Merge pull request #5 from 335g/cmyk

CMYK support

src/decoder/mod.rs

@@ -124,7 +124,7 @@ fn rev_hpredict(image: DecodingResult, size: (u32, u32), color_type: ColorType)
     let samples = match color_type {
         ColorType::Gray(8) | ColorType::Gray(16) => 1,
         ColorType::RGB(8) | ColorType::RGB(16) => 3,
-        ColorType::RGBA(8) | ColorType::RGBA(16) => 4,
+        ColorType::RGBA(8) | ColorType::RGBA(16) | ColorType::CMYK(8) => 4,
         _ => return Err(TiffError::UnsupportedError(format!(
             "Horizontal predictor for {:?} is unsupported.", color_type
         )))
@@ -167,6 +167,7 @@ impl<R: Read + Seek> Decoder<R> {
             PhotometricInterpretation::RGB if self.bits_per_sample == [8, 8, 8] => Ok(ColorType::RGB(8)),
             PhotometricInterpretation::RGB if self.bits_per_sample == [16, 16, 16, 16] => Ok(ColorType::RGBA(16)),
             PhotometricInterpretation::RGB if self.bits_per_sample == [16, 16, 16] => Ok(ColorType::RGB(16)),
+            PhotometricInterpretation::CMYK if self.bits_per_sample == [8, 8, 8, 8] => Ok(ColorType::CMYK(8)),
             PhotometricInterpretation::BlackIsZero | PhotometricInterpretation::WhiteIsZero
                                            if self.bits_per_sample.len() == 1 => Ok(ColorType::Gray(self.bits_per_sample[0])),
 
@@ -419,7 +420,8 @@ impl<R: Read + Seek> Decoder<R> {
         };
         Ok(match (color_type, buffer) {
             (ColorType:: RGB(8), DecodingBuffer::U8(ref mut buffer)) |
-            (ColorType::RGBA(8), DecodingBuffer::U8(ref mut buffer)) => {
+            (ColorType::RGBA(8), DecodingBuffer::U8(ref mut buffer)) | 
+            (ColorType::CMYK(8), DecodingBuffer::U8(ref mut buffer)) => {
                 try!(reader.read(&mut buffer[..bytes]))
             }
             (ColorType::RGBA(16), DecodingBuffer::U16(ref mut buffer)) |

src/lib.rs

@@ -33,4 +33,7 @@ pub enum ColorType {
 
     /// Pixel is RGB with an alpha channel
     RGBA(u8),
+
+    /// Pixel is CMYK
+    CMYK(u8),
 }