diff --git a/crates/engine/src/export.rs b/crates/engine/src/export.rs
index d294ed4d9..e9d1cbc58 100644
--- a/crates/engine/src/export.rs
+++ b/crates/engine/src/export.rs
@@ -1310,7 +1310,15 @@ pub fn encode_with_metadata(img: &Rgba8, o: &ExportOptions, meta: Option<&Metada
     let exif = meta.map(lightcraft_meta::write_exif);
     let xmp = meta.map(|m| lightcraft_meta::write_xmp(m, None));
     let meta = EncodeMeta { icc: Some(&profile), exif: exif.as_deref(), xmp: xmp.as_deref(), ppi: Some(o.ppi) };
-    let e = EncodeImage::rgba8(&img);
+    // Opaque photo exports need no alpha channel (#1670). Keep real transparency for
+    // callers of this encoder, and leave unrelated formats on their existing path.
+    let rgb: Option<Vec<u8>> = (matches!(o.format, ExportFormat::Png | ExportFormat::Tiff | ExportFormat::Webp)
+        && img.data.iter().all(|p| p.last() == Some(&255)))
+    .then(|| img.data.iter().flat_map(|p| p.iter().take(3).copied()).collect());
+    let e = match &rgb {
+        Some(data) => EncodeImage::new(img.width as u32, img.height as u32, 3, Samples::U8(data)),
+        None => EncodeImage::rgba8(&img),
+    };
     let r = match o.format {
         ExportFormat::Jpeg => {
             // 4:4:4 normally; 4:2:0 when targeting a file size (much smaller at equal visual quality).
@@ -2281,6 +2289,43 @@ mod tests {
         img
     }
 
+    /// Issue #1670: removing a redundant alpha channel preserves samples and metadata.
+    #[test]
+    fn opaque_eight_bit_exports_are_rgb() {
+        let img = test_image();
+        let metadata = Metadata { copyright: Some("Synthetic export test".into()), ..Default::default() };
+        for format in [ExportFormat::Png, ExportFormat::Tiff, ExportFormat::Webp] {
+            for compression in [TiffCompression::None, TiffCompression::Lzw, TiffCompression::Deflate, TiffCompression::PackBits] {
+                let options = ExportOptions { format, tiff_compression: compression, ..Default::default() };
+                let bytes = encode_with_metadata(&img, &options, Some(&metadata)).unwrap();
+                let decoded = lightcraft_codecs::decode(&bytes, Default::default()).unwrap();
+                assert!(!decoded.has_alpha, "{format:?}/{compression:?} must be RGB");
+                assert_eq!((decoded.width, decoded.height, decoded.bit_depth), (96, 64, 8));
+                assert_eq!(decoded.to_srgb8().data, img.data, "{format:?}/{compression:?} pixels");
+                assert_eq!(decoded.icc.as_deref(), Some(icc::write_named(NamedSpace::Srgb).as_slice()));
+                assert!(decoded.xmp.as_deref().unwrap_or_default().contains("Synthetic export test"));
+                if format == ExportFormat::Png {
+                    assert_eq!(bytes[25], 2, "PNG IHDR declares RGB");
+                }
+                if format != ExportFormat::Tiff {
+                    break;
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn eight_bit_exports_preserve_real_alpha() {
+        let mut img = test_image();
+        img.data[0][3] = 128;
+        for format in [ExportFormat::Png, ExportFormat::Tiff, ExportFormat::Webp] {
+            let bytes = encode_image(&img, &ExportOptions { format, ..Default::default() }).unwrap();
+            let decoded = lightcraft_codecs::decode(&bytes, Default::default()).unwrap();
+            assert!(decoded.has_alpha, "{format:?} must retain real alpha");
+            assert_eq!(decoded.to_srgb8().data, img.data, "{format:?} samples");
+        }
+    }
+
     #[test]
     fn formats_have_magic() {
         let img = test_image();
diff --git a/docs/parity-checklist.md b/docs/parity-checklist.md
index aaf2e1dff..0fb8e2d5b 100644
--- a/docs/parity-checklist.md
+++ b/docs/parity-checklist.md
@@ -390,7 +390,7 @@ differences and missing bindings are in [ui-parity.md](ui-parity.md#shortcuts).
 | Id | Feature | Tier | Status | Evidence | Missing / notes |
 |---|---|---|---|---|---|
 | LR-EXP-DIALOG | Export dialog | P0 | ✅ | `cmd:dialog.export`, `cmd:app.export` (`preset`), `cmd:export.presets`, `cmd:export.savePreset`, `cmd:export.deletePreset`, `crates/ui-egui/src/panels/dialogs.rs`, `crates/engine/src/export.rs` | batch export; built-in presets (JPEG Small 2048 px / Large full size, Original + Settings, DNG) and saved user presets (library prefs) load into the dialog; deleting a user preset is command-only; on a short window the options scroll and Cancel / OK stay visible (LR-BEHAV-DIALOGS, issue #781) |
-| LR-EXP-TYPE | File types | P0 | ✅ | `cmd:app.export` (`format`), `crates/engine/src/export.rs` (`ExportFormat`), `crates/engine/src/tests_export.rs` | JPEG, PNG, TIFF, PSD (flat, 8/16-bit, no layers: `crates/codecs/src/psd.rs`), WebP, AVIF, JPEG XL (issue #247: `jixel`, native only; lossy with quality or lossless, 8/16-bit, effort fast/normal (jixel's slowest search left out: jxl-oxide misdecodes its files), progressive, EXIF/XMP boxes; lossy files in Adobe RGB / ProPhoto are written as Rec. 2020, lossless keep any space via ICC; `crates/codecs/src/jxl_encode.rs`), DNG (raw photos: lossless re-encode with the edits in the embedded XMP; a raw without colour matrices of its own, as a NEF, gets the colour it opens with as `ColorMatrix1` / `ForwardMatrix1` / `AsShotNeutral`, also in Convert / Copy as DNG, so other raw converters open it, issue #1745), Original (+ XMP sidecar). Non-raw → DNG not supported; no JPEG XL export in the web build |
+| LR-EXP-TYPE | File types | P0 | ✅ | `cmd:app.export` (`format`), `crates/engine/src/export.rs` (`ExportFormat`), `crates/engine/src/tests_export.rs` | JPEG, PNG, TIFF, PSD (flat, 8/16-bit, no layers: `crates/codecs/src/psd.rs`), WebP, AVIF, JPEG XL (issue #247: `jixel`, native only; lossy with quality or lossless, 8/16-bit, effort fast/normal (jixel's slowest search left out: jxl-oxide misdecodes its files), progressive, EXIF/XMP boxes; lossy files in Adobe RGB / ProPhoto are written as Rec. 2020, lossless keep any space via ICC; `crates/codecs/src/jxl_encode.rs`), DNG (raw photos: lossless re-encode with the edits in the embedded XMP; a raw without colour matrices of its own, as a NEF, gets the colour it opens with as `ColorMatrix1` / `ForwardMatrix1` / `AsShotNeutral`, also in Convert / Copy as DNG, so other raw converters open it, issue #1745), Original (+ XMP sidecar). Non-raw → DNG not supported; no JPEG XL export in the web build. Opaque 8-bit PNG/TIFF/WebP exports omit the redundant alpha channel; real transparency is retained (#1670). |
 | LR-EXP-DIM | Output size | P0 | ✅ | `cmd:app.export` (`longEdge`, `shortEdge`, `width`, `height`, `megapixels`, `percent`, `dontEnlarge`, `ppi`), `crates/engine/src/export.rs` (`Resize`), `crates/ui-egui/src/panels/dialogs.rs` | full size = the cropped native size (no longer upscaled); W × H fits either orientation; ppi written to JFIF / pHYs / TIFF tags; at most 65,535 px an edge, and an export enlarged past the photo's size stops at 512 megapixels (Lightroom's ceiling too) and is refused, with the size it would need, when it needs more memory than the computer has (it aborted the process before) |
 | LR-EXP-QUALITY | JPEG quality | P0 | ✅ | `cmd:app.export` (`quality`, `limitKb`), `crates/codecs/src/jpeg_par.rs` | 4:4:4 chroma (4:2:0 when a file-size limit is set); Huffman tables made for each image from its own symbol counts (T.81 Annex K.2) instead of the example tables: the same pixels, 12–14 % smaller files at quality 80–100 on a 24 MP photo-like image, still interleaved baseline (issue #1373) |
 | LR-EXP-BITDEPTH | Bit depth | P1 | ✅ | `cmd:app.export` (`bitDepth`), `crates/pipeline/src/output.rs` (`OutputDepth`), `crates/engine/src/export.rs` | 16-bit PNG/TIFF/JPEG XL rendered at 16 bits (TIFF defaults to 16), 32-bit float linear TIFF with a linear profile, 10-bit AVIF; high-bit-depth renders run on the CPU |
@@ -797,6 +797,7 @@ Latin stays upright. Advanced Japanese composition remains open. Regression cove
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-14 | patch | LR-EXP-TYPE: opaque 8-bit PNG/TIFF/WebP use RGB; transparent exports retain alpha (#1670). Statuses and feature counts unchanged. |
 | 2026-10-12 | minor | LR-EDIT-OPTICS-PROFILE: Sony ARW shading, CA and distortion tables decoded with settings and provenance (raw IFD, `SR2SubIFD` fallback); applied corrections unchanged (ILCE-7RM4A and ILCE-7RM6 distortion); status unchanged (🟡) |
 | 2026-10-14 | minor | LR-IMP-CAMERA-COVERAGE: Camera-coverage sweep (#1327): 30 models verified on 40 CC0 files (coverage.py 515 → 545 verified); sensor verification does not establish colour parity (#1277); status unchanged (🟡) |
 | 2026-10-13 | minor | LR-MERGE-PANO: a panorama's DNG takes its `AsShotNeutral` from the median of its frames' vendor white-balance multipliers (CR2, NEF, ARW…) instead of the first frame's tags, and frames now carry the multipliers (issue #1144); status unchanged (✅) |