diff --git a/benches/reductions.rs b/benches/reductions.rs
index 3e05a2e1..28803a38 100644
--- a/benches/reductions.rs
+++ b/benches/reductions.rs
@@ -158,7 +158,7 @@ fn reductions_rgba_to_grayscale_alpha_16(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| color::reduce_rgb_to_grayscale(&png.raw));
+    b.iter(|| color::reduced_rgb_to_grayscale(&png.raw));
 }
 
 #[bench]
@@ -168,7 +168,7 @@ fn reductions_rgba_to_grayscale_alpha_8(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| color::reduce_rgb_to_grayscale(&png.raw));
+    b.iter(|| color::reduced_rgb_to_grayscale(&png.raw));
 }
 
 #[bench]
@@ -179,7 +179,7 @@ fn reductions_rgba_to_grayscale_16(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        color::reduce_rgb_to_grayscale(&png.raw)
+        color::reduced_rgb_to_grayscale(&png.raw)
             .and_then(|r| alpha::reduced_alpha_channel(&r, false))
     });
 }
@@ -192,7 +192,7 @@ fn reductions_rgba_to_grayscale_8(b: &mut Bencher) {
     let png = PngData::new(&input, false).unwrap();
 
     b.iter(|| {
-        color::reduce_rgb_to_grayscale(&png.raw)
+        color::reduced_rgb_to_grayscale(&png.raw)
             .and_then(|r| alpha::reduced_alpha_channel(&r, false))
     });
 }
@@ -204,7 +204,7 @@ fn reductions_rgb_to_grayscale_16(b: &mut Bencher) {
     ));
     let png = PngData::new(&input, false).unwrap();
 
-    b.iter(|| color::reduce_rgb_to_grayscale(&png.raw));
+    b.iter(|| color::reduced_rgb_to_grayscale(&png.raw));
 }
 
 #[bench]
@@ -212,7 +212,7 @@ 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(|| color::reduce_rgb_to_grayscale(&png.raw));
+    b.iter(|| color::reduced_rgb_to_grayscale(&png.raw));
 }
 
 #[bench]
@@ -220,7 +220,7 @@ 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(|| color::reduce_to_palette(&png.raw));
+    b.iter(|| color::reduced_to_indexed(&png.raw));
 }
 
 #[bench]
@@ -228,7 +228,27 @@ 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(|| color::reduce_to_palette(&png.raw));
+    b.iter(|| color::reduced_to_indexed(&png.raw));
+}
+
+#[bench]
+fn reductions_grayscale_8_to_palette_8(b: &mut Bencher) {
+    let input = test::black_box(PathBuf::from(
+        "tests/files/grayscale_8_should_be_palette_8.png",
+    ));
+    let png = PngData::new(&input, false).unwrap();
+
+    b.iter(|| color::reduced_to_indexed(&png.raw));
+}
+
+#[bench]
+fn reductions_palette_8_to_grayscale_8(b: &mut Bencher) {
+    let input = test::black_box(PathBuf::from(
+        "tests/files/palette_8_should_be_grayscale_8.png",
+    ));
+    let png = PngData::new(&input, false).unwrap();
+
+    b.iter(|| color::indexed_to_channels(&png.raw));
 }
 
 #[bench]
diff --git a/tests/files/grayscale_8_should_be_grayscale_4.png b/tests/files/grayscale_8_should_be_grayscale_4.png
index c561432e..e5e62cb1 100644
Binary files a/tests/files/grayscale_8_should_be_grayscale_4.png and b/tests/files/grayscale_8_should_be_grayscale_4.png differ
diff --git a/tests/files/grayscale_8_should_be_palette_8.png b/tests/files/grayscale_8_should_be_palette_8.png
new file mode 100644
index 00000000..ff94dfb8
Binary files /dev/null and b/tests/files/grayscale_8_should_be_palette_8.png differ
diff --git a/tests/files/palette_8_should_be_rgb.png b/tests/files/palette_8_should_be_rgb.png
new file mode 100644
index 00000000..cb6b1678
Binary files /dev/null and b/tests/files/palette_8_should_be_rgb.png differ
diff --git a/tests/files/palette_8_should_be_rgba.png b/tests/files/palette_8_should_be_rgba.png
new file mode 100644
index 00000000..351a7a1b
Binary files /dev/null and b/tests/files/palette_8_should_be_rgba.png differ
diff --git a/tests/flags.rs b/tests/flags.rs
index 3690f21a..ebb2108e 100644
--- a/tests/flags.rs
+++ b/tests/flags.rs
@@ -427,8 +427,8 @@ fn interlacing_0_to_1_small_files() {
     };
 
     assert_eq!(png.raw.ihdr.interlaced, Interlacing::Adam7);
-    assert_eq!(png.raw.ihdr.color_type.png_header_code(), INDEXED);
-    assert_eq!(png.raw.ihdr.bit_depth, BitDepth::One);
+    assert_eq!(png.raw.ihdr.color_type.png_header_code(), RGB);
+    assert_eq!(png.raw.ihdr.bit_depth, BitDepth::Eight);
 
     remove_file(output).ok();
 }
@@ -461,8 +461,8 @@ fn interlacing_1_to_0_small_files() {
     };
 
     assert_eq!(png.raw.ihdr.interlaced, Interlacing::None);
-    assert_eq!(png.raw.ihdr.color_type.png_header_code(), INDEXED);
-    // the depth can't be asserted reliably, because on such small file different zlib implementations pick different depth as the best
+    assert_eq!(png.raw.ihdr.color_type.png_header_code(), RGB);
+    assert_eq!(png.raw.ihdr.bit_depth, BitDepth::Eight);
 
     remove_file(output).ok();
 }
diff --git a/tests/interlaced.rs b/tests/interlaced.rs
index ff884b1a..52540a85 100644
--- a/tests/interlaced.rs
+++ b/tests/interlaced.rs
@@ -546,6 +546,17 @@ fn interlaced_palette_1_should_be_palette_1() {
     );
 }
 
+#[test]
+fn interlaced_palette_8_should_be_grayscale_8() {
+    test_it_converts(
+        "tests/files/interlaced_palette_8_should_be_grayscale_8.png",
+        INDEXED,
+        BitDepth::Eight,
+        GRAYSCALE,
+        BitDepth::Eight,
+    );
+}
+
 #[test]
 fn interlaced_grayscale_alpha_16_should_be_grayscale_alpha_16() {
     test_it_converts(
@@ -651,8 +662,8 @@ fn interlaced_small_files() {
         "tests/files/interlaced_small_files.png",
         INDEXED,
         BitDepth::Eight,
-        INDEXED,
-        BitDepth::One,
+        RGB,
+        BitDepth::Eight,
     );
 }
 
diff --git a/tests/reduction.rs b/tests/reduction.rs
index a7fe5e39..3d6577eb 100644
--- a/tests/reduction.rs
+++ b/tests/reduction.rs
@@ -556,6 +556,42 @@ fn palette_4_should_be_palette_2() {
     );
 }
 
+#[test]
+fn palette_8_should_be_grayscale_8() {
+    test_it_converts(
+        "tests/files/palette_8_should_be_grayscale_8.png",
+        false,
+        INDEXED,
+        BitDepth::Eight,
+        GRAYSCALE,
+        BitDepth::Eight,
+    );
+}
+
+#[test]
+fn palette_8_should_be_rgb() {
+    test_it_converts(
+        "tests/files/palette_8_should_be_rgb.png",
+        false,
+        INDEXED,
+        BitDepth::Eight,
+        RGB,
+        BitDepth::Eight,
+    );
+}
+
+#[test]
+fn palette_8_should_be_rgba() {
+    test_it_converts(
+        "tests/files/palette_8_should_be_rgba.png",
+        false,
+        INDEXED,
+        BitDepth::Eight,
+        RGBA,
+        BitDepth::Eight,
+    );
+}
+
 #[test]
 fn palette_2_should_be_palette_2() {
     test_it_converts(
@@ -808,6 +844,54 @@ fn grayscale_2_should_be_grayscale_1() {
     );
 }
 
+#[test]
+fn grayscale_8_should_be_palette_8() {
+    test_it_converts(
+        "tests/files/grayscale_8_should_be_palette_8.png",
+        false,
+        GRAYSCALE,
+        BitDepth::Eight,
+        INDEXED,
+        BitDepth::Eight,
+    );
+}
+
+#[test]
+fn grayscale_8_should_be_palette_4() {
+    test_it_converts(
+        "tests/files/grayscale_8_should_be_palette_4.png",
+        false,
+        GRAYSCALE,
+        BitDepth::Eight,
+        INDEXED,
+        BitDepth::Four,
+    );
+}
+
+#[test]
+fn grayscale_8_should_be_palette_2() {
+    test_it_converts(
+        "tests/files/grayscale_8_should_be_palette_2.png",
+        false,
+        GRAYSCALE,
+        BitDepth::Eight,
+        INDEXED,
+        BitDepth::Two,
+    );
+}
+
+#[test]
+fn grayscale_8_should_be_palette_1() {
+    test_it_converts(
+        "tests/files/grayscale_8_should_be_palette_1.png",
+        false,
+        GRAYSCALE,
+        BitDepth::Eight,
+        INDEXED,
+        BitDepth::One,
+    );
+}
+
 #[test]
 fn grayscale_alpha_16_should_be_grayscale_trns_16() {
     test_it_converts(
@@ -834,33 +918,14 @@ fn grayscale_alpha_8_should_be_grayscale_trns_8() {
 
 #[test]
 fn small_files() {
-    let input = PathBuf::from("tests/files/small_files.png");
-    let (output, opts) = get_opts(&input);
-
-    let png = PngData::new(&input, opts.fix_errors).unwrap();
-
-    assert_eq!(png.raw.ihdr.color_type.png_header_code(), INDEXED);
-    assert_eq!(png.raw.ihdr.bit_depth, BitDepth::Eight);
-
-    match oxipng::optimize(&InFile::Path(input), &output, &opts) {
-        Ok(_) => (),
-        Err(x) => panic!("{}", x),
-    };
-    let output = output.path().unwrap();
-    assert!(output.exists());
-
-    let png = match PngData::new(output, opts.fix_errors) {
-        Ok(x) => x,
-        Err(x) => {
-            remove_file(output).ok();
-            panic!("{}", x)
-        }
-    };
-
-    assert_eq!(png.raw.ihdr.color_type.png_header_code(), INDEXED);
-    // depth varies depending on zlib implementation used
-
-    remove_file(output).ok();
+    test_it_converts(
+        "tests/files/small_files.png",
+        false,
+        INDEXED,
+        BitDepth::Eight,
+        RGB,
+        BitDepth::Eight,
+    );
 }
 
 #[test]