ycbcr_test.go

Documentation: image

		 1  // Copyright 2012 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  package image
		 6  
		 7  import (
		 8  	"image/color"
		 9  	"testing"
		10  )
		11  
		12  func TestYCbCr(t *testing.T) {
		13  	rects := []Rectangle{
		14  		Rect(0, 0, 16, 16),
		15  		Rect(1, 0, 16, 16),
		16  		Rect(0, 1, 16, 16),
		17  		Rect(1, 1, 16, 16),
		18  		Rect(1, 1, 15, 16),
		19  		Rect(1, 1, 16, 15),
		20  		Rect(1, 1, 15, 15),
		21  		Rect(2, 3, 14, 15),
		22  		Rect(7, 0, 7, 16),
		23  		Rect(0, 8, 16, 8),
		24  		Rect(0, 0, 10, 11),
		25  		Rect(5, 6, 16, 16),
		26  		Rect(7, 7, 8, 8),
		27  		Rect(7, 8, 8, 9),
		28  		Rect(8, 7, 9, 8),
		29  		Rect(8, 8, 9, 9),
		30  		Rect(7, 7, 17, 17),
		31  		Rect(8, 8, 17, 17),
		32  		Rect(9, 9, 17, 17),
		33  		Rect(10, 10, 17, 17),
		34  	}
		35  	subsampleRatios := []YCbCrSubsampleRatio{
		36  		YCbCrSubsampleRatio444,
		37  		YCbCrSubsampleRatio422,
		38  		YCbCrSubsampleRatio420,
		39  		YCbCrSubsampleRatio440,
		40  		YCbCrSubsampleRatio411,
		41  		YCbCrSubsampleRatio410,
		42  	}
		43  	deltas := []Point{
		44  		Pt(0, 0),
		45  		Pt(1000, 1001),
		46  		Pt(5001, -400),
		47  		Pt(-701, -801),
		48  	}
		49  	for _, r := range rects {
		50  		for _, subsampleRatio := range subsampleRatios {
		51  			for _, delta := range deltas {
		52  				testYCbCr(t, r, subsampleRatio, delta)
		53  			}
		54  		}
		55  		if testing.Short() {
		56  			break
		57  		}
		58  	}
		59  }
		60  
		61  func testYCbCr(t *testing.T, r Rectangle, subsampleRatio YCbCrSubsampleRatio, delta Point) {
		62  	// Create a YCbCr image m, whose bounds are r translated by (delta.X, delta.Y).
		63  	r1 := r.Add(delta)
		64  	m := NewYCbCr(r1, subsampleRatio)
		65  
		66  	// Test that the image buffer is reasonably small even if (delta.X, delta.Y) is far from the origin.
		67  	if len(m.Y) > 100*100 {
		68  		t.Errorf("r=%v, subsampleRatio=%v, delta=%v: image buffer is too large",
		69  			r, subsampleRatio, delta)
		70  		return
		71  	}
		72  
		73  	// Initialize m's pixels. For 422 and 420 subsampling, some of the Cb and Cr elements
		74  	// will be set multiple times. That's OK. We just want to avoid a uniform image.
		75  	for y := r1.Min.Y; y < r1.Max.Y; y++ {
		76  		for x := r1.Min.X; x < r1.Max.X; x++ {
		77  			yi := m.YOffset(x, y)
		78  			ci := m.COffset(x, y)
		79  			m.Y[yi] = uint8(16*y + x)
		80  			m.Cb[ci] = uint8(y + 16*x)
		81  			m.Cr[ci] = uint8(y + 16*x)
		82  		}
		83  	}
		84  
		85  	// Make various sub-images of m.
		86  	for y0 := delta.Y + 3; y0 < delta.Y+7; y0++ {
		87  		for y1 := delta.Y + 8; y1 < delta.Y+13; y1++ {
		88  			for x0 := delta.X + 3; x0 < delta.X+7; x0++ {
		89  				for x1 := delta.X + 8; x1 < delta.X+13; x1++ {
		90  					subRect := Rect(x0, y0, x1, y1)
		91  					sub := m.SubImage(subRect).(*YCbCr)
		92  
		93  					// For each point in the sub-image's bounds, check that m.At(x, y) equals sub.At(x, y).
		94  					for y := sub.Rect.Min.Y; y < sub.Rect.Max.Y; y++ {
		95  						for x := sub.Rect.Min.X; x < sub.Rect.Max.X; x++ {
		96  							color0 := m.At(x, y).(color.YCbCr)
		97  							color1 := sub.At(x, y).(color.YCbCr)
		98  							if color0 != color1 {
		99  								t.Errorf("r=%v, subsampleRatio=%v, delta=%v, x=%d, y=%d, color0=%v, color1=%v",
	 100  									r, subsampleRatio, delta, x, y, color0, color1)
	 101  								return
	 102  							}
	 103  						}
	 104  					}
	 105  				}
	 106  			}
	 107  		}
	 108  	}
	 109  }
	 110  
	 111  func TestYCbCrSlicesDontOverlap(t *testing.T) {
	 112  	m := NewYCbCr(Rect(0, 0, 8, 8), YCbCrSubsampleRatio420)
	 113  	names := []string{"Y", "Cb", "Cr"}
	 114  	slices := [][]byte{
	 115  		m.Y[:cap(m.Y)],
	 116  		m.Cb[:cap(m.Cb)],
	 117  		m.Cr[:cap(m.Cr)],
	 118  	}
	 119  	for i, slice := range slices {
	 120  		want := uint8(10 + i)
	 121  		for j := range slice {
	 122  			slice[j] = want
	 123  		}
	 124  	}
	 125  	for i, slice := range slices {
	 126  		want := uint8(10 + i)
	 127  		for j, got := range slice {
	 128  			if got != want {
	 129  				t.Fatalf("m.%s[%d]: got %d, want %d", names[i], j, got, want)
	 130  			}
	 131  		}
	 132  	}
	 133  }
	 134
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