diff --git a/canvas/src/lib.rs b/canvas/src/lib.rs
index f4ba5aeb..5962b86a 100644
--- a/canvas/src/lib.rs
+++ b/canvas/src/lib.rs
@@ -524,11 +524,15 @@ pub enum LineJoin {
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum CompositeOperation {
     SourceOver,
-    DestinationOver,
-    DestinationOut,
+    SourceIn,
+    SourceOut,
     SourceAtop,
-    Xor,
+    DestinationOver,
+    DestinationIn,
+    DestinationOut,
+    DestinationAtop,
     Lighter,
+    Xor,
     Multiply,
     Screen,
     Overlay,
@@ -547,9 +551,13 @@ impl CompositeOperation {
     fn to_blend_mode(self) -> BlendMode {
         match self {
             CompositeOperation::SourceOver => BlendMode::SrcOver,
-            CompositeOperation::DestinationOver => BlendMode::DestOver,
-            CompositeOperation::DestinationOut => BlendMode::DestOut,
+            CompositeOperation::SourceIn => BlendMode::SrcIn,
+            CompositeOperation::SourceOut => BlendMode::SrcOut,
             CompositeOperation::SourceAtop => BlendMode::SrcAtop,
+            CompositeOperation::DestinationOver => BlendMode::DestOver,
+            CompositeOperation::DestinationIn => BlendMode::DestIn,
+            CompositeOperation::DestinationOut => BlendMode::DestOut,
+            CompositeOperation::DestinationAtop => BlendMode::DestAtop,
             CompositeOperation::Xor => BlendMode::Xor,
             CompositeOperation::Lighter => BlendMode::Lighter,
             CompositeOperation::Multiply => BlendMode::Multiply,
diff --git a/content/src/effects.rs b/content/src/effects.rs
index f985db3f..3f0ed9b0 100644
--- a/content/src/effects.rs
+++ b/content/src/effects.rs
@@ -75,6 +75,12 @@ pub enum BlendMode {
     Lighten,
     Darken,
 
+    // Porter-Duff
+    SrcIn,
+    DestIn,
+    SrcOut,
+    DestAtop,
+
     // Overlay
     Multiply,
     Screen,
@@ -123,6 +129,10 @@ impl BlendMode {
             BlendMode::Lighter |
             BlendMode::Lighten |
             BlendMode::Darken |
+            BlendMode::SrcIn |
+            BlendMode::DestIn |
+            BlendMode::SrcOut |
+            BlendMode::DestAtop |
             BlendMode::Multiply |
             BlendMode::Screen |
             BlendMode::HardLight |
diff --git a/renderer/src/gpu/renderer.rs b/renderer/src/gpu/renderer.rs
index 125ea1cd..d3f4cff8 100644
--- a/renderer/src/gpu/renderer.rs
+++ b/renderer/src/gpu/renderer.rs
@@ -11,12 +11,13 @@
 use crate::gpu::debug::DebugUIPresenter;
 use crate::gpu::options::{DestFramebuffer, RendererOptions};
 use crate::gpu::shaders::{AlphaTileDodgeBurnProgram, AlphaTileHSLProgram, AlphaTileOverlayProgram};
-use crate::gpu::shaders::{AlphaTileProgram, AlphaTileVertexArray, CopyTileProgram};
-use crate::gpu::shaders::{CopyTileVertexArray, FillProgram, FillVertexArray, FilterBasicProgram};
-use crate::gpu::shaders::{FilterBasicVertexArray, FilterTextProgram, FilterTextVertexArray};
-use crate::gpu::shaders::{MAX_FILLS_PER_BATCH, MaskTileProgram, MaskTileVertexArray};
-use crate::gpu::shaders::{ReprojectionProgram, ReprojectionVertexArray, SolidTileProgram};
-use crate::gpu::shaders::{SolidTileVertexArray, StencilProgram, StencilVertexArray};
+use crate::gpu::shaders::{AlphaTilePorterDuffProgram, AlphaTileProgram, AlphaTileVertexArray};
+use crate::gpu::shaders::{CopyTileProgram, CopyTileVertexArray, FillProgram, FillVertexArray};
+use crate::gpu::shaders::{FilterBasicProgram, FilterBasicVertexArray, FilterTextProgram};
+use crate::gpu::shaders::{FilterTextVertexArray, MAX_FILLS_PER_BATCH, MaskTileProgram};
+use crate::gpu::shaders::{MaskTileVertexArray, ReprojectionProgram, ReprojectionVertexArray};
+use crate::gpu::shaders::{SolidTileProgram, SolidTileVertexArray};
+use crate::gpu::shaders::{StencilProgram, StencilVertexArray};
 use crate::gpu_data::{AlphaTile, FillBatchPrimitive, MaskTile, PaintData, PaintPageContents};
 use crate::gpu_data::{PaintPageId, RenderCommand, SolidTileVertex};
 use crate::options::BoundingQuad;
@@ -61,6 +62,11 @@ const OVERLAY_BLEND_MODE_SCREEN:     i32 = 1;
 const OVERLAY_BLEND_MODE_HARD_LIGHT: i32 = 2;
 const OVERLAY_BLEND_MODE_OVERLAY:    i32 = 3;
 
+const PORTER_DUFF_FACTOR_ZERO:                 i32 = 0;
+const PORTER_DUFF_FACTOR_DEST_ALPHA:           i32 = 1;
+const PORTER_DUFF_FACTOR_SRC_ALPHA:            i32 = 2;
+const PORTER_DUFF_FACTOR_ONE_MINUS_DEST_ALPHA: i32 = 3;
+
 pub struct Renderer<D>
 where
     D: Device,
@@ -77,6 +83,7 @@ where
     copy_tile_program: CopyTileProgram<D>,
     solid_tile_program: SolidTileProgram<D>,
     alpha_tile_program: AlphaTileProgram<D>,
+    alpha_tile_porterduff_program: AlphaTilePorterDuffProgram<D>,
     alpha_tile_overlay_program: AlphaTileOverlayProgram<D>,
     alpha_tile_dodgeburn_program: AlphaTileDodgeBurnProgram<D>,
     alpha_tile_hsl_program: AlphaTileHSLProgram<D>,
@@ -85,6 +92,7 @@ where
     copy_tile_vertex_array: CopyTileVertexArray<D>,
     solid_tile_vertex_array: SolidTileVertexArray<D>,
     alpha_tile_vertex_array: AlphaTileVertexArray<D>,
+    alpha_tile_porterduff_vertex_array: AlphaTileVertexArray<D>,
     alpha_tile_overlay_vertex_array: AlphaTileVertexArray<D>,
     alpha_tile_dodgeburn_vertex_array: AlphaTileVertexArray<D>,
     alpha_tile_hsl_vertex_array: AlphaTileVertexArray<D>,
@@ -158,6 +166,7 @@ where
         let copy_tile_program = CopyTileProgram::new(&device, resources);
         let solid_tile_program = SolidTileProgram::new(&device, resources);
         let alpha_tile_program = AlphaTileProgram::new(&device, resources);
+        let alpha_tile_porterduff_program = AlphaTilePorterDuffProgram::new(&device, resources);
         let alpha_tile_overlay_program = AlphaTileOverlayProgram::new(&device, resources);
         let alpha_tile_dodgeburn_program = AlphaTileDodgeBurnProgram::new(&device, resources);
         let alpha_tile_hsl_program = AlphaTileHSLProgram::new(&device, resources);
@@ -214,6 +223,12 @@ where
             &alpha_tile_vertex_buffer,
             &quads_vertex_indices_buffer,
         );
+        let alpha_tile_porterduff_vertex_array = AlphaTileVertexArray::new(
+            &device,
+            &alpha_tile_porterduff_program.alpha_tile_program,
+            &alpha_tile_vertex_buffer,
+            &quads_vertex_indices_buffer,
+        );
         let alpha_tile_overlay_vertex_array = AlphaTileVertexArray::new(
             &device,
             &alpha_tile_overlay_program.alpha_tile_program,
@@ -293,6 +308,7 @@ where
             copy_tile_program,
             solid_tile_program,
             alpha_tile_program,
+            alpha_tile_porterduff_program,
             alpha_tile_overlay_program,
             alpha_tile_dodgeburn_program,
             alpha_tile_hsl_program,
@@ -301,6 +317,7 @@ where
             copy_tile_vertex_array,
             solid_tile_vertex_array,
             alpha_tile_vertex_array,
+            alpha_tile_porterduff_vertex_array,
             alpha_tile_overlay_vertex_array,
             alpha_tile_dodgeburn_vertex_array,
             alpha_tile_hsl_vertex_array,
@@ -735,6 +752,10 @@ where
 
         let (alpha_tile_program, alpha_tile_vertex_array) = match blend_mode_program {
             BlendModeProgram::Regular => (&self.alpha_tile_program, &self.alpha_tile_vertex_array),
+            BlendModeProgram::PorterDuff => {
+                (&self.alpha_tile_porterduff_program.alpha_tile_program,
+                 &self.alpha_tile_porterduff_vertex_array)
+            }
             BlendModeProgram::Overlay => {
                 (&self.alpha_tile_overlay_program.alpha_tile_program,
                  &self.alpha_tile_overlay_vertex_array)
@@ -777,6 +798,11 @@ where
 
         match blend_mode_program {
             BlendModeProgram::Regular => {}
+            BlendModeProgram::PorterDuff => {
+                self.set_uniforms_for_porter_duff_blend_mode(&mut textures,
+                                                             &mut uniforms,
+                                                             blend_mode);
+            }
             BlendModeProgram::Overlay => {
                 self.set_uniforms_for_overlay_blend_mode(&mut textures, &mut uniforms, blend_mode);
             }
@@ -809,6 +835,37 @@ where
         self.preserve_draw_framebuffer();
     }
 
+    fn set_uniforms_for_porter_duff_blend_mode<'a>(
+            &'a self,
+            textures: &mut Vec<&'a D::Texture>,
+            uniforms: &mut Vec<(&'a D::Uniform, UniformData)>,
+            blend_mode: BlendMode) {
+        let (src_factor, dest_factor) = match blend_mode {
+            BlendMode::SrcIn => {
+                (PORTER_DUFF_FACTOR_DEST_ALPHA, PORTER_DUFF_FACTOR_ZERO)
+            }
+            BlendMode::DestIn => {
+                (PORTER_DUFF_FACTOR_ZERO, PORTER_DUFF_FACTOR_SRC_ALPHA)
+            }
+            BlendMode::SrcOut => {
+                (PORTER_DUFF_FACTOR_ONE_MINUS_DEST_ALPHA, PORTER_DUFF_FACTOR_ZERO)
+            }
+            BlendMode::DestAtop => {
+                (PORTER_DUFF_FACTOR_ONE_MINUS_DEST_ALPHA, PORTER_DUFF_FACTOR_SRC_ALPHA)
+            }
+            _ => unreachable!(),
+        };
+
+        uniforms.push((&self.alpha_tile_porterduff_program.src_factor_uniform,
+                       UniformData::Int(src_factor)));
+        uniforms.push((&self.alpha_tile_porterduff_program.dest_factor_uniform,
+                       UniformData::Int(dest_factor)));
+
+        textures.push(self.device.framebuffer_texture(&self.dest_blend_framebuffer));
+        uniforms.push((&self.alpha_tile_porterduff_program.dest_uniform,
+                        UniformData::TextureUnit(textures.len() as u32 - 1)));
+    }
+
     fn set_uniforms_for_overlay_blend_mode<'a>(&'a self,
                                                textures: &mut Vec<&'a D::Texture>,
                                                uniforms: &mut Vec<(&'a D::Uniform, UniformData)>,
@@ -1477,6 +1534,10 @@ impl BlendModeExt for BlendMode {
                     op: BlendOp::Min,
                 })
             }
+            BlendMode::SrcIn |
+            BlendMode::DestIn |
+            BlendMode::SrcOut |
+            BlendMode::DestAtop |
             BlendMode::Multiply |
             BlendMode::Screen |
             BlendMode::HardLight |
@@ -1497,6 +1558,7 @@ impl BlendModeExt for BlendMode {
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub(crate) enum BlendModeProgram {
     Regular,
+    PorterDuff,
     Overlay,
     DodgeBurn,
     HSL,
@@ -1514,6 +1576,10 @@ impl BlendModeProgram {
             BlendMode::Lighter |
             BlendMode::Lighten |
             BlendMode::Darken => BlendModeProgram::Regular,
+            BlendMode::SrcIn |
+            BlendMode::DestIn |
+            BlendMode::SrcOut |
+            BlendMode::DestAtop => BlendModeProgram::PorterDuff,
             BlendMode::Multiply |
             BlendMode::Screen |
             BlendMode::HardLight |
@@ -1530,6 +1596,7 @@ impl BlendModeProgram {
     pub(crate) fn needs_readable_framebuffer(self) -> bool {
         match self {
             BlendModeProgram::Regular => false,
+            BlendModeProgram::PorterDuff |
             BlendModeProgram::Overlay |
             BlendModeProgram::DodgeBurn |
             BlendModeProgram::HSL => true,
diff --git a/renderer/src/gpu/shaders.rs b/renderer/src/gpu/shaders.rs
index e06c8fd0..efc1b377 100644
--- a/renderer/src/gpu/shaders.rs
+++ b/renderer/src/gpu/shaders.rs
@@ -450,6 +450,31 @@ impl<D> CopyTileProgram<D> where D: Device {
     }
 }
 
+pub struct AlphaTilePorterDuffProgram<D> where D: Device {
+    pub alpha_tile_program: AlphaTileProgram<D>,
+    pub dest_uniform: D::Uniform,
+    pub dest_factor_uniform: D::Uniform,
+    pub src_factor_uniform: D::Uniform,
+}
+
+impl<D> AlphaTilePorterDuffProgram<D> where D: Device {
+    pub fn new(device: &D, resources: &dyn ResourceLoader) -> AlphaTilePorterDuffProgram<D> {
+        let alpha_tile_program =
+            AlphaTileProgram::from_fragment_shader_name(device,
+                                                        resources,
+                                                        "tile_alpha_porterduff");
+        let dest_uniform = device.get_uniform(&alpha_tile_program.program, "Dest");
+        let dest_factor_uniform = device.get_uniform(&alpha_tile_program.program, "DestFactor");
+        let src_factor_uniform = device.get_uniform(&alpha_tile_program.program, "SrcFactor");
+        AlphaTilePorterDuffProgram {
+            alpha_tile_program,
+            dest_uniform,
+            dest_factor_uniform,
+            src_factor_uniform,
+        }
+    }
+}
+
 pub struct AlphaTileHSLProgram<D> where D: Device {
     pub alpha_tile_program: AlphaTileProgram<D>,
     pub dest_uniform: D::Uniform,
diff --git a/resources/shaders/gl3/tile_alpha_porterduff.fs.glsl b/resources/shaders/gl3/tile_alpha_porterduff.fs.glsl
new file mode 100644
index 00000000..d44ae323
--- /dev/null
+++ b/resources/shaders/gl3/tile_alpha_porterduff.fs.glsl
@@ -0,0 +1,96 @@
+#version {{version}}
+// Automatically generated from files in pathfinder/shaders/. Do not edit!
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+#extension GL_GOOGLE_include_directive : enable
+
+
+
+
+
+
+precision highp float;
+
+uniform int uDestFactor;
+uniform int uSrcFactor;
+
+out vec4 oFragColor;
+
+
+
+
+
+
+
+
+
+
+
+
+uniform sampler2D uStencilTexture;
+uniform sampler2D uPaintTexture;
+uniform sampler2D uDest;
+uniform vec2 uFramebufferSize;
+
+in vec2 vColorTexCoord;
+in vec2 vMaskTexCoord;
+
+
+vec4 sampleSrcColor(){
+    float coverage = texture(uStencilTexture, vMaskTexCoord). r;
+    vec4 srcRGBA = texture(uPaintTexture, vColorTexCoord);
+    return vec4(srcRGBA . rgb, srcRGBA . a * coverage);
+}
+
+vec4 sampleDestColor(){
+    vec2 destTexCoord = gl_FragCoord . xy / uFramebufferSize;
+    return texture(uDest, destTexCoord);
+}
+
+
+vec4 blendColors(vec4 destRGBA, vec4 srcRGBA, vec3 blendedRGB){
+    return vec4(srcRGBA . a *(1.0 - destRGBA . a)* srcRGBA . rgb +
+                srcRGBA . a * destRGBA . a * blendedRGB +
+                (1.0 - srcRGBA . a)* destRGBA . a * destRGBA . rgb,
+                1.0);
+}
+
+vec3 select3(bvec3 cond, vec3 a, vec3 b){
+    return vec3(cond . x ? a . x : b . x, cond . y ? a . y : b . y, cond . z ? a . z : b . z);
+}
+
+
+vec4 getFactor(int factor, vec4 destRGBA, vec4 srcRGBA){
+    if(factor == 0)
+        return vec4(0.0);
+    if(factor == 1)
+        return vec4(destRGBA . a);
+    if(factor == 2)
+        return vec4(srcRGBA . a);
+    return vec4(1.0 - destRGBA . a);
+}
+
+void main(){
+    vec4 srcRGBA = sampleSrcColor();
+    vec4 destRGBA = sampleDestColor();
+
+    vec4 destFactor = getFactor(uDestFactor, destRGBA, srcRGBA);
+    vec4 srcFactor = getFactor(uSrcFactor, destRGBA, srcRGBA);
+
+    vec4 blended = destFactor * destRGBA * vec4(destRGBA . aaa, 1.0)+
+        srcFactor * srcRGBA * vec4(srcRGBA . aaa, 1.0);
+    oFragColor = blended;
+}
+
diff --git a/resources/shaders/metal/tile_alpha_porterduff.fs.metal b/resources/shaders/metal/tile_alpha_porterduff.fs.metal
new file mode 100644
index 00000000..cd414300
--- /dev/null
+++ b/resources/shaders/metal/tile_alpha_porterduff.fs.metal
@@ -0,0 +1,80 @@
+// Automatically generated from files in pathfinder/shaders/. Do not edit!
+#pragma clang diagnostic ignored "-Wmissing-prototypes"
+
+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+struct spvDescriptorSetBuffer0
+{
+    texture2d<float> uStencilTexture [[id(0)]];
+    sampler uStencilTextureSmplr [[id(1)]];
+    texture2d<float> uPaintTexture [[id(2)]];
+    sampler uPaintTextureSmplr [[id(3)]];
+    constant float2* uFramebufferSize [[id(4)]];
+    texture2d<float> uDest [[id(5)]];
+    sampler uDestSmplr [[id(6)]];
+    constant int* uDestFactor [[id(7)]];
+    constant int* uSrcFactor [[id(8)]];
+};
+
+struct main0_out
+{
+    float4 oFragColor [[color(0)]];
+};
+
+struct main0_in
+{
+    float2 vColorTexCoord [[user(locn0)]];
+    float2 vMaskTexCoord [[user(locn1)]];
+};
+
+float4 sampleSrcColor(thread texture2d<float> uStencilTexture, thread const sampler uStencilTextureSmplr, thread float2& vMaskTexCoord, thread texture2d<float> uPaintTexture, thread const sampler uPaintTextureSmplr, thread float2& vColorTexCoord)
+{
+    float coverage = uStencilTexture.sample(uStencilTextureSmplr, vMaskTexCoord).x;
+    float4 srcRGBA = uPaintTexture.sample(uPaintTextureSmplr, vColorTexCoord);
+    return float4(srcRGBA.xyz, srcRGBA.w * coverage);
+}
+
+float4 sampleDestColor(thread float4& gl_FragCoord, thread float2 uFramebufferSize, thread texture2d<float> uDest, thread const sampler uDestSmplr)
+{
+    float2 destTexCoord = gl_FragCoord.xy / uFramebufferSize;
+    return uDest.sample(uDestSmplr, destTexCoord);
+}
+
+float4 getFactor(thread const int& factor, thread const float4& destRGBA, thread const float4& srcRGBA)
+{
+    if (factor == 0)
+    {
+        return float4(0.0);
+    }
+    if (factor == 1)
+    {
+        return float4(destRGBA.w);
+    }
+    if (factor == 2)
+    {
+        return float4(srcRGBA.w);
+    }
+    return float4(1.0 - destRGBA.w);
+}
+
+fragment main0_out main0(main0_in in [[stage_in]], constant spvDescriptorSetBuffer0& spvDescriptorSet0 [[buffer(0)]], float4 gl_FragCoord [[position]])
+{
+    main0_out out = {};
+    float4 srcRGBA = sampleSrcColor(spvDescriptorSet0.uStencilTexture, spvDescriptorSet0.uStencilTextureSmplr, in.vMaskTexCoord, spvDescriptorSet0.uPaintTexture, spvDescriptorSet0.uPaintTextureSmplr, in.vColorTexCoord);
+    float4 destRGBA = sampleDestColor(gl_FragCoord, (*spvDescriptorSet0.uFramebufferSize), spvDescriptorSet0.uDest, spvDescriptorSet0.uDestSmplr);
+    int param = (*spvDescriptorSet0.uDestFactor);
+    float4 param_1 = destRGBA;
+    float4 param_2 = srcRGBA;
+    float4 destFactor = getFactor(param, param_1, param_2);
+    int param_3 = (*spvDescriptorSet0.uSrcFactor);
+    float4 param_4 = destRGBA;
+    float4 param_5 = srcRGBA;
+    float4 srcFactor = getFactor(param_3, param_4, param_5);
+    float4 blended = ((destFactor * destRGBA) * float4(destRGBA.www, 1.0)) + ((srcFactor * srcRGBA) * float4(srcRGBA.www, 1.0));
+    out.oFragColor = blended;
+    return out;
+}
+
diff --git a/shaders/Makefile b/shaders/Makefile
index 2f438e67..ce19feba 100644
--- a/shaders/Makefile
+++ b/shaders/Makefile
@@ -26,6 +26,7 @@ SHADERS=\
 	tile_alpha_dodgeburn.fs.glsl \
 	tile_alpha_hsl.fs.glsl \
 	tile_alpha_overlay.fs.glsl \
+	tile_alpha_porterduff.fs.glsl \
 	tile_copy.fs.glsl \
 	tile_copy.vs.glsl \
 	tile_solid.fs.glsl \
diff --git a/shaders/tile_alpha_porterduff.fs.glsl b/shaders/tile_alpha_porterduff.fs.glsl
new file mode 100644
index 00000000..a5011b67
--- /dev/null
+++ b/shaders/tile_alpha_porterduff.fs.glsl
@@ -0,0 +1,51 @@
+#version 330
+
+// pathfinder/shaders/tile_alpha_porterduff.fs.glsl
+//
+// Copyright © 2020 The Pathfinder Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Porter-Duff blend modes not supported by the standard GPU blender.
+
+#extension GL_GOOGLE_include_directive : enable
+
+#define PORTER_DUFF_FACTOR_ZERO                 0
+#define PORTER_DUFF_FACTOR_DEST_ALPHA           1
+#define PORTER_DUFF_FACTOR_SRC_ALPHA            2
+#define PORTER_DUFF_FACTOR_ONE_MINUS_DEST_ALPHA 3
+
+precision highp float;
+
+uniform int uDestFactor;
+uniform int uSrcFactor;
+
+out vec4 oFragColor;
+
+#include "tile_alpha_sample.inc.glsl"
+
+vec4 getFactor(int factor, vec4 destRGBA, vec4 srcRGBA) {
+    if (factor == PORTER_DUFF_FACTOR_ZERO)
+        return vec4(0.0);
+    if (factor == PORTER_DUFF_FACTOR_DEST_ALPHA)
+        return vec4(destRGBA.a);
+    if (factor == PORTER_DUFF_FACTOR_SRC_ALPHA)
+        return vec4(srcRGBA.a);
+    return vec4(1.0 - destRGBA.a);
+}
+
+void main() {
+    vec4 srcRGBA = sampleSrcColor();
+    vec4 destRGBA = sampleDestColor();
+
+    vec4 destFactor = getFactor(uDestFactor, destRGBA, srcRGBA);
+    vec4 srcFactor = getFactor(uSrcFactor, destRGBA, srcRGBA);
+
+    vec4 blended = destFactor * destRGBA * vec4(destRGBA.aaa, 1.0) +
+        srcFactor * srcRGBA * vec4(srcRGBA.aaa, 1.0);
+    oFragColor = blended;
+}