cmd/handsum: append '\n' to base64 output

cmd/handsum/main.go

diff --git a/cmd/handsum/main.go b/cmd/handsum/main.go
index 84842d8..980fb91 100644
--- a/cmd/handsum/main.go
+++ b/cmd/handsum/main.go
@@ -203,6 +203,7 @@
 
 	if b64e != nil {
 		enc := b64e.AppendEncode(nil, buf.Bytes())
+		enc = append(enc, '\n')
 		if _, err := w.Write(enc); err != nil {
 			return err
 		}

lib/handsum/example_test.go

diff --git a/lib/handsum/example_test.go b/lib/handsum/example_test.go
new file mode 100644
index 0000000..8d5da05
--- /dev/null
+++ b/lib/handsum/example_test.go
@@ -0,0 +1,71 @@
+// Copyright 2026 The Wuffs Authors.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+package handsum_test
+
+import (
+	"bytes"
+	"encoding/base64"
+	"fmt"
+	"image/png"
+	"log"
+	"os"
+
+	"github.com/google/wuffs/lib/handsum"
+)
+
+func Example_decode() {
+	srcBytes, err := base64.URLEncoding.DecodeString("" +
+		"_tdrdX33KcrhdVU1hFi3h2mtY0qqd2dswzeX9jmJckmUxD15c1Vqk1iGdjmYoknlZDl5dmmZ" +
+		"xEczhliahXRDpC3JFoiItjAtQ2vJpjBsUziLiXivgimZqDq6skhwhkxIsimmragKTLa-_Hmn" +
+		"C5rf_acAvXR4zebYyq-Qc2SVtVnIA_mX9zVlEmn_Ul9pIzwHaFBb")
+	if err != nil {
+		log.Fatalf("base64.URLEncoding.DecodeString: %v", err)
+	}
+
+	img, err := handsum.Decode(bytes.NewReader(srcBytes))
+	if err != nil {
+		log.Fatalf("handsum.Decode: %v", err)
+	}
+	fmt.Printf("%T %v\n", img, img.Bounds())
+
+	// Output:
+	// *image.RGBA (0,0)-(16,12)
+}
+
+func Example_encode() {
+	f, err := os.Open("../../test/data/bricks-color.png")
+	if err != nil {
+		log.Fatalf("os.Open: %v", err)
+	}
+	defer f.Close()
+
+	srcImage, err := png.Decode(f)
+	if err != nil {
+		log.Fatalf("png.Decode: %v", err)
+	}
+
+	buf := &bytes.Buffer{}
+	err = handsum.Encode(buf, srcImage, nil)
+	if err != nil {
+		log.Fatalf("handsum.Encode: %v", err)
+	}
+
+	s := base64.URLEncoding.EncodeToString(buf.Bytes())
+	for ; len(s) > 72; s = s[72:] {
+		fmt.Println(s[:72])
+	}
+	fmt.Println(s)
+
+	// Output:
+	// _tdrdX33KcrhdVU1hFi3h2mtY0qqd2dswzeX9jmJckmUxD15c1Vqk1iGdjmYoknlZDl5dmmZ
+	// xEczhliahXRDpC3JFoiItjAtQ2vJpjBsUziLiXivgimZqDq6skhwhkxIsimmragKTLa-_Hmn
+	// C5rf_acAvXR4zebYyq-Qc2SVtVnIA_mX9zVlEmn_Ul9pIzwHaFBb
+}

lib/handsum/handsum.go

diff --git a/lib/handsum/handsum.go b/lib/handsum/handsum.go
index ea8933f..2a964bb 100644
--- a/lib/handsum/handsum.go
+++ b/lib/handsum/handsum.go
@@ -47,9 +47,9 @@
 // 4.59375 bits per pixel for a 16×16 pixel image (a 1:1 aspect ratio), or
 // 6.125 bits per pixel for a 16×12 pixel image (a 4:3 aspect ratio).
 //
-// A Handsum file's starts with a 3 byte header: a 15-bit magic signature, a
-// 2-bit color (Gray, RGB or RGBA), a 2-bit quality and a 5-bit aspect ratio.
-// An image's longest dimension (width or height) is 16 pixels and the aspect
+// Handsum files start with a 3 byte header: a 15-bit magic signature, a 2-bit
+// color (Gray, RGB or RGBA), a 2-bit quality and a 5-bit aspect ratio. An
+// image's longest dimension (width or height) is 16 pixels and the aspect
 // ratio gives the shorter dimension.
 //
 // The color=RGB payload, after the header, holds a scaled 16×16 pixel YCbCr
@@ -79,10 +79,11 @@
 //
 // All Handsum images use the sRGB color profile and non-premultiplied alpha.
 //
-// The "Handsum" name was inspired by the "Thumbhash" image file format, which
-// is also designed for very small thumbnails (or very compact representations
-// of image placeholders). Handsum files are bigger (but better quality) than
-// Thumbhash. "Handsum" also sounds like "handsome", meaning "good looking".
+// The "Handsum" name was inspired by the "Thumbhash" image file format (which
+// was in turn inspired by "Blurhash"), which is also designed for very small
+// thumbnails (or very compact representations of image placeholders). Handsum
+// files are bigger (but better quality) than Thumbhash (and Blurhash).
+// "Handsum" also sounds like "handsome", meaning "good looking".
 //
 // Other techniques and image formats, similar to Thumbhash, can be found by
 // search for "LQIP" or "Low Quality Image Placeholders".