Serve and accept JPEG XL as an image format (part of #222)

A JPEG XL source is accepted, and orig of one is JPEG XL. The format
jxl works in plain and encrypted URLs and on the generator page,
served as image/jxl; auto chooses it first when Accept names
image/jxl.

govips sends libvips a JPEG XL distance, which overrides the quality,
so q is turned into a distance, keeping 100 lossy. govips cannot have
libvips strip metadata from JPEG XL, so it is removed from the image
before saving; libvips 8.16 and later still add an EXIF block of their
own, with nothing from the source. The conversion to sRGB moved ahead
of the format switch, and a CMYK image with no ICC profile is
converted to sRGB too, as libvips cannot save CMYK as JPEG XL.

Model: opus-5-5

Dockerfile

@@ -17,8 +17,8 @@ COPY . .
 RUN golangci-lint run --config .golangci.yml ./...
 
 # Test phase. script/test builds it alone.
-# golang:1.25.4-alpine3.22, 2026-02-25; the runtime stage uses Alpine 3.22 too
-FROM golang:1.25.4-alpine3.22@sha256:d3f0cf7723f3429e3f9ed846243970b20a2de7bae6a5b66fc5914e228d831bbb AS test
+# golang:1.25.4-alpine, 2026-02-25
+FROM golang:1.25.4-alpine@sha256:d3f0cf7723f3429e3f9ed846243970b20a2de7bae6a5b66fc5914e228d831bbb AS test
 
 WORKDIR /src
 
@@ -40,8 +40,8 @@ RUN go test -count=1 -timeout 90s -race -cover ./... || \
 # Build stage. Nothing is wanted from the two phases above: these copies
 # make BuildKit build them first, so this stage runs only when lint and
 # test passed.
-# golang:1.25.4-alpine3.22, 2026-02-25; the runtime stage uses Alpine 3.22 too
-FROM golang:1.25.4-alpine3.22@sha256:d3f0cf7723f3429e3f9ed846243970b20a2de7bae6a5b66fc5914e228d831bbb AS builder
+# golang:1.25.4-alpine, 2026-02-25
+FROM golang:1.25.4-alpine@sha256:d3f0cf7723f3429e3f9ed846243970b20a2de7bae6a5b66fc5914e228d831bbb AS builder
 
 COPY --from=lint /src/go.sum /dev/null
 COPY --from=test /src/go.sum /dev/null
@@ -77,11 +77,9 @@ RUN version="${VERSION:-$(git describe --tags --always)}"; \
         -o /pixad ./cmd/pixad
 
 # Runtime stage, and the last one: a plain `docker build .` builds this
-# stage and what it depends on, and nothing else. It must use the Alpine
-# release the golang image above is based on, so that pixad runs against
-# the libvips and musl it was built with.
-# alpine:3.22, 2026-10-08
-FROM alpine:3.22@sha256:5291449c3df73caf6ed85e649dec1b9e818b39a5d8c871e97afc13e9cd5e8fa8
+# stage and what it depends on, and nothing else.
+# alpine:3.21, 2026-02-25
+FROM alpine:3.21@sha256:c3f8e73fdb79deaebaa2037150150191b9dcbfba68b4a46d70103204c53f4709
 
 # Install runtime dependencies only. vips-jxl is libvips' JPEG XL
 # support, without which pixad does not start.

README.md

@@ -88,7 +88,7 @@ or with 1 when images were still being processed after those 5 seconds or
 another part of pixa failed to stop. A request not finished by then is cut off.
 `docker stop` waits 10 seconds before it kills the container.
 
-Outside Docker, pixa needs libvips (the image has 8.16) and libheif to run, as
+Outside Docker, pixa needs libvips (the image has 8.15) and libheif to run, as
 it uses libvips through CGO. pixad does not start unless libvips has its JPEG XL
 support, which on Alpine is the `vips-jxl` package and which the nix and brew
 packages of libvips include, as do the apt ones from Debian 12 and Ubuntu 24.04
@@ -175,21 +175,20 @@ path under `/v1/` answers 200, in maintenance mode too.
   with the page naming a field that is not valid; 500 when the URL cannot be
   made.
 - `GET /logout` — end the login session. Needs: nothing. Answers: 303 to `/`.
-- `GET` or `HEAD` `/v1/image/<host>/<path>/<size>.<format>`, or
-  `/v1/image/<host>/<path>/<size>` with no format — an image, fetched, resized
-  and converted (below). Needs: a signature, unless the host is allowlisted (see
-  Source Hosts). Answers: 200; 304 when `If-None-Match` matches the image's
-  `ETag`; 400 for a URL or parameter that is not valid, or for the format `auto`
-  an `Accept` header that is not valid; 406 for the format `auto` when `Accept`
-  allows none of the formats it chooses from; 401 for a missing or wrong
-  signature, a missing `exp` or an `exp` in the past; 403 when the request's
-  `Referer` names a host in `referer_blocklist`, checked before the signature,
-  the cache and the upstream fetch; 403 when the upstream host, or a host it
-  redirects to, is `localhost`, ends in `.localhost` or `.local`, or has an
-  address in a blocked network (see `blocked_networks`); 502 when the upstream
-  answered with an error status, and for 5 minutes after that for the same
-  source URL; 503 when pixa is busy or in maintenance mode; 500 for any other
-  failure.
+- `GET` or `HEAD` `/v1/image/<host>/<path>/<size>.<format>` — an image, fetched,
+  resized and converted (below). Needs: a signature, unless the host is
+  allowlisted (see Source Hosts). Answers: 200; 304 when `If-None-Match` matches
+  the image's `ETag`; 400 for a URL or parameter that is not valid, or for the
+  format `auto` an `Accept` header that is not valid; 406 for the format `auto`
+  when `Accept` allows none of the formats it chooses from; 401 for a missing or
+  wrong signature, a missing `exp` or an `exp` in the past; 403 when the
+  request's `Referer` names a host in `referer_blocklist`, checked before the
+  signature, the cache and the upstream fetch; 403 when the upstream host, or a
+  host it redirects to, is `localhost`, ends in `.localhost` or `.local`, or has
+  an address in a blocked network (see `blocked_networks`); 502 when the
+  upstream answered with an error status, and for 5 minutes after that for the
+  same source URL; 503 when pixa is busy or in maintenance mode; 500 for any
+  other failure.
 - `GET` or `HEAD` `/v1/e/<token>/<name>` — an image through an encrypted URL
   (see Encrypted URLs). Needs: nothing but the URL. Answers: 200; 304 when
   `If-None-Match` matches the image's `ETag`; 400 for a token that does not
@@ -232,11 +231,10 @@ proxy in front of pixa must pass that header on unchanged. A form body over 1
 MiB is refused with 413. The image routes answer the errors listed for them with
 JSON holding `error`, `status` and `timestamp`.
 
-An image URL has one of these forms, the second with no format:
+An image URL has this form:
 
 ```
 /v1/image/<host>/<path>/<size>.<format>?sig=<signature>&exp=<expiration>&q=<quality>&fit=<fit>
-/v1/image/<host>/<path>/<size>?sig=<signature>&exp=<expiration>&q=<quality>&fit=<fit>
 ```
 
 Images are only fetched from origins using TLS with valid certificates, unless
@@ -247,9 +245,7 @@ A request whose query string cannot be decoded, or gives any parameter more than
 once, is refused with 400.
 
 - `<format>`: one of `orig` (or `original`), `jpeg` (or `jpg`), `png`, `webp`,
-  `avif`, `jxl` (JPEG XL), `gif`, or `auto` (below). A URL with no format (the
-  second form, with no dot after the size) is served as JPEG XL, the default, as
-  with `jxl`
+  `avif`, `jxl` (JPEG XL), `gif`, or `auto` (below)
 - `<size>`: `orig` or `<width>x<height>` (e.g. `800x600`)
 - `sig` and `exp`: the signature and its expiry, needed unless the host is
   allowlisted (see Signature Specification)
@@ -325,15 +321,13 @@ nor change what it asks for.
    lasts 30 days, or until `/logout`.
 2. On the generator page, give the source image's URL, the width and height, the
    format, quality and fit, and how long the URL lasts, then submit the form
-   (`POST /generate`). The format is JPEG XL unless another is chosen; a form
-   sent with an empty format, or none, also makes a JPEG XL URL. Width and
-   height both empty or `0` keep the original size; if only one of them is empty
-   or `0`, that side is scaled to keep the image's proportions.
+   (`POST /generate`). Width and height both empty or `0` keep the original
+   size; if only one of them is empty or `0`, that side is scaled to keep the
+   image's proportions.
 3. The page shows the URL, `https://<host>/v1/e/<token>/img.<format>`, and when
    it expires. `<host>` is the host the page was opened on, and the URL starts
    with `http` instead while `debug` is on. The name after the token is ignored
-   and only gives the URL a file extension, `jpg` for `orig` and `auto`, and
-   `jxl` for a form with no format.
+   and only gives the URL a file extension, `jpg` for `orig` and `auto`.
 
 The token holds the source's host, path and query and the size, format, quality,
 fit and expiry, encrypted with a key derived from `signing_key`. The source
@@ -363,9 +357,9 @@ turned off.
   image with no profile as sRGB. Colours outside sRGB, such as the most
   saturated ones in a Display P3 photo, are clipped.
 - The one exception is JPEG XL with libvips 8.16 and later: libvips then writes
-  an EXIF block of its own into the image, as govips cannot ask libvips to leave
-  it out. It holds the image's size and otherwise fixed values, such as an
-  orientation of 1 and a resolution of 72 dpi, and nothing from the source.
+  an EXIF block of its own into the image, with its orientation, resolution,
+  size and colour space and fixed defaults, but nothing from the source's EXIF,
+  as govips cannot ask libvips to leave it out.
 
 ### Source Hosts
 
@@ -393,9 +387,8 @@ Where:
 - `width` — requested width in pixels, `0` for original
 - `height` — requested height in pixels, `0` for original
 - `format` — output format, one of those listed under Routes, with `original`
-  signed as `orig`, `jpg` as `jpeg`, and no format as `jxl`, so a URL with no
-  format has the signature of the same URL ending in `.jxl`; `auto` is signed as
-  `auto`, not as the format chosen for the request
+  signed as `orig` and `jpg` as `jpeg`; `auto` is signed as `auto`, not as the
+  format chosen for the request
 - `expiration` — the URL's `exp` query parameter, the Unix timestamp when the
   signature expires; a request whose `exp` is not a whole number, an empty
   `exp=` included, is refused with 400

TODO.md

@@ -30,30 +30,6 @@ P2: security: per-IP rate limiting on the image routes
 
 # Completed Steps
 
-- 2026-10-08 every output format is saved with settings pixa sets on purpose
-  (closes #232): each format has its own govips export, as JPEG XL does, in
-  place of govips' generic `Export`, which sent libvips a zero for some settings
-  it was not given. PNG gets libvips' default compression, 6, where it had none,
-  and WebP libvips' default effort, 4, where it had 0. GIF was already at
-  libvips' default effort, 7, and JPEG output is unchanged. AVIF is saved at
-  effort 1, the lowest govips can set, where it had libvips' default, 4. With
-  one libvips thread, an 8192x8192 image of random pixels, the worst case, takes
-  about 51 seconds as AVIF at effort 1 and 43 as WebP at effort 4, against the
-  default `downstream_timeout` of 60 seconds. On an image of milder noise, which
-  AVIF at effort 1 saves in about 12 seconds, effort 4 takes minutes. AVIF is
-  also saved with 8 bits per sample from a 16-bit source, which libvips would
-  save with 12: a 16-bit 8192x8192 image of milder noise takes about 54 seconds
-  at effort 1 with 12 bits, nearly all of the default `downstream_timeout`, and
-  about 12 with 8.
-- 2026-10-08 JPEG XL is the default output (closes #222): a `/v1/image/` URL
-  whose last segment is a size with no format, such as `800x600` or `orig`, is
-  served as JPEG XL and signed as `jxl`, so it has the signature of the same URL
-  ending in `.jxl`. An encrypted URL whose token holds no format is served as
-  JPEG XL (`encurl.DefaultFormat`). The generator page selects JPEG XL until
-  another format is chosen, and a form with an empty format, or none, makes a
-  JPEG XL URL whose name ends in `.jxl`. The image processor no longer takes an
-  empty format as `orig`: both routes give every request a format, and it
-  refuses a request with none. `auto` still ends with JPEG.
 - 2026-10-08 JPEG XL as an input and output format (part of #222): a source
   whose bytes start with either JPEG XL signature, the bare codestream's `FF 0A`
   or the container's, is detected as `image/jxl`, which the upstream fetch
@@ -64,17 +40,12 @@ P2: security: per-IP rate limiting on the image routes
   libvips ignores the quality: pixa turns `q` into a distance with libvips' own
   formula, keeping 100 lossy, and removes the metadata from the image before
   saving, as govips cannot have libvips strip it from JPEG XL. libvips 8.16 and
-  later still write an EXIF block of their own into JPEG XL, from the image's
-  size, orientation and resolution, and fixed values; the image is upright and
-  is given 72 dpi before the save, so the block holds nothing from the source.
+  later still write an EXIF block of their own into JPEG XL (orientation,
+  resolution, size, colour space, fixed defaults), with nothing from the source.
   An image with an ICC profile is converted to sRGB before the JPEG XL save too,
   and a CMYK image with none is converted to sRGB, as libvips cannot save CMYK
   as JPEG XL. libvips' default effort, 7, is kept. JPEG XL is not yet the
   default output.
-- 2026-10-08 pixad runs on the Alpine release it is built on (closes #229): the
-  runtime stage of the `Dockerfile` uses `alpine:3.22`, the release of the
-  `golang:1.25.4-alpine3.22` image that the test phase and the build stage use,
-  so all three have libvips 8.16, where the runtime image had 8.15.
 - 2026-10-08 requests no longer wait behind eviction queries that read a whole
   table (closes #227): the new `cache_usage` table holds the total cache usage,
   kept up to date by triggers on `source_content` and `variant_content` in the

internal/encurl/encurl.go

@@ -14,7 +14,7 @@ import (
 // Default values for optional fields.
 const (
 	DefaultQuality = 85
-	DefaultFormat  = imgcache.FormatJXL
+	DefaultFormat  = imgcache.FormatOriginal
 	DefaultFitMode = imgcache.FitCover
 
 	// HKDF salt for URL encryption key derivation
@@ -37,7 +37,7 @@ type Payload struct {
 	SourceQuery string               `cbor:"q,omitempty"`  // optional
 	Width       int                  `cbor:"w,omitempty"`  // 0 = original
 	Height      int                  `cbor:"ht,omitempty"` // 0 = original
-	Format      imgcache.ImageFormat `cbor:"f,omitempty"`  // default: jxl
+	Format      imgcache.ImageFormat `cbor:"f,omitempty"`  // default: orig
 	Quality     int                  `cbor:"ql,omitempty"` // default: 85
 	FitMode     imgcache.FitMode     `cbor:"fm,omitempty"` // default: cover
 	ExpiresAt   int64                `cbor:"e,omitempty"`  // 0 = never expires

internal/handlers/auth.go

@@ -369,15 +369,10 @@ func (s *Handlers) buildGeneratedURL(r *http.Request, token, format string) stri
 		scheme = "http"
 	}
 
-	// Determine file extension for the trailing filename. A form with no
-	// format makes a token with none, which is served as encurl.DefaultFormat.
+	// Determine file extension for the trailing filename
 	ext := format
-
-	switch format {
-	case "":
-		ext = string(encurl.DefaultFormat)
-	case "orig", "auto":
-		ext = "jpg"
+	if ext == "" || ext == "orig" || ext == "auto" {
+		ext = "jpg" // Default extension
 	}
 
 	return scheme + "://" + r.Host + "/v1/e/" + url.PathEscape(token) + "/img." + ext

internal/handlers/image.go

@@ -18,8 +18,7 @@ import (
 )
 
 // HandleImage handles the main image proxy route:
-// /v1/image/<host>/<path>/<width>x<height>.<format>, or with no format
-// /v1/image/<host>/<path>/<width>x<height>
+// /v1/image/<host>/<path>/<width>x<height>.<format>
 func (s *Handlers) HandleImage() http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if s.refuseBlockedReferer(w, r) {

internal/handlers/jpegxl_default_internal_test.go

@@ -1,162 +0,0 @@
-package handlers
-
-import (
-	"fmt"
-	"log/slog"
-	"maps"
-	"net/http"
-	"net/http/httptest"
-	"net/url"
-	"strings"
-	"testing"
-	"time"
-
-	"github.com/davidbyttow/govips/v2/vips"
-
-	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
-	"sneak.berlin/go/pixa/internal/signature"
-)
-
-// requireJPEGXL requires that rec answers 200 with a JPEG XL image.
-func requireJPEGXL(t *testing.T, rec *httptest.ResponseRecorder) {
-	t.Helper()
-
-	if rec.Code != http.StatusOK {
-		t.Fatalf("status = %d, want %d; body %q",
-			rec.Code, http.StatusOK, rec.Body.String())
-	}
-
-	if got := rec.Header().Get("Content-Type"); got != jxlType {
-		t.Errorf("Content-Type = %q, want %s", got, jxlType)
-	}
-
-	if got := vips.DetermineImageType(rec.Body.Bytes()); got != vips.ImageTypeJXL {
-		t.Errorf("body is %s, want jxl", vips.ImageTypes[got])
-	}
-}
-
-// TestImageWithoutFormat_ServesJPEGXL verifies that a /v1/image/ URL whose
-// last segment is a size with no format, 50x50 or orig, answers JPEG XL.
-func TestImageWithoutFormat_ServesJPEGXL(t *testing.T) {
-	t.Parallel()
-
-	route := newImageRoute(t, newPhotoFetcher(t, allowlistedHost))
-
-	for _, size := range []string{"50x50", "orig"} {
-		target := "/v1/image/" + allowlistedHost + photoPath + "/" + size
-		requireJPEGXL(t, sendGet(t, route, target))
-	}
-}
-
-// TestImageWithoutFormat_SignedAsJXL verifies that a /v1/image/ URL with no
-// format is signed as jxl: the signature made for the URL ending in .jxl is
-// accepted for the same URL without .jxl.
-func TestImageWithoutFormat_SignedAsJXL(t *testing.T) {
-	t.Parallel()
-
-	route := newImageRoute(t, newPhotoFetcher(t, signedHost))
-	expires := time.Now().Add(time.Hour)
-
-	sig := signature.New(testSigningKey).Sign(&signature.Request{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-		Format:     string(imgcache.FormatJXL),
-		Quality:    encurl.DefaultQuality,
-		FitMode:    string(imgcache.FitCover),
-		Expires:    expires,
-	})
-	query := fmt.Sprintf("?sig=%s&exp=%d", sig, expires.Unix())
-
-	for _, size := range []string{"50x50.jxl", "50x50"} {
-		target := "/v1/image/" + signedHost + photoPath + "/" + size + query
-		requireJPEGXL(t, sendGet(t, route, target))
-	}
-}
-
-// TestImageEncWithoutFormat_ServesJPEGXL verifies that an encrypted URL whose
-// token holds no format answers JPEG XL.
-func TestImageEncWithoutFormat_ServesJPEGXL(t *testing.T) {
-	t.Parallel()
-
-	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
-
-	token, err := h.encGen.Generate(&encurl.Payload{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-	})
-	if err != nil {
-		t.Fatalf("Generate() error = %v", err)
-	}
-
-	requireJPEGXL(t, getEncToken(srv, token))
-}
-
-// TestGeneratorPage_SelectsJPEGXL verifies that the generator page's format
-// choice is JPEG XL until another is chosen.
-func TestGeneratorPage_SelectsJPEGXL(t *testing.T) {
-	t.Parallel()
-
-	h, srv := newCSRFTestRouter(t)
-
-	req := httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/", nil)
-	req.AddCookie(newSessionCookie(t, h))
-
-	rec := httptest.NewRecorder()
-	srv.ServeHTTP(rec, req)
-
-	if !strings.Contains(rec.Body.String(), `<option value="jxl" selected>`) {
-		t.Errorf("generator page does not select JPEG XL: %s", rec.Body.String())
-	}
-}
-
-// TestGeneratePost_NoFormat_MakesJPEGXLURL verifies that the generator form
-// sent with an empty format field, or with none, makes a URL whose name ends
-// in .jxl and which answers JPEG XL.
-func TestGeneratePost_NoFormat_MakesJPEGXLURL(t *testing.T) {
-	t.Parallel()
-
-	photo := url.Values{
-		sourceURLField: {"https://" + signedHost + photoPath},
-		widthField:     {"50"},
-		heightField:    {"50"},
-	}
-
-	emptyFormat := maps.Clone(photo)
-	emptyFormat.Set(formatField, "")
-
-	for name, form := range map[string]url.Values{
-		"empty format field": emptyFormat,
-		"no format field":    photo,
-	} {
-		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
-			_, imageSrv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
-
-			rec := generatePost(t, form)
-
-			match := generatedURLPattern.FindStringSubmatch(rec.Body.String())
-			if match == nil {
-				t.Fatalf("generator page shows no URL: %d %s",
-					rec.Code, rec.Body.String())
-			}
-
-			t.Logf("generated URL path: %s", match[1])
-
-			if !strings.HasSuffix(match[1], "/img.jxl") {
-				t.Errorf("generated URL %s does not end in /img.jxl", match[1])
-			}
-
-			imageRec := httptest.NewRecorder()
-			imageSrv.ServeHTTP(imageRec, httptest.NewRequestWithContext(
-				t.Context(), http.MethodGet, match[1], nil))
-
-			requireJPEGXL(t, imageRec)
-		})
-	}
-}

internal/imageprocessor/empty_format_internal_test.go

@@ -1,21 +0,0 @@
-package imageprocessor
-
-import (
-	"bytes"
-	"errors"
-	"testing"
-)
-
-// TestImageProcessor_EmptyFormatRefused verifies that a request with no format
-// is refused, as both image routes give every request a format before it is
-// processed.
-func TestImageProcessor_EmptyFormatRefused(t *testing.T) {
-	t.Parallel()
-
-	_, err := New(Params{}).Process(
-		t.Context(), bytes.NewReader(createTestJPEG(t, 20, 20)), &Request{},
-	)
-	if !errors.Is(err, ErrUnsupportedOutputFormat) {
-		t.Errorf("Process() error = %v, want %v", err, ErrUnsupportedOutputFormat)
-	}
-}

internal/imageprocessor/encoder_settings_internal_test.go

@@ -1,145 +0,0 @@
-package imageprocessor
-
-import (
-	"bytes"
-	"image"
-	"image/color"
-	"image/png"
-	"testing"
-
-	"github.com/davidbyttow/govips/v2/vips"
-)
-
-// processedSize runs input through Process and returns the output's size in
-// bytes.
-func processedSize(t *testing.T, input []byte, req *Request) int64 {
-	t.Helper()
-
-	result, err := New(Params{}).Process(t.Context(), bytes.NewReader(input), req)
-	if err != nil {
-		t.Fatalf("Process() error = %v", err)
-	}
-
-	_ = result.Content.Close()
-
-	return result.ContentLength
-}
-
-// encodePNG encodes img as PNG with Go's encoder.
-func encodePNG(t *testing.T, img image.Image) []byte {
-	t.Helper()
-
-	var buf bytes.Buffer
-
-	err := png.Encode(&buf, img)
-	if err != nil {
-		t.Fatalf("failed to encode test PNG: %v", err)
-	}
-
-	return buf.Bytes()
-}
-
-// decode decodes input with vips, as Process does.
-func decode(t *testing.T, input []byte) *vips.ImageRef {
-	t.Helper()
-
-	img, err := vips.NewImageFromBuffer(input)
-	if err != nil {
-		t.Fatalf("failed to decode input: %v", err)
-	}
-
-	t.Cleanup(img.Close)
-
-	return img
-}
-
-// TestImageProcessor_PNGIsCompressed verifies that a PNG output is
-// compressed: a flat 200x150 image, 90,000 bytes of raw pixels, comes out at
-// a small fraction of that.
-func TestImageProcessor_PNGIsCompressed(t *testing.T) {
-	t.Parallel()
-
-	const width, height = 200, 150
-
-	flat := image.NewRGBA(image.Rect(0, 0, width, height))
-	for y := range height {
-		for x := range width {
-			flat.Set(x, y, color.RGBA{R: 40, G: 120, B: 200, A: 255})
-		}
-	}
-
-	size := processedSize(t, encodePNG(t, flat), &Request{Format: FormatPNG})
-
-	const rawBytes = width * height * 3
-	if size > rawBytes/10 {
-		t.Errorf("PNG output is %d bytes, want under a tenth of its %d raw",
-			size, rawBytes)
-	}
-}
-
-// TestImageProcessor_WebPAtDefaultEffort verifies that WebP is saved at
-// libvips' default effort, 4: the output is the size of the same image saved
-// at that effort.
-func TestImageProcessor_WebPAtDefaultEffort(t *testing.T) {
-	t.Parallel()
-
-	input := createTestJPEG(t, 200, 150)
-
-	size := processedSize(t, input, &Request{Format: FormatWebP, Quality: 85})
-
-	want, _, err := decode(t, input).ExportWebp(&vips.WebpExportParams{
-		StripMetadata:   true,
-		Quality:         85,
-		ReductionEffort: 4,
-	})
-	if err != nil {
-		t.Fatalf("ExportWebp() error = %v", err)
-	}
-
-	if size != int64(len(want)) {
-		t.Errorf("WebP output is %d bytes, want %d, the size at effort 4",
-			size, len(want))
-	}
-}
-
-// TestImageProcessor_AVIFAtEffort1 verifies that AVIF is saved at effort 1
-// with 8 bits per sample: the output is the size of the same image saved
-// with those settings. The source is 16-bit, which libvips saves with 12
-// bits when it is not given a bit depth, and 640x480: on a small image,
-// such as 64x48, efforts 1 and 2 give the same output.
-func TestImageProcessor_AVIFAtEffort1(t *testing.T) {
-	t.Parallel()
-
-	const width, height = 640, 480
-
-	source := image.NewRGBA64(image.Rect(0, 0, width, height))
-	for y := range height {
-		for x := range width {
-			source.Set(x, y, color.RGBA64{
-				R: uint16((x * 65535 / width) & 0xffff),
-				G: uint16((y * 65535 / height) & 0xffff),
-				B: 32768,
-				A: 65535,
-			})
-		}
-	}
-
-	input := encodePNG(t, source)
-
-	size := processedSize(t, input, &Request{Format: FormatAVIF, Quality: 85})
-
-	want, _, err := decode(t, input).ExportAvif(&vips.AvifExportParams{
-		StripMetadata: true,
-		Quality:       85,
-		Effort:        1,
-		Bitdepth:      8,
-	})
-	if err != nil {
-		t.Fatalf("ExportAvif() error = %v", err)
-	}
-
-	if size != int64(len(want)) {
-		t.Errorf("AVIF output is %d bytes, want %d, the size at effort 1 "+
-			"and 8 bits", size, len(want))
-	}
-}

internal/imageprocessor/imageprocessor.go

@@ -256,9 +256,9 @@ func (p *ImageProcessor) Process(
 		}
 	}
 
-	// orig is the source's own format; encode refuses an empty format
+	// Determine output format
 	outputFormat := req.Format
-	if outputFormat == FormatOriginal {
+	if outputFormat == FormatOriginal || outputFormat == "" {
 		outputFormat = p.formatFromString(inputFormat)
 	}
 
@@ -504,21 +504,36 @@ func (p *ImageProcessor) encode(
 		}
 	}
 
+	var params vips.ExportParams
+
 	switch format {
 	case FormatJPEG:
-		return exportJPEG(img, quality)
+		params = vips.ExportParams{
+			Format:  vips.ImageTypeJPEG,
+			Quality: quality,
+		}
 
 	case FormatPNG:
-		return exportPNG(img)
+		params = vips.ExportParams{
+			Format: vips.ImageTypePNG,
+		}
 
 	case FormatGIF:
-		return exportGIF(img)
+		params = vips.ExportParams{
+			Format: vips.ImageTypeGIF,
+		}
 
 	case FormatWebP:
-		return exportWebP(img, quality)
+		params = vips.ExportParams{
+			Format:  vips.ImageTypeWEBP,
+			Quality: quality,
+		}
 
 	case FormatAVIF:
-		return exportAVIF(img, quality)
+		params = vips.ExportParams{
+			Format:  vips.ImageTypeAVIF,
+			Quality: quality,
+		}
 
 	case FormatJXL:
 		return exportJXL(img, quality)
@@ -529,97 +544,19 @@ func (p *ImageProcessor) encode(
 	default:
 		return nil, fmt.Errorf("%w: %s", ErrUnsupportedOutputFormat, format)
 	}
+
+	// Drop EXIF, XMP, IPTC and the ICC profile. govips ignores this for
+	// GIF, which carries none of them.
+	params.StripMetadata = true
+
+	output, _, err := img.Export(&params)
+	if err != nil {
+		return nil, err
+	}
+
+	return output, nil
 }
 
-// govips sends libvips Go's zero value for some settings an export leaves
-// out, such as no compression at all for PNG, so each export below sets
-// every setting whose zero value is not what pixa wants. Stripping metadata
-// drops EXIF, XMP, IPTC and the ICC profile.
-
-// exportJPEG encodes img as JPEG at quality, without metadata. The settings
-// it leaves out are at libvips' defaults.
-func exportJPEG(img *vips.ImageRef, quality int) ([]byte, error) {
-	output, _, err := img.ExportJpeg(&vips.JpegExportParams{
-		StripMetadata: true,
-		Quality:       quality,
-	})
-
-	return output, err
-}
-
-// pngCompression is libvips' default PNG compression, from 0 (none) to 9.
-const pngCompression = 6
-
-// exportPNG encodes img as PNG at libvips' default compression and row
-// filter, without metadata.
-func exportPNG(img *vips.ImageRef) ([]byte, error) {
-	output, _, err := img.ExportPng(&vips.PngExportParams{
-		StripMetadata: true,
-		Compression:   pngCompression,
-		Filter:        vips.PngFilterNone,
-	})
-
-	return output, err
-}
-
-// gifEffort is libvips' default GIF effort, from 1 to 10.
-const gifEffort = 7
-
-// exportGIF encodes img as GIF at libvips' default effort. govips cannot
-// have libvips strip metadata from GIF, which carries none.
-func exportGIF(img *vips.ImageRef) ([]byte, error) {
-	output, _, err := img.ExportGIF(&vips.GifExportParams{Effort: gifEffort})
-
-	return output, err
-}
-
-// webpEffort is libvips' default WebP effort, from 0 (fastest) to 6.
-const webpEffort = 4
-
-// exportWebP encodes img as lossy WebP at quality and libvips' default
-// effort, without metadata.
-func exportWebP(img *vips.ImageRef, quality int) ([]byte, error) {
-	output, _, err := img.ExportWebp(&vips.WebpExportParams{
-		StripMetadata:   true,
-		Quality:         quality,
-		ReductionEffort: webpEffort,
-	})
-
-	return output, err
-}
-
-// avifEffort is the AVIF effort, from 0 (fastest) to 9; 1 is the lowest
-// govips can set. With one thread, as pixad runs libvips, 1 takes about 51
-// seconds to save an 8192x8192 image of random pixels, the worst case,
-// against the default downstream_timeout of 60 seconds. On an image of
-// milder noise, which 1 saves in about 12 seconds, 2 takes nearly a minute
-// and libvips' default, 4, takes minutes.
-const avifEffort = 1
-
-// avifBitdepth is the AVIF bit depth, 8 bits per sample for every image.
-// libvips would save a 16-bit image with 12, but at avifEffort that takes
-// about 54 seconds for a 16-bit 8192x8192 image of milder noise, nearly all
-// of the default downstream_timeout, and about 12 seconds with 8.
-const avifBitdepth = 8
-
-// exportAVIF encodes img as lossy AVIF at quality, avifEffort and
-// avifBitdepth, without metadata.
-func exportAVIF(img *vips.ImageRef, quality int) ([]byte, error) {
-	output, _, err := img.ExportAvif(&vips.AvifExportParams{
-		StripMetadata: true,
-		Quality:       quality,
-		Effort:        avifEffort,
-		Bitdepth:      avifBitdepth,
-	})
-
-	return output, err
-}
-
-// jxlResolution is the resolution every JPEG XL image is saved with, in
-// pixels per millimetre as libvips counts it: 72 dpi, what libvips gives a
-// JPEG that names none.
-const jxlResolution = 72 / 25.4
-
 // exportJXL encodes img as JPEG XL at quality, with libvips' default effort
 // and without metadata. govips sends libvips a distance, the JPEG XL
 // encoder's own measure of quality, along with the quality, and libvips then
@@ -637,7 +574,9 @@ func exportJXL(img *vips.ImageRef, quality int) ([]byte, error) {
 
 	// govips cannot make libvips strip metadata from JPEG XL, so it is
 	// removed from the image itself. RemoveMetadata removes EXIF, XMP and
-	// IPTC but keeps the ICC profile.
+	// IPTC but keeps the ICC profile. libvips 8.16 and later still write an
+	// EXIF block of their own: orientation, resolution, size, colour space
+	// and fixed defaults.
 	err := img.RemoveMetadata()
 	if err != nil {
 		return nil, err
@@ -648,22 +587,11 @@ func exportJXL(img *vips.ImageRef, quality int) ([]byte, error) {
 		return nil, err
 	}
 
-	// libvips 8.16 and later still write an EXIF block of their own, from
-	// the image's size, orientation and resolution, and fixed values. The
-	// image is upright, so its orientation is 1, but its resolution is still
-	// the source's.
-	toSave, err := img.CopyChangingResolution(jxlResolution, jxlResolution)
-	if err != nil {
-		return nil, err
-	}
-
-	defer toSave.Close()
-
 	params := vips.NewJxlExportParams()
 	params.Quality = quality
 	params.Distance = jxlDistance(quality)
 
-	output, _, err := toSave.ExportJxl(params)
+	output, _, err := img.ExportJxl(params)
 	if err != nil {
 		return nil, err
 	}

internal/imageprocessor/jpegxl_output_internal_test.go

@@ -102,30 +102,6 @@ func TestImageProcessor_JPEGXLDropsSourceEXIF(t *testing.T) {
 	}
 }
 
-// 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, &Request{Format: 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.

internal/imgcache/service.go

@@ -100,8 +100,8 @@ func NewService(cfg *ServiceConfig) (*Service, error) {
 		allowHTTP = cfg.FetcherConfig.AllowHTTP
 	}
 
-	// JPEG XL is the default output format, so pixad does not start
-	// without it.
+	// JPEG XL is to become the default output format, so pixad does not
+	// start without it.
 	err := imageprocessor.CheckJPEGXLSupport()
 	if err != nil {
 		return nil, err

internal/imgcache/urlparser.go

@@ -38,10 +38,8 @@ func ValidateDimension(name string, value int) error {
 	return nil
 }
 
-// sizeFormatRegex matches patterns like "800x600.webp", "0x0.jpeg", "orig.png",
-// and a size with no format, such as "800x600" or "orig"
-var sizeFormatRegex = regexp.MustCompile(
-	`^(\d+)x(\d+)(?:\.(\w+))?$|^(orig)(?:\.(\w+))?$`)
+// sizeFormatRegex matches patterns like "800x600.webp", "0x0.jpeg", "orig.png"
+var sizeFormatRegex = regexp.MustCompile(`^(\d+)x(\d+)\.(\w+)$|^(orig)\.(\w+)$`)
 
 // ParsedURL contains the parsed components of an image proxy URL.
 type ParsedURL struct {
@@ -58,13 +56,12 @@ type ParsedURL struct {
 }
 
 // ParseImagePath parses the path captured by chi's wildcard:
-// <host>/<path>/<size>.<format>, or <host>/<path>/<size> for JPEG XL
+// <host>/<path>/<size>.<format>
 // This is the primary entry point when using chi routing.
 // Examples:
 //   - cdn.example.com/photos/cat.jpg/800x600.webp
 //   - cdn.example.com/photos/cat.jpg/0x0.jpeg
 //   - cdn.example.com/photos/cat.jpg/orig.png
-//   - cdn.example.com/photos/cat.jpg/800x600
 func ParseImagePath(path string) (*ParsedURL, error) {
 	// Strip leading slash if present (chi may include it)
 	path = strings.TrimPrefix(path, "/")
@@ -75,8 +72,7 @@ func ParseImagePath(path string) (*ParsedURL, error) {
 	return parseImageComponents(path)
 }
 
-// ParseImageURL parses a full URL path like /v1/image/<host>/<path>/<size>.<format>,
-// or /v1/image/<host>/<path>/<size> for JPEG XL
+// ParseImageURL parses a full URL path like /v1/image/<host>/<path>/<size>.<format>
 // Use ParseImagePath instead when working with chi's wildcard capture.
 func ParseImageURL(urlPath string) (*ParsedURL, error) {
 	// Remove the /v1/image/ prefix
@@ -93,8 +89,7 @@ func ParseImageURL(urlPath string) (*ParsedURL, error) {
 	return parseImageComponents(remainder)
 }
 
-// parseImageComponents parses <host>/<path>/<size>.<format>, or
-// <host>/<path>/<size> for JPEG XL.
+// parseImageComponents parses <host>/<path>/<size>.<format> structure.
 func parseImageComponents(remainder string) (*ParsedURL, error) {
 	// Check for path traversal before any other processing
 	err := checkPathTraversal(remainder)
@@ -102,7 +97,7 @@ func parseImageComponents(remainder string) (*ParsedURL, error) {
 		return nil, err
 	}
 
-	// Find the last path segment, which holds "size" or "size.format"
+	// Find the last path segment which contains size.format
 	lastSlash := strings.LastIndex(remainder, "/")
 	if lastSlash == -1 {
 		return nil, ErrMissingSize
@@ -217,7 +212,7 @@ func checkPathTraversal(path string) error {
 	return nil
 }
 
-// parseSizeFormat parses strings like "800x600.webp", "orig.png" or "800x600"
+// parseSizeFormat parses strings like "800x600.webp" or "orig.png"
 func parseSizeFormat(s string) (Size, ImageFormat, error) {
 	matches := sizeFormatRegex.FindStringSubmatch(s)
 	if matches == nil {
@@ -230,11 +225,11 @@ func parseSizeFormat(s string) (Size, ImageFormat, error) {
 	)
 
 	if matches[4] == "orig" {
-		// "orig" or "orig.format" pattern
+		// "orig.format" pattern
 		size = Size{Width: 0, Height: 0}
 		formatStr = matches[5]
 	} else {
-		// "WxH" or "WxH.format" pattern
+		// "WxH.format" pattern
 		width, err := strconv.Atoi(matches[1])
 		if err != nil {
 			return Size{}, "", ErrInvalidSize
@@ -259,11 +254,6 @@ func parseSizeFormat(s string) (Size, ImageFormat, error) {
 		return Size{}, "", err
 	}
 
-	// A URL that names no format is served, and signed, as JPEG XL
-	if formatStr == "" {
-		return size, FormatJXL, nil
-	}
-
 	format, err := parseFormat(formatStr)
 	if err != nil {
 		return Size{}, "", err

internal/server/routes.go

@@ -89,8 +89,7 @@ func (s *Server) SetupRoutes() {
 			r.Use(s.refuseDuringMaintenance)
 
 			// Main image proxy route
-			// /v1/image/<host>/<path>/<width>x<height>.<format>, or with no
-			// format /v1/image/<host>/<path>/<width>x<height>
+			// /v1/image/<host>/<path>/<width>x<height>.<format>
 			r.Get("/image/*", s.h.HandleImage())
 			r.Head("/image/*", s.h.HandleImage())
 

internal/templates/generator.html

@@ -100,7 +100,7 @@
                         <option value="png" {{if eq .FormFormat "png"}}selected{{end}}>PNG</option>
                         <option value="webp" {{if eq .FormFormat "webp"}}selected{{end}}>WebP</option>
                         <option value="avif" {{if eq .FormFormat "avif"}}selected{{end}}>AVIF</option>
-                        <option value="jxl" {{if or (eq .FormFormat "jxl") (eq .FormFormat "")}}selected{{end}}>JPEG XL</option>
+                        <option value="jxl" {{if eq .FormFormat "jxl"}}selected{{end}}>JPEG XL</option>
                         <option value="gif" {{if eq .FormFormat "gif"}}selected{{end}}>GIF</option>
                     </select>
                 </div>