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// 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 jpeg
import (
"bytes"
"fmt"
"image"
"image/color"
"io/ioutil"
"math/rand"
"os"
"strings"
"testing"
)
// TestDecodeProgressive tests that decoding the baseline and progressive
// versions of the same image result in exactly the same pixel data, in YCbCr
// space for color images, and Y space for grayscale images.
func TestDecodeProgressive(t *testing.T) {
testCases := []string{
"../testdata/video-001",
"../testdata/video-001.q50.420",
"../testdata/video-001.q50.422",
"../testdata/video-001.q50.440",
"../testdata/video-001.q50.444",
"../testdata/video-005.gray.q50",
"../testdata/video-005.gray.q50.2x2",
"../testdata/video-001.separate.dc.progression",
}
for _, tc := range testCases {
m0, err := decodeFile(tc + ".jpeg")
if err != nil {
t.Errorf("%s: %v", tc+".jpeg", err)
continue
}
m1, err := decodeFile(tc + ".progressive.jpeg")
if err != nil {
t.Errorf("%s: %v", tc+".progressive.jpeg", err)
continue
}
if m0.Bounds() != m1.Bounds() {
t.Errorf("%s: bounds differ: %v and %v", tc, m0.Bounds(), m1.Bounds())
continue
}
// All of the video-*.jpeg files are 150x103.
if m0.Bounds() != image.Rect(0, 0, 150, 103) {
t.Errorf("%s: bad bounds: %v", tc, m0.Bounds())
continue
}
switch m0 := m0.(type) {
case *image.YCbCr:
m1 := m1.(*image.YCbCr)
if err := check(m0.Bounds(), m0.Y, m1.Y, m0.YStride, m1.YStride); err != nil {
t.Errorf("%s (Y): %v", tc, err)
continue
}
if err := check(m0.Bounds(), m0.Cb, m1.Cb, m0.CStride, m1.CStride); err != nil {
t.Errorf("%s (Cb): %v", tc, err)
continue
}
if err := check(m0.Bounds(), m0.Cr, m1.Cr, m0.CStride, m1.CStride); err != nil {
t.Errorf("%s (Cr): %v", tc, err)
continue
}
case *image.Gray:
m1 := m1.(*image.Gray)
if err := check(m0.Bounds(), m0.Pix, m1.Pix, m0.Stride, m1.Stride); err != nil {
t.Errorf("%s: %v", tc, err)
continue
}
default:
t.Errorf("%s: unexpected image type %T", tc, m0)
continue
}
}
}
func decodeFile(filename string) (image.Image, error) {
f, err := os.Open(filename)
if err != nil {
return nil, err
}
defer f.Close()
return Decode(f)
}
// check checks that the two pix data are equal, within the given bounds.
func check(bounds image.Rectangle, pix0, pix1 []byte, stride0, stride1 int) error {
if stride0 <= 0 || stride0%8 != 0 {
return fmt.Errorf("bad stride %d", stride0)
}
if stride1 <= 0 || stride1%8 != 0 {
return fmt.Errorf("bad stride %d", stride1)
}
// Compare the two pix data, one 8x8 block at a time.
for y := 0; y < len(pix0)/stride0 && y < len(pix1)/stride1; y += 8 {
for x := 0; x < stride0 && x < stride1; x += 8 {
if x >= bounds.Max.X || y >= bounds.Max.Y {
// We don't care if the two pix data differ if the 8x8 block is
// entirely outside of the image's bounds. For example, this can
// occur with a 4:2:0 chroma subsampling and a 1x1 image. Baseline
// decoding works on the one 16x16 MCU as a whole; progressive
// decoding's first pass works on that 16x16 MCU as a whole but
// refinement passes only process one 8x8 block within the MCU.
continue
}
for j := 0; j < 8; j++ {
for i := 0; i < 8; i++ {
index0 := (y+j)*stride0 + (x + i)
index1 := (y+j)*stride1 + (x + i)
if pix0[index0] != pix1[index1] {
return fmt.Errorf("blocks at (%d, %d) differ:\n%sand\n%s", x, y,
pixString(pix0, stride0, x, y),
pixString(pix1, stride1, x, y),
)
}
}
}
}
}
return nil
}
func pixString(pix []byte, stride, x, y int) string {
s := bytes.NewBuffer(nil)
for j := 0; j < 8; j++ {
fmt.Fprintf(s, "\t")
for i := 0; i < 8; i++ {
fmt.Fprintf(s, "%02x ", pix[(y+j)*stride+(x+i)])
}
fmt.Fprintf(s, "\n")
}
return s.String()
}
func TestExtraneousData(t *testing.T) {
// Encode a 1x1 red image.
src := image.NewRGBA(image.Rect(0, 0, 1, 1))
src.Set(0, 0, color.RGBA{0xff, 0x00, 0x00, 0xff})
buf := new(bytes.Buffer)
if err := Encode(buf, src, nil); err != nil {
t.Fatalf("encode: %v", err)
}
enc := buf.String()
// Sanity check that the encoded JPEG is long enough, that it ends in a
// "\xff\xd9" EOI marker, and that it contains a "\xff\xda" SOS marker
// somewhere in the final 64 bytes.
if len(enc) < 64 {
t.Fatalf("encoded JPEG is too short: %d bytes", len(enc))
}
if got, want := enc[len(enc)-2:], "\xff\xd9"; got != want {
t.Fatalf("encoded JPEG ends with %q, want %q", got, want)
}
if s := enc[len(enc)-64:]; !strings.Contains(s, "\xff\xda") {
t.Fatalf("encoded JPEG does not contain a SOS marker (ff da) near the end: % x", s)
}
// Test that adding some random junk between the SOS marker and the
// EOI marker does not affect the decoding.
rnd := rand.New(rand.NewSource(1))
for i, nerr := 0, 0; i < 1000 && nerr < 10; i++ {
buf.Reset()
// Write all but the trailing "\xff\xd9" EOI marker.
buf.WriteString(enc[:len(enc)-2])
// Write some random extraneous data.
for n := rnd.Intn(10); n > 0; n-- {
if x := byte(rnd.Intn(256)); x != 0xff {
buf.WriteByte(x)
} else {
// The JPEG format escapes a SOS 0xff data byte as "\xff\x00".
buf.WriteString("\xff\x00")
}
}
// Write the "\xff\xd9" EOI marker.
buf.WriteString("\xff\xd9")
// Check that we can still decode the resultant image.
got, err := Decode(buf)
if err != nil {
t.Errorf("could not decode image #%d: %v", i, err)
nerr++
continue
}
if got.Bounds() != src.Bounds() {
t.Errorf("image #%d, bounds differ: %v and %v", i, got.Bounds(), src.Bounds())
nerr++
continue
}
if averageDelta(got, src) > 2<<8 {
t.Errorf("image #%d changed too much after a round trip", i)
nerr++
continue
}
}
}
func benchmarkDecode(b *testing.B, filename string) {
b.StopTimer()
data, err := ioutil.ReadFile(filename)
if err != nil {
b.Fatal(err)
}
cfg, err := DecodeConfig(bytes.NewReader(data))
if err != nil {
b.Fatal(err)
}
b.SetBytes(int64(cfg.Width * cfg.Height * 4))
b.StartTimer()
for i := 0; i < b.N; i++ {
Decode(bytes.NewReader(data))
}
}
func BenchmarkDecodeBaseline(b *testing.B) {
benchmarkDecode(b, "../testdata/video-001.jpeg")
}
func BenchmarkDecodeProgressive(b *testing.B) {
benchmarkDecode(b, "../testdata/video-001.progressive.jpeg")
}
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