diff --git a/example/freetype/main.go b/example/freetype/main.go
index f28d3cd..3467d3b 100644
--- a/example/freetype/main.go
+++ b/example/freetype/main.go
@@ -88,7 +88,7 @@ func main() {
 		ruler = image.RGBAColor{0x22, 0x22, 0x22, 0xff}
 	}
 	rgba := image.NewRGBA(640, 480)
-	draw.Draw(rgba, draw.Rect(0, 0, rgba.Width(), rgba.Height()), bg, draw.ZP)
+	draw.Draw(rgba, draw.Rect(0, 0, 640, 480), bg, draw.ZP)
 	c := freetype.NewContext()
 	c.SetDPI(*dpi)
 	c.SetFont(font)
diff --git a/example/gamma/main.go b/example/gamma/main.go
index a86cd45..7845b7f 100644
--- a/example/gamma/main.go
+++ b/example/gamma/main.go
@@ -22,9 +22,12 @@ func p(x, y int) raster.Point {
 }
 
 func clear(m *image.Alpha) {
-	for y := 0; y < m.Height(); y++ {
-		for x := 0; x < m.Width(); x++ {
-			m.Pixel[y][x] = image.AlphaColor{0}
+	b := m.Bounds()
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		base := y * m.Stride
+		p := m.Pix[base+b.Min.X : base+b.Max.X]
+		for i, _ := range p {
+			p[i] = image.AlphaColor{0}
 		}
 	}
 }
diff --git a/example/raster/main.go b/example/raster/main.go
index 685e6e8..b63a51b 100644
--- a/example/raster/main.go
+++ b/example/raster/main.go
@@ -113,7 +113,7 @@ func showNodes(m *image.RGBA, ns []node) {
 	for _, n := range ns {
 		p := p(n)
 		x, y := int(p.X)/256, int(p.Y)/256
-		if x < 0 || x >= m.Width() || y < 0 || y >= m.Height() {
+		if !m.Bounds().Contains(image.Point{x, y}) {
 			continue
 		}
 		var c image.Color
diff --git a/example/round/main.go b/example/round/main.go
index 0fad99d..6f51d95 100644
--- a/example/round/main.go
+++ b/example/round/main.go
@@ -31,9 +31,10 @@ func main() {
 	t := raster.Fix32(r * math.Tan(math.Pi/8))
 
 	m := image.NewRGBA(800, 600)
-	for y := 0; y < m.Height(); y++ {
-		for x := 0; x < m.Width(); x++ {
-			m.Pixel[y][x] = image.RGBAColor{63, 63, 63, 255}
+	for y := 0; y < 600; y++ {
+		p := m.Pix[y*m.Stride : y*m.Stride+800]
+		for i := range p {
+			p[i] = image.RGBAColor{63, 63, 63, 255}
 		}
 	}
 	mp := raster.NewRGBAPainter(m)
diff --git a/freetype/raster/paint.go b/freetype/raster/paint.go
index beac34c..f2f093b 100644
--- a/freetype/raster/paint.go
+++ b/freetype/raster/paint.go
@@ -43,31 +43,33 @@ type AlphaPainter struct {
 
 // Paint satisfies the Painter interface by painting ss onto an image.Alpha.
 func (r *AlphaPainter) Paint(ss []Span, done bool) {
+	b := r.Image.Bounds()
 	for _, s := range ss {
-		if s.Y < 0 {
+		if s.Y < b.Min.Y {
 			continue
 		}
-		if s.Y >= len(r.Image.Pixel) {
+		if s.Y >= b.Max.Y {
 			return
 		}
-		p := r.Image.Pixel[s.Y]
-		if s.X0 < 0 {
-			s.X0 = 0
+		if s.X0 < b.Min.X {
+			s.X0 = b.Min.X
 		}
-		if s.X1 > len(p) {
-			s.X1 = len(p)
+		if s.X1 > b.Max.X {
+			s.X1 = b.Max.X
 		}
+		base := s.Y * r.Image.Stride
+		p := r.Image.Pix[base+s.X0 : base+s.X1]
 		if r.Op == draw.Over {
 			a := int(s.A >> 24)
-			for x := s.X0; x < s.X1; x++ {
-				ax := int(p[x].A)
+			for i, c := range p {
+				ax := int(c.A)
 				ax = (ax*255 + (255-ax)*a) / 255
-				p[x] = image.AlphaColor{uint8(ax)}
+				p[i] = image.AlphaColor{uint8(ax)}
 			}
 		} else {
 			color := image.AlphaColor{uint8(s.A >> 24)}
-			for x := s.X0; x < s.X1; x++ {
-				p[x] = color
+			for i := range p {
+				p[i] = color
 			}
 		}
 	}
@@ -89,28 +91,29 @@ type RGBAPainter struct {
 
 // Paint satisfies the Painter interface by painting ss onto an image.RGBA.
 func (r *RGBAPainter) Paint(ss []Span, done bool) {
+	b := r.Image.Bounds()
 	for _, s := range ss {
-		if s.Y < 0 {
+		if s.Y < b.Min.Y {
 			continue
 		}
-		if s.Y >= len(r.Image.Pixel) {
+		if s.Y >= b.Max.Y {
 			return
 		}
-		p := r.Image.Pixel[s.Y]
-		if s.X0 < 0 {
-			s.X0 = 0
+		if s.X0 < b.Min.X {
+			s.X0 = b.Min.X
 		}
-		if s.X1 > len(p) {
-			s.X1 = len(p)
+		if s.X1 > b.Max.X {
+			s.X1 = b.Max.X
 		}
-		for x := s.X0; x < s.X1; x++ {
+		base := s.Y * r.Image.Stride
+		p := r.Image.Pix[base+s.X0 : base+s.X1]
+		for i, rgba := range p {
 			// This code is duplicated from drawGlyphOver in $GOROOT/src/pkg/exp/draw/draw.go.
 			// TODO(nigeltao): Factor out common code into a utility function, once the compiler
 			// can inline such function calls.
 			ma := s.A >> 16
 			const M = 1<<16 - 1
 			if r.Op == draw.Over {
-				rgba := p[x]
 				dr := uint32(rgba.R)
 				dg := uint32(rgba.G)
 				db := uint32(rgba.B)
@@ -121,13 +124,13 @@ func (r *RGBAPainter) Paint(ss []Span, done bool) {
 				dg = (dg*a + r.cg*ma) / M
 				db = (db*a + r.cb*ma) / M
 				da = (da*a + r.ca*ma) / M
-				p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
+				p[i] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
 			} else {
 				dr := r.cr * ma / M
 				dg := r.cg * ma / M
 				db := r.cb * ma / M
 				da := r.ca * ma / M
-				p[x] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
+				p[i] = image.RGBAColor{uint8(dr >> 8), uint8(dg >> 8), uint8(db >> 8), uint8(da >> 8)}
 			}
 		}
 	}