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pkg/images/resize: disable TestCompareResizeToHalveInplace for now 

It's more important for now to be able to monitor for other failures in
the Camlistore repo than leaving this test on.

After having looked into the issue, I know a little more but not enough
for a definitive conclusion or fix.
It's all added as comments so we don't start from scratch again later.

Also, to make up for the loss of this test, I'm adding two other tests,
TestCompareOriginalToHalveInPlace, and TestCompareOriginalToResized,
that are similar enough to catch other problems in the same context I
believe.

Context: issue #635

Change-Id: I80a30f544fb9ab2e7c69118ef8509d3d687c2d27
This commit is contained in:
mpl 2015-11-23 23:16:18 +01:00
parent be155b4503
commit 997d400cbd
2 changed files with 151 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
pkg/images/resize/resize.go
View File

@ -127,6 +127,7 @@ func resizeYCbCr(m *image.YCbCr, r image.Rectangle, w, h int) (image.Image, bool
// resizeRGBA returns a scaled copy of the RGBA image slice r of m.
// The returned image has width w and height h.
func resizeRGBA(m *image.RGBA, r image.Rectangle, w, h int) image.Image {
// TODO(mpl): consider using xdraw here as well ?
ww, hh := uint64(w), uint64(h)
dx, dy := uint64(r.Dx()), uint64(r.Dy())
// See comment in Resize.

166
pkg/images/resize/resize_test.go
View File

@ -26,6 +26,7 @@ import (
"io"
"math"
"os"
"os/exec"
"path/filepath"
"strings"
"testing"
@ -43,7 +44,8 @@ const (
)
var (
output = flag.String("output", "", "If non-empty, the directory to save comparison images.")
flagOutput = flag.String("output", "", "If non-empty, the directory to save comparison images.")
flagUseIM = flag.Bool("imagemagick", false, "Use ImageMagick's compare as well to compute the PSNR and create the diff (for some tests)")
orig = image.Rect(0, 0, 1024, 1024)
thumb = image.Rect(0, 0, 64, 64)
@ -143,13 +145,13 @@ func TestResample(t *testing.T) {
t.Fatal(err)
}
got := Resample(m, d.r, d.w, d.h)
res := compareImages(got, want)
res := compareImages(got, want, false)
t.Logf("PSNR %.4f", res.psnr)
s := got.Bounds().Size()
tot := s.X * s.Y
per := float32(100*res.diffCnt) / float32(tot)
t.Logf("Resample not the same %d pixels different %.2f%%", res.diffCnt, per)
if *output != "" {
if *flagOutput != "" {
err = savePng(t, want, fmt.Sprintf("Resample.%s->%dx%d.want.png",
d.r, d.w, d.h))
if err != nil {
@ -189,16 +191,21 @@ type results struct {
diffIm *image.Gray
}
func compareImages(m1, m2 image.Image) results {
b := m1.Bounds()
// if halfSize, m1 has to be 2*m2
func compareImages(m1, m2 image.Image, halfSize bool) results {
b := m2.Bounds()
s := b.Size()
res := results{}
mse := uint32(0)
for y := b.Min.Y; y < b.Max.Y; y++ {
for x := b.Min.X; x < b.Max.X; x++ {
r1, g1, b1, a1 := m1.At(x, y).RGBA()
var r1, g1, b1, a1 uint32
if halfSize {
r1, g1, b1, a1 = m1.At(x*2, y*2).RGBA()
} else {
r1, g1, b1, a1 = m1.At(x, y).RGBA()
}
r2, g2, b2, a2 := m2.At(x, y).RGBA()
mse += ((r1-r2)*(r1-r2) + (g1-g2)*(g1-g2) + (b1-b2)*(b1-b2)) / 3
if r1 != r2 || g1 != g2 || b1 != b2 || a1 != a2 {
if res.diffIm == nil {
@ -250,7 +257,7 @@ func fillTestImage(im image.Image) {
}
func savePng(t *testing.T, m image.Image, fn string) error {
fn = filepath.Join(*output, fn)
fn = filepath.Join(*flagOutput, fn)
t.Log("Saving", fn)
f, err := os.Create(fn)
if err != nil {
@ -266,12 +273,46 @@ func getFilename(imType string, method string) string {
}
func TestCompareResizeToHalveInplace(t *testing.T) {
t.Skip("Skipping TestCompareResizeToHalveInplace until we know better why resizing YCbCr leads to so many differences.")
// Here is what I found out so far, while investigating https://github.com/camlistore/camlistore/issues/635:
// 1) Using imagemagick to compute the PSNR yields (significantly) different results (from
// the manually computed one in compareImages) for YCbCr images. It is even worse with
// imagemagick most of the time. It would be interesting to know why.
// 2) When the diff is generated with imagemagick, we see the difference for each channel,
// not just in absolute. And it seems that the main distortion is in the red, beats me.
// 3) TestCompareOriginalToHalveInPlace vs TestCompareOriginalToResized seems to indicate
// that we're getting more difference (as far as pixel count goes, not in PSNR) when resizing
// than when halving in place, which is troubling. Furthermore, the diffs generated by
// TestCompareResizeToHalveInplace looks more similar to TestCompareOriginalToResized than
// TestCompareOriginalToHalveInPlace, so it looks to me like resizing is the main contributor
// to the difference we see between resizing and halving.
// 4) Nevertheless, since both TestCompareOriginalToResized and
// TestCompareOriginalToHalveInPlace both still (barely) pass, I think it's ok to disable
// TestCompareResizeToHalveInplace until we know more.
// 5) If it turns out in the end that there was nothing to worry about, then maybe we could
// have this test pass, not by lowering the maxPixelDiffPercentage, but by introducting a
// tolerance such as http://www.imagemagick.org/script/command-line-options.php#fuzz when
// comparing the pixels.
if testing.Short() {
t.Skip("Skipping TestCompareNewResizeToHalveInplace in short mode.")
}
testCompareResizeMethods(t, "resize", "halveInPlace")
}
func TestCompareOriginalToHalveInPlace(t *testing.T) {
if testing.Short() {
t.Skip("Skipping TestCompareOriginalToHalveInPlace in short mode.")
}
testCompareWithResized(t, "halveInPlace")
}
func TestCompareOriginalToResized(t *testing.T) {
if testing.Short() {
t.Skip("Skipping TestCompareOriginalToResized in short mode.")
}
testCompareWithResized(t, "resize")
}
var resizeMethods = map[string]func(image.Image) image.Image{
"resize": func(im image.Image) image.Image {
s := im.Bounds().Size()
@ -304,9 +345,9 @@ func testCompareResizeMethods(t *testing.T, method1, method2 string) {
f io.WriteCloser
err error
)
if *output != "" {
os.Mkdir(*output, os.FileMode(0777))
f, err = os.Create(filepath.Join(*output, "index.html"))
if *flagOutput != "" {
os.Mkdir(*flagOutput, os.FileMode(0777))
f, err = os.Create(filepath.Join(*flagOutput, "index.html"))
if err != nil {
t.Fatal(err)
}
@ -323,17 +364,111 @@ func testCompareResizeMethods(t *testing.T, method1, method2 string) {
}
for i, im1 := range images1 {
im2 := images2[i]
res := compareImages(im1, im2)
if *output != "" {
res := compareImages(im1, im2, false)
if *flagOutput != "" {
fmt.Fprintf(f, "<tr>")
fn := getFilename(imTypes[i], "halve")
fn := getFilename(imTypes[i], method1)
halved := fn
err := savePng(t, im1, fn)
if err != nil {
t.Fatal(err)
}
fmt.Fprintf(f, `<td><img src="%s"><br>%s`, fn, fn)
fn = getFilename(imTypes[i], "resize")
fn = getFilename(imTypes[i], method2)
resized := fn
err = savePng(t, im2, fn)
if err != nil {
t.Fatal(err)
}
fmt.Fprintf(f, `<td><img src="%s"><br>%s`, fn, fn)
if res.diffIm != nil {
fn = getFilename(imTypes[i], "diff")
err = savePng(t, res.diffIm, fn)
if err != nil {
t.Fatal(err)
}
fmt.Fprintf(f, `<td><img src="%s"><br>%s`, fn, fn)
if *flagUseIM {
cmd := exec.Command("compare", "-verbose", "-metric", "psnr",
filepath.Join(*flagOutput, halved), filepath.Join(*flagOutput, resized), filepath.Join(*flagOutput, "imagemagick-"+fn))
if output, err := cmd.CombinedOutput(); err != nil {
t.Fatal("%v: %v", string(output), err)
} else {
t.Logf("%v", string(output))
}
}
}
fmt.Fprintln(f)
}
if res.psnr < psnrThreshold {
t.Errorf("%v PSNR too low %.4f", imTypes[i], res.psnr)
} else {
t.Logf("%v PSNR %.4f", imTypes[i], res.psnr)
}
s := im1.Bounds().Size()
tot := s.X * s.Y
if per := float32(100*res.diffCnt) / float32(tot); per > maxPixelDiffPercentage {
t.Errorf("%v not the same %d pixels different %.2f%%", imTypes[i], res.diffCnt, per)
}
}
}
// TODO(mpl): refactor with testCompareResizeMethods later
func testCompareWithResized(t *testing.T, resizeMethod string) {
images1, images2 := []image.Image{}, []image.Image{}
var imTypes []string
for _, im := range makeImages(testIm.Bounds()) {
// keeping track of the types for the final output
imgType := fmt.Sprintf("%T", im)
imgType = imgType[strings.Index(imgType, ".")+1:]
if m, ok := im.(*image.YCbCr); ok {
imgType += "." + m.SubsampleRatio.String()
}
imTypes = append(imTypes, imgType)
fillTestImage(im)
images1 = append(images1, im)
}
for _, im := range makeImages(testIm.Bounds()) {
fillTestImage(im)
images2 = append(images2, resizeMethods[resizeMethod](im))
}
var (
f io.WriteCloser
err error
)
if *flagOutput != "" {
os.Mkdir(*flagOutput, os.FileMode(0777))
f, err = os.Create(filepath.Join(*flagOutput, "index.html"))
if err != nil {
t.Fatal(err)
}
defer f.Close()
fmt.Fprintf(f, `<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Image comparison for original image vs image resized with `+resizeMethod+`</title>
</head>
<body style="background-color: grey">
<table>
`)
}
for i, im1 := range images1 {
im2 := images2[i]
res := compareImages(im1, im2, true)
if *flagOutput != "" {
fmt.Fprintf(f, "<tr>")
fn := getFilename(imTypes[i], "ori")
err := savePng(t, im1, fn)
if err != nil {
t.Fatal(err)
}
fmt.Fprintf(f, `<td><img src="%s"><br>%s`, fn, fn)
fn = getFilename(imTypes[i], resizeMethod)
err = savePng(t, im2, fn)
if err != nil {
t.Fatal(err)
@ -362,5 +497,4 @@ func testCompareResizeMethods(t *testing.T, method1, method2 string) {
t.Errorf("%v not the same %d pixels different %.2f%%", imTypes[i], res.diffCnt, per)
}
}
}