diff --git a/testdata/blue-purple-pink.lossy.webp b/testdata/blue-purple-pink.lossy.webp
new file mode 100644
index 0000000..d5143c0
--- /dev/null
+++ b/testdata/blue-purple-pink.lossy.webp
Binary files differ
diff --git a/testdata/blue-purple-pink.lossy.webp.ycbcr.png b/testdata/blue-purple-pink.lossy.webp.ycbcr.png
new file mode 100644
index 0000000..eb51560
--- /dev/null
+++ b/testdata/blue-purple-pink.lossy.webp.ycbcr.png
Binary files differ
diff --git a/testdata/video-001.webp b/testdata/video-001.lossy.webp
similarity index 100%
rename from testdata/video-001.webp
rename to testdata/video-001.lossy.webp
Binary files differ
diff --git a/testdata/video-001.webp.ycbcr.png b/testdata/video-001.lossy.webp.ycbcr.png
similarity index 100%
rename from testdata/video-001.webp.ycbcr.png
rename to testdata/video-001.lossy.webp.ycbcr.png
Binary files differ
diff --git a/testdata/yellow_rose.lossy.webp.ycbcr.png b/testdata/yellow_rose.lossy.webp.ycbcr.png
new file mode 100644
index 0000000..5e3bcd8
--- /dev/null
+++ b/testdata/yellow_rose.lossy.webp.ycbcr.png
Binary files differ
diff --git a/vp8/decode.go b/vp8/decode.go
index ab1115c..41daee6 100644
--- a/vp8/decode.go
+++ b/vp8/decode.go
@@ -368,7 +368,7 @@
 		if d.filterHeader.simple {
 			d.simpleFilter()
 		} else {
-			// TODO(nigeltao): normal filtering.
+			d.normalFilter()
 		}
 	}
 	return d.img, nil
diff --git a/vp8/filter.go b/vp8/filter.go
index aa7e119..9a52451 100644
--- a/vp8/filter.go
+++ b/vp8/filter.go
@@ -4,14 +4,14 @@
 
 package vp8
 
-// filter2 modifies a 2-pixel-wide or 2-pixel-high band along an edge.
-func filter2(pix []byte, thresh int, index int, iStep int, jStep int) {
-	for i := 0; i < 16; i, index = i+1, index+iStep {
+// filter2 modifies a 2-pixel wide or 2-pixel high band along an edge.
+func filter2(pix []byte, level, index, iStep, jStep int) {
+	for n := 16; n > 0; n, index = n-1, index+iStep {
 		p1 := int(pix[index-2*jStep])
 		p0 := int(pix[index-1*jStep])
 		q0 := int(pix[index+0*jStep])
 		q1 := int(pix[index+1*jStep])
-		if int(lutAbs[lutAbsBase+p0-q0])<<1+int(lutAbs[lutAbsBase+p1-q1])>>1 > thresh {
+		if int(lutAbs[lutAbsBase+p0-q0])<<1+int(lutAbs[lutAbsBase+p1-q1])>>1 > level {
 			continue
 		}
 		a := 3*(q0-p0) + int(lutClamp127[lutClamp127Base+p1-q1])
@@ -22,32 +22,126 @@
 	}
 }
 
-// TODO(nigeltao): filter4 and filter6 functions, for normal filtering.
+// filter246 modifies a 2-, 4- or 6-pixel wide or high band along an edge.
+func filter246(pix []byte, n, level, ilevel, hlevel, index, iStep, jStep int, fourNotSix bool) {
+	for ; n > 0; n, index = n-1, index+iStep {
+		p3 := int(pix[index-4*jStep])
+		p2 := int(pix[index-3*jStep])
+		p1 := int(pix[index-2*jStep])
+		p0 := int(pix[index-1*jStep])
+		q0 := int(pix[index+0*jStep])
+		q1 := int(pix[index+1*jStep])
+		q2 := int(pix[index+2*jStep])
+		q3 := int(pix[index+3*jStep])
+		if int(lutAbs[lutAbsBase+p0-q0])<<1+int(lutAbs[lutAbsBase+p1-q1])>>1 > level {
+			continue
+		}
+		if int(lutAbs[lutAbsBase+p3-p2]) > ilevel ||
+			int(lutAbs[lutAbsBase+p2-p1]) > ilevel ||
+			int(lutAbs[lutAbsBase+p1-p0]) > ilevel ||
+			int(lutAbs[lutAbsBase+q1-q0]) > ilevel ||
+			int(lutAbs[lutAbsBase+q2-q1]) > ilevel ||
+			int(lutAbs[lutAbsBase+q3-q2]) > ilevel {
+			continue
+		}
+		if int(lutAbs[lutAbsBase+p1-p0]) > hlevel || int(lutAbs[lutAbsBase+q1-q0]) > hlevel {
+			// Filter 2 pixels.
+			a := 3*(q0-p0) + int(lutClamp127[lutClamp127Base+p1-q1])
+			a1 := int(lutClamp15[lutClamp15Base+((a+4)>>3)])
+			a2 := int(lutClamp15[lutClamp15Base+((a+3)>>3)])
+			pix[index-1*jStep] = lutClamp255[lutClamp255Base+p0+a2]
+			pix[index+0*jStep] = lutClamp255[lutClamp255Base+q0-a1]
+		} else if fourNotSix {
+			// Filter 4 pixels.
+			a := 3 * (q0 - p0)
+			a1 := int(lutClamp15[lutClamp15Base+((a+4)>>3)])
+			a2 := int(lutClamp15[lutClamp15Base+((a+3)>>3)])
+			a3 := (a1 + 1) >> 1
+			pix[index-2*jStep] = lutClamp255[lutClamp255Base+p1+a3]
+			pix[index-1*jStep] = lutClamp255[lutClamp255Base+p0+a2]
+			pix[index+0*jStep] = lutClamp255[lutClamp255Base+q0-a1]
+			pix[index+1*jStep] = lutClamp255[lutClamp255Base+q1-a3]
+		} else {
+			// Filter 6 pixels.
+			a := 3*(q0-p0) + int(lutClamp127[lutClamp127Base+p1-q1])
+			a = int(lutClamp127[lutClamp127Base+a])
+			a1 := (27*a + 63) >> 7
+			a2 := (18*a + 63) >> 7
+			a3 := (9*a + 63) >> 7
+			pix[index-3*jStep] = lutClamp255[lutClamp255Base+p2+a3]
+			pix[index-2*jStep] = lutClamp255[lutClamp255Base+p1+a2]
+			pix[index-1*jStep] = lutClamp255[lutClamp255Base+p0+a1]
+			pix[index+0*jStep] = lutClamp255[lutClamp255Base+q0-a1]
+			pix[index+1*jStep] = lutClamp255[lutClamp255Base+q1-a2]
+			pix[index+2*jStep] = lutClamp255[lutClamp255Base+q2-a3]
+		}
+	}
+}
 
 // simpleFilter implements the simple filter, as specified in section 15.2.
 func (d *Decoder) simpleFilter() {
 	for mby := 0; mby < d.mbh; mby++ {
 		for mbx := 0; mbx < d.mbw; mbx++ {
 			f := d.perMBFilterParams[d.mbw*mby+mbx]
-			if f.limit == 0 {
+			if f.level == 0 {
 				continue
 			}
-			index := (mby*d.img.YStride + mbx) * 16
+			l := int(f.level)
+			yIndex := (mby*d.img.YStride + mbx) * 16
 			if mbx > 0 {
-				filter2(d.img.Y, int(f.limit)+4, index, d.img.YStride, 1)
+				filter2(d.img.Y, l+4, yIndex, d.img.YStride, 1)
 			}
 			if f.inner {
-				filter2(d.img.Y, int(f.limit), index+4, d.img.YStride, 1)
-				filter2(d.img.Y, int(f.limit), index+8, d.img.YStride, 1)
-				filter2(d.img.Y, int(f.limit), index+12, d.img.YStride, 1)
+				filter2(d.img.Y, l, yIndex+0x4, d.img.YStride, 1)
+				filter2(d.img.Y, l, yIndex+0x8, d.img.YStride, 1)
+				filter2(d.img.Y, l, yIndex+0xc, d.img.YStride, 1)
 			}
 			if mby > 0 {
-				filter2(d.img.Y, int(f.limit)+4, index, 1, d.img.YStride)
+				filter2(d.img.Y, l+4, yIndex, 1, d.img.YStride)
 			}
 			if f.inner {
-				filter2(d.img.Y, int(f.limit), index+d.img.YStride*4, 1, d.img.YStride)
-				filter2(d.img.Y, int(f.limit), index+d.img.YStride*8, 1, d.img.YStride)
-				filter2(d.img.Y, int(f.limit), index+d.img.YStride*12, 1, d.img.YStride)
+				filter2(d.img.Y, l, yIndex+d.img.YStride*0x4, 1, d.img.YStride)
+				filter2(d.img.Y, l, yIndex+d.img.YStride*0x8, 1, d.img.YStride)
+				filter2(d.img.Y, l, yIndex+d.img.YStride*0xc, 1, d.img.YStride)
+			}
+		}
+	}
+}
+
+// normalFilter implements the normal filter, as specified in section 15.3.
+func (d *Decoder) normalFilter() {
+	for mby := 0; mby < d.mbh; mby++ {
+		for mbx := 0; mbx < d.mbw; mbx++ {
+			f := d.perMBFilterParams[d.mbw*mby+mbx]
+			if f.level == 0 {
+				continue
+			}
+			l, il, hl := int(f.level), int(f.ilevel), int(f.hlevel)
+			yIndex := (mby*d.img.YStride + mbx) * 16
+			cIndex := (mby*d.img.CStride + mbx) * 8
+			if mbx > 0 {
+				filter246(d.img.Y, 16, l+4, il, hl, yIndex, d.img.YStride, 1, false)
+				filter246(d.img.Cb, 8, l+4, il, hl, cIndex, d.img.CStride, 1, false)
+				filter246(d.img.Cr, 8, l+4, il, hl, cIndex, d.img.CStride, 1, false)
+			}
+			if f.inner {
+				filter246(d.img.Y, 16, l, il, hl, yIndex+0x4, d.img.YStride, 1, true)
+				filter246(d.img.Y, 16, l, il, hl, yIndex+0x8, d.img.YStride, 1, true)
+				filter246(d.img.Y, 16, l, il, hl, yIndex+0xc, d.img.YStride, 1, true)
+				filter246(d.img.Cb, 8, l, il, hl, cIndex+0x4, d.img.CStride, 1, true)
+				filter246(d.img.Cr, 8, l, il, hl, cIndex+0x4, d.img.CStride, 1, true)
+			}
+			if mby > 0 {
+				filter246(d.img.Y, 16, l+4, il, hl, yIndex, 1, d.img.YStride, false)
+				filter246(d.img.Cb, 8, l+4, il, hl, cIndex, 1, d.img.CStride, false)
+				filter246(d.img.Cr, 8, l+4, il, hl, cIndex, 1, d.img.CStride, false)
+			}
+			if f.inner {
+				filter246(d.img.Y, 16, l, il, hl, yIndex+d.img.YStride*0x4, 1, d.img.YStride, true)
+				filter246(d.img.Y, 16, l, il, hl, yIndex+d.img.YStride*0x8, 1, d.img.YStride, true)
+				filter246(d.img.Y, 16, l, il, hl, yIndex+d.img.YStride*0xc, 1, d.img.YStride, true)
+				filter246(d.img.Cb, 8, l, il, hl, cIndex+d.img.CStride*0x4, 1, d.img.CStride, true)
+				filter246(d.img.Cr, 8, l, il, hl, cIndex+d.img.CStride*0x4, 1, d.img.CStride, true)
 			}
 		}
 	}
@@ -55,10 +149,14 @@
 
 // filterParam holds the loop filter parameters for a macroblock.
 type filterParam struct {
-	limit      uint8
-	inner      bool
-	innerLevel uint8
-	hevThresh  uint8
+	// The first three fields are thresholds used by the loop filter to smooth
+	// over the edges and interior of a macroblock. level is used by both the
+	// simple and normal filters. The inner level and high edge variance level
+	// are only used by the normal filter.
+	level, ilevel, hlevel uint8
+	// inner is whether the inner loop filter cannot be optimized out as a
+	// no-op for this particular macroblock.
+	inner bool
 }
 
 // computeFilterParams computes the loop filter parameters, as specified in
@@ -85,7 +183,7 @@
 				}
 			}
 			if level <= 0 {
-				p.limit = 0
+				p.level = 0
 				continue
 			}
 			if level > 63 {
@@ -105,25 +203,25 @@
 			if ilevel < 1 {
 				ilevel = 1
 			}
-			p.innerLevel = uint8(ilevel)
-			p.limit = uint8(2*level + ilevel)
+			p.ilevel = uint8(ilevel)
+			p.level = uint8(2*level + ilevel)
 			if d.frameHeader.KeyFrame {
 				if level < 15 {
-					p.hevThresh = 0
+					p.hlevel = 0
 				} else if level < 40 {
-					p.hevThresh = 1
+					p.hlevel = 1
 				} else {
-					p.hevThresh = 2
+					p.hlevel = 2
 				}
 			} else {
 				if level < 15 {
-					p.hevThresh = 0
+					p.hlevel = 0
 				} else if level < 20 {
-					p.hevThresh = 1
+					p.hlevel = 1
 				} else if level < 40 {
-					p.hevThresh = 2
+					p.hlevel = 2
 				} else {
-					p.hevThresh = 3
+					p.hlevel = 3
 				}
 			}
 		}
@@ -243,10 +341,10 @@
 	+0x0f, +0x0f, +0x0f, +0x0f, +0x0f, +0x0f, +0x0f,
 }
 
-const lutClamp127Base = 255
+const lutClamp127Base = 1020
 
-// lutClamp127[lutClamp127Base+x] is equal to clamp(x, -128, +127), for x in [-255, 255].
-var lutClamp127 = [255 + 1 + 255]int8{
+// lutClamp127[lutClamp127Base+x] is equal to clamp(x, -128, +127), for x in [-1020, 1020].
+var lutClamp127 = [1020 + 1 + 1020]int8{
 	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
 	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
 	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
@@ -263,38 +361,134 @@
 	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
 	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
 	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
-	-0x7f, -0x7e, -0x7d, -0x7c, -0x7b, -0x7a, -0x79, -0x78,
-	-0x77, -0x76, -0x75, -0x74, -0x73, -0x72, -0x71, -0x70,
-	-0x6f, -0x6e, -0x6d, -0x6c, -0x6b, -0x6a, -0x69, -0x68,
-	-0x67, -0x66, -0x65, -0x64, -0x63, -0x62, -0x61, -0x60,
-	-0x5f, -0x5e, -0x5d, -0x5c, -0x5b, -0x5a, -0x59, -0x58,
-	-0x57, -0x56, -0x55, -0x54, -0x53, -0x52, -0x51, -0x50,
-	-0x4f, -0x4e, -0x4d, -0x4c, -0x4b, -0x4a, -0x49, -0x48,
-	-0x47, -0x46, -0x45, -0x44, -0x43, -0x42, -0x41, -0x40,
-	-0x3f, -0x3e, -0x3d, -0x3c, -0x3b, -0x3a, -0x39, -0x38,
-	-0x37, -0x36, -0x35, -0x34, -0x33, -0x32, -0x31, -0x30,
-	-0x2f, -0x2e, -0x2d, -0x2c, -0x2b, -0x2a, -0x29, -0x28,
-	-0x27, -0x26, -0x25, -0x24, -0x23, -0x22, -0x21, -0x20,
-	-0x1f, -0x1e, -0x1d, -0x1c, -0x1b, -0x1a, -0x19, -0x18,
-	-0x17, -0x16, -0x15, -0x14, -0x13, -0x12, -0x11, -0x10,
-	-0x0f, -0x0e, -0x0d, -0x0c, -0x0b, -0x0a, -0x09, -0x08,
-	-0x07, -0x06, -0x05, -0x04, -0x03, -0x02, -0x01, +0x00,
-	+0x01, +0x02, +0x03, +0x04, +0x05, +0x06, +0x07, +0x08,
-	+0x09, +0x0a, +0x0b, +0x0c, +0x0d, +0x0e, +0x0f, +0x10,
-	+0x11, +0x12, +0x13, +0x14, +0x15, +0x16, +0x17, +0x18,
-	+0x19, +0x1a, +0x1b, +0x1c, +0x1d, +0x1e, +0x1f, +0x20,
-	+0x21, +0x22, +0x23, +0x24, +0x25, +0x26, +0x27, +0x28,
-	+0x29, +0x2a, +0x2b, +0x2c, +0x2d, +0x2e, +0x2f, +0x30,
-	+0x31, +0x32, +0x33, +0x34, +0x35, +0x36, +0x37, +0x38,
-	+0x39, +0x3a, +0x3b, +0x3c, +0x3d, +0x3e, +0x3f, +0x40,
-	+0x41, +0x42, +0x43, +0x44, +0x45, +0x46, +0x47, +0x48,
-	+0x49, +0x4a, +0x4b, +0x4c, +0x4d, +0x4e, +0x4f, +0x50,
-	+0x51, +0x52, +0x53, +0x54, +0x55, +0x56, +0x57, +0x58,
-	+0x59, +0x5a, +0x5b, +0x5c, +0x5d, +0x5e, +0x5f, +0x60,
-	+0x61, +0x62, +0x63, +0x64, +0x65, +0x66, +0x67, +0x68,
-	+0x69, +0x6a, +0x6b, +0x6c, +0x6d, +0x6e, +0x6f, +0x70,
-	+0x71, +0x72, +0x73, +0x74, +0x75, +0x76, +0x77, +0x78,
-	+0x79, +0x7a, +0x7b, +0x7c, +0x7d, +0x7e, +0x7f, +0x7f,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
+	-0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80, -0x80,
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+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f, +0x7f,
+	+0x7f,
 }
 
 const lutClamp255Base = 255
diff --git a/webp/decode_test.go b/webp/decode_test.go
index 37d6913..635c5d0 100644
--- a/webp/decode_test.go
+++ b/webp/decode_test.go
@@ -31,82 +31,85 @@
 }
 
 func TestDecodeVP8(t *testing.T) {
-	// The original video-001.png image is 150x103.
-	const w, h = 150, 103
-	// w2 and h2 are the half-width and half-height, rounded up.
-	const w2, h2 = int((w + 1) / 2), int((h + 1) / 2)
-
-	f0, err := os.Open("../testdata/video-001.webp.ycbcr.png")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer f0.Close()
-	img0, err := png.Decode(f0)
-	if err != nil {
-		t.Fatal(err)
+	testCases := []string{
+		"blue-purple-pink",
+		"video-001",
+		"yellow_rose",
 	}
 
-	// The split-into-YCbCr-planes golden image is a 2*w2 wide and h+h2 high
-	// gray image arranged in IMC4 format:
-	//   YYYY
-	//   YYYY
-	//   BBRR
-	// See http://www.fourcc.org/yuv.php#IMC4
-	if got, want := img0.Bounds(), image.Rect(0, 0, 2*w2, h+h2); got != want {
-		t.Fatalf("bounds0: got %v, want %v", got, want)
-	}
-	m0, ok := img0.(*image.Gray)
-	if !ok {
-		t.Fatal("decoded PNG image is not a Gray")
-	}
+	for _, tc := range testCases {
+		f0, err := os.Open("../testdata/" + tc + ".lossy.webp")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer f0.Close()
+		img0, err := Decode(f0)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	f1, err := os.Open("../testdata/video-001.webp")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer f1.Close()
-	img1, err := Decode(f1)
-	if err != nil {
-		t.Fatal(err)
-	}
+		m0, ok := img0.(*image.YCbCr)
+		if !ok || m0.SubsampleRatio != image.YCbCrSubsampleRatio420 {
+			t.Fatal("decoded WEBP image is not a 4:2:0 YCbCr")
+		}
+		// w2 and h2 are the half-width and half-height, rounded up.
+		w, h := m0.Bounds().Dx(), m0.Bounds().Dy()
+		w2, h2 := int((w+1)/2), int((h+1)/2)
 
-	if got, want := img1.Bounds(), image.Rect(0, 0, w, h); got != want {
-		t.Fatalf("bounds1: got %v, want %v", got, want)
-	}
-	m1, ok := img1.(*image.YCbCr)
-	if !ok || m1.SubsampleRatio != image.YCbCrSubsampleRatio420 {
-		t.Fatal("decoded WEBP image is not a 4:2:0 YCbCr")
-	}
+		f1, err := os.Open("../testdata/" + tc + ".lossy.webp.ycbcr.png")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer f1.Close()
+		img1, err := png.Decode(f1)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	planes := []struct {
-		name     string
-		m1Pix    []uint8
-		m1Stride int
-		m0Rect   image.Rectangle
-	}{
-		{"Y", m1.Y, m1.YStride, image.Rect(0, 0, w, h)},
-		{"Cb", m1.Cb, m1.CStride, image.Rect(0*w2, h, 1*w2, h+h2)},
-		{"Cr", m1.Cr, m1.CStride, image.Rect(1*w2, h, 2*w2, h+h2)},
-	}
-	for _, plane := range planes {
-		dx := plane.m0Rect.Dx()
-		nDiff, diff := 0, make([]byte, dx)
-		for j, y := 0, plane.m0Rect.Min.Y; y < plane.m0Rect.Max.Y; j, y = j+1, y+1 {
-			got := plane.m1Pix[j*plane.m1Stride:][:dx]
-			want := m0.Pix[y*m0.Stride+plane.m0Rect.Min.X:][:dx]
-			if bytes.Equal(got, want) {
-				continue
+		// The split-into-YCbCr-planes golden image is a 2*w2 wide and h+h2 high
+		// gray image arranged in IMC4 format:
+		//   YYYY
+		//   YYYY
+		//   BBRR
+		// See http://www.fourcc.org/yuv.php#IMC4
+		if got, want := img1.Bounds(), image.Rect(0, 0, 2*w2, h+h2); got != want {
+			t.Fatalf("bounds0: got %v, want %v", got, want)
+		}
+		m1, ok := img1.(*image.Gray)
+		if !ok {
+			t.Fatal("decoded PNG image is not a Gray")
+		}
+
+		planes := []struct {
+			name     string
+			m0Pix    []uint8
+			m0Stride int
+			m1Rect   image.Rectangle
+		}{
+			{"Y", m0.Y, m0.YStride, image.Rect(0, 0, w, h)},
+			{"Cb", m0.Cb, m0.CStride, image.Rect(0*w2, h, 1*w2, h+h2)},
+			{"Cr", m0.Cr, m0.CStride, image.Rect(1*w2, h, 2*w2, h+h2)},
+		}
+		for _, plane := range planes {
+			dx := plane.m1Rect.Dx()
+			nDiff, diff := 0, make([]byte, dx)
+			for j, y := 0, plane.m1Rect.Min.Y; y < plane.m1Rect.Max.Y; j, y = j+1, y+1 {
+				got := plane.m0Pix[j*plane.m0Stride:][:dx]
+				want := m1.Pix[y*m1.Stride+plane.m1Rect.Min.X:][:dx]
+				if bytes.Equal(got, want) {
+					continue
+				}
+				nDiff++
+				if nDiff > 10 {
+					t.Errorf("%s plane: more rows differ", plane.name)
+					break
+				}
+				for i := range got {
+					diff[i] = got[i] - want[i]
+				}
+				t.Errorf("%s plane: m0 row %d, m1 row %d\ngot %s\nwant%s\ndiff%s",
+					plane.name, j, y, hex(got), hex(want), hex(diff))
 			}
-			nDiff++
-			if nDiff > 10 {
-				t.Errorf("%s plane: more rows differ", plane.name)
-				break
-			}
-			for i := range got {
-				diff[i] = got[i] - want[i]
-			}
-			t.Errorf("%s plane: m0 row %d, m1 row %d\ngot %s\nwant%s\ndiff%s",
-				plane.name, y, j, hex(got), hex(want), hex(diff))
 		}
 	}
 }
@@ -210,5 +213,6 @@
 	}
 }
 
-func BenchmarkDecodeVP8(b *testing.B)  { benchmarkDecode(b, "yellow_rose.lossy") }
-func BenchmarkDecodeVP8L(b *testing.B) { benchmarkDecode(b, "yellow_rose.lossless") }
+func BenchmarkDecodeVP8SimpleFilter(b *testing.B) { benchmarkDecode(b, "blue-purple-pink.lossy") }
+func BenchmarkDecodeVP8NormalFilter(b *testing.B) { benchmarkDecode(b, "yellow_rose.lossy") }
+func BenchmarkDecodeVP8L(b *testing.B)            { benchmarkDecode(b, "yellow_rose.lossless") }