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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package jpeg
import (
"bytes"
"image"
"image/color"
"image/png"
"io/ioutil"
"math/rand"
"os"
"testing"
)
var testCase = []struct {
filename string
quality int
tolerance int64
}{
{"../testdata/video-001.png", 1, 24 << 8},
{"../testdata/video-001.png", 20, 12 << 8},
{"../testdata/video-001.png", 60, 8 << 8},
{"../testdata/video-001.png", 80, 6 << 8},
{"../testdata/video-001.png", 90, 4 << 8},
{"../testdata/video-001.png", 100, 2 << 8},
}
func delta(u0, u1 uint32) int64 {
d := int64(u0) - int64(u1)
if d < 0 {
return -d
}
return d
}
func readPng(filename string) (image.Image, error) {
f, err := os.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
return png.Decode(f)
}
func TestWriter(t *testing.T) {
for _, tc := range testCase {
// Read the image.
m0, err := readPng(tc.filename)
if err != nil {
t.Error(tc.filename, err)
continue
}
// Encode that image as JPEG.
buf := bytes.NewBuffer(nil)
err = Encode(buf, m0, &Options{Quality: tc.quality})
if err != nil {
t.Error(tc.filename, err)
continue
}
// Decode that JPEG.
m1, err := Decode(buf)
if err != nil {
t.Error(tc.filename, err)
continue
}
// Compute the average delta in RGB space.
b := m0.Bounds()
var sum, n int64
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
c0 := m0.At(x, y)
c1 := m1.At(x, y)
r0, g0, b0, _ := c0.RGBA()
r1, g1, b1, _ := c1.RGBA()
sum += delta(r0, r1)
sum += delta(g0, g1)
sum += delta(b0, b1)
n += 3
}
}
// Compare the average delta to the tolerance level.
if sum/n > tc.tolerance {
t.Errorf("%s, quality=%d: average delta is too high", tc.filename, tc.quality)
continue
}
}
}
func BenchmarkEncodeRGBOpaque(b *testing.B) {
b.StopTimer()
img := image.NewRGBA(image.Rect(0, 0, 640, 480))
// Set all pixels to 0xFF alpha to force opaque mode.
bo := img.Bounds()
rnd := rand.New(rand.NewSource(123))
for y := bo.Min.Y; y < bo.Max.Y; y++ {
for x := bo.Min.X; x < bo.Max.X; x++ {
img.Set(x, y, color.RGBA{
uint8(rnd.Intn(256)),
uint8(rnd.Intn(256)),
uint8(rnd.Intn(256)),
255})
}
}
if !img.Opaque() {
panic("expected image to be opaque")
}
b.SetBytes(640 * 480 * 4)
b.StartTimer()
options := &Options{Quality: 90}
for i := 0; i < b.N; i++ {
Encode(ioutil.Discard, img, options)
}
}
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