pixa/internal/imageprocessor/jpegxl_output_internal_test.go

package imageprocessor

import (
	"bytes"
	"io"
	"math"
	"os"
	"testing"

	"github.com/davidbyttow/govips/v2/vips"
	"sneak.berlin/go/pixa/internal/imagerequest"
)

// TestImageProcessor_EncodeJPEGXL converts a JPEG to a smaller JPEG XL and
// checks the content type, and the format and size the output loads as.
func TestImageProcessor_EncodeJPEGXL(t *testing.T) {
	t.Parallel()

	transform := &imagerequest.Transform{
		Size:   imagerequest.Size{Width: 100, Height: 75},
		Format: imagerequest.FormatJXL,
	}

	result, err := New(Params{}).Process(
		t.Context(), bytes.NewReader(createTestJPEG(t, 200, 150)), transform,
	)
	if err != nil {
		t.Fatalf("Process() error = %v", err)
	}

	defer func() { _ = result.Content.Close() }()

	if result.ContentType != "image/jxl" {
		t.Errorf("ContentType = %q, want image/jxl", result.ContentType)
	}

	data, err := io.ReadAll(result.Content)
	if err != nil {
		t.Fatalf("failed to read result: %v", err)
	}

	output, err := vips.NewImageFromBuffer(data)
	if err != nil {
		t.Fatalf("failed to load the output: %v", err)
	}

	defer output.Close()

	if output.Format() != vips.ImageTypeJXL {
		t.Errorf("output format = %s, want jxl", vips.ImageTypes[output.Format()])
	}

	if output.Width() != 100 || output.Height() != 75 {
		t.Errorf("output size = %dx%d, want 100x75", output.Width(), output.Height())
	}
}

// TestImageProcessor_JPEGXLQuality verifies that the quality reaches the JPEG
// XL encoder: the same image comes out smaller at quality 30 than at 90.
func TestImageProcessor_JPEGXLQuality(t *testing.T) {
	t.Parallel()

	input := createTestJPEG(t, 400, 300)
	outputBytes := make(map[int]int64)

	for _, quality := range []int{30, 90} {
		result, err := New(Params{}).Process(t.Context(),
			bytes.NewReader(input),
			&imagerequest.Transform{Format: imagerequest.FormatJXL, Quality: quality})
		if err != nil {
			t.Fatalf("Process() at quality %d error = %v", quality, err)
		}

		_ = result.Content.Close()
		outputBytes[quality] = result.ContentLength
	}

	if outputBytes[30] >= outputBytes[90] {
		t.Errorf("%d bytes at quality 30, %d at 90, want fewer at 30",
			outputBytes[30], outputBytes[90])
	}
}

// TestImageProcessor_JPEGXLDropsSourceEXIF verifies that none of the source's
// EXIF reaches a JPEG XL output. libvips 8.16 and later write an EXIF block of
// their own into JPEG XL (orientation, resolution, size, colour space and
// fixed defaults), and govips cannot ask them to leave it out, so the test
// looks for the source's fields rather than for no EXIF at all.
func TestImageProcessor_JPEGXLDropsSourceEXIF(t *testing.T) {
	t.Parallel()

	input, err := os.ReadFile("testdata/gps-exif.jpg")
	if err != nil {
		t.Fatalf("failed to read test JPEG: %v", err)
	}

	exif := processAndDecode(t, input,
		&imagerequest.Transform{Format: imagerequest.FormatJXL}).GetExif()

	for _, field := range []string{
		"exif-ifd0-Make", "exif-ifd0-Model", "exif-ifd2-BodySerialNumber",
		"exif-ifd2-DateTimeOriginal", "exif-ifd3-GPSLatitude",
		"exif-ifd3-GPSLongitude",
	} {
		if value, found := exif[field]; found {
			t.Errorf("output has %s: %s", field, value)
		}
	}
}

// TestImageProcessor_JPEGXLDropsSourceResolution verifies that the source's
// resolution does not reach the EXIF block libvips 8.16 and later write into
// JPEG XL. A JPEG XL image holds its resolution in that block alone, so the
// resolution the output loads with is the block's.
func TestImageProcessor_JPEGXLDropsSourceResolution(t *testing.T) {
	t.Parallel()

	// dpi-300.jpg is a flat 8x8 grey image with a resolution of 300 dpi.
	input, err := os.ReadFile("testdata/dpi-300.jpg")
	if err != nil {
		t.Fatalf("failed to read test JPEG: %v", err)
	}

	output := processAndDecode(t, input,
		&imagerequest.Transform{Format: imagerequest.FormatJXL})

	// libvips gives the resolution in pixels per millimetre.
	xDPI := math.Round(output.ResX() * 25.4)
	yDPI := math.Round(output.ResY() * 25.4)

	if xDPI == 300 || yDPI == 300 {
		t.Errorf("output resolution = %vx%v dpi, the source's", xDPI, yDPI)
	}
}

// TestImageProcessor_JPEGXLAppliesEXIFOrientation verifies that a JPEG XL
// output is turned upright, as TestImageProcessor_AppliesEXIFOrientation does
// for PNG.
func TestImageProcessor_JPEGXLAppliesEXIFOrientation(t *testing.T) {
	t.Parallel()

	// orientation-6.jpg is stored 16x8, red on the left and blue on the
	// right, with EXIF orientation 6 (turn 90 degrees clockwise to view).
	// Upright it is 8x16, red on top and blue below.
	input, err := os.ReadFile("testdata/orientation-6.jpg")
	if err != nil {
		t.Fatalf("failed to read test JPEG: %v", err)
	}

	output := processAndDecode(t, input,
		&imagerequest.Transform{Format: imagerequest.FormatJXL})

	if output.Width() != 8 || output.Height() != 16 {
		t.Fatalf("output is %dx%d, want 8x16", output.Width(), output.Height())
	}

	top, err := output.GetPoint(4, 0)
	if err != nil {
		t.Fatalf("GetPoint() error = %v", err)
	}

	bottom, err := output.GetPoint(4, 15)
	if err != nil {
		t.Fatalf("GetPoint() error = %v", err)
	}

	if top[0] <= top[2] || bottom[2] <= bottom[0] {
		t.Errorf("top pixel = %v, bottom pixel = %v, want red above blue",
			top, bottom)
	}
}

// TestImageProcessor_JPEGXLConvertsWideGamutToSRGB verifies that a JPEG XL
// output is converted to sRGB, as TestImageProcessor_ConvertsWideGamutToSRGB
// does for PNG. It does not check for an ICC profile, as libvips reports one
// for every JPEG XL image it loads.
func TestImageProcessor_JPEGXLConvertsWideGamutToSRGB(t *testing.T) {
	t.Parallel()

	// display-p3.jpg is a flat 8x8 image with the Display P3 profile
	// embedded, filled with Display P3 (234, 51, 35), which is sRGB red.
	input, err := os.ReadFile("testdata/display-p3.jpg")
	if err != nil {
		t.Fatalf("failed to read test JPEG: %v", err)
	}

	output := processAndDecode(t, input,
		&imagerequest.Transform{Format: imagerequest.FormatJXL})

	pixel, err := output.GetPoint(4, 4)
	if err != nil {
		t.Fatalf("GetPoint() error = %v", err)
	}

	want := []float64{255, 0, 0}
	for i := range want {
		if math.Abs(pixel[i]-want[i]) > 5 {
			t.Fatalf("pixel = %v, want within 5 of %v", pixel, want)
		}
	}
}

// TestImageProcessor_JPEGXLFromCMYK verifies that a CMYK JPEG with no ICC
// profile can be served as JPEG XL, in sRGB.
func TestImageProcessor_JPEGXLFromCMYK(t *testing.T) {
	t.Parallel()

	// cmyk.jpg is a flat 8x8 CMYK image with no ICC profile, filled with
	// full cyan and no magenta, yellow or black.
	input, err := os.ReadFile("testdata/cmyk.jpg")
	if err != nil {
		t.Fatalf("failed to read test JPEG: %v", err)
	}

	output := processAndDecode(t, input,
		&imagerequest.Transform{Format: imagerequest.FormatJXL})

	if output.Bands() != 3 {
		t.Fatalf("output has %d bands, want 3", output.Bands())
	}

	pixel, err := output.GetPoint(4, 4)
	if err != nil {
		t.Fatalf("GetPoint() error = %v", err)
	}

	// Cyan in sRGB: little red, much green and blue.
	if pixel[0] > 50 || pixel[1] < 100 || pixel[2] < 200 {
		t.Errorf("pixel = %v, want cyan", pixel)
	}
}

// TestJXLDistance verifies the JPEG XL distance for a few qualities: 90 is
// distance 1, the encoder's own default, and 100 stays lossy.
func TestJXLDistance(t *testing.T) {
	t.Parallel()

	tests := []struct {
		quality int
		want    float64
	}{
		{quality: 100, want: 0.1},
		{quality: 90, want: 1},
		{quality: 30, want: 6.4},
		{quality: 20, want: 9.0667},
	}

	for _, tt := range tests {
		got := jxlDistance(tt.quality)
		if math.Abs(got-tt.want) > 0.0001 {
			t.Errorf("jxlDistance(%d) = %v, want %v", tt.quality, got, tt.want)
		}
	}
}