feat: add HEIC/HEIF decoding and encoding support

.github/workflows/check.yml

@@ -15,9 +15,8 @@ jobs:
         os:
           - ubuntu-latest
           - macos-15
-        # 1.25 is the floor imposed by golang.org/x/image; keep in sync with go.mod.
+        # 1.26 is the floor imposed by github.com/gen2brain/h265; keep in sync with go.mod.
         go-version:
-          - '1.25'
           - '1.26'
 
     steps:

.github/workflows/release.yml

@@ -19,7 +19,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v6
       with:
-        go-version: '1.26.0'
+        go-version: '1.26.4'
 
     - name: Test
       run: make test

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+- Add HEIC/HEIF decoding and encoding via `imgio.HEICEncoder` and `.heic`/`.heif` CLI output, backed by the pure Go `github.com/gen2brain/h265` codec
+- Bump minimum supported Go version to 1.26
+
 ## 0.17.1
 - Fix transparent pixels when resizing with the Box filter by @youdie006 in https://github.com/anthonynsimon/bild/pull/115
 - Bump golang.org/x/image from 0.44.0 to 0.45.0 to address CVE-2026-46603 in the VP8L decoder, reported in https://github.com/anthonynsimon/bild/pull/116

README.md

@@ -84,7 +84,7 @@ bild imgio encode input.png output.webp
 
 ## Install package
 
-bild requires Go version 1.25 or greater.
+bild requires Go version 1.26 or greater.
 
 ```bash
 go get github.com/anthonynsimon/bild/...
@@ -120,14 +120,19 @@ func main() {
 
 ## Supported formats
 
-`imgio.Open` decodes PNG, JPEG, BMP and WebP images. The following encoders are available:
+`imgio.Open` decodes PNG, JPEG, BMP, WebP and HEIC/HEIF images. The following encoders are available:
 
 - `imgio.PNGEncoder()`
 - `imgio.JPEGEncoder(quality)`
 - `imgio.BMPEncoder()`
 - `imgio.WEBPEncoder(options)` — pass `nil` for defaults
+- `imgio.HEICEncoder(options)` — pass `nil` for defaults
 
-The CLI selects the encoder from the output file extension (`.png`, `.jpg`/`.jpeg`, `.bmp`, `.webp`).
+The CLI selects the encoder from the output file extension (`.png`, `.jpg`/`.jpeg`, `.bmp`, `.webp`, `.heic`/`.heif`).
+
+HEIC support is pure Go and adds no transitive dependencies, but note that HEVC is
+covered by patents; distributing software that decodes or encodes it may require a
+licence from the patent holders.
 
 # Output examples
 ## Adjustment

cmd/helpers.go

@@ -16,6 +16,7 @@ var jpgExtensions = []string{".jpg", ".jpeg"}
 var pngExtensions = []string{".png"}
 var bmpExtensions = []string{".bmp"}
 var webpExtensions = []string{".webp"}
+var heicExtensions = []string{".heic", ".heif"}
 
 var (
 	// ErrWrongSize is thrown when the provided size string does not match the expected form.
@@ -58,6 +59,12 @@ func resolveEncoder(outputfile string, defaultEncoding imgio.Encoder) imgio.Enco
 		}
 	}
 
+	for _, ext := range heicExtensions {
+		if strings.HasSuffix(lower, ext) {
+			return imgio.HEICEncoder(nil)
+		}
+	}
+
 	return defaultEncoding
 }
 

go.mod

@@ -1,9 +1,10 @@
 module github.com/anthonynsimon/bild
 
-go 1.25.0
+go 1.26.4
 
 require (
 	github.com/HugoSmits86/nativewebp v1.3.0
+	github.com/gen2brain/h265 v0.2.2
 	github.com/spf13/cobra v1.10.2
 	golang.org/x/image v0.45.0
 )

go.sum

@@ -1,6 +1,8 @@
 github.com/HugoSmits86/nativewebp v1.3.0 h1:n1egtEzSV4KwFtealr7dzdYq1wI/uj/bOQ/QcTcIyVE=
 github.com/HugoSmits86/nativewebp v1.3.0/go.mod h1:YNQuWenlVmSUUASVNhTDwf4d7FwYQGbGhklC8p72Vr8=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/gen2brain/h265 v0.2.2 h1:rnpfo8I4PFhohbij8ySYZlJFn07TTwV+/uWBrKsOEas=
+github.com/gen2brain/h265 v0.2.2/go.mod h1:kefpLxLhGpNCUG/q/aabJcD6GqB9Nhet3fNi9xX9Wzw=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=

imgio/io.go

@@ -9,6 +9,7 @@ import (
 	"os"
 
 	"github.com/HugoSmits86/nativewebp"
+	"github.com/gen2brain/h265/heic"
 	"golang.org/x/image/bmp"
 )
 
@@ -65,6 +66,17 @@ func WEBPEncoder(o *nativewebp.Options) Encoder {
 	}
 }
 
+// HEICEncoder returns an encoder to HEIC. Pass nil to encode with the
+// default options, which are lossy 4:2:0 at 8 bits.
+func HEICEncoder(o *heic.EncodeOptions) Encoder {
+	return func(w io.Writer, img image.Image) error {
+		if o == nil {
+			return heic.Encode(w, img)
+		}
+		return heic.Encode(w, img, *o)
+	}
+}
+
 // Save creates a file and writes to it an image using the provided encoder.
 //
 // Usage example:

imgio/io_test.go

@@ -5,6 +5,9 @@ import (
 	"image"
 	"strings"
 	"testing"
+
+	"github.com/anthonynsimon/bild/clone"
+	"github.com/anthonynsimon/bild/util"
 )
 
 func TestEncode(t *testing.T) {
@@ -52,6 +55,19 @@ func TestEncode(t *testing.T) {
 				},
 			},
 		},
+		{
+			format:  "heic",
+			encoder: HEICEncoder(nil),
+			value: &image.RGBA{
+				Rect:   image.Rect(0, 0, 3, 3),
+				Stride: 3 * 4,
+				Pix: []uint8{
+					0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF,
+					0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0x80, 0x00, 0x00, 0xFF,
+					0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF,
+				},
+			},
+		},
 		{
 			format:  "webp",
 			encoder: WEBPEncoder(nil),
@@ -79,3 +95,29 @@ func TestEncode(t *testing.T) {
 		}
 	}
 }
+
+func TestOpenHEIC(t *testing.T) {
+	// A 4x4 image of four solid 2x2 quadrants: red, green, blue, white,
+	// written losslessly at 4:4:4. The coded samples are exact, but the
+	// RGB to YCbCr conversion either way rounds, hence the tolerance.
+	expected := &image.RGBA{
+		Rect:   image.Rect(0, 0, 4, 4),
+		Stride: 4 * 4,
+		Pix: []uint8{
+			0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF,
+			0xFF, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF,
+			0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+			0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+		},
+	}
+
+	img, err := Open("testdata/quadrants.heic")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	actual := clone.AsRGBA(img)
+	if !util.RGBAImageApproxEqual(actual, expected, 1) {
+		t.Errorf("%s: expected: %#v, actual: %#v", "Open HEIC", expected, actual)
+	}
+}