diff --git a/wgpu/src/image/cache.rs b/wgpu/src/image/cache.rs
index 8eea9771..b05e8ccd 100644
--- a/wgpu/src/image/cache.rs
+++ b/wgpu/src/image/cache.rs
@@ -2,11 +2,11 @@ use crate::core::{self, Size};
 use crate::graphics::Shell;
 use crate::image::atlas::{self, Atlas};
 
-#[cfg(feature = "image")]
-use std::collections::HashMap;
+#[cfg(all(feature = "image", not(target_arch = "wasm32")))]
+use worker::Worker;
 
 #[cfg(feature = "image")]
-use std::sync::mpsc;
+use std::collections::HashMap;
 
 use std::sync::Arc;
 
@@ -16,14 +16,8 @@ pub struct Cache {
     raster: Raster,
     #[cfg(feature = "svg")]
     vector: crate::image::vector::Cache,
-    #[cfg(feature = "image")]
-    jobs: mpsc::SyncSender<Job>,
-    #[cfg(feature = "image")]
-    quit: mpsc::SyncSender<()>,
-    #[cfg(feature = "image")]
-    work: mpsc::Receiver<Work>,
     #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
-    worker_: Option<std::thread::JoinHandle<()>>,
+    worker: Worker,
 }
 
 impl Cache {
@@ -35,33 +29,20 @@ impl Cache {
         _shell: &Shell,
     ) -> Self {
         #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
-        let (worker, jobs, quit, work) =
+        let worker =
             Worker::new(device, _queue, backend, layout.clone(), _shell);
 
-        #[cfg(all(feature = "image", target_arch = "wasm32"))]
-        let (jobs, work) = (mpsc::sync_channel(0).0, mpsc::sync_channel(0).1);
-
-        #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
-        let handle = std::thread::spawn(move || worker.run());
-
         Self {
             atlas: Atlas::new(device, backend, layout),
             #[cfg(feature = "image")]
             raster: Raster {
                 cache: crate::image::raster::Cache::default(),
                 pending: HashMap::new(),
-                jobs: jobs.clone(),
             },
             #[cfg(feature = "svg")]
             vector: crate::image::vector::Cache::default(),
-            #[cfg(feature = "image")]
-            jobs,
-            #[cfg(feature = "image")]
-            quit,
-            #[cfg(feature = "image")]
-            work,
             #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
-            worker_: Some(handle),
+            worker,
         }
     }
 
@@ -100,7 +81,7 @@ impl Cache {
         }
 
         let _ = self.raster.pending.insert(handle.id(), vec![callback]);
-        let _ = self.raster.jobs.send(Job::Load(handle.clone()));
+        self.worker.load(handle);
     }
 
     #[cfg(feature = "image")]
@@ -110,7 +91,7 @@ impl Cache {
         if let Some(memory) = load_image(
             &mut self.raster.cache,
             &mut self.raster.pending,
-            &mut self.raster.jobs,
+            &self.worker,
             handle,
             None,
         ) {
@@ -141,7 +122,7 @@ impl Cache {
         let memory = load_image(
             &mut self.raster.cache,
             &mut self.raster.pending,
-            &mut self.raster.jobs,
+            &self.worker,
             handle,
             None,
         )?;
@@ -183,14 +164,8 @@ impl Cache {
         }
 
         if !self.raster.pending.contains_key(&handle.id()) {
-            let _ = self.jobs.send(Job::Upload {
-                handle: handle.clone(),
-                rgba: image.clone().into_raw(),
-                width: image.width(),
-                height: image.height(),
-            });
-
             let _ = self.raster.pending.insert(handle.id(), Vec::new());
+            self.worker.upload(handle, image);
         }
 
         None
@@ -225,7 +200,7 @@ impl Cache {
     pub fn trim(&mut self) {
         #[cfg(feature = "image")]
         self.raster.cache.trim(&mut self.atlas, |bind_group| {
-            let _ = self.jobs.send(Job::Drop(bind_group));
+            self.worker.drop(bind_group);
         });
 
         #[cfg(feature = "svg")]
@@ -236,9 +211,9 @@ impl Cache {
     fn receive(&mut self) {
         use crate::image::raster::Memory;
 
-        while let Ok(work) = self.work.try_recv() {
+        while let Ok(work) = self.worker.try_recv() {
             match work {
-                Work::Upload {
+                worker::Work::Upload {
                     handle,
                     entry,
                     bind_group,
@@ -270,7 +245,7 @@ impl Cache {
                         },
                     );
                 }
-                Work::Error { handle, error } => {
+                worker::Work::Error { handle, error } => {
                     self.raster.cache.insert(&handle, Memory::error(error));
                 }
             }
@@ -281,9 +256,7 @@ impl Cache {
 #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
 impl Drop for Cache {
     fn drop(&mut self) {
-        let _ = self.quit.try_send(());
-        let _ = self.jobs.send(Job::Quit);
-        let _ = self.worker_.take().unwrap().join();
+        self.worker.quit();
     }
 }
 
@@ -291,7 +264,6 @@ impl Drop for Cache {
 struct Raster {
     cache: crate::image::raster::Cache,
     pending: HashMap<core::image::Id, Vec<Callback>>,
-    jobs: mpsc::SyncSender<Job>,
 }
 
 #[cfg(feature = "image")]
@@ -301,7 +273,7 @@ type Callback = Box<dyn FnOnce(core::image::Allocation) + Send>;
 fn load_image<'a>(
     cache: &'a mut crate::image::raster::Cache,
     pending: &mut HashMap<core::image::Id, Vec<Callback>>,
-    jobs: &mut mpsc::SyncSender<Job>,
+    worker: &Worker,
     handle: &core::image::Handle,
     callback: Option<Callback>,
 ) -> Option<&'a mut crate::image::raster::Memory> {
@@ -315,74 +287,45 @@ fn load_image<'a>(
             // Load RGBA handles synchronously, since it's very cheap
             cache.insert(handle, Memory::load(handle));
         } else if !pending.contains_key(&handle.id()) {
-            let _ = jobs.send(Job::Load(handle.clone()));
             let _ = pending.insert(handle.id(), Vec::from_iter(callback));
+            worker.load(handle);
         }
     }
 
     cache.get_mut(handle)
 }
 
-#[cfg(feature = "image")]
-#[derive(Debug)]
-enum Job {
-    Load(core::image::Handle),
-    Upload {
-        handle: core::image::Handle,
-        rgba: core::image::Bytes,
-        width: u32,
-        height: u32,
-    },
-    Drop(Arc<wgpu::BindGroup>),
-    Quit,
-}
-
-#[cfg(feature = "image")]
-enum Work {
-    Upload {
-        handle: core::image::Handle,
-        entry: atlas::Entry,
-        bind_group: Arc<wgpu::BindGroup>,
-    },
-    Error {
-        handle: core::image::Handle,
-        error: crate::graphics::image::image_rs::error::ImageError,
-    },
-}
-
-#[cfg(feature = "image")]
-struct Worker {
-    device: wgpu::Device,
-    queue: wgpu::Queue,
-    backend: wgpu::Backend,
-    texture_layout: wgpu::BindGroupLayout,
-    shell: Shell,
-    belt: wgpu::util::StagingBelt,
-    jobs: mpsc::Receiver<Job>,
-    output: mpsc::SyncSender<Work>,
-    quit: mpsc::Receiver<()>,
-}
-
 #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
-impl Worker {
-    fn new(
-        device: &wgpu::Device,
-        queue: &wgpu::Queue,
-        backend: wgpu::Backend,
-        texture_layout: wgpu::BindGroupLayout,
-        shell: &Shell,
-    ) -> (
-        Self,
-        mpsc::SyncSender<Job>,
-        mpsc::SyncSender<()>,
-        mpsc::Receiver<Work>,
-    ) {
-        let (jobs_sender, jobs_receiver) = mpsc::sync_channel(1_000);
-        let (quit_sender, quit_receiver) = mpsc::sync_channel(1);
-        let (work_sender, work_receiver) = mpsc::sync_channel(1_000);
+mod worker {
+    use crate::core::image;
+    use crate::graphics::Shell;
+    use crate::image::atlas::{self, Atlas};
+    use crate::image::raster;
 
-        (
-            Self {
+    use std::sync::Arc;
+    use std::sync::mpsc;
+    use std::thread;
+
+    pub struct Worker {
+        jobs: mpsc::SyncSender<Job>,
+        quit: mpsc::SyncSender<()>,
+        work: mpsc::Receiver<Work>,
+        handle: Option<std::thread::JoinHandle<()>>,
+    }
+
+    impl Worker {
+        pub fn new(
+            device: &wgpu::Device,
+            queue: &wgpu::Queue,
+            backend: wgpu::Backend,
+            texture_layout: wgpu::BindGroupLayout,
+            shell: &Shell,
+        ) -> Self {
+            let (jobs_sender, jobs_receiver) = mpsc::sync_channel(1_000);
+            let (quit_sender, quit_receiver) = mpsc::sync_channel(1);
+            let (work_sender, work_receiver) = mpsc::sync_channel(1_000);
+
+            let instance = Instance {
                 device: device.clone(),
                 queue: queue.clone(),
                 backend,
@@ -392,114 +335,190 @@ impl Worker {
                 jobs: jobs_receiver,
                 output: work_sender,
                 quit: quit_receiver,
-            },
-            jobs_sender,
-            quit_sender,
-            work_receiver,
-        )
-    }
-
-    fn run(mut self) {
-        loop {
-            if self.quit.try_recv().is_ok() {
-                return;
-            }
-
-            let Ok(job) = self.jobs.recv() else {
-                return;
             };
 
-            match job {
-                Job::Load(handle) => {
-                    match crate::graphics::image::load(&handle) {
-                        Ok(image) => self.upload(
-                            handle,
-                            image.width(),
-                            image.height(),
-                            image.into_raw(),
-                            Shell::invalidate_layout,
-                        ),
-                        Err(error) => {
-                            let _ =
-                                self.output.send(Work::Error { handle, error });
-                        }
-                    }
-                }
-                Job::Upload {
-                    handle,
-                    rgba,
-                    width,
-                    height,
-                } => {
-                    self.upload(
-                        handle,
-                        width,
-                        height,
-                        rgba,
-                        Shell::request_redraw,
-                    );
-                }
-                Job::Drop(bind_group) => {
-                    drop(bind_group);
-                }
-                Job::Quit => return,
+            let handle = thread::spawn(move || instance.run());
+
+            Self {
+                jobs: jobs_sender,
+                quit: quit_sender,
+                work: work_receiver,
+                handle: Some(handle),
             }
         }
+
+        pub fn load(&self, handle: &image::Handle) {
+            let _ = self.jobs.send(Job::Load(handle.clone()));
+        }
+
+        pub fn upload(&self, handle: &image::Handle, image: raster::Image) {
+            let _ = self.jobs.send(Job::Upload {
+                handle: handle.clone(),
+                width: image.width(),
+                height: image.height(),
+                rgba: image.into_raw(),
+            });
+        }
+
+        pub fn drop(&self, bind_group: Arc<wgpu::BindGroup>) {
+            let _ = self.jobs.send(Job::Drop(bind_group));
+        }
+
+        pub fn try_recv(&self) -> Result<Work, mpsc::TryRecvError> {
+            self.work.try_recv()
+        }
+
+        pub fn quit(&mut self) {
+            let _ = self.quit.try_send(());
+            let _ = self.jobs.send(Job::Quit);
+            let _ = self.handle.take().map(thread::JoinHandle::join);
+        }
     }
 
-    fn upload(
-        &mut self,
-        handle: core::image::Handle,
-        width: u32,
-        height: u32,
-        rgba: core::image::Bytes,
-        callback: fn(&Shell),
-    ) {
-        let mut encoder = self.device.create_command_encoder(
-            &wgpu::CommandEncoderDescriptor {
-                label: Some("raster image upload"),
-            },
-        );
+    pub struct Instance {
+        device: wgpu::Device,
+        queue: wgpu::Queue,
+        backend: wgpu::Backend,
+        texture_layout: wgpu::BindGroupLayout,
+        shell: Shell,
+        belt: wgpu::util::StagingBelt,
+        jobs: mpsc::Receiver<Job>,
+        output: mpsc::SyncSender<Work>,
+        quit: mpsc::Receiver<()>,
+    }
 
-        let mut atlas = Atlas::with_size(
-            &self.device,
-            self.backend,
-            self.texture_layout.clone(),
-            width.max(height),
-        );
+    #[cfg(feature = "image")]
+    #[derive(Debug)]
+    enum Job {
+        Load(image::Handle),
+        Upload {
+            handle: image::Handle,
+            rgba: image::Bytes,
+            width: u32,
+            height: u32,
+        },
+        Drop(Arc<wgpu::BindGroup>),
+        Quit,
+    }
 
-        let Some(entry) = atlas.upload(
-            &self.device,
-            &mut encoder,
-            &mut self.belt,
-            width,
-            height,
-            &rgba,
-        ) else {
-            return;
-        };
+    #[cfg(feature = "image")]
+    pub enum Work {
+        Upload {
+            handle: image::Handle,
+            entry: atlas::Entry,
+            bind_group: Arc<wgpu::BindGroup>,
+        },
+        Error {
+            handle: image::Handle,
+            error: crate::graphics::image::image_rs::error::ImageError,
+        },
+    }
 
-        let output = self.output.clone();
-        let shell = self.shell.clone();
+    #[cfg(all(feature = "image", not(target_arch = "wasm32")))]
+    impl Instance {
+        fn run(mut self) {
+            loop {
+                if self.quit.try_recv().is_ok() {
+                    return;
+                }
 
-        self.belt.finish();
-        let submission = self.queue.submit([encoder.finish()]);
-        self.belt.recall();
+                let Ok(job) = self.jobs.recv() else {
+                    return;
+                };
 
-        let bind_group = atlas.bind_group().clone();
+                match job {
+                    Job::Load(handle) => {
+                        match crate::graphics::image::load(&handle) {
+                            Ok(image) => self.upload(
+                                handle,
+                                image.width(),
+                                image.height(),
+                                image.into_raw(),
+                                Shell::invalidate_layout,
+                            ),
+                            Err(error) => {
+                                let _ = self
+                                    .output
+                                    .send(Work::Error { handle, error });
+                            }
+                        }
+                    }
+                    Job::Upload {
+                        handle,
+                        rgba,
+                        width,
+                        height,
+                    } => {
+                        self.upload(
+                            handle,
+                            width,
+                            height,
+                            rgba,
+                            Shell::request_redraw,
+                        );
+                    }
+                    Job::Drop(bind_group) => {
+                        drop(bind_group);
+                    }
+                    Job::Quit => return,
+                }
+            }
+        }
 
-        self.queue.on_submitted_work_done(move || {
-            let _ = output.send(Work::Upload {
-                handle,
-                entry,
-                bind_group,
+        fn upload(
+            &mut self,
+            handle: image::Handle,
+            width: u32,
+            height: u32,
+            rgba: image::Bytes,
+            callback: fn(&Shell),
+        ) {
+            let mut encoder = self.device.create_command_encoder(
+                &wgpu::CommandEncoderDescriptor {
+                    label: Some("raster image upload"),
+                },
+            );
+
+            let mut atlas = Atlas::with_size(
+                &self.device,
+                self.backend,
+                self.texture_layout.clone(),
+                width.max(height),
+            );
+
+            let Some(entry) = atlas.upload(
+                &self.device,
+                &mut encoder,
+                &mut self.belt,
+                width,
+                height,
+                &rgba,
+            ) else {
+                return;
+            };
+
+            let output = self.output.clone();
+            let shell = self.shell.clone();
+
+            self.belt.finish();
+            let submission = self.queue.submit([encoder.finish()]);
+            self.belt.recall();
+
+            let bind_group = atlas.bind_group().clone();
+
+            self.queue.on_submitted_work_done(move || {
+                let _ = output.send(Work::Upload {
+                    handle,
+                    entry,
+                    bind_group,
+                });
+
+                callback(&shell);
             });
 
-            callback(&shell);
-        });
-
-        let _ = self
-            .device
-            .poll(wgpu::PollType::WaitForSubmissionIndex(submission));
+            let _ = self
+                .device
+                .poll(wgpu::PollType::WaitForSubmissionIndex(submission));
+        }
     }
 }
diff --git a/wgpu/src/image/raster.rs b/wgpu/src/image/raster.rs
index 5e333546..4300e935 100644
--- a/wgpu/src/image/raster.rs
+++ b/wgpu/src/image/raster.rs
@@ -7,7 +7,7 @@ use crate::image::atlas::{self, Atlas};
 use rustc_hash::{FxHashMap, FxHashSet};
 use std::sync::{Arc, Weak};
 
-type Image = image_rs::ImageBuffer<image_rs::Rgba<u8>, image::Bytes>;
+pub type Image = image_rs::ImageBuffer<image_rs::Rgba<u8>, image::Bytes>;
 
 /// Entry in cache corresponding to an image handle
 #[derive(Debug)]
diff --git a/wgpu/src/shader/image.wgsl b/wgpu/src/shader/image.wgsl
index b2754d61..a356cc8b 100644
--- a/wgpu/src/shader/image.wgsl
+++ b/wgpu/src/shader/image.wgsl
@@ -82,9 +82,9 @@ fn fs_main(input: VertexOutput) -> @location(0) vec4<f32> {
         2.0 * (fragment - position - scale / 2.0),
         scale,
         input.border_radius * 2.0,
-    );
+    ) / 2.0;
 
-    let antialias: f32 = clamp(0.5 - d, 0.0, 1.0);
+    let antialias: f32 = clamp(1.0 - d, 0.0, 1.0);
 
     return textureSample(u_texture, u_sampler, input.uv, i32(input.layer)) * vec4<f32>(1.0, 1.0, 1.0, antialias * input.opacity);
 }