writer_test.go

// Copyright 2012 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 tiff

import (
	"bytes"
	"image"
	"io/ioutil"
	"os"
	"testing"
)

var roundtripTests = []struct {
	filename string
	opts     *Options
}{
	{"g4test_1.tiff", nil},
	{"g4test_2.tiff", nil},
	{"video-001.tiff", nil},
	{"video-001-16bit.tiff", nil},
	{"video-001-gray.tiff", nil},
	{"video-001-gray-16bit.tiff", nil},
	{"video-001-paletted.tiff", nil},
	{"bw-packbits.tiff", nil},
	{"video-001.tiff", &Options{Predictor: true}},
	{"video-001.tiff", &Options{Compression: Deflate}},
	{"video-001.tiff", &Options{Predictor: true, Compression: Deflate}},
	{"video-001.tiff", &Options{Compression: LZW}},
	{"video-001.tiff", &Options{Predictor: true, Compression: LZW}},
	{"video-001-16bit.tiff", &Options{Predictor: true, Compression: LZW}},
	{"video-001-gray.tiff", &Options{Predictor: true, Compression: LZW}},
	{"video-001-gray-16bit.tiff", &Options{Predictor: true, Compression: LZW}},
	{"go-aqua-cmyk.tiff", nil},
	{"go-aqua-cmyk.tiff", &Options{Compression: LZW}},
	{"go-aqua-cmyk.tiff", &Options{Predictor: true, Compression: LZW}},
	{"zookeeper-cmyk.tiff", nil},
	{"zookeeper-cmyk.tiff", &Options{Compression: LZW}},
	{"zookeeper-cmyk.tiff", &Options{Predictor: true, Compression: LZW}},
}

func openImage(filename string) (image.Image, error) {
	f, err := os.Open(testdataDir + filename)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	return Decode(f)
}

func TestRoundtrip(t *testing.T) {
	for _, rt := range roundtripTests {
		img, err := openImage(rt.filename)
		if err != nil {
			t.Fatal(err)
		}

		out := new(bytes.Buffer)
		err = Encode(out, img, rt.opts)
		if err != nil {
			t.Fatal(err)
		}

		img2, err := Decode(&buffer{buf: out.Bytes()})
		if err != nil {
			t.Fatal(err)
		}
		compare(t, img, img2)
	}
}

// TestRoundtrip2 tests that encoding and decoding an image whose
// origin is not (0, 0) gives the same thing.
func TestRoundtrip2(t *testing.T) {
	m0 := image.NewRGBA(image.Rect(3, 4, 9, 8))
	for i := range m0.Pix {
		m0.Pix[i] = byte(i)
	}
	out := new(bytes.Buffer)
	if err := Encode(out, m0, nil); err != nil {
		t.Fatal(err)
	}
	m1, err := Decode(&buffer{buf: out.Bytes()})
	if err != nil {
		t.Fatal(err)
	}
	compare(t, m0, m1)
}

func delta(u0, u1 uint32) int64 {
	d := int64(u0) - int64(u1)
	if d < 0 {
		return -d
	}
	return d
}

// averageDelta returns the average delta in RGB space. The two images must
// have the same bounds.
func averageDelta(m0, m1 image.Image) int64 {
	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
		}
	}
	return sum / n
}

// TestRoundtrip3 tests that encoding and decoding an image use JPEG compression.
func TestRoundtrip3(t *testing.T) {
	roundtripTests := []string{
		"bw-jpeg.tiff",
		"video-001-jpeg.tiff",
	}
	for _, rt := range roundtripTests {
		img, err := openImage(rt)
		if err != nil {
			t.Fatal(err)
		}

		out := new(bytes.Buffer)
		err = Encode(out, img, &Options{Compression: JPEG})
		if err != nil {
			t.Fatal(err)
		}

		img2, err := Decode(&buffer{buf: out.Bytes()})
		if err != nil {
			t.Fatal(err)
		}
		want := int64(6 << 8)
		if got := averageDelta(img, img2); got > want {
			t.Errorf("average delta too high; got %d, want <= %d", got, want)
		}
	}
}

func benchmarkEncode(b *testing.B, name string, pixelSize int) {
	img, err := openImage(name)
	if err != nil {
		b.Fatal(err)
	}
	s := img.Bounds().Size()
	b.SetBytes(int64(s.X * s.Y * pixelSize))
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		Encode(ioutil.Discard, img, nil)
	}
}

func BenchmarkEncode(b *testing.B)         { benchmarkEncode(b, "video-001.tiff", 4) }
func BenchmarkEncodePaletted(b *testing.B) { benchmarkEncode(b, "video-001-paletted.tiff", 1) }
func BenchmarkEncodeGray(b *testing.B)     { benchmarkEncode(b, "video-001-gray.tiff", 1) }
func BenchmarkEncodeGray16(b *testing.B)   { benchmarkEncode(b, "video-001-gray-16bit.tiff", 2) }
func BenchmarkEncodeRGBA(b *testing.B)     { benchmarkEncode(b, "video-001.tiff", 4) }
func BenchmarkEncodeRGBA64(b *testing.B)   { benchmarkEncode(b, "video-001-16bit.tiff", 8) }