draw/scale_test.go - image - Git at Google

 // Copyright 2015 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 draw

 import (
 	"bytes"
 	"flag"
 	"fmt"
 	"image"
 	"image/color"
 	"image/png"
 	"math/rand"
 	"os"
 	"reflect"
 	"testing"

 	_ "image/jpeg"
 )

 var genScaleFiles = flag.Bool("gen_scale_files", false, "whether to generate the TestScaleXxx golden files.")

 // testScale tests that scaling the source image gives the exact destination
 // image. This is to ensure that any refactoring or optimization of the scaling
 // code doesn't change the scaling behavior. Changing the actual algorithm or
 // kernel used by any particular quality setting will obviously change the
 // resultant pixels. In such a case, use the gen_scale_files flag to regenerate
 // the golden files.
 func testScale(t *testing.T, w int, h int, direction, srcFilename string) {
 	f, err := os.Open("../testdata/go-turns-two-" + srcFilename)
 	if err != nil {
 		t.Fatalf("Open: %v", err)
 	}
 	defer f.Close()
 	src, _, err := image.Decode(f)
 	if err != nil {
 		t.Fatalf("Decode: %v", err)
 	}
 	testCases := map[string]Interpolator{
 		"nn": NearestNeighbor,
 		"ab": ApproxBiLinear,
 		"bl": BiLinear,
 		"cr": CatmullRom,
 	}
 	for name, q := range testCases {
 		gotFilename := fmt.Sprintf("../testdata/go-turns-two-%s-%s.png", direction, name)

 		got := image.NewRGBA(image.Rect(0, 0, w, h))
 		Scale(got, got.Bounds(), src, src.Bounds(), q)
 		if *genScaleFiles {
 			g, err := os.Create(gotFilename)
 			if err != nil {
 				t.Errorf("Create: %v", err)
 				continue
 			}
 			defer g.Close()
 			if err := png.Encode(g, got); err != nil {
 				t.Errorf("Encode: %v", err)
 				continue
 			}
 			continue
 		}

 		g, err := os.Open(gotFilename)
 		if err != nil {
 			t.Errorf("Open: %v", err)
 			continue
 		}
 		defer g.Close()
 		want, err := png.Decode(g)
 		if err != nil {
 			t.Errorf("Decode: %v", err)
 			continue
 		}

 		if !reflect.DeepEqual(got, want) {
 			t.Errorf("%s: actual image differs from golden image", gotFilename)
 			continue
 		}
 	}
 }

 func TestScaleDown(t *testing.T) { testScale(t, 100, 100, "down", "280x360.jpeg") }
 func TestScaleUp(t *testing.T)   { testScale(t, 75, 100, "up", "14x18.png") }

 // The fooWrapper types wrap the dst or src image to avoid triggering the
 // type-specific fast path implementations.
 type (
 	dstWrapper struct{ Image }
 	srcWrapper struct{ image.Image }
 )

 // TestFastPaths tests that the fast path implementations produce identical
 // results to the generic implementation.
 func TestFastPaths(t *testing.T) {
 	drs := []image.Rectangle{
 		image.Rect(0, 0, 10, 10),   // The dst bounds.
 		image.Rect(3, 4, 8, 6),     // A strict subset of the dst bounds.
 		image.Rect(-3, -5, 2, 4),   // Partial out-of-bounds #0.
 		image.Rect(4, -2, 6, 12),   // Partial out-of-bounds #1.
 		image.Rect(12, 14, 23, 45), // Complete out-of-bounds.
 		image.Rect(5, 5, 5, 5),     // Empty.
 	}
 	srs := []image.Rectangle{
 		image.Rect(0, 0, 12, 9),    // The src bounds.
 		image.Rect(2, 2, 10, 8),    // A strict subset of the src bounds.
 		image.Rect(10, 5, 20, 20),  // Partial out-of-bounds #0.
 		image.Rect(-40, 0, 40, 8),  // Partial out-of-bounds #1.
 		image.Rect(-8, -8, -4, -4), // Complete out-of-bounds.
 		image.Rect(5, 5, 5, 5),     // Empty.
 	}
 	srcfs := []func(image.Rectangle) (image.Image, error){
 		srcNRGBA,
 		srcRGBA,
 		srcUniform,
 		srcYCbCr,
 	}
 	var srcs []image.Image
 	for _, srcf := range srcfs {
 		src, err := srcf(srs[0])
 		if err != nil {
 			t.Fatal(err)
 		}
 		srcs = append(srcs, src)
 	}
 	qs := []Interpolator{
 		NearestNeighbor,
 		ApproxBiLinear,
 		CatmullRom,
 	}
 	blue := image.NewUniform(color.RGBA{0x11, 0x22, 0x44, 0x7f})

 	for _, dr := range drs {
 		for _, src := range srcs {
 			for _, sr := range srs {
 				for _, q := range qs {
 					dst0 := image.NewRGBA(drs[0])
 					dst1 := image.NewRGBA(drs[0])
 					Draw(dst0, dst0.Bounds(), blue, image.Point{}, Src)
 					Draw(dstWrapper{dst1}, dst1.Bounds(), srcWrapper{blue}, image.Point{}, Src)
 					Scale(dst0, dr, src, sr, q)
 					Scale(dstWrapper{dst1}, dr, srcWrapper{src}, sr, q)
 					if !bytes.Equal(dst0.Pix, dst1.Pix) {
 						t.Errorf("pix differ for dr=%v, src=%T, sr=%v, q=%T", dr, src, sr, q)
 					}
 				}
 			}
 		}
 	}
 }

 func srcNRGBA(boundsHint image.Rectangle) (image.Image, error) {
 	m := image.NewNRGBA(boundsHint)
 	r := rand.New(rand.NewSource(1))
 	for i := range m.Pix {
 		m.Pix[i] = uint8(r.Intn(256))
 	}
 	return m, nil
 }

 func srcRGBA(boundsHint image.Rectangle) (image.Image, error) {
 	m := image.NewRGBA(boundsHint)
 	r := rand.New(rand.NewSource(2))
 	for i := range m.Pix {
 		m.Pix[i] = uint8(r.Intn(256))
 	}
 	// RGBA is alpha-premultiplied, so the R, G and B values should
 	// be <= the A values.
 	for i := 0; i < len(m.Pix); i += 4 {
 		m.Pix[i+0] = uint8(uint32(m.Pix[i+0]) * uint32(m.Pix[i+3]) / 0xff)
 		m.Pix[i+1] = uint8(uint32(m.Pix[i+1]) * uint32(m.Pix[i+3]) / 0xff)
 		m.Pix[i+2] = uint8(uint32(m.Pix[i+2]) * uint32(m.Pix[i+3]) / 0xff)
 	}
 	return m, nil
 }

 func srcUniform(boundsHint image.Rectangle) (image.Image, error) {
 	return image.NewUniform(color.RGBA64{0x1234, 0x5555, 0x9181, 0xbeef}), nil
 }

 func srcYCbCr(boundsHint image.Rectangle) (image.Image, error) {
 	m := image.NewYCbCr(boundsHint, image.YCbCrSubsampleRatio420)
 	r := rand.New(rand.NewSource(3))
 	for i := range m.Y {
 		m.Y[i] = uint8(r.Intn(256))
 	}
 	for i := range m.Cb {
 		m.Cb[i] = uint8(r.Intn(256))
 	}
 	for i := range m.Cr {
 		m.Cr[i] = uint8(r.Intn(256))
 	}
 	return m, nil
 }

 func srcYCbCrLarge(boundsHint image.Rectangle) (image.Image, error) {
 	// 3072 x 2304 is over 7 million pixels at 4:3, comparable to a
 	// 2015 smart-phone camera's output.
 	return srcYCbCr(image.Rect(0, 0, 3072, 2304))
 }

 func srcTux(boundsHint image.Rectangle) (image.Image, error) {
 	// tux.png is a 386 x 395 image.
 	f, err := os.Open("../testdata/tux.png")
 	if err != nil {
 		return nil, fmt.Errorf("Open: %v", err)
 	}
 	defer f.Close()
 	src, err := png.Decode(f)
 	if err != nil {
 		return nil, fmt.Errorf("Decode: %v", err)
 	}
 	return src, nil
 }

 func benchScale(b *testing.B, srcf func(image.Rectangle) (image.Image, error), w int, h int, q Interpolator) {
 	dst := image.NewRGBA(image.Rect(0, 0, w, h))
 	src, err := srcf(image.Rect(0, 0, 1024, 768))
 	if err != nil {
 		b.Fatal(err)
 	}
 	dr, sr := dst.Bounds(), src.Bounds()
 	scaler := q.NewScaler(int32(dr.Dx()), int32(dr.Dy()), int32(sr.Dx()), int32(sr.Dy()))

 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		scaler.Scale(dst, dr.Min, src, sr.Min)
 	}
 }

 func BenchmarkScaleLargeDownNN(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, NearestNeighbor) }
 func BenchmarkScaleLargeDownAB(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, ApproxBiLinear) }
 func BenchmarkScaleLargeDownBL(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, BiLinear) }
 func BenchmarkScaleLargeDownCR(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, CatmullRom) }

 func BenchmarkScaleDownNN(b *testing.B) { benchScale(b, srcTux, 120, 80, NearestNeighbor) }
 func BenchmarkScaleDownAB(b *testing.B) { benchScale(b, srcTux, 120, 80, ApproxBiLinear) }
 func BenchmarkScaleDownBL(b *testing.B) { benchScale(b, srcTux, 120, 80, BiLinear) }
 func BenchmarkScaleDownCR(b *testing.B) { benchScale(b, srcTux, 120, 80, CatmullRom) }

 func BenchmarkScaleUpNN(b *testing.B) { benchScale(b, srcTux, 800, 600, NearestNeighbor) }
 func BenchmarkScaleUpAB(b *testing.B) { benchScale(b, srcTux, 800, 600, ApproxBiLinear) }
 func BenchmarkScaleUpBL(b *testing.B) { benchScale(b, srcTux, 800, 600, BiLinear) }
 func BenchmarkScaleUpCR(b *testing.B) { benchScale(b, srcTux, 800, 600, CatmullRom) }

 func BenchmarkScaleSrcNRGBA(b *testing.B)   { benchScale(b, srcNRGBA, 200, 150, ApproxBiLinear) }
 func BenchmarkScaleSrcRGBA(b *testing.B)    { benchScale(b, srcRGBA, 200, 150, ApproxBiLinear) }
 func BenchmarkScaleSrcUniform(b *testing.B) { benchScale(b, srcUniform, 200, 150, ApproxBiLinear) }
 func BenchmarkScaleSrcYCbCr(b *testing.B)   { benchScale(b, srcYCbCr, 200, 150, ApproxBiLinear) }
	// Copyright 2015 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 draw

	import (
	"bytes"
	"flag"
	"fmt"
	"image"
	"image/color"
	"image/png"
	"math/rand"
	"os"
	"reflect"
	"testing"

	_ "image/jpeg"
	)

	var genScaleFiles = flag.Bool("gen_scale_files", false, "whether to generate the TestScaleXxx golden files.")

	// testScale tests that scaling the source image gives the exact destination
	// image. This is to ensure that any refactoring or optimization of the scaling
	// code doesn't change the scaling behavior. Changing the actual algorithm or
	// kernel used by any particular quality setting will obviously change the
	// resultant pixels. In such a case, use the gen_scale_files flag to regenerate
	// the golden files.
	func testScale(t *testing.T, w int, h int, direction, srcFilename string) {
	f, err := os.Open("../testdata/go-turns-two-" + srcFilename)
	if err != nil {
	t.Fatalf("Open: %v", err)
	}
	defer f.Close()
	src, _, err := image.Decode(f)
	if err != nil {
	t.Fatalf("Decode: %v", err)
	}
	testCases := map[string]Interpolator{
	"nn": NearestNeighbor,
	"ab": ApproxBiLinear,
	"bl": BiLinear,
	"cr": CatmullRom,
	}
	for name, q := range testCases {
	gotFilename := fmt.Sprintf("../testdata/go-turns-two-%s-%s.png", direction, name)

	got := image.NewRGBA(image.Rect(0, 0, w, h))
	Scale(got, got.Bounds(), src, src.Bounds(), q)
	if *genScaleFiles {
	g, err := os.Create(gotFilename)
	if err != nil {
	t.Errorf("Create: %v", err)
	continue
	}
	defer g.Close()
	if err := png.Encode(g, got); err != nil {
	t.Errorf("Encode: %v", err)
	continue
	}
	continue
	}

	g, err := os.Open(gotFilename)
	if err != nil {
	t.Errorf("Open: %v", err)
	continue
	}
	defer g.Close()
	want, err := png.Decode(g)
	if err != nil {
	t.Errorf("Decode: %v", err)
	continue
	}

	if !reflect.DeepEqual(got, want) {
	t.Errorf("%s: actual image differs from golden image", gotFilename)
	continue
	}
	}
	}

	func TestScaleDown(t *testing.T) { testScale(t, 100, 100, "down", "280x360.jpeg") }
	func TestScaleUp(t *testing.T) { testScale(t, 75, 100, "up", "14x18.png") }

	// The fooWrapper types wrap the dst or src image to avoid triggering the
	// type-specific fast path implementations.
	type (
	dstWrapper struct{ Image }
	srcWrapper struct{ image.Image }
	)

	// TestFastPaths tests that the fast path implementations produce identical
	// results to the generic implementation.
	func TestFastPaths(t *testing.T) {
	drs := []image.Rectangle{
	image.Rect(0, 0, 10, 10), // The dst bounds.
	image.Rect(3, 4, 8, 6), // A strict subset of the dst bounds.
	image.Rect(-3, -5, 2, 4), // Partial out-of-bounds #0.
	image.Rect(4, -2, 6, 12), // Partial out-of-bounds #1.
	image.Rect(12, 14, 23, 45), // Complete out-of-bounds.
	image.Rect(5, 5, 5, 5), // Empty.
	}
	srs := []image.Rectangle{
	image.Rect(0, 0, 12, 9), // The src bounds.
	image.Rect(2, 2, 10, 8), // A strict subset of the src bounds.
	image.Rect(10, 5, 20, 20), // Partial out-of-bounds #0.
	image.Rect(-40, 0, 40, 8), // Partial out-of-bounds #1.
	image.Rect(-8, -8, -4, -4), // Complete out-of-bounds.
	image.Rect(5, 5, 5, 5), // Empty.
	}
	srcfs := []func(image.Rectangle) (image.Image, error){
	srcNRGBA,
	srcRGBA,
	srcUniform,
	srcYCbCr,
	}
	var srcs []image.Image
	for _, srcf := range srcfs {
	src, err := srcf(srs[0])
	if err != nil {
	t.Fatal(err)
	}
	srcs = append(srcs, src)
	}
	qs := []Interpolator{
	NearestNeighbor,
	ApproxBiLinear,
	CatmullRom,
	}
	blue := image.NewUniform(color.RGBA{0x11, 0x22, 0x44, 0x7f})

	for _, dr := range drs {
	for _, src := range srcs {
	for _, sr := range srs {
	for _, q := range qs {
	dst0 := image.NewRGBA(drs[0])
	dst1 := image.NewRGBA(drs[0])
	Draw(dst0, dst0.Bounds(), blue, image.Point{}, Src)
	Draw(dstWrapper{dst1}, dst1.Bounds(), srcWrapper{blue}, image.Point{}, Src)
	Scale(dst0, dr, src, sr, q)
	Scale(dstWrapper{dst1}, dr, srcWrapper{src}, sr, q)
	if !bytes.Equal(dst0.Pix, dst1.Pix) {
	t.Errorf("pix differ for dr=%v, src=%T, sr=%v, q=%T", dr, src, sr, q)
	}
	}
	}
	}
	}
	}

	func srcNRGBA(boundsHint image.Rectangle) (image.Image, error) {
	m := image.NewNRGBA(boundsHint)
	r := rand.New(rand.NewSource(1))
	for i := range m.Pix {
	m.Pix[i] = uint8(r.Intn(256))
	}
	return m, nil
	}

	func srcRGBA(boundsHint image.Rectangle) (image.Image, error) {
	m := image.NewRGBA(boundsHint)
	r := rand.New(rand.NewSource(2))
	for i := range m.Pix {
	m.Pix[i] = uint8(r.Intn(256))
	}
	// RGBA is alpha-premultiplied, so the R, G and B values should
	// be <= the A values.
	for i := 0; i < len(m.Pix); i += 4 {
	m.Pix[i+0] = uint8(uint32(m.Pix[i+0]) * uint32(m.Pix[i+3]) / 0xff)
	m.Pix[i+1] = uint8(uint32(m.Pix[i+1]) * uint32(m.Pix[i+3]) / 0xff)
	m.Pix[i+2] = uint8(uint32(m.Pix[i+2]) * uint32(m.Pix[i+3]) / 0xff)
	}
	return m, nil
	}

	func srcUniform(boundsHint image.Rectangle) (image.Image, error) {
	return image.NewUniform(color.RGBA64{0x1234, 0x5555, 0x9181, 0xbeef}), nil
	}

	func srcYCbCr(boundsHint image.Rectangle) (image.Image, error) {
	m := image.NewYCbCr(boundsHint, image.YCbCrSubsampleRatio420)
	r := rand.New(rand.NewSource(3))
	for i := range m.Y {
	m.Y[i] = uint8(r.Intn(256))
	}
	for i := range m.Cb {
	m.Cb[i] = uint8(r.Intn(256))
	}
	for i := range m.Cr {
	m.Cr[i] = uint8(r.Intn(256))
	}
	return m, nil
	}

	func srcYCbCrLarge(boundsHint image.Rectangle) (image.Image, error) {
	// 3072 x 2304 is over 7 million pixels at 4:3, comparable to a
	// 2015 smart-phone camera's output.
	return srcYCbCr(image.Rect(0, 0, 3072, 2304))
	}

	func srcTux(boundsHint image.Rectangle) (image.Image, error) {
	// tux.png is a 386 x 395 image.
	f, err := os.Open("../testdata/tux.png")
	if err != nil {
	return nil, fmt.Errorf("Open: %v", err)
	}
	defer f.Close()
	src, err := png.Decode(f)
	if err != nil {
	return nil, fmt.Errorf("Decode: %v", err)
	}
	return src, nil
	}

	func benchScale(b *testing.B, srcf func(image.Rectangle) (image.Image, error), w int, h int, q Interpolator) {
	dst := image.NewRGBA(image.Rect(0, 0, w, h))
	src, err := srcf(image.Rect(0, 0, 1024, 768))
	if err != nil {
	b.Fatal(err)
	}
	dr, sr := dst.Bounds(), src.Bounds()
	scaler := q.NewScaler(int32(dr.Dx()), int32(dr.Dy()), int32(sr.Dx()), int32(sr.Dy()))

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
	scaler.Scale(dst, dr.Min, src, sr.Min)
	}
	}

	func BenchmarkScaleLargeDownNN(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, NearestNeighbor) }
	func BenchmarkScaleLargeDownAB(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, ApproxBiLinear) }
	func BenchmarkScaleLargeDownBL(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, BiLinear) }
	func BenchmarkScaleLargeDownCR(b *testing.B) { benchScale(b, srcYCbCrLarge, 200, 150, CatmullRom) }

	func BenchmarkScaleDownNN(b *testing.B) { benchScale(b, srcTux, 120, 80, NearestNeighbor) }
	func BenchmarkScaleDownAB(b *testing.B) { benchScale(b, srcTux, 120, 80, ApproxBiLinear) }
	func BenchmarkScaleDownBL(b *testing.B) { benchScale(b, srcTux, 120, 80, BiLinear) }
	func BenchmarkScaleDownCR(b *testing.B) { benchScale(b, srcTux, 120, 80, CatmullRom) }

	func BenchmarkScaleUpNN(b *testing.B) { benchScale(b, srcTux, 800, 600, NearestNeighbor) }
	func BenchmarkScaleUpAB(b *testing.B) { benchScale(b, srcTux, 800, 600, ApproxBiLinear) }
	func BenchmarkScaleUpBL(b *testing.B) { benchScale(b, srcTux, 800, 600, BiLinear) }
	func BenchmarkScaleUpCR(b *testing.B) { benchScale(b, srcTux, 800, 600, CatmullRom) }

	func BenchmarkScaleSrcNRGBA(b *testing.B) { benchScale(b, srcNRGBA, 200, 150, ApproxBiLinear) }
	func BenchmarkScaleSrcRGBA(b *testing.B) { benchScale(b, srcRGBA, 200, 150, ApproxBiLinear) }
	func BenchmarkScaleSrcUniform(b *testing.B) { benchScale(b, srcUniform, 200, 150, ApproxBiLinear) }
	func BenchmarkScaleSrcYCbCr(b *testing.B) { benchScale(b, srcYCbCr, 200, 150, ApproxBiLinear) }