LR-IMP-FORMATS: read DNG BaselineSharpness and keep it in DNG exports

ColorData::baseline_sharpness holds the file's BaselineSharpness (raw IFD
or IFD 0; zero, negative, non-finite or above 16 is ignored) and the DNG
writer writes it back, so a conversion or smart preview keeps it. Merge
outputs leave it unset. Rendering doesn't use it yet.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

crates/merge/src/output.rs

@@ -51,6 +51,7 @@ pub fn color_data(color: &FrameColor) -> ColorData {
                 as_shot_neutral: Some([1.0, 1.0, 1.0]),
                 as_shot_white_xy: None,
                 baseline_exposure: 0.0,
+                baseline_sharpness: None,
                 profile: Default::default(),
             }
         }

crates/raw/src/dng.rs

@@ -48,6 +48,8 @@ pub(crate) fn color_data(ifd0: &Ifd, raw: &Ifd, order: ByteOrder) -> ColorData {
         as_shot_white_xy: get(t::AS_SHOT_WHITE_XY).filter(|v| v.len() == 2 && v[0] > 0.0 && v[1] > 0.0).map(|v| Xy::new(v[0], v[1])),
         baseline_exposure: get(t::BASELINE_EXPOSURE).and_then(|v| v.first().copied()).filter(|v| v.is_finite()).unwrap_or(0.0)
             + get(t::BASELINE_EXPOSURE_OFFSET).and_then(|v| v.first().copied()).filter(|v| v.is_finite()).unwrap_or(0.0),
+        // DNG 1.7 BaselineSharpness (IFD 0 or the enhanced IFD); implausible values are ignored
+        baseline_sharpness: get(t::BASELINE_SHARPNESS).and_then(|v| v.first().copied()).filter(|v| v.is_finite() && *v > 0.0 && *v <= 16.0),
         profile: profile_look(ifd0, raw, order),
     }
 }

crates/raw/src/dngwrite.rs

@@ -182,6 +182,9 @@ pub fn write_dng(raw: &RawImage, opts: &DngWriteOptions) -> Result<Vec<u8>> {
         ifd.set(t::AS_SHOT_NEUTRAL, rat_vec(&m.map(|v| 1.0 / v as f64)));
     }
     ifd.set(t::BASELINE_EXPOSURE, Value::SRational(vec![srational(c.baseline_exposure)]));
+    if let Some(v) = c.baseline_sharpness {
+        ifd.set(t::BASELINE_SHARPNESS, rat_vec(&[v]));
+    }
     // the source's own profile look travels with its data (conversions, smart previews, merges)
     let p = &c.profile;
     let table_tags = |ifd: &mut IfdBuilder, table: &crate::profile::HsvTable, dims: u16, enc: u16| {

crates/raw/src/lib.rs

@@ -516,6 +516,10 @@ pub struct ColorData {
     pub as_shot_white_xy: Option<Xy>,
     /// EV to add for a "normal" rendering (`BaselineExposure` + `BaselineExposureOffset`).
     pub baseline_exposure: f64,
+    /// `BaselineSharpness`: sharpening relative to a reference camera (`None`: the DNG default,
+    /// 1). Read and written back by DNG export; rendering doesn't use it yet.
+    #[serde(default)]
+    pub baseline_sharpness: Option<f64>,
     /// The file's own camera-profile look (`ProfileHueSatMap*`, `ProfileLookTable*`,
     /// `ProfileToneCurve`), applied by [`color`]'s users at render time, and its
     /// `ProfileGainTableMap*`, kept (a DNG export writes it back) but not rendered.

crates/raw/tests/dng.rs

@@ -39,6 +39,7 @@ fn synthetic(w: usize, h: usize, cfa: Option<Cfa>, cpp: usize) -> RawImage {
         ],
         as_shot_neutral: Some([0.5, 1.0, 0.7]),
         baseline_exposure: 0.35,
+        baseline_sharpness: Some(1.5),
         ..Default::default()
     };
     let metadata = lightcraft_meta::Metadata { make: Some("Synth".into()), model: Some("Cam 1".into()), rating: Some(3), ..Default::default() };
@@ -84,6 +85,7 @@ fn assert_same(a: &RawImage, b: &RawImage) {
     let (n1, n2) = (a.color.as_shot_neutral.unwrap(), b.color.as_shot_neutral.unwrap());
     assert!((0..3).all(|i| (n1[i] - n2[i]).abs() < 1e-6));
     assert!((a.color.baseline_exposure - b.color.baseline_exposure).abs() < 1e-6);
+    assert!(b.color.baseline_sharpness.is_some_and(|v| (v - 1.5).abs() < 1e-6), "{:?}", b.color.baseline_sharpness);
     assert_eq!(b.metadata.make.as_deref(), Some("Synth"));
     assert_eq!(b.metadata.rating, Some(3));
 }
@@ -951,3 +953,19 @@ fn semantic_mask_ifds_past_the_cap_are_not_decoded() {
     let names: Vec<String> = lightcraft_raw::semantic_masks(&with(MAX_MASKS - 1, 3 * MAX_MASKS)).into_iter().map(|m| m.name).collect();
     assert_eq!(names, ["valid 0"]);
 }
+
+/// `BaselineSharpness` is read from IFD 0; a zero, negative or absurd value is ignored.
+#[test]
+fn baseline_sharpness_is_read_when_plausible() {
+    for (value, want) in [((3, 2), Some(1.5)), ((0, 1), None), ((1, 0), None), ((100, 1), None)] {
+        let bytes = profile_dng(ByteOrder::Big, |ifd0| {
+            ifd0.set(t::BASELINE_SHARPNESS, Value::Rational(vec![value]));
+        });
+        assert_eq!(decode(&bytes).unwrap().color.baseline_sharpness, want, "{value:?}");
+    }
+    let bytes = profile_dng(ByteOrder::Big, |ifd0| {
+        ifd0.set(t::BASELINE_SHARPNESS, Value::SRational(vec![(-1, 1)]));
+    });
+    assert_eq!(decode(&bytes).unwrap().color.baseline_sharpness, None);
+    assert_eq!(decode(&profile_dng(ByteOrder::Big, |_| {})).unwrap().color.baseline_sharpness, None);
+}