LR-IMP-FORMATS: transparent areas develop on white instead of black (#1212)

The decoders keep the alpha plane, but to_working converted only the
colour, so transparent pixels kept the black most encoders store under
them: renders, previews, exports and contact sheets showed it. The
working image is now flattened onto white, in linear light like the
rest of the pipeline.

crates/codecs/README.md

@@ -11,7 +11,7 @@ let fmt: Option<Format> = sniff(&bytes);                 // JPEG/PNG/TIFF/WebP/A
 let d: Decoded = decode(&bytes, DecodeOptions::default())?;
 // d.image: Rgb32f, linear light in the source primaries (d.space: SourceSpace)
 // d.alpha, d.bit_depth, d.float, d.orientation (EXIF value, NOT applied), d.exif/xmp/icc (raw blobs)
-let working: Rgb32f = to_working(&d);                    // linear Rec.2020 D65 (Bradford)
+let working: Rgb32f = to_working(&d);                    // linear Rec.2020 D65 (Bradford), alpha flattened onto white
 let fast = decode(&bytes, DecodeOptions::fit(2048, 2048))?; // JPEG: DCT-domain 1/2..1/8 scaling
 let t: Thumbnail = decode_thumbnail(&bytes, 256)?;       // embedded EXIF/MPF preview or scaled decode
 let h: Header = read_header(&bytes)?;                    // stored width/height + orientation, no pixels decoded

crates/codecs/src/lib.rs

@@ -244,12 +244,24 @@ pub fn decode_unguarded(bytes: &[u8], format: Format, opts: &DecodeOptions) -> R
 }
 
 /// Convert a decode result to linear Rec.2020 D65 (Bradford-adapted), the develop working space.
+///
+/// The working space has no alpha: transparency is flattened onto white, in linear light like the rest
+/// of the pipeline (issue #1212).
 pub fn to_working(d: &Decoded) -> Rgb32f {
-    if d.space.is_working() {
-        return d.image.clone();
+    let mut img = if d.space.is_working() {
+        d.image.clone()
+    } else {
+        let m = d.space.to_working().to_f32();
+        d.image.map(|p| mat_apply(&m, p))
+    };
+    // white is (1, 1, 1) in the working space too: the conversion is white-preserving
+    if let Some(a) = d.alpha.as_ref().filter(|a| a.width == img.width && a.height == img.height) {
+        for (p, &av) in img.data.iter_mut().zip(&a.data) {
+            let av = av.clamp(0.0, 1.0);
+            *p = p.map(|c| c * av + (1.0 - av));
+        }
     }
-    let m = d.space.to_working().to_f32();
-    d.image.map(|p| mat_apply(&m, p))
+    img
 }
 
 /// Where a thumbnail came from.

crates/codecs/tests/roundtrip.rs

@@ -140,6 +140,24 @@ fn png_metadata_and_gray_alpha() {
     assert!((a - 128.0 / 255.0).abs() < 1e-6);
 }
 
+/// The working image has no alpha: transparency is flattened onto white, in linear light (issue #1212:
+/// transparent areas, stored black, rendered black).
+#[test]
+fn png_transparency_develops_on_white() {
+    // opaque red, transparent black (as most encoders store it), half-transparent red
+    let data = [200, 40, 40, 255, 0, 0, 0, 0, 200, 40, 40, 128];
+    let bytes = encode_png(&EncodeImage::new(3, 1, 4, Samples::U8(&data)), &EncodeMeta::default()).unwrap();
+    let d = decode(&bytes, DecodeOptions::default()).unwrap();
+    assert!(d.has_alpha);
+    let opaque = encode_png(&EncodeImage::new(1, 1, 3, Samples::U8(&[200, 40, 40])), &EncodeMeta::default()).unwrap();
+    let red = decode(&opaque, DecodeOptions::default()).unwrap().to_working().get(0, 0);
+    let w = d.to_working();
+    let a = 128.0 / 255.0;
+    for (got, want) in [(w.get(0, 0), red), (w.get(1, 0), [1.0; 3]), (w.get(2, 0), red.map(|c| a * c + (1.0 - a)))] {
+        assert!(got.iter().zip(want).all(|(g, w)| (g - w).abs() < 1e-5), "{got:?} != {want:?}");
+    }
+}
+
 #[test]
 fn p3_icc_to_working() {
     let icc = write_named(NamedSpace::DisplayP3);

crates/engine/src/files.rs

@@ -1016,6 +1016,17 @@ mod tests {
         assert!(probe_bytes("x.jpg", b"not an image").is_err());
     }
 
+    /// Issue #1212: a transparent PNG develops on white (what renders, previews, exports and contact sheets
+    /// start from), not on the black its transparent pixels store.
+    #[test]
+    fn transparent_png_develops_on_white() {
+        let rgba = [200, 40, 40, 255, 0, 0, 0, 0];
+        let png = lightcraft_codecs::encode_png(&EncodeImage::new(2, 1, 4, Samples::U8(&rgba)), &EncodeMeta::default()).unwrap();
+        let (img, _) = load_bytes(&png, 64).unwrap();
+        assert!(img.get(0, 0)[0] > 0.3 && img.get(0, 0)[1] < 0.1, "{:?}", img.get(0, 0));
+        assert!(img.get(1, 0).iter().all(|&c| (c - 1.0).abs() < 1e-4), "{:?}", img.get(1, 0));
+    }
+
     /// Issue #548: a small preview bins the mosaic by 8; specular points that clip a single green sample
     /// of a block on a grey surface must not become green speckles (the block's green used to take the
     /// clip level, which highlight reconstruction then kept).

docs/parity-checklist.md

@@ -1,6 +1,6 @@
 # Lightroom parity checklist
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (rapid slider entry; LR-PROF-CAMERACOLOR: tone curve from black-and-white camera JPEGs; LR-VIEW-ZOOM, LR-VIEW-COMPARE: Compare and Reference zoom windows; LR-IMP-FORMATS, LR-IMP-CAMERA-COVERAGE: EOS R5 Mark II CR3 decodes; renamed from `parity.md`; Top gaps moved to gaps.md, shortcut notes to ui-parity.md; filesystem history retry/Undo/Redo evidence; renamed from `parity.md`; Top gaps moved to gaps.md, shortcut notes to ui-parity.md) · **Target:** Adobe Lightroom Classic 15.5 / Lightroom 9.6
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-12 · **Change:** minor (LR-IMP-FORMATS: transparent images develop on white; rapid slider entry; LR-PROF-CAMERACOLOR: tone curve from black-and-white camera JPEGs; LR-VIEW-ZOOM, LR-VIEW-COMPARE: Compare and Reference zoom windows; LR-IMP-FORMATS, LR-IMP-CAMERA-COVERAGE: EOS R5 Mark II CR3 decodes; renamed from `parity.md`; Top gaps moved to gaps.md, shortcut notes to ui-parity.md; filesystem history retry/Undo/Redo evidence; renamed from `parity.md`; Top gaps moved to gaps.md, shortcut notes to ui-parity.md) · **Target:** Adobe Lightroom Classic 15.5 / Lightroom 9.6
 
 The measured, row-by-row checklist: one row per Lightroom feature, menu item and shortcut, what we
 have and what is missing. It answers *does the feature exist?* (feature breadth). Whether it is good
@@ -80,7 +80,7 @@ differences and missing bindings are in [ui-parity.md](ui-parity.md#shortcuts).
 | LR-IMP-PROFILES | Import profiles & presets | P1 | ✅ | `cmd:file.importPresets`, `cmd:preset.import`, `cmd:profile.import`, `crates/engine/src/preset_import.rs`, `crates/engine/src/preset_luminar.rs` | presets: .lcpreset, XMP, classic .lrtemplate, photos carrying edits ("DNG presets"), Luminar looks (.lmp, .mplumpack collections; sliders with a counterpart), .zip bundles, folders (folder → group), drag & drop (an `.xmp` dropped together with its photo is that photo's sidecar and is not imported as a preset, issue #936); masks carried over; unmapped settings reported (fields that only describe the preset or photo, e.g. `Cluster`, `SortName`, `SupportsAmount2`, the as-shot white, empty Point Color slots, are not); profiles: .cube 3D LUTs (one toast reports both halves; a LUT that fails is named with its reason); Adobe profile formats deliberately unsupported |
 | LR-IMP-LOCAL | Work on files in place | P0 | ✅ | `cmd:library.browse`, `cmd:photo.addToLibrary`, `cmd:library.import` (mode add), `cmd:local.addRoot`, `cmd:local.hide`, `cmd:local.restoreHidden`, `crates/engine/src/cmd/browse.rs`, `crates/ui-egui/src/panels/left.rs` (`local_section`), `crates/ui-egui/src/panels/grid.rs` (`folder_header`) | Local: browse Pictures / Desktop / Downloads / Home or any folder without adding it (breadcrumb, Include subfolders, Add N to My Photos); browsed photos stay out of All Photos, albums and counts (album commands skip them and the album menus say to Add to My Photos first, issue #684); folders picked with Browse Folder… (or Keep in Local / Add to Local on a folder row) stay listed across restarts, and browsing a folder inside a listed one highlights it inside that tree (opened down to it, siblings reachable) instead of adding a root; edits go to XMP sidecars; importing promotes them; right-click a top-level location → Remove from Local hides the shortcut only (nothing on disk or in the catalog changes), saved with the UI state, and “Show N hidden locations” (or Browse Folder… on it) brings it back; a folder is one location however its path is spelled (`/` or `\`, trailing separator, `.`/`..`, drive-letter case; `folder_key` in `crates/catalog/src/query.rs`); browsed photos nobody changed are forgotten once their folder has not been browsed for 30 days (Settings → Performance → Local folders, 0 = never; checked when the library opens, or `cmd:library.forgetLocal` with `dryRun`; files and sidecars stay, browsing again brings them back; see `crates/catalog/src/local.rs` for what counts as a change) |
 | LR-IMP-SIDECAR-SPLIT | Separate XMP sidecar variants | P2 | ⬜ | `cmd:library.xmpPreferences` | sidecar naming option exists (stem/full), no split sidecars |
-| LR-IMP-FORMATS | Supported formats | P0 | 🟡 | `crates/codecs/src/lib.rs`, `crates/raw/src/lib.rs`, `crates/raw/src/jxl.rs` | JPEG, PNG, TIFF (1- to 64-bit integer, 16- to 64-bit float, incl. bilevel and CCITT fax), WebP, JXL, PSD, GIF, BMP (lossy wide-gamut JXL decodes to the right colours: jxl-oxide desaturated XYB rendered to P3/Rec. 2020, worked around in `crates/codecs/src/jxl.rs`); DNG (incl. lossy / Smart Preview DNG and DNG 1.7 JPEG XL tiles/strips: lossless ones decode bit-exactly on synthetic CFA and LinearRaw files, lossy ones are restored to the declared linear primaries without clipping or gamut mapping, checked on one real file with 108 lossy tiles, and any tile that fails to decode makes the file preview-only; DNG 1.7 row/column-interleaved rasters (`RowInterleaveFactor` / `ColumnInterleaveFactor`) are undone before the mosaic is read, so a file from Adobe's converter with a 2×2 interleave no longer decodes as four scaled-down copies in the wrong colours; a dimension the factor does not divide decodes with short trailing fields; verified on 4 real ILCE-6400 JPEG XL DNGs rendering bit-identical to their non-interleaved twins, factors above 2 rest on the plain reading of the tag; a single-chunk JPEG XL preview IFD is offered as the embedded preview; a DNG whose samples pile up at one value well below its stated `WhiteLevel`, as a camera app's 12-bit Bayer DNG that states 4095 and clips at 3567, has those samples raised to the white level on decode, so highlight reconstruction sees the clipped areas instead of white balance tinting them magenta, issue #548, `crates/raw/src/saturation.rs`), CR2 (colour-filter layout from the file's `CR2CFAPattern` tag, issue #85), ARW (pre-2017 bodies: white balance and black level from the encrypted `SR2SubIFD`, issue #148, its `WB_RGGBLevels` being the white balance the camera applied, issue #535; the DSLR-A900's packed 12-bit strip, two pixels per three bytes, read only when the strip is exactly 1.5 bytes per pixel, with its camera-JPEG window centred, checked on one CC0 file (A850 unmeasured); downsized Sony lossless YCbCr 4:2:0 / 4:2:2 tiles decoded to linear RGB, verified on private ILCE-7M4 3:2 & 4:3 examples including 16-bit full-resolution export; Sony DSC-R1 .SR2 decodes, its big-endian 16-bit words read in the order that fits the sample range, checked on the CC0 3221 sample; its crop and white balance live in the SR2SubIFD and are not read yet; ARW6 Compressed / Compressed (HQ) of the ILCE-7RM6 (`crates/raw/src/vendor/arw6.rs`, `crates/raw/src/llvc.rs`; 12-bit codes exact against a black-box oracle on 8 CC0 files, FF over the full frame, APS-C in the interior (LibRaw's own edge rows differ); output through our own companding curve, measured from CC0 lossless / ARW6 pairs; geometry checked against the camera JPEG, `docs/arw6-compression.md`; the ILCE-7M5 writes the same codec, unverified)), NEF (uncompressed, lossless and lossy compressed 12/14-bit, `crates/raw/src/vendor/nefc.rs`), RAF (uncompressed, lossless/lossy compressed Bayer and X-Trans; `crates/raw/src/vendor/rafc.rs`, full sensor verification on 13 bodies, `docs/raf-compression.md`), RW2 / Leica RWL / Panasonic RAW in every raw format (compressed 4 and 6, the prefix-coded strips of format 8 from the GH6 on, packed 2/5/7, the 16-bit words of the 2005–2007 bodies; black levels, in-camera aspect crops and mapped-out defect pixels; 178 CC0 files from 118 bodies checked, `crates/raw/src/vendor/rw2.rs`), PEF, ORF (uncompressed; colour-filter layout from the file's Exif `CFAPattern`; 12.8 bit/px 16-byte blocks of ten 12-bit samples + a zero pad byte, E-300 / E-330 / E-500 verified on CC0 files, E-M5 Mark II / PEN-F high-res files decode smooth but CFA and black unverified), Kodak DCS520C TIFF (a two-component 12-bit lossless JPEG strip, the two components the even and odd columns; the file's `GrayResponseCurve` table linearises the companded samples to 12 bits, black measured per CFA position, white balance from the `KodakIFD`; `RawFormat::KodakDcs`, `crates/raw/src/vendor/kodak.rs`, checked on the one CC0 sample against its IFD0 thumbnail), Hasselblad 3FR and FFF (a TIFF without a DNG version tag that describes its CFA IFD, levels, crop and white balance with DNG's tags; `RawFormat::CfaTiff`, read by `dng::decode_as`, RGGB when the file states no `CFAPattern`): uncompressed (X1D, X1D II, X2D, CFV 100C) and Hasselblad's lossless JPEG with scan selection value 8 (every FFF; H3D, H4D and CFV-50c 3FR), `ljpeg::decode_hasselblad`, its rule measured on 14 CC0 files with the ljpeg-explorer tool, Samsung SRW without compression (NX5, NX10, NX11 and the NX20-generation bodies NX20, NX200, NX210, NX1000 and NX1100 as 12-bit packed samples in either bit order, EX1 and WB2000 as 16-bit words; layout, camera-JPEG framing, levels and white balance from the maker note, `crates/raw/src/vendor/srw.rs`; median ΔE vs the camera JPEG 2.2–7.6 on 11 of the 12 files from 10 bodies checked, 10.7 (5.7 registered)Line truncated
+| LR-IMP-FORMATS | Supported formats | P0 | 🟡 | `crates/codecs/src/lib.rs`, `crates/raw/src/lib.rs`, `crates/raw/src/jxl.rs` | JPEG, PNG, TIFF (1- to 64-bit integer, 16- to 64-bit float, incl. bilevel and CCITT fax), WebP, JXL, PSD, GIF, BMP (lossy wide-gamut JXL decodes to the right colours: jxl-oxide desaturated XYB rendered to P3/Rec. 2020, worked around in `crates/codecs/src/jxl.rs`); transparency is flattened onto white, in linear light, where the working image is built (`to_working` in `crates/codecs/src/lib.rs`): renders, previews, exports and contact sheets no longer turn transparent areas black, issue #1212; DNG (incl. lossy / Smart Preview DNG and DNG 1.7 JPEG XL tiles/strips: lossless ones decode bit-exactly on synthetic CFA and LinearRaw files, lossy ones are restored to the declared linear primaries without clipping or gamut mapping, checked on one real file with 108 lossy tiles, and any tile that fails to decode makes the file preview-only; DNG 1.7 row/column-interleaved rasters (`RowInterleaveFactor` / `ColumnInterleaveFactor`) are undone before the mosaic is read, so a file from Adobe's converter with a 2×2 interleave no longer decodes as four scaled-down copies in the wrong colours; a dimension the factor does not divide decodes with short trailing fields; verified on 4 real ILCE-6400 JPEG XL DNGs rendering bit-identical to their non-interleaved twins, factors above 2 rest on the plain reading of the tag; a single-chunk JPEG XL preview IFD is offered as the embedded preview; a DNG whose samples pile up at one value well below its stated `WhiteLevel`, as a camera app's 12-bit Bayer DNG that states 4095 and clips at 3567, has those samples raised to the white level on decode, so highlight reconstruction sees the clipped areas instead of white balance tinting them magenta, issue #548, `crates/raw/src/saturation.rs`), CR2 (colour-filter layout from the file's `CR2CFAPattern` tag, issue #85), ARW (pre-2017 bodies: white balance and black level from the encrypted `SR2SubIFD`, issue #148, its `WB_RGGBLevels` being the white balance the camera applied, issue #535; the DSLR-A900's packed 12-bit strip, two pixels per three bytes, read only when the strip is exactly 1.5 bytes per pixel, with its camera-JPEG window centred, checked on one CC0 file (A850 unmeasured); downsized Sony lossless YCbCr 4:2:0 / 4:2:2 tiles decoded to linear RGB, verified on private ILCE-7M4 3:2 & 4:3 examples including 16-bit full-resolution export; Sony DSC-R1 .SR2 decodes, its big-endian 16-bit words read in the order that fits the sample range, checked on the CC0 3221 sample; its crop and white balance live in the SR2SubIFD and are not read yet; ARW6 Compressed / Compressed (HQ) of the ILCE-7RM6 (`crates/raw/src/vendor/arw6.rs`, `crates/raw/src/llvc.rs`; 12-bit codes exact against a black-box oracle on 8 CC0 files, FF over the full frame, APS-C in the interior (LibRaw's own edge rows differ); output through our own companding curve, measured from CC0 lossless / ARW6 pairs; geometry checked against the camera JPEG, `docs/arw6-compression.md`; the ILCE-7M5 writes the same codec, unverified)), NEF (uncompressed, lossless and lossy compressed 12/14-bit, `crates/raw/src/vendor/nefc.rs`), RAF (uncompressed, lossless/lossy compressed Bayer and X-Trans; `crates/raw/src/vendor/rafc.rs`, full sensor verification on 13 bodies, `docs/raf-compression.md`), RW2 / Leica RWL / Panasonic RAW in every raw format (compressed 4 and 6, the prefix-coded strips of format 8 from the GH6 on, packed 2/5/7, the 16-bit words of the 2005–2007 bodies; black levels, in-camera aspect crops and mapped-out defect pixels; 178 CC0 files from 118 bodies checked, `crates/raw/src/vendor/rw2.rs`), PEF, ORF (uncompressed; colour-filter layout from the file's Exif `CFAPattern`; 12.8 bit/px 16-byte blocks of ten 12-bit samples + a zero pad byte, E-300 / E-330 / E-500 verified on CC0 files, E-M5 Mark II / PEN-F high-res files decode smooth but CFA and black unverified), Kodak DCS520C TIFF (a two-component 12-bit lossless JPEG strip, the two components the even and odd columns; the file's `GrayResponseCurve` table linearises the companded samples to 12 bits, black measured per CFA position, white balance from the `KodakIFD`; `RawFormat::KodakDcs`, `crates/raw/src/vendor/kodak.rs`, checked on the one CC0 sample against its IFD0 thumbnail), Hasselblad 3FR and FFF (a TIFF without a DNG version tag that describes its CFA IFD, levels, crop and white balance with DNG's tags; `RawFormat::CfaTiff`, read by `dng::decode_as`, RGGB when the file states no `CFAPattern`): uncompressed (X1D, X1D II, X2D, CFV 100C) and Hasselblad's lossless JPEG with scan selection value 8 (every FFF; H3D, H4D and CFV-50c 3FR), `ljpeg::decode_hasselblad`, its rule measured on 14 CC0 files with the ljpeg-explorer tool, Samsung SRW without compression (NX5, NX10, NX11 and the NX20-generation bodies NX20, NX200, NX210, NX1000 and NX1100 as 12-bit packed samples in either bit order, EX1 and WB200Line truncated
 | LR-IMP-CAMERA-COVERAGE | Camera coverage, verified per model | P0 | 🟡 | `crates/raw/tests/corpus.rs`, `xtask/src/main.rs` | a supported container is not the same as every camera that writes it decoding correctly: ~55 CC0 corpus files plus 6 exact-sensor CR3 cases and 4 pinned EOS R5 Mark II files (plus ~60 NEFs checked by hand and 178 Panasonic / Leica RW2, RWL and RAW files from 118 bodies, checked against each file's own JPEG) against the >1,000 models Lightroom lists; per-model differences still surface (e.g. the CR2 colour-filter layout differed by model until it was read from the file's own tag, issue #85, checked on 35 CR2 bodies; CR2 black levels were read from border columns light already reaches, left of `SensorInfo`'s border, so CR2s rendered dark with crushed shadows (EOS 6D: 2591 instead of 2047), now measured from the masked columns only, checked on 8 corpus bodies; pre-2017 Sony ARWs opened green until their scrambled white balance / black level were read, issue #148, checked on 16 ARWs from 15 Sony bodies; their white balance now comes from the encrypted `SR2SubIFD`'s `WB_RGGBLevels`, the gains the camera applied, which 14 bodies (DSLR-A450 … A700, NEX-3/5/C3, SLT-A33/A35/A55, ILCE-6001, UMC-R10C) had no other source for and which the maker-note estimate read before missed by up to 100 % on preset shots, issue #535, checked against ExifTool on 100 decoded ARWs from 87 Sony bodies; the encrypted SR2 black level is now read from its directory entry (the DSLR-A450/A500/A550/A700 read 354–975 instead of 512), checked on 126 ARWs from 97 Sony bodies, and downsized lossless M/S ARWs use their measured black level 1024 instead of 512, checked on 12 files from 4 bodies, issue #535, and on a fifth, the ILCE-7CM2 (issue #697: 0.5.0 rendered its lossless M file with that 512 pedestal, the darkest half of a dusk scene +11 L* and blue, the lamplight white; its darkest 0.1 % per channel sits at 1017/1020/1024, and with 1024 the render is within +3 L* of the camera JPEG; the body's compressed and uncompressed "M-size" files are Bayer at 4736×3132 with black 512, two public ones in the corpus); pre-2017 Sony bodies shot in the camera's 16:9 mode (ILCE-7SM2, DSLR-A580) now get the 16:9 crop of their camera JPEG instead of the whole 3:2 frame with padding columns, issue #535; Canon PowerShot and EOS M CR2s whose `ColorData` is stored as bytes opened green until the bytes were read as 16-bit words, 25 files from 25 bodies checked). Compressed RAF sensor arrays verified on 13 Fujifilm bodies (`docs/raf-compression.md`). ILCE-7RM6 ARW6 12-bit codes verified on 8 CC0 files (FF and APS-C, both compression modes). Sony ILCE-7CR (61 MP): lossless compressed L and M and compressed ARW2 samples of one scene in the corpus (black level, default crop, as-shot gains, lossless vs compressed mosaic agreement, fitted camera look), and all nine public codings (also uncompressed, small and APS-C crop) decode and fit. Grow the CC0 corpus per model and test each sample decodes with plausible colour. Nikon CropArea and untagged-preview colour-space regression tests; private Z 8 crop verified; the Nikon D4, which records no CropArea, gets its image area and white level measured on 148 NEFs against the camera JPEG (optical-black stripes and magenta clipped highlights gone). |
 | LR-IMP-PREVIEW-READ | Preview reads the header, not the raw | P0 | ✅ | `crates/raw/src/preview.rs` (`bounded_preview`, `embedded_preview_from_range`), `crates/engine/src/files.rs` (`preview_window`), `docs/raw-preview-reads.md` | a grid thumbnail and a loupe preview of an unedited raw show the camera's embedded JPEG, which sits near the start of the file (a 24 MP Fuji RAF keeps its 5.6 MB JPEG in a 56 MB file), so the preview loader reads the header and that JPEG instead of the whole file: 56.5 MB → 5.9 MB and ~10 s → 0.96 s measured on one real RAF over a GVFS/SMB Wi-Fi share (byte-identical preview pixels; `LIGHTCRAFT_PROFILE=1` reports the bytes); the RAF pointer is read from its fixed header fields, formats whose preview only the whole file reveals (CR3 boxes, TIFF pointer tags past the prefix, CRW/MRW/X3F scans) keep the whole-file path, and a lying pointer, a short read or a file that changes underneath us falls back to it rather than losing the preview. An unedited raw's **grid thumbnail is that camera JPEG itself**, so no sensor decode is scheduled behind it (`Session::embedded_thumb_is_final`, `grid::skips_the_real_render`): drawing a 512 px thumbnail used to decode the whole raw — 45 s a photo at 1.2 MB/s, 8.3 GB for a 149-raw folder — and the queue it built delayed the render the user was waiting for; a cached render as stand-in, an edited photo and a raw without an embedded JPEG still render |
 | LR-IMP-CULL-AT-IMPORT | Culling analysis at import | P2 | 🟡 | `cmd:photo.analyze` | run Assisted Culling on the imported photos (they're selected after an import); not automatic |
@@ -787,6 +787,7 @@ Latin stays upright. Advanced Japanese composition remains open. Regression cove
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-12 | minor | LR-IMP-FORMATS: transparent areas are flattened onto white in linear light instead of rendering black (issue #1212); status unchanged (🟡) |
 | 2026-10-11 | minor | KEY-SLIDER-TYPE: honor immediate Return/Escape and keep typed keys in the value editor; add regression references |
 | 2026-10-11 | minor | LR-PROF-CAMERACOLOR: raws with a black-and-white camera JPEG take its tone curve (issue #577) |
 | 2026-10-11 | minor | LR-VIEW-ZOOM and LR-VIEW-COMPARE: Compare and Reference are sharp at 1:1 (zoom windows per pane, two originals kept decoded while they are open); statuses unchanged |