diff --git a/src/encoder/colortype.rs b/src/encoder/colortype.rs
new file mode 100644
index 0000000..92beaaf
--- /dev/null
+++ b/src/encoder/colortype.rs
@@ -0,0 +1,68 @@
+pub trait ColorType {
+    type Inner: super::TiffValue;
+    const TIFF_VALUE: u8;
+    fn bits_per_sample() -> Vec<u16>;
+}
+
+pub struct Grey8;
+impl ColorType for Grey8 {
+    type Inner = u8;
+    const TIFF_VALUE: u8 = 1;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![8]
+    }
+}
+
+pub struct Grey16;
+impl ColorType for Grey16 {
+    type Inner = u16;
+    const TIFF_VALUE: u8 = 1;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![16]
+    }
+}
+
+pub struct RGB8;
+impl ColorType for RGB8 {
+    type Inner = u8;
+    const TIFF_VALUE: u8 = 2;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![8,8,8]
+    }
+}
+
+pub struct RGB16;
+impl ColorType for RGB16 {
+    type Inner = u16;
+    const TIFF_VALUE: u8 = 2;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![16,16,16]
+    }
+}
+
+pub struct RGBA8;
+impl ColorType for RGBA8 {
+    type Inner = u8;
+    const TIFF_VALUE: u8 = 2;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![8,8,8,8]
+    }
+}
+
+pub struct RGBA16;
+impl ColorType for RGBA16 {
+    type Inner = u16;
+    const TIFF_VALUE: u8 = 2;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![16,16,16,16]
+    }
+}
+
+pub struct CMYK8;
+impl ColorType for CMYK8 {
+    type Inner = u8;
+    const TIFF_VALUE: u8 = 5;
+    fn bits_per_sample() -> Vec<u16> {
+        vec![8,8,8,8]
+    }
+}
diff --git a/src/encoder/mod.rs b/src/encoder/mod.rs
index 95d8a37..a30c81c 100644
--- a/src/encoder/mod.rs
+++ b/src/encoder/mod.rs
@@ -6,7 +6,10 @@ use crate::decoder::ifd;
 use crate::error::{TiffResult, TiffFormatError, TiffError};
 
 mod writer;
+pub mod colortype;
+
 use self::writer::*;
+use self::colortype::*;
 
 pub struct Rational {
     pub n: u32,
@@ -117,29 +120,6 @@ impl TiffValue for str {
 }
 
 
-pub trait ColorType {
-    type Inner: TiffValue;
-    const TIFF_VALUE: u8;
-    fn bits_per_sample() -> Vec<u16>;
-}
-
-pub struct RGB8;
-impl ColorType for RGB8 {
-    type Inner = u8;
-    const TIFF_VALUE: u8 = 2;
-    fn bits_per_sample() -> Vec<u16> {
-        vec![8,8,8]
-    }
-}
-
-pub struct RGBA8;
-impl ColorType for RGBA8 {
-    type Inner = u8;
-    const TIFF_VALUE: u8 = 2;
-    fn bits_per_sample() -> Vec<u16> {
-        vec![8,8,8,8]
-    }
-}
 
 
 pub struct TiffEncoder<W> {
diff --git a/tests/encode_images.rs b/tests/encode_images.rs
index 8a6a098..22965b3 100644
--- a/tests/encode_images.rs
+++ b/tests/encode_images.rs
@@ -3,9 +3,10 @@ extern crate tempfile;
 
 use tiff::ColorType;
 use tiff::decoder::{Decoder, DecodingResult};
-use tiff::encoder::{TiffEncoder, RGB8};
+use tiff::encoder::{colortype, TiffEncoder};
 
 use std::io::{Seek, SeekFrom};
+use std::fs::File;
 
 #[test]
 fn encode_decode() {
@@ -22,7 +23,7 @@ fn encode_decode() {
     {
         let mut tiff = TiffEncoder::new(&mut file).unwrap();
 
-        tiff.write_image::<RGB8>(100, 100, &image_data).unwrap();
+        tiff.write_image::<colortype::RGB8>(100, 100, &image_data).unwrap();
     }
     {
         file.seek(SeekFrom::Start(0)).unwrap();
@@ -37,3 +38,59 @@ fn encode_decode() {
         }
     }
 }
+
+
+#[test]
+fn test_gray_u8_roundtrip()
+{
+    let img_file = File::open("./tests/images/minisblack-1c-8b.tiff").expect("Cannot find test image!");
+    let mut decoder = Decoder::new(img_file).expect("Cannot create decoder");
+    assert_eq!(decoder.colortype().unwrap(), ColorType::Gray(8));
+    let img_res = decoder.read_image();
+    assert!(img_res.is_ok());
+}
+
+#[test]
+fn test_rgb_u8()
+{
+    let img_file = File::open("./tests/images/rgb-3c-8b.tiff").expect("Cannot find test image!");
+    let mut decoder = Decoder::new(img_file).expect("Cannot create decoder");
+    assert_eq!(decoder.colortype().unwrap(), ColorType::RGB(8));
+    let img_res = decoder.read_image();
+
+    let mut file = tempfile::tempfile().unwrap();
+    let mut tiff = TiffEncoder::new(&mut file).unwrap();
+
+    tiff.write_image::<colortype::RGB8>(100, 100, &image_data).unwrap();
+    file.seek(SeekFrom::Start(0)).unwrap();
+
+    let mut decoder = Decoder::new(&mut file).unwrap();
+    assert_eq!(decoder.colortype().unwrap(), ColorType::RGB(8));
+    assert_eq!(decoder.dimensions().unwrap(), (100, 100));
+    if let DecodingResult::U8(img_res) = decoder.read_image().unwrap() {
+        assert_eq!(image_data, img_res);
+    }
+    else {
+        panic!("Wrong data type");
+    }
+}
+
+#[test]
+fn test_gray_u16()
+{
+    let img_file = File::open("./tests/images/minisblack-1c-16b.tiff").expect("Cannot find test image!");
+    let mut decoder = Decoder::new(img_file).expect("Cannot create decoder");
+    assert_eq!(decoder.colortype().unwrap(), ColorType::Gray(16));
+    let img_res = decoder.read_image();
+    assert!(img_res.is_ok());
+}
+
+#[test]
+fn test_rgb_u16()
+{
+    let img_file = File::open("./tests/images/rgb-3c-16b.tiff").expect("Cannot find test image!");
+    let mut decoder = Decoder::new(img_file).expect("Cannot create decoder");
+    assert_eq!(decoder.colortype().unwrap(), ColorType::RGB(16));
+    let img_res = decoder.read_image();
+    assert!(img_res.is_ok());
+}