Merge PR #1177

crates/engine/src/media.rs

@@ -62,7 +62,7 @@ impl SettingsHashes {
 }
 
 /// Bump when the pipeline's output changes, to invalidate cached thumbnails.
-pub const RENDER_CACHE_VERSION: u64 = 61;
+pub const RENDER_CACHE_VERSION: u64 = 62;
 
 /// Thumbnails render at one of these long edges (so window/cell size changes reuse the cache).
 pub const THUMB_SIZES: [usize; 4] = [128, 256, 384, 512];

crates/raw/src/dng.rs

@@ -300,7 +300,9 @@ pub(crate) fn decode_as(bytes: &[u8], mode: Mode, format: RawFormat) -> Result<R
         if cpp != 1 {
             return Err(RawError::Unsupported("CFA data with several samples per pixel".into()));
         }
-        Some(Cfa { width: cols, height: rows, pattern })
+        // the tag is anchored at the top-left of the ActiveArea (DNG spec); `RawImage::cfa` is anchored at the
+        // sensor origin (the crop to the active area shifts it back), so move the anchor out by the area's offset
+        Some(Cfa { width: cols, height: rows, pattern }.shifted(cols - active_area.x % cols, rows - active_area.y % rows))
     } else {
         None
     };

crates/raw/src/dngwrite.rs

@@ -125,7 +125,9 @@ pub fn write_dng(raw: &RawImage, opts: &DngWriteOptions) -> Result<Vec<u8>> {
 
     if let Some(cfa) = &raw.cfa {
         ifd.set(t::CFA_REPEAT_PATTERN_DIM, Value::Short(vec![cfa.height as u16, cfa.width as u16]));
-        ifd.set(t::CFA_PATTERN_EP, Value::Byte(cfa.pattern.clone()));
+        // the tag is anchored at the ActiveArea's top-left, `raw.cfa` at the sensor origin
+        let a = raw.active_area;
+        ifd.set(t::CFA_PATTERN_EP, Value::Byte(cfa.shifted(a.x, a.y).pattern));
         ifd.set(t::CFA_PLANE_COLOR, Value::Byte(vec![0, 1, 2]));
         ifd.set(t::CFA_LAYOUT, Value::Short(vec![1]));
     }

crates/raw/tests/dng.rs

@@ -1026,3 +1026,24 @@ fn baseline_sharpness_is_read_when_plausible() {
     assert_eq!(decode(&bytes).unwrap().color.baseline_sharpness, None);
     assert_eq!(decode(&profile_dng(ByteOrder::Big, |_| {})).unwrap().color.baseline_sharpness, None);
 }
+
+/// The DNG CFAPattern is anchored at the top-left of the ActiveArea: a DNG whose area starts on an odd row or
+/// column still demosaics with the pattern the tag states (#1086), and the writer states it back the same way.
+#[test]
+fn cfa_pattern_is_relative_to_the_active_area() {
+    let (w, h) = (20, 12);
+    for (top, left, sensor_name) in [(0u32, 0u32, "GRBG"), (1, 0, "BGGR"), (0, 1, "RGGB"), (1, 1, "GBRG"), (3, 5, "GBRG"), (2, 4, "GRBG")] {
+        let mut raw = base_ifd(w, h, 16, 1, true);
+        raw.set_image(ImageData::Strips { rows_per_strip: h as u32, strips: vec![u16_bytes(&pattern(w, h, 1, 16), ByteOrder::Little)] });
+        raw.set(t::WHITE_LEVEL, Value::Short(vec![65535]));
+        raw.set(t::ACTIVE_AREA, Value::Long(vec![top, left, h as u32 - 1, w as u32 - 1]));
+        let img = decode(&dng(raw, ByteOrder::Little)).unwrap();
+        assert_eq!(img.cfa.as_ref().unwrap().name(), sensor_name, "sensor anchor for area at ({left}, {top})");
+        assert_eq!(img.normalized().unwrap().cfa.unwrap().name(), "GRBG", "tag pattern for area at ({left}, {top})");
+        let back =
+            decode(&write_dng(&img, &DngWriteOptions { compression: DngCompression::Uncompressed, order: ByteOrder::Little, xmp: None }).unwrap())
+                .unwrap();
+        assert_eq!(back.cfa.as_ref().unwrap().name(), sensor_name);
+        assert_eq!(back.normalized().unwrap().cfa.unwrap().name(), "GRBG");
+    }
+}