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image: add support for image/jpeg and image/png (#303)
* Copy from go1.17 image package * Remove unnecessary files * Reduce memory usage * Add examples/ili9341/slideshow * image: add ./image/README.md * image: change convert2bin to . /cmd * Makefile: add ./cmd to NOTEST
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package jpeg
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import (
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"bytes"
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"fmt"
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"image"
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"image/color"
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"image/png"
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"io"
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"math/rand"
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"os"
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"testing"
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)
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// zigzag maps from the natural ordering to the zig-zag ordering. For example,
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// zigzag[0*8 + 3] is the zig-zag sequence number of the element in the fourth
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// column and first row.
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var zigzag = [blockSize]int{
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0, 1, 5, 6, 14, 15, 27, 28,
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2, 4, 7, 13, 16, 26, 29, 42,
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3, 8, 12, 17, 25, 30, 41, 43,
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9, 11, 18, 24, 31, 40, 44, 53,
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10, 19, 23, 32, 39, 45, 52, 54,
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20, 22, 33, 38, 46, 51, 55, 60,
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21, 34, 37, 47, 50, 56, 59, 61,
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35, 36, 48, 49, 57, 58, 62, 63,
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}
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func TestZigUnzig(t *testing.T) {
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for i := 0; i < blockSize; i++ {
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if unzig[zigzag[i]] != i {
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t.Errorf("unzig[zigzag[%d]] == %d", i, unzig[zigzag[i]])
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}
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if zigzag[unzig[i]] != i {
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t.Errorf("zigzag[unzig[%d]] == %d", i, zigzag[unzig[i]])
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}
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}
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}
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// unscaledQuantInNaturalOrder are the unscaled quantization tables in
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// natural (not zig-zag) order, as specified in section K.1.
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var unscaledQuantInNaturalOrder = [nQuantIndex][blockSize]byte{
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// Luminance.
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{
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16, 11, 10, 16, 24, 40, 51, 61,
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12, 12, 14, 19, 26, 58, 60, 55,
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14, 13, 16, 24, 40, 57, 69, 56,
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14, 17, 22, 29, 51, 87, 80, 62,
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18, 22, 37, 56, 68, 109, 103, 77,
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24, 35, 55, 64, 81, 104, 113, 92,
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49, 64, 78, 87, 103, 121, 120, 101,
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72, 92, 95, 98, 112, 100, 103, 99,
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},
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// Chrominance.
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{
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17, 18, 24, 47, 99, 99, 99, 99,
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18, 21, 26, 66, 99, 99, 99, 99,
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24, 26, 56, 99, 99, 99, 99, 99,
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47, 66, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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99, 99, 99, 99, 99, 99, 99, 99,
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},
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}
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func TestUnscaledQuant(t *testing.T) {
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bad := false
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for i := quantIndex(0); i < nQuantIndex; i++ {
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for zig := 0; zig < blockSize; zig++ {
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got := unscaledQuant[i][zig]
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want := unscaledQuantInNaturalOrder[i][unzig[zig]]
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if got != want {
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t.Errorf("i=%d, zig=%d: got %d, want %d", i, zig, got, want)
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bad = true
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}
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}
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}
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if bad {
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names := [nQuantIndex]string{"Luminance", "Chrominance"}
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buf := &bytes.Buffer{}
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for i, name := range names {
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fmt.Fprintf(buf, "// %s.\n{\n", name)
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for zig := 0; zig < blockSize; zig++ {
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fmt.Fprintf(buf, "%d, ", unscaledQuantInNaturalOrder[i][unzig[zig]])
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if zig%8 == 7 {
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buf.WriteString("\n")
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}
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}
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buf.WriteString("},\n")
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}
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t.Logf("expected unscaledQuant values:\n%s", buf.String())
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}
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}
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var testCase = []struct {
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filename string
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quality int
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tolerance int64
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}{
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{"../testdata/video-001.png", 1, 24 << 8},
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{"../testdata/video-001.png", 20, 12 << 8},
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{"../testdata/video-001.png", 60, 8 << 8},
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{"../testdata/video-001.png", 80, 6 << 8},
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{"../testdata/video-001.png", 90, 4 << 8},
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{"../testdata/video-001.png", 100, 2 << 8},
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}
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func delta(u0, u1 uint32) int64 {
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d := int64(u0) - int64(u1)
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if d < 0 {
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return -d
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}
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return d
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}
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func readPng(filename string) (image.Image, error) {
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f, err := os.Open(filename)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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return png.Decode(f)
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}
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func TestWriter(t *testing.T) {
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for _, tc := range testCase {
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// Read the image.
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m0, err := readPng(tc.filename)
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if err != nil {
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t.Error(tc.filename, err)
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continue
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}
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// Encode that image as JPEG.
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var buf bytes.Buffer
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err = Encode(&buf, m0, &Options{Quality: tc.quality})
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if err != nil {
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t.Error(tc.filename, err)
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continue
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}
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// Decode that JPEG.
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m1, err := Decode(&buf)
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if err != nil {
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t.Error(tc.filename, err)
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continue
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}
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if m0.Bounds() != m1.Bounds() {
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t.Errorf("%s, bounds differ: %v and %v", tc.filename, m0.Bounds(), m1.Bounds())
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continue
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}
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// Compare the average delta to the tolerance level.
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if averageDelta(m0, m1) > tc.tolerance {
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t.Errorf("%s, quality=%d: average delta is too high", tc.filename, tc.quality)
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continue
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}
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}
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}
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// TestWriteGrayscale tests that a grayscale images survives a round-trip
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// through encode/decode cycle.
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func TestWriteGrayscale(t *testing.T) {
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m0 := image.NewGray(image.Rect(0, 0, 32, 32))
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for i := range m0.Pix {
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m0.Pix[i] = uint8(i)
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}
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var buf bytes.Buffer
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if err := Encode(&buf, m0, nil); err != nil {
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t.Fatal(err)
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}
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m1, err := Decode(&buf)
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if err != nil {
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t.Fatal(err)
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}
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if m0.Bounds() != m1.Bounds() {
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t.Fatalf("bounds differ: %v and %v", m0.Bounds(), m1.Bounds())
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}
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if _, ok := m1.(*image.Gray); !ok {
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t.Errorf("got %T, want *image.Gray", m1)
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}
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// Compare the average delta to the tolerance level.
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want := int64(2 << 8)
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if got := averageDelta(m0, m1); got > want {
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t.Errorf("average delta too high; got %d, want <= %d", got, want)
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}
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}
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// averageDelta returns the average delta in RGB space. The two images must
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// have the same bounds.
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func averageDelta(m0, m1 image.Image) int64 {
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b := m0.Bounds()
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var sum, n int64
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for y := b.Min.Y; y < b.Max.Y; y++ {
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for x := b.Min.X; x < b.Max.X; x++ {
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c0 := m0.At(x, y)
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c1 := m1.At(x, y)
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r0, g0, b0, _ := c0.RGBA()
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r1, g1, b1, _ := c1.RGBA()
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sum += delta(r0, r1)
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sum += delta(g0, g1)
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sum += delta(b0, b1)
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n += 3
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}
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}
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return sum / n
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}
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func TestEncodeYCbCr(t *testing.T) {
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bo := image.Rect(0, 0, 640, 480)
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imgRGBA := image.NewRGBA(bo)
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// Must use 444 subsampling to avoid lossy RGBA to YCbCr conversion.
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imgYCbCr := image.NewYCbCr(bo, image.YCbCrSubsampleRatio444)
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rnd := rand.New(rand.NewSource(123))
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// Create identical rgba and ycbcr images.
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for y := bo.Min.Y; y < bo.Max.Y; y++ {
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for x := bo.Min.X; x < bo.Max.X; x++ {
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col := color.RGBA{
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uint8(rnd.Intn(256)),
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uint8(rnd.Intn(256)),
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uint8(rnd.Intn(256)),
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255,
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}
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imgRGBA.SetRGBA(x, y, col)
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yo := imgYCbCr.YOffset(x, y)
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co := imgYCbCr.COffset(x, y)
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cy, ccr, ccb := color.RGBToYCbCr(col.R, col.G, col.B)
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imgYCbCr.Y[yo] = cy
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imgYCbCr.Cb[co] = ccr
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imgYCbCr.Cr[co] = ccb
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}
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}
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// Now check that both images are identical after an encode.
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var bufRGBA, bufYCbCr bytes.Buffer
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Encode(&bufRGBA, imgRGBA, nil)
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Encode(&bufYCbCr, imgYCbCr, nil)
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if !bytes.Equal(bufRGBA.Bytes(), bufYCbCr.Bytes()) {
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t.Errorf("RGBA and YCbCr encoded bytes differ")
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}
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}
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func BenchmarkEncodeRGBA(b *testing.B) {
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img := image.NewRGBA(image.Rect(0, 0, 640, 480))
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bo := img.Bounds()
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rnd := rand.New(rand.NewSource(123))
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for y := bo.Min.Y; y < bo.Max.Y; y++ {
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for x := bo.Min.X; x < bo.Max.X; x++ {
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img.SetRGBA(x, y, color.RGBA{
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uint8(rnd.Intn(256)),
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uint8(rnd.Intn(256)),
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uint8(rnd.Intn(256)),
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255,
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})
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}
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}
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b.SetBytes(640 * 480 * 4)
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b.ReportAllocs()
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b.ResetTimer()
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options := &Options{Quality: 90}
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for i := 0; i < b.N; i++ {
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Encode(io.Discard, img, options)
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}
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}
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func BenchmarkEncodeYCbCr(b *testing.B) {
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img := image.NewYCbCr(image.Rect(0, 0, 640, 480), image.YCbCrSubsampleRatio420)
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bo := img.Bounds()
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rnd := rand.New(rand.NewSource(123))
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for y := bo.Min.Y; y < bo.Max.Y; y++ {
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for x := bo.Min.X; x < bo.Max.X; x++ {
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cy := img.YOffset(x, y)
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ci := img.COffset(x, y)
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img.Y[cy] = uint8(rnd.Intn(256))
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img.Cb[ci] = uint8(rnd.Intn(256))
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img.Cr[ci] = uint8(rnd.Intn(256))
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}
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}
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b.SetBytes(640 * 480 * 3)
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b.ReportAllocs()
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b.ResetTimer()
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options := &Options{Quality: 90}
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for i := 0; i < b.N; i++ {
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Encode(io.Discard, img, options)
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}
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}
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