test fails with libjpeg on Mac

[edvakf]

I was trying around with this branch #15 and found out that there is a failing test using libjpeg whereas it is passing with libjpeg-turbo.

$ CGO_CFLAGS=-I/usr/local/opt/jpeg/include CGO_LDFLAGS=-L/usr/local/opt/jpeg/lib go test -a -test.v .
=== RUN   TestDecode
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecode (1.70s)
=== RUN   TestDecodeScaled
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeScaled (0.12s)
=== RUN   TestDecodeIntoRGBA
--- SKIP: TestDecodeIntoRGBA (0.00s)
    jpeg_test.go:109: This build is not support DecodeIntoRGBA.
=== RUN   TestDecodeScaledIntoRGBA
--- SKIP: TestDecodeScaledIntoRGBA (0.00s)
    jpeg_test.go:128: This build is not support DecodeIntoRGBA.
=== RUN   TestDecodeScaledIntoRGB
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeScaledIntoRGB (0.12s)
=== RUN   TestDecodeSubsampledImage
 - test: checkerboard_444.jpg
 - test: checkerboard_440.jpg
 - test: checkerboard_422.jpg
 - test: checkerboard_420.jpg
--- PASS: TestDecodeSubsampledImage (0.07s)
=== RUN   TestDecodeAndEncode
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeAndEncode (0.07s)
=== RUN   TestDecodeAndEncodeSubsampledImages
 - test: checkerboard_444.jpg
 - test: checkerboard_440.jpg
 - test: checkerboard_422.jpg
 - test: checkerboard_420.jpg
--- PASS: TestDecodeAndEncodeSubsampledImages (0.01s)
=== RUN   TestDecodeConfig
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeConfig (0.00s)
=== RUN   TestNewYCbCrAlignedWithLandscape
--- PASS: TestNewYCbCrAlignedWithLandscape (0.00s)
=== RUN   TestNewYCbCrAlignedWithPortrait
--- PASS: TestNewYCbCrAlignedWithPortrait (0.00s)
=== RUN   TestDecodeTestdataFromGoStdlib
--- FAIL: TestDecodeTestdataFromGoStdlib (0.11s)
    testdata_test.go:110: testdata/video-001.221212.jpeg: at (93, 0): got {96 11 0 255} want {34 106 166}
FAIL
exit status 1
FAIL    github.com/pixiv/go-libjpeg/jpeg    2.209s

$ CGO_CFLAGS=-I/usr/local/opt/jpeg-turbo/include CGO_LDFLAGS=-L/usr/local/opt/jpeg-turbo/lib go test -a -test.v .
=== RUN   TestDecode
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecode (1.69s)
=== RUN   TestDecodeScaled
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeScaled (0.11s)
=== RUN   TestDecodeIntoRGBA
--- SKIP: TestDecodeIntoRGBA (0.00s)
    jpeg_test.go:109: This build is not support DecodeIntoRGBA.
=== RUN   TestDecodeScaledIntoRGBA
--- SKIP: TestDecodeScaledIntoRGBA (0.00s)
    jpeg_test.go:128: This build is not support DecodeIntoRGBA.
=== RUN   TestDecodeScaledIntoRGB
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeScaledIntoRGB (0.13s)
=== RUN   TestDecodeSubsampledImage
 - test: checkerboard_444.jpg
 - test: checkerboard_440.jpg
 - test: checkerboard_422.jpg
 - test: checkerboard_420.jpg
--- PASS: TestDecodeSubsampledImage (0.06s)
=== RUN   TestDecodeAndEncode
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeAndEncode (0.03s)
=== RUN   TestDecodeAndEncodeSubsampledImages
 - test: checkerboard_444.jpg
 - test: checkerboard_440.jpg
 - test: checkerboard_422.jpg
 - test: checkerboard_420.jpg
--- PASS: TestDecodeAndEncodeSubsampledImages (0.01s)
=== RUN   TestDecodeConfig
 - test: cosmos.jpg
 - test: kinkaku.jpg
--- PASS: TestDecodeConfig (0.00s)
=== RUN   TestNewYCbCrAlignedWithLandscape
--- PASS: TestNewYCbCrAlignedWithLandscape (0.00s)
=== RUN   TestNewYCbCrAlignedWithPortrait
--- PASS: TestNewYCbCrAlignedWithPortrait (0.00s)
=== RUN   TestDecodeTestdataFromGoStdlib
--- PASS: TestDecodeTestdataFromGoStdlib (0.11s)
PASS
ok      github.com/pixiv/go-libjpeg/jpeg    2.149s

libjpeg version 8g and libjpeg-turbo 1.4.1 installed with homebrew.

[edvakf]

It turned out that the lowest tolerance values for libjpeg-turbo are;

var imageTests = []imageTest{
    {"testdata/video-001.221212.png", "testdata/video-001.221212.jpeg", 8 << 6},
    // {"testdata/video-001.cmyk.png", "testdata/video-001.cmyk.jpeg", 8 << 8},
    {"testdata/video-001.png", "testdata/video-001.jpeg", 8 << 8},
    {"testdata/video-001.png", "testdata/video-001.progressive.jpeg", 8 << 8},
    {"testdata/video-001.png", "testdata/video-001.rgb.jpeg", 8 << 13},
    {"testdata/video-005.gray.png", "testdata/video-005.gray.jpeg", 8 << 8},
}

On the other hand, those for libjpeg are;

var imageTests = []imageTest{
    {"testdata/video-001.221212.png", "testdata/video-001.221212.jpeg", 8 << 11},
    // {"testdata/video-001.cmyk.png", "testdata/video-001.cmyk.jpeg", 8 << 8},
    {"testdata/video-001.png", "testdata/video-001.jpeg", 8 << 8},
    {"testdata/video-001.png", "testdata/video-001.progressive.jpeg", 8 << 8},
    {"testdata/video-001.png", "testdata/video-001.rgb.jpeg", 8 << 13},
    {"testdata/video-005.gray.png", "testdata/video-005.gray.jpeg", 8 << 8},
}

[edvakf]

We should probably stop comparing dot by dot.