diff --git a/docs/manual/README.md b/docs/manual/README.md
index 15c6008..4b368be 100644
--- a/docs/manual/README.md
+++ b/docs/manual/README.md
@@ -205,6 +205,35 @@ the sensor recorded.
 
 ![Zooming to 1:1 with a double-click, panning, then further in with the wheel](media/develop-zoom.gif)
 
+### AI denoise
+
+For a photograph taken in poor light at a high ISO. `AI Denoise`, in the
+Detail group, replaces how the camera's raw data is turned into colour: a
+network trained on this library's own photographs removes the noise and
+the blotches of colour that come with it, while keeping the fine detail.
+Look at it at 1:1, where noise lives.
+
+Switch it on with `Apply`. The photograph keeps showing as it was while
+the network works, with its progress in the bar at the top, and changes
+when it is done — a few seconds on a computer with a graphics card, about
+fifteen on its processor alone, longer on the tablet. `Keep grain` puts
+back some of what was removed, as grain without colour, for a picture that
+does not look too smooth.
+
+![An ISO 8000 night frame at 1:1, AI Denoise switched on, then some grain kept](media/develop-denoise.gif)
+
+| Before | After |
+|---|---|
+| ![The railing and the lamp at ISO 8000, as the camera recorded them](media/develop-denoise-before.png) | ![The same, with AI Denoise](media/develop-denoise-after.png) |
+
+It works on raw files from any camera with the usual colour pattern of
+red, green and blue squares — not on JPEGs, and not yet on Fujifilm's
+X-Trans. How noisy the camera is at each ISO was measured for the Canon
+EOS 6D; for other cameras it is read from a DNG's own figures or
+estimated from the photograph, and the finished job in the activity list
+says which. An export uses
+it whenever the photograph has it switched on.
+
 ### Moving between photographs
 
 The roll along the foot of the canvas holds the photographs the grid was
diff --git a/docs/manual/index.html b/docs/manual/index.html
index cc903d8..3939c00 100644
--- a/docs/manual/index.html
+++ b/docs/manual/index.html
@@ -117,6 +117,7 @@ th { color: var(--ink-dim); font-weight: 600; }
 <ul>
 <li><a href="#light">Light</a></li>
 <li><a href="#looking-closer">Looking closer</a></li>
+<li><a href="#ai-denoise">AI denoise</a></li>
 <li><a href="#moving-between-photographs">Moving between photographs</a></li>
 <li><a href="#white-balance-from-the-photograph">White balance from the photograph</a></li>
 <li><a href="#composing">Composing</a></li>
@@ -287,6 +288,29 @@ wheel zooms to any amount in between. Past 1:1 the file's own pixels are
 drawn as hard-edged blocks rather than smoothed, so what you see is what
 the sensor recorded.</p>
 <figure><img loading="lazy" src="media/develop-zoom.gif" alt="Zooming to 1:1 with a double-click, panning, then further in with the wheel"><figcaption>Zooming to 1:1 with a double-click, panning, then further in with the wheel</figcaption></figure>
+<h3 id="ai-denoise">AI denoise</h3>
+<p>For a photograph taken in poor light at a high ISO. <code>AI Denoise</code>, in the
+Detail group, replaces how the camera's raw data is turned into colour: a
+network trained on this library's own photographs removes the noise and
+the blotches of colour that come with it, while keeping the fine detail.
+Look at it at 1:1, where noise lives.</p>
+<p>Switch it on with <code>Apply</code>. The photograph keeps showing as it was while
+the network works, with its progress in the bar at the top, and changes
+when it is done — a few seconds on a computer with a graphics card, about
+fifteen on its processor alone, longer on the tablet. <code>Keep grain</code> puts
+back some of what was removed, as grain without colour, for a picture that
+does not look too smooth.</p>
+<figure><img loading="lazy" src="media/develop-denoise.gif" alt="An ISO 8000 night frame at 1:1, AI Denoise switched on, then some grain kept"><figcaption>An ISO 8000 night frame at 1:1, AI Denoise switched on, then some grain kept</figcaption></figure>
+<table><thead><tr><th>Before</th><th>After</th></tr></thead><tbody>
+<tr><td><img src="media/develop-denoise-before.png" alt="The railing and the lamp at ISO 8000, as the camera recorded them" /></td><td><img src="media/develop-denoise-after.png" alt="The same, with AI Denoise" /></td></tr>
+</tbody></table>
+<p>It works on raw files from any camera with the usual colour pattern of
+red, green and blue squares — not on JPEGs, and not yet on Fujifilm's
+X-Trans. How noisy the camera is at each ISO was measured for the Canon
+EOS 6D; for other cameras it is read from a DNG's own figures or
+estimated from the photograph, and the finished job in the activity list
+says which. An export uses
+it whenever the photograph has it switched on.</p>
 <h3 id="moving-between-photographs">Moving between photographs</h3>
 <p>The roll along the foot of the canvas holds the photographs the grid was
 showing; click one to open it. The right arrow, <code>D</code> or space opens the next,
diff --git a/docs/manual/media/develop-denoise-after.png b/docs/manual/media/develop-denoise-after.png
new file mode 100644
index 0000000..68f5751
--- /dev/null
+++ b/docs/manual/media/develop-denoise-after.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d68ed4c943ff7848f4010f1ac64d5ff25e0dbdc6afd7de0780e4d44c31a3217a
+size 1018071
diff --git a/docs/manual/media/develop-denoise-before.png b/docs/manual/media/develop-denoise-before.png
new file mode 100644
index 0000000..44f0784
--- /dev/null
+++ b/docs/manual/media/develop-denoise-before.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:30be3acd23e36208bd536096b964560f822fae39f80ce5125fd179000e8d1da4
+size 2394740
diff --git a/docs/manual/media/develop-denoise.gif b/docs/manual/media/develop-denoise.gif
new file mode 100644
index 0000000..b650b53
--- /dev/null
+++ b/docs/manual/media/develop-denoise.gif
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:5f2fecb1a22fdba6745ed0e208ae69528fc9999316acffe5ac780fc580e26faf
+size 1186287
diff --git a/tools/manual/scenes.py b/tools/manual/scenes.py
index a0d0030..c0403a9 100755
--- a/tools/manual/scenes.py
+++ b/tools/manual/scenes.py
@@ -63,6 +63,7 @@ ALPS_SKY = '_MG_8330'       # an upright alpine frame, its top third sky and clo
 TOWER = '_MG_8693'          # towers shot looking up: verticals that converge
 ROAD = '_MG_8672'           # a road under a sky, with marks on it: masks and repair
 ROAD_MARK = (0.305, 0.794)  # a dark mark on its tarmac
+DENOISE = '_MG_8862'        # Brooklyn Bridge at ISO 8000: a lit railing, a lamp and a camera against the night
 
 # --- the registry -----------------------------------------------------------
 SCENES = {}
@@ -841,6 +842,68 @@ def develop_zoom():
     pause(1.2)
 
 
+@scene(media=['develop-denoise.gif', 'develop-denoise-before.png', 'develop-denoise-after.png'],
+       sources=DEVELOP_SRC + ['ui/dr-ui/src/develop/denoise.rs', 'core/dr-denoise/**',
+                              'core/dr-gpu/src/grain.rs', 'models/denoise/**'])
+def develop_denoise():
+    """A night frame at ISO 8000 at 1:1, AI Denoise switched on and landed,
+    then some grain kept. Waits for the network rather than for a fixed
+    time: on the CPU it takes several times what it does on a GPU."""
+    at_develop(DENOISE)
+    a = dr.photo(0.45, 0.55)         # the lit lamp, the railing and the skyline over the water
+    dr.move(*a)
+    pause(0.3)
+    dr.x('click', '--repeat', 2, '--delay', 80, 1)
+    pause(1.5)
+    group('Detail')
+    in_column('AI Denoise@Text')
+    shot('develop-denoise-before')
+    rec('develop-denoise')
+    pause(0.8)
+    mark = log_size()
+    dr.click(*denoise_switch())
+    t0 = time.time()
+    while time.time() - t0 < 300 and not denoise_landed(mark):
+        pause(0.5)
+    pause(1.5)
+    shot('develop-denoise-after')
+    slide('Keep grain', 60)
+    pause(2.0)
+    cut()
+    undo_all()
+    dr.move(*a)
+    dr.x('click', '--repeat', 2, '--delay', 80, 1)
+    pause(1.2)
+
+
+def denoise_switch():
+    """The `Apply` box under the AI Denoise heading — the lens profile's
+    switch is also called Apply, so it is found by where it sits."""
+    head = dr.matches('AI Denoise@Text', within=column())[0]
+    below = [e for e in dr.matches('Apply@CheckBox', within=column()) if e['y'] > head['y']]
+    e = min(below, key=lambda e: e['y'])
+    return int(e['x'] + e['w'] / 2), int(e['y'] + e['h'] / 2)
+
+
+def log_size():
+    try:
+        return os.path.getsize(f'{dr.HOME}/app.log')
+    except OSError:
+        return 0
+
+
+def denoise_landed(since):
+    """The app has logged the result landing since `since` bytes into its
+    log. The activity bar's progress has no name to wait on, and the time
+    it takes is the device's — seconds on a GPU, more on the CPU."""
+    try:
+        with open(f'{dr.HOME}/app.log', 'rb') as f:
+            f.seek(since)
+            return b'learned denoise:' in f.read()
+    except OSError:
+        return False
+
+
 @scene(media=['develop-wb.gif'], sources=DEVELOP_SRC + ['ui/dr-ui/src/develop/white_balance.rs'])
 def develop_wb():
     at_develop()