Add ColorType::Multiband enum variant to support samples>1 per pixel (#224)

Co-authored-by: tromper <scott@hopkinsunderground.com>

src/decoder/image.rs

@@ -346,14 +346,19 @@ impl Image {
                     ),
                 )),
             },
-            PhotometricInterpretation::BlackIsZero | PhotometricInterpretation::WhiteIsZero
+            PhotometricInterpretation::BlackIsZero | PhotometricInterpretation::WhiteIsZero => {
-                if self.samples == 1 =>
+                match self.samples {
-            {
+                    1 => Ok(ColorType::Gray(self.bits_per_sample)),
-                Ok(ColorType::Gray(self.bits_per_sample))
+                    _ => Ok(ColorType::Multiband {
+                        bit_depth: self.bits_per_sample,
+                        num_samples: self.samples,
+                    }),
+                }
             }
-
             // TODO: this is bad we should not fail at this point
-            _ => Err(TiffError::UnsupportedError(
+            PhotometricInterpretation::RGBPalette
+            | PhotometricInterpretation::TransparencyMask
+            | PhotometricInterpretation::CIELab => Err(TiffError::UnsupportedError(
                 TiffUnsupportedError::InterpretationWithBits(
                     self.photometric_interpretation,
                     vec![self.bits_per_sample; self.samples as usize],
@@ -555,13 +560,26 @@ impl Image {
             | (ColorType::CMYK(n), _)
             | (ColorType::YCbCr(n), _)
             | (ColorType::Gray(n), _)
-                if usize::from(n) == buffer.byte_len() * 8 => {}
+            | (
-            (ColorType::Gray(n), DecodingBuffer::U8(_)) if n < 8 => match self.predictor {
+                ColorType::Multiband {
+                    bit_depth: n,
+                    num_samples: _,
+                },
+                _,
+            ) if usize::from(n) == buffer.byte_len() * 8 => {}
+            (
+                ColorType::Gray(n)
+                | ColorType::Multiband {
+                    bit_depth: n,
+                    num_samples: _,
+                },
+                DecodingBuffer::U8(_),
+            ) if n < 8 => match self.predictor {
                 Predictor::None => {}
                 Predictor::Horizontal => {
                     return Err(TiffError::UnsupportedError(
                         TiffUnsupportedError::HorizontalPredictor(color_type),
-                    ))
+                    ));
                 }
                 Predictor::FloatingPoint => {
                     return Err(TiffError::UnsupportedError(
@@ -572,7 +590,7 @@ impl Image {
             (type_, _) => {
                 return Err(TiffError::UnsupportedError(
                     TiffUnsupportedError::UnsupportedColorType(type_),
-                ))
+                ));
             }
         }
 

src/lib.rs

@@ -40,4 +40,7 @@ pub enum ColorType {
 
     /// Pixel is YCbCr
     YCbCr(u8),
+
+    /// Pixel has multiple bands/channels
+    Multiband { bit_depth: u8, num_samples: u16 },
 }

tests/decode_geotiff_images.rs

@@ -0,0 +1,63 @@
+extern crate tiff;
+
+use tiff::decoder::{Decoder, DecodingResult};
+use tiff::tags::Tag;
+use tiff::ColorType;
+
+use std::fs::File;
+use std::path::PathBuf;
+
+const TEST_IMAGE_DIR: &str = "./tests/images";
+
+#[test]
+fn test_geo_tiff() {
+    let filenames = ["geo-5b.tif"];
+    for filename in filenames.iter() {
+        let path = PathBuf::from(TEST_IMAGE_DIR).join(filename);
+        let img_file = File::open(path).expect("Cannot find test image!");
+        let mut decoder = Decoder::new(img_file).expect("Cannot create decoder");
+        decoder = decoder.with_limits(tiff::decoder::Limits::unlimited());
+
+        assert_eq!(
+            decoder.dimensions().expect("Cannot get dimensions"),
+            (10, 10)
+        );
+        assert_eq!(
+            decoder.colortype().expect("Cannot get colortype"),
+            ColorType::Multiband {
+                bit_depth: 16,
+                num_samples: 5
+            }
+        );
+        assert_eq!(
+            decoder
+                .get_tag_u64(Tag::StripOffsets)
+                .expect("Cannot get StripOffsets"),
+            418
+        );
+        assert_eq!(
+            decoder
+                .get_tag_u64(Tag::RowsPerStrip)
+                .expect("Cannot get RowsPerStrip"),
+            10
+        );
+        assert_eq!(
+            decoder
+                .get_tag_u64(Tag::StripByteCounts)
+                .expect("Cannot get StripByteCounts"),
+            1000
+        );
+        assert_eq!(
+            decoder
+                .get_tag(Tag::ModelPixelScaleTag)
+                .expect("Cannot get pixel scale")
+                .into_f64_vec()
+                .expect("Cannot get pixel scale"),
+            vec![60.0, 60.0, 0.0]
+        );
+        let DecodingResult::I16(data) = decoder.read_image().unwrap() else {
+            panic!("Cannot read band data")
+        };
+        assert_eq!(data.len(), 500);
+    }
+}