image/gif: add more writer benchmarks

The two existing benchmarks encode randomized pixels, which isn't very
representative. The two new benchmarks encode a PNG photo as a GIF.

Also rename the benchmarks for consistency.

Also fix the bytes-per-op measure for paletted images, which are 1 (not
4) bytes per pixel.

Also simplify BenchmarkEncodeRandomPaletted (formerly just called
BenchmarkEncode). It doesn't need to generate a random palette (and the
GIF encoder largely doesn't care about the palette's RGBA values).
Use palette.Plan9 instead, a pre-existing 256-element color palette.

Change-Id: I10a6ea4e9590bb0d9f76e8cc0f4a88d43b1d650d
Reviewed-on: https://go-review.googlesource.com/c/go/+/248218
Reviewed-by: David Symonds <dsymonds@golang.org>

diff --git a/src/image/gif/writer_test.go b/src/image/gif/writer_test.go
index 9b15c8d99d4aaa7dd9937915c36480f37bb5fa63..5d1b2c439ee6d9a0c111053d2a8c1df12099156c 100644 (file)
--- a/src/image/gif/writer_test.go
+++ b/src/image/gif/writer_test.go
@@ -9,6 +9,7 @@ import (
        "image"
        "image/color"
        "image/color/palette"
+       "image/draw"
        _ "image/png"
        "io/ioutil"
        "math/rand"
@@ -656,25 +657,14 @@ func TestEncodeWrappedImage(t *testing.T) {
        }
 }
 
-func BenchmarkEncode(b *testing.B) {
+func BenchmarkEncodeRandomPaletted(b *testing.B) {
+       img := image.NewPaletted(image.Rect(0, 0, 640, 480), palette.Plan9)
        rnd := rand.New(rand.NewSource(123))
-
-       // Restrict to a 256-color paletted image to avoid quantization path.
-       palette := make(color.Palette, 256)
-       for i := range palette {
-               palette[i] = color.RGBA{
-                       uint8(rnd.Intn(256)),
-                       uint8(rnd.Intn(256)),
-                       uint8(rnd.Intn(256)),
-                       255,
-               }
-       }
-       img := image.NewPaletted(image.Rect(0, 0, 640, 480), palette)
        for i := range img.Pix {
                img.Pix[i] = uint8(rnd.Intn(256))
        }
 
-       b.SetBytes(640 * 480 * 4)
+       b.SetBytes(640 * 480 * 1)
        b.ReportAllocs()
        b.ResetTimer()
        for i := 0; i < b.N; i++ {
@@ -682,7 +672,7 @@ func BenchmarkEncode(b *testing.B) {
        }
 }
 
-func BenchmarkQuantizedEncode(b *testing.B) {
+func BenchmarkEncodeRandomRGBA(b *testing.B) {
        img := image.NewRGBA(image.Rect(0, 0, 640, 480))
        bo := img.Bounds()
        rnd := rand.New(rand.NewSource(123))
@@ -696,6 +686,7 @@ func BenchmarkQuantizedEncode(b *testing.B) {
                        })
                }
        }
+
        b.SetBytes(640 * 480 * 4)
        b.ReportAllocs()
        b.ResetTimer()
@@ -703,3 +694,35 @@ func BenchmarkQuantizedEncode(b *testing.B) {
                Encode(ioutil.Discard, img, nil)
        }
 }
+
+func BenchmarkEncodeRealisticPaletted(b *testing.B) {
+       rgba, err := readImg("../testdata/video-001.png")
+       if err != nil {
+               b.Fatalf("readImg: %v", err)
+       }
+       bo := rgba.Bounds()
+       img := image.NewPaletted(bo, palette.Plan9)
+       draw.Draw(img, bo, rgba, bo.Min, draw.Src)
+
+       b.SetBytes(int64(bo.Dx() * bo.Dy() * 1))
+       b.ReportAllocs()
+       b.ResetTimer()
+       for i := 0; i < b.N; i++ {
+               Encode(ioutil.Discard, img, nil)
+       }
+}
+
+func BenchmarkEncodeRealisticRGBA(b *testing.B) {
+       img, err := readImg("../testdata/video-001.png")
+       if err != nil {
+               b.Fatalf("readImg: %v", err)
+       }
+       bo := img.Bounds()
+
+       b.SetBytes(int64(bo.Dx() * bo.Dy() * 4))
+       b.ReportAllocs()
+       b.ResetTimer()
+       for i := 0; i < b.N; i++ {
+               Encode(ioutil.Discard, img, nil)
+       }
+}