diff --git a/crates/engine/src/export.rs b/crates/engine/src/export.rs
index 403cb71f6..69f4f7b03 100644
--- a/crates/engine/src/export.rs
+++ b/crates/engine/src/export.rs
@@ -1351,7 +1351,15 @@ 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).
@@ -2268,6 +2276,43 @@ 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 7bb187811..4f922e47d 100644
--- a/docs/parity-checklist.md
+++ b/docs/parity-checklist.md
@@ -385,7 +385,7 @@ 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), 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), 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`) | |
 | 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 |
@@ -790,6 +790,7 @@ 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. |
 | 2026-10-13 | patch | LR-VIEW-COMPARE, LRC-LIB-COMPARE: ⌘/Ctrl- and Shift-clicks on the filmstrip in Compare change the selection as in the grid; the two photos shown stay selected and the active photo is unchanged (#187); statuses unchanged |
 | 2026-10-13 | minor | KEYC-SELECTONLYACTIVE: Edit → Select Only Active Photo (⌘⇧D) lands as a new row; status 🟡 (headless-tested, native macOS menu path unverified) |
 | 2026-10-13 | patch | LRC-LIB-CATALOG-IMPORT: a catalog whose tables are all still in its `-wal` file (main file schema format 0) opens instead of failing as an unsupported schema format; status unchanged |