_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(0)
-    });
+    b.iter(|| png.raw.change_interlacing(0));
 }
 
 #[bench]
@@ -127,8 +100,5 @@ fn deinterlacing_1_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.change_interlacing(0)
-    });
+    b.iter(|| png.raw.change_interlacing(0));
 }
diff --git a/benches/libdeflater.rs b/benches/libdeflater.rs
index d3323253..cac7a723 100644
--- a/benches/libdeflater.rs
+++ b/benches/libdeflater.rs
@@ -13,7 +13,7 @@ fn libdeflater_16_bits_strategy_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        libdeflater_deflate(png.raw.data.as_ref()).ok();
+        libdeflater_deflate(png.raw.data.as_ref(), &AtomicMin::new(None)).ok();
     });
 }
 
@@ -23,7 +23,7 @@ fn libdeflater_8_bits_strategy_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        libdeflater_deflate(png.raw.data.as_ref()).ok();
+        libdeflater_deflate(png.raw.data.as_ref(), &AtomicMin::new(None)).ok();
     });
 }
 
@@ -35,7 +35,7 @@ fn libdeflater_4_bits_strategy_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        libdeflater_deflate(png.raw.data.as_ref()).ok();
+        libdeflater_deflate(png.raw.data.as_ref(), &AtomicMin::new(None)).ok();
     });
 }
 
@@ -47,7 +47,7 @@ fn libdeflater_2_bits_strategy_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        libdeflater_deflate(png.raw.data.as_ref()).ok();
+        libdeflater_deflate(png.raw.data.as_ref(), &AtomicMin::new(None)).ok();
     });
 }
 
@@ -59,6 +59,6 @@ fn libdeflater_1_bits_strategy_0(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        libdeflater_deflate(png.raw.data.as_ref()).ok();
+        libdeflater_deflate(png.raw.data.as_ref(), &AtomicMin::new(None)).ok();
     });
 }
diff --git a/benches/reductions.rs b/benches/reductions.rs
index 83dc50b9..e94d8280 100644
--- a/benches/reductions.rs
+++ b/benches/reductions.rs
@@ -12,10 +12,7 @@ fn reductions_16_to_8_bits(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgb_16_should_be_rgb_8.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -25,10 +22,7 @@ fn reductions_8_to_4_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -38,10 +32,7 @@ fn reductions_8_to_2_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -51,10 +42,7 @@ fn reductions_8_to_1_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -64,10 +52,7 @@ fn reductions_4_to_2_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -77,10 +62,7 @@ fn reductions_4_to_1_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -90,10 +72,7 @@ fn reductions_2_to_1_bits(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_bit_depth()
-    });
+    b.iter(|| bit_depth::reduce_bit_depth(&png.raw, 1));
 }
 
 #[bench]
@@ -101,10 +80,7 @@ fn reductions_rgba_to_rgb_16(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_16_should_be_rgb_16.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -112,10 +88,7 @@ fn reductions_rgba_to_rgb_8(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_should_be_rgb_8.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -125,10 +98,7 @@ fn reductions_rgba_to_grayscale_alpha_16(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -138,10 +108,7 @@ fn reductions_rgba_to_grayscale_alpha_8(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -151,10 +118,7 @@ fn reductions_rgba_to_grayscale_16(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -164,10 +128,7 @@ fn reductions_rgba_to_grayscale_8(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -177,10 +138,7 @@ fn reductions_rgb_to_grayscale_16(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -188,10 +146,7 @@ fn reductions_rgb_to_grayscale_8(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgb_8_should_be_grayscale_8.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -199,10 +154,7 @@ fn reductions_rgba_to_palette_8(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_should_be_palette_8.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -210,10 +162,7 @@ fn reductions_rgb_to_palette_8(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgb_8_should_be_palette_8.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_color_type()
-    });
+    b.iter(|| reduce_color_type(&png.raw));
 }
 
 #[bench]
@@ -223,10 +172,7 @@ fn reductions_palette_duplicate_reduction(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_palette()
-    });
+    b.iter(|| reduced_palette(&png.raw));
 }
 
 #[bench]
@@ -236,10 +182,7 @@ fn reductions_palette_unused_reduction(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_palette()
-    });
+    b.iter(|| reduced_palette(&png.raw));
 }
 
 #[bench]
@@ -249,10 +192,7 @@ fn reductions_palette_full_reduction(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| {
-        let mut safe_png = png.clone();
-        safe_png.reduce_palette()
-    });
+    b.iter(|| reduced_palette(&png.raw));
 }
 
 #[bench]
@@ -260,7 +200,7 @@ fn reductions_alpha_black(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_reduce_alpha_black.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| png.reduced_alpha_channel(AlphaOptim::Black));
+    b.iter(|| alpha::filtered_alpha_channel(&png.raw, AlphaOptim::Black));
 }
 
 #[bench]
@@ -268,7 +208,7 @@ fn reductions_alpha_white(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_reduce_alpha_white.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| png.reduced_alpha_channel(AlphaOptim::White));
+    b.iter(|| alpha::filtered_alpha_channel(&png.raw, AlphaOptim::White));
 }
 
 #[bench]
@@ -276,7 +216,7 @@ fn reductions_alpha_left(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_reduce_alpha_left.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| png.reduced_alpha_channel(AlphaOptim::Left));
+    b.iter(|| alpha::filtered_alpha_channel(&png.raw, AlphaOptim::Left));
 }
 
 #[bench]
@@ -284,7 +224,7 @@ fn reductions_alpha_right(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_reduce_alpha_right.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| png.reduced_alpha_channel(AlphaOptim::Right));
+    b.iter(|| alpha::filtered_alpha_channel(&png.raw, AlphaOptim::Right));
 }
 
 #[bench]
@@ -292,7 +232,7 @@ fn reductions_alpha_up(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_reduce_alpha_up.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| png.reduced_alpha_channel(AlphaOptim::Up));
+    b.iter(|| alpha::filtered_alpha_channel(&png.raw, AlphaOptim::Up));
 }
 
 #[bench]
@@ -300,5 +240,5 @@ fn reductions_alpha_down(b: &mut Bencher) {
     let input = test::black_box(PathBuf::from("tests/files/rgba_8_reduce_alpha_down.png"));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| png.reduced_alpha_channel(AlphaOptim::Down));
+    b.iter(|| alpha::filtered_alpha_channel(&png.raw, AlphaOptim::Down));
 }
diff --git a/src/deflate/mod.rs b/src/deflate/mod.rs
index 9648c813..e37e6b68 100644
--- a/src/deflate/mod.rs
+++ b/src/deflate/mod.rs
@@ -29,7 +29,8 @@ pub fn inflate(data: &[u8]) -> PngResult<Vec<u8>> {
 }
 
 /// Compress a data stream using the DEFLATE algorithm
-pub(crate) fn deflate(
+#[doc(hidden)]
+pub fn deflate(
     data: &[u8],
     zc: u8,
     zs: u8,
diff --git a/src/lib.rs b/src/lib.rs
index 360dec9d..3395510b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -62,6 +62,7 @@ pub mod internal_tests {
     pub use crate::deflate::*;
     pub use crate::headers::*;
     pub use crate::png::*;
+    pub use crate::reduction::*;
 }
 
 #[derive(Clone, Debug)]
@@ -801,6 +802,7 @@ fn perform_reductions(
     try_alpha_reductions(png, &opts.alphas, eval);
 }
 
+#[derive(Debug)]
 struct DeadlineImp {
     start: Instant,
     timeout: Duration,
@@ -808,7 +810,9 @@ struct DeadlineImp {
 }
 
 /// Keep track of processing timeout
-pub(crate) struct Deadline {
+#[doc(hidden)]
+#[derive(Debug)]
+pub struct Deadline {
     imp: Option<DeadlineImp>,
 }