diff --git a/bin/toucan-render/main.cpp b/bin/toucan-render/main.cpp
index 0b8f40f..e7c8364 100644
--- a/bin/toucan-render/main.cpp
+++ b/bin/toucan-render/main.cpp
@@ -102,8 +102,8 @@ int main(int argc, char** argv)
 
     // Initialize the filmstrip.
     OIIO::ImageBuf filmstripBuf;
-    const int thumbnailWidth = 120;
-    const int thumbnailSpacing = 20;
+    const int thumbnailWidth = 360;
+    const int thumbnailSpacing = 0;
     IMATH_NAMESPACE::V2d thumbnailSize;
     if (filmstrip && imageSize.x > 0 && imageSize.y > 0)
     {
diff --git a/bin/toucan-view/App.cpp b/bin/toucan-view/App.cpp
index d4634fe..993108f 100644
--- a/bin/toucan-view/App.cpp
+++ b/bin/toucan-view/App.cpp
@@ -54,7 +54,7 @@ namespace toucan
             context,
             std::dynamic_pointer_cast<App>(shared_from_this()),
             "toucan-view",
-            dtk::Size2I(1920, 1080));
+            dtk::Size2I(1820 * 2, 910 * 2));
         addWindow(_window);
 
         if (!_path.empty())
@@ -89,6 +89,11 @@ namespace toucan
         return _timeUnitsModel;
     }
 
+    const std::shared_ptr<ImageEffectHost>& App::getHost() const
+    {
+        return _host;
+    }
+
     const std::shared_ptr<DocumentsModel>& App::getDocumentsModel() const
     {
         return _documentsModel;
diff --git a/bin/toucan-view/App.h b/bin/toucan-view/App.h
index 52af5ee..d90c71b 100644
--- a/bin/toucan-view/App.h
+++ b/bin/toucan-view/App.h
@@ -28,6 +28,7 @@ namespace toucan
             std::vector<std::string>&);
 
         const std::shared_ptr<TimeUnitsModel>& getTimeUnitsModel() const;
+        const std::shared_ptr<ImageEffectHost>& getHost() const;
         const std::shared_ptr<DocumentsModel>& getDocumentsModel() const;
         const std::shared_ptr<WindowModel>& getWindowModel() const;
 
diff --git a/bin/toucan-view/CMakeLists.txt b/bin/toucan-view/CMakeLists.txt
index 1409f17..f9bc4dc 100644
--- a/bin/toucan-view/CMakeLists.txt
+++ b/bin/toucan-view/CMakeLists.txt
@@ -14,6 +14,7 @@ set(HEADERS
     PlaybackModel.h
     SelectionModel.h
     StackItem.h
+    ThumbnailGenerator.h
     TimeUnitsModel.h
     TimeWidgets.h
     TimelineItem.h
@@ -41,6 +42,7 @@ set(SOURCE
     PlaybackModel.cpp
     SelectionModel.cpp
     StackItem.cpp
+    ThumbnailGenerator.cpp
     TimeUnitsModel.cpp
     TimeWidgets.cpp
     TimelineItem.cpp
diff --git a/bin/toucan-view/Document.cpp b/bin/toucan-view/Document.cpp
index 86fbb99..6d9ffa9 100644
--- a/bin/toucan-view/Document.cpp
+++ b/bin/toucan-view/Document.cpp
@@ -6,6 +6,7 @@
 
 #include "PlaybackModel.h"
 #include "SelectionModel.h"
+#include "ThumbnailGenerator.h"
 #include "ViewModel.h"
 
 #include <dtk/core/Math.h>
@@ -41,6 +42,11 @@ namespace toucan
 
         _selectionModel = std::make_shared<SelectionModel>();
 
+        _thumbnailGenerator = std::make_shared<ThumbnailGenerator>(
+            _path.parent_path(),
+            _timeline,
+            _host);
+
         _currentImage = dtk::ObservableValue<std::shared_ptr<dtk::Image> >::create();
 
         _rootNode = dtk::ObservableValue<std::shared_ptr<IImageNode> >::create();
@@ -93,6 +99,11 @@ namespace toucan
         return _selectionModel;
     }
 
+    const std::shared_ptr<ThumbnailGenerator>& Document::getThumbnailGenerator() const
+    {
+        return _thumbnailGenerator;
+    }
+
     std::shared_ptr<dtk::IObservableValue<std::shared_ptr<dtk::Image> > > Document::observeCurrentImage() const
     {
         return _currentImage;
diff --git a/bin/toucan-view/Document.h b/bin/toucan-view/Document.h
index 3030667..366d899 100644
--- a/bin/toucan-view/Document.h
+++ b/bin/toucan-view/Document.h
@@ -19,6 +19,7 @@ namespace toucan
 {
     class PlaybackModel;
     class SelectionModel;
+    class ThumbnailGenerator;
     class ViewModel;
 
     class Document : std::enable_shared_from_this<Document>
@@ -38,6 +39,7 @@ namespace toucan
         const std::shared_ptr<PlaybackModel>& getPlaybackModel() const;
         const std::shared_ptr<ViewModel>& getViewModel() const;
         const std::shared_ptr<SelectionModel>& getSelectionModel() const;
+        const std::shared_ptr<ThumbnailGenerator>& getThumbnailGenerator() const;
 
         std::shared_ptr<dtk::IObservableValue<std::shared_ptr<dtk::Image> > > observeCurrentImage() const;
 
@@ -54,6 +56,7 @@ namespace toucan
         std::shared_ptr<PlaybackModel> _playbackModel;
         std::shared_ptr<ViewModel> _viewModel;
         std::shared_ptr<SelectionModel> _selectionModel;
+        std::shared_ptr<ThumbnailGenerator> _thumbnailGenerator;
         std::shared_ptr<dtk::ObservableValue<std::shared_ptr<dtk::Image> > > _currentImage;
         OTIO_NS::RationalTime _currentTime;
 
diff --git a/bin/toucan-view/StackItem.cpp b/bin/toucan-view/StackItem.cpp
index c56da05..b040612 100644
--- a/bin/toucan-view/StackItem.cpp
+++ b/bin/toucan-view/StackItem.cpp
@@ -29,6 +29,8 @@ namespace toucan
         _text = !stack->name().empty() ? stack->name() : "Stack";
         _color = dtk::Color4F(.2F, .2F, .2F);
 
+        setTooltip(_text);
+
         for (const auto& child : stack->children())
         {
             if (auto track = OTIO_NS::dynamic_retainer_cast<OTIO_NS::Track>(child))
diff --git a/bin/toucan-view/ThumbnailGenerator.cpp b/bin/toucan-view/ThumbnailGenerator.cpp
new file mode 100644
index 0000000..f3e3c03
--- /dev/null
+++ b/bin/toucan-view/ThumbnailGenerator.cpp
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (c) 2024 Darby Johnston
+// All rights reserved.
+
+#include "ThumbnailGenerator.h"
+
+#include <toucan/ImageGraph.h>
+
+#include <OpenImageIO/imagebufalgo.h>
+
+#include <sstream>
+
+namespace toucan
+{
+    ThumbnailGenerator::ThumbnailGenerator(
+        const std::filesystem::path& path,
+        const OTIO_NS::SerializableObject::Retainer<OTIO_NS::Timeline>& timeline,
+        const std::shared_ptr<ImageEffectHost>& host) :
+        _path(path),
+        _timeline(timeline),
+        _host(host)
+    {
+        _graph = std::make_shared<ImageGraph>(_path, _timeline);
+        const IMATH_NAMESPACE::V2i& imageSize = _graph->getImageSize();
+        _aspect = imageSize.y > 0 ?
+            (imageSize.x / static_cast<float>(imageSize.y)) :
+            0.F;
+    }
+
+    ThumbnailGenerator::~ThumbnailGenerator()
+    {}
+
+    float ThumbnailGenerator::getAspect() const
+    {
+        return _aspect;
+    }
+
+    std::future<Thumbnail> ThumbnailGenerator::getThumbnail(
+        const OTIO_NS::RationalTime& time,
+        int height)
+    {
+        auto graph = _graph->exec(_host, time);
+        return std::async(
+            std::launch::async,
+            [this, graph, time, height]
+            {
+                const auto sourceBuf = graph->exec(time);
+                const auto& sourceSpec = sourceBuf.spec();
+
+                const dtk::Size2I thumbnailSize(height * _aspect, height);
+                dtk::ImageInfo info;
+                info.size = thumbnailSize;
+                switch (sourceSpec.nchannels)
+                {
+                case 1:
+                    switch (sourceSpec.format.basetype)
+                    {
+                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::L_U8; break;
+                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::L_U16; break;
+                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::L_F16; break;
+                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::L_F32; break;
+                    }
+                    break;
+                case 2:
+                    switch (sourceSpec.format.basetype)
+                    {
+                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::LA_U8; break;
+                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::LA_U16; break;
+                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::LA_F16; break;
+                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::LA_F32; break;
+                    }
+                    break;
+                case 3:
+                    switch (sourceSpec.format.basetype)
+                    {
+                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::RGB_U8; break;
+                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::RGB_U16; break;
+                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::RGB_F16; break;
+                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::RGB_F32; break;
+                    }
+                    break;
+                default:
+                    switch (sourceSpec.format.basetype)
+                    {
+                    case OIIO::TypeDesc::UINT8: info.type = dtk::ImageType::RGBA_U8; break;
+                    case OIIO::TypeDesc::UINT16: info.type = dtk::ImageType::RGBA_U16; break;
+                    case OIIO::TypeDesc::HALF: info.type = dtk::ImageType::RGBA_F16; break;
+                    case OIIO::TypeDesc::FLOAT: info.type = dtk::ImageType::RGBA_F32; break;
+                    }
+                    break;
+                }
+                info.layout.mirror.y = true;
+
+                std::shared_ptr<dtk::Image> thumbnail;
+                if (info.isValid())
+                {
+                    thumbnail = dtk::Image::create(info);
+                    auto resizedBuf = OIIO::ImageBufAlgo::resize(
+                        sourceBuf,
+                        "",
+                        0.F,
+                        OIIO::ROI(
+                            0, info.size.w,
+                            0, info.size.h,
+                            0, 1,
+                            0, std::min(4, sourceSpec.nchannels)));
+                    memcpy(
+                        thumbnail->getData(),
+                        resizedBuf.localpixels(),
+                        thumbnail->getByteCount());
+                }
+                return Thumbnail{ time, thumbnail };
+            });
+    }
+}
diff --git a/bin/toucan-view/ThumbnailGenerator.h b/bin/toucan-view/ThumbnailGenerator.h
new file mode 100644
index 0000000..9e6799e
--- /dev/null
+++ b/bin/toucan-view/ThumbnailGenerator.h
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (c) 2024 Darby Johnston
+// All rights reserved.
+
+#pragma once
+
+#include <toucan/ImageEffectHost.h>
+#include <toucan/ImageGraph.h>
+
+#include <dtk/core/Image.h>
+
+#include <opentimelineio/timeline.h>
+
+#include <filesystem>
+#include <future>
+
+namespace toucan
+{
+    struct Thumbnail
+    {
+        OTIO_NS::RationalTime time;
+        std::shared_ptr<dtk::Image> image;
+    };
+
+    class ThumbnailGenerator : public std::enable_shared_from_this<ThumbnailGenerator>
+    {
+    public:
+        ThumbnailGenerator(
+            const std::filesystem::path&,
+            const OTIO_NS::SerializableObject::Retainer<OTIO_NS::Timeline>&,
+            const std::shared_ptr<ImageEffectHost>&);
+
+        ~ThumbnailGenerator();
+
+        float getAspect() const;
+
+        std::future<Thumbnail> getThumbnail(
+            const OTIO_NS::RationalTime&,
+            int height);
+
+    private:
+        std::filesystem::path _path;
+        OTIO_NS::SerializableObject::Retainer<OTIO_NS::Timeline> _timeline;
+        std::shared_ptr<ImageEffectHost> _host;
+        std::shared_ptr<ImageGraph> _graph;
+        float _aspect = 1.F;
+    };
+}
diff --git a/bin/toucan-view/TimelineItem.cpp b/bin/toucan-view/TimelineItem.cpp
index b573724..5217b00 100644
--- a/bin/toucan-view/TimelineItem.cpp
+++ b/bin/toucan-view/TimelineItem.cpp
@@ -43,6 +43,7 @@ namespace toucan
         _timeline = timeline;
         _timeUnitsModel = app->getTimeUnitsModel();
         _selectionModel = document->getSelectionModel();
+        _thumbnailGenerator = document->getThumbnailGenerator();
 
         StackItem::create(context, app, _timeline->tracks(), shared_from_this());
 
@@ -133,7 +134,7 @@ namespace toucan
             const dtk::Size2I& sizeHint = child->getSizeHint();
             child->setGeometry(dtk::Box2I(
                 g.min.x,
-                g.min.y + timeHeight,
+                g.min.y + timeHeight + _size.thumbnailSize.h,
                 sizeHint.w,
                 sizeHint.h));
         }
@@ -143,6 +144,21 @@ namespace toucan
         }
     }
 
+    void TimelineItem::tickEvent(
+        bool parentsVisible,
+        bool parentsEnabled,
+        const dtk::TickEvent& event)
+    {
+        IItem::tickEvent(parentsVisible, parentsEnabled, event);
+        if (_thumbnailFuture.valid() &&
+            _thumbnailFuture.wait_for(std::chrono::seconds(0)) == std::future_status::ready)
+        {
+            const auto thumbnail = _thumbnailFuture.get();
+            _thumbnails[thumbnail.time] = thumbnail.image;
+            _setDrawUpdate();
+        }
+    }
+
     void TimelineItem::sizeHintEvent(const dtk::SizeHintEvent& event)
     {
         IItem::sizeHintEvent(event);
@@ -154,8 +170,12 @@ namespace toucan
             _size.margin = event.style->getSizeRole(dtk::SizeRole::MarginInside, event.displayScale);
             _size.border = event.style->getSizeRole(dtk::SizeRole::Border, event.displayScale);
             _size.handle = event.style->getSizeRole(dtk::SizeRole::Handle, event.displayScale);
+            _size.thumbnailSize.h = 2 * event.style->getSizeRole(dtk::SizeRole::SwatchLarge, event.displayScale);
+            _size.thumbnailSize.w = _size.thumbnailSize.h * _thumbnailGenerator->getAspect();
             _size.fontInfo = event.style->getFontRole(dtk::FontRole::Label, event.displayScale);
             _size.fontMetrics = event.fontSystem->getMetrics(_size.fontInfo);
+            _thumbnailFuture = std::future<Thumbnail>();
+            _thumbnails.clear();
         }
         int childSizeHint = 0;
         for (const auto& child : getChildren())
@@ -164,10 +184,41 @@ namespace toucan
         }
         dtk::Size2I sizeHint(
             _timeRange.duration().rescaled_to(1.0).value() * _scale,
-            _size.fontMetrics.lineHeight + _size.margin * 2 + childSizeHint);
+            _size.fontMetrics.lineHeight + _size.margin * 2);
+        sizeHint.h += _size.thumbnailSize.h;
+        sizeHint.h += childSizeHint;
         _setSizeHint(sizeHint);
     }
 
+    void TimelineItem::drawEvent(const dtk::Box2I& drawRect, const dtk::DrawEvent& event)
+    {
+        IItem::drawEvent(drawRect, event);
+        const dtk::Box2I& g = getGeometry();
+        const int y = g.min.y + _size.fontMetrics.lineHeight + _size.margin * 2;
+        for (int x = g.min.x; x < g.max.x; x += _size.thumbnailSize.w)
+        {
+            const dtk::Box2I g2(x, y, _size.thumbnailSize.w, _size.thumbnailSize.h);
+            if (dtk::intersects(g2, drawRect))
+            {
+                const OTIO_NS::RationalTime t = posToTime(x);
+                const auto i = _thumbnails.find(t);
+                if (i != _thumbnails.end())
+                {
+                    if (i->second)
+                    {
+                        event.render->drawImage(
+                            i->second,
+                            dtk::Box2I(x, y, i->second->getWidth(), i->second->getHeight()));
+                    }
+                }
+                else if (!_thumbnailFuture.valid())
+                {
+                    _thumbnailFuture = _thumbnailGenerator->getThumbnail(t, _size.thumbnailSize.h);
+                }
+            }
+        }
+    }
+
     void TimelineItem::drawOverlayEvent(const dtk::Box2I& drawRect, const dtk::DrawEvent& event)
     {
         IItem::drawOverlayEvent(drawRect, event);
diff --git a/bin/toucan-view/TimelineItem.h b/bin/toucan-view/TimelineItem.h
index ca3ea1c..381e40e 100644
--- a/bin/toucan-view/TimelineItem.h
+++ b/bin/toucan-view/TimelineItem.h
@@ -6,6 +6,7 @@
 
 #include "IItem.h"
 #include "SelectionModel.h"
+#include "ThumbnailGenerator.h"
 #include "TimeUnitsModel.h"
 
 namespace toucan
@@ -38,7 +39,12 @@ namespace toucan
         int timeToPos(const OTIO_NS::RationalTime&) const;
 
         void setGeometry(const dtk::Box2I&) override;
+        void tickEvent(
+            bool parentsVisible,
+            bool parentsEnabled,
+            const dtk::TickEvent&) override;
         void sizeHintEvent(const dtk::SizeHintEvent&) override;
+        void drawEvent(const dtk::Box2I&, const dtk::DrawEvent&) override;
         void drawOverlayEvent(const dtk::Box2I&, const dtk::DrawEvent&) override;
         void mouseMoveEvent(dtk::MouseMoveEvent&) override;
         void mousePressEvent(dtk::MouseClickEvent&) override;
@@ -70,6 +76,9 @@ namespace toucan
         std::function<void(const OTIO_NS::RationalTime&)> _currentTimeCallback;
         std::shared_ptr<TimeUnitsModel> _timeUnitsModel;
         std::shared_ptr<SelectionModel> _selectionModel;
+        std::shared_ptr<ThumbnailGenerator> _thumbnailGenerator;
+        std::future<Thumbnail> _thumbnailFuture;
+        std::map<OTIO_NS::RationalTime, std::shared_ptr<dtk::Image> > _thumbnails;
 
         struct SizeData
         {
@@ -78,6 +87,7 @@ namespace toucan
             int margin = 0;
             int border = 0;
             int handle = 0;
+            dtk::Size2I thumbnailSize;
             dtk::FontInfo fontInfo;
             dtk::FontMetrics fontMetrics;
             dtk::V2I scrollPos;
diff --git a/bin/toucan-view/TrackItem.cpp b/bin/toucan-view/TrackItem.cpp
index d9acc52..5b92691 100644
--- a/bin/toucan-view/TrackItem.cpp
+++ b/bin/toucan-view/TrackItem.cpp
@@ -33,6 +33,8 @@ namespace toucan
             dtk::Color4F(.2F, .2F, .3F) :
             dtk::Color4F(.2F, .3F, .2F);
 
+        setTooltip(_text);
+
         for (const auto& child : track->children())
         {
             if (auto clip = OTIO_NS::dynamic_retainer_cast<OTIO_NS::Clip>(child))