Bake input orientation into output image

img.js

@@ -439,9 +439,10 @@ class Image {
   }
 
   // https://jdhao.github.io/2019/07/31/image_rotation_exif_info/
-  // Orientation 5 to 8 means width/height are flipped
-  needsRotation(orientation) {
-    return orientation >= 5;
+  // Orientations 5 to 8 mean image is rotated ±90º (width/height are flipped)
+  isQuarterTurn(orientation) {
+    // Sharp's metadata API exposes undefined EXIF orientations >8 as 1 (normal) but check anyways
+    return orientation >= 5 && orientation <= 8;
   }
 
   // metadata so far: width, height, format
@@ -450,11 +451,8 @@ class Image {
     let results = [];
     let outputFormats = Image.getFormatsArray(this.options.formats, metadata.format || this.options.overrideInputFormat, this.options.svgShortCircuit);
 
-    if (this.needsRotation(metadata.orientation)) {
-      let height = metadata.height;
-      let width = metadata.width;
-      metadata.width = height;
-      metadata.height = width;
+    if (this.isQuarterTurn(metadata.orientation)) {
+      [metadata.height, metadata.width] = [metadata.width, metadata.height];
     }
 
     if(metadata.pageHeight) {
@@ -541,21 +539,22 @@ class Image {
         }
 
         let sharpInstance = sharpImage.clone();
+        // Output images do not include orientation metadata (https://github.com/11ty/eleventy-img/issues/52)
+        // Use sharp.rotate to bake orientation into the image (https://github.com/lovell/sharp/blob/v0.32.6/docs/api-operation.md#rotate):
+        // > If no angle is provided, it is determined from the EXIF data. Mirroring is supported and may infer the use of a flip operation.
+        // > The use of rotate without an angle will remove the EXIF Orientation tag, if any.
+        if(this.options.fixOrientation || this.needsRotation(metadata.orientation)) {
+          sharpInstance.rotate();
+        }
         if(stat.width < metadata.width || (this.options.svgAllowUpscale && metadata.format === "svg")) {
           let resizeOptions = {
             width: stat.width
           };
           if(metadata.format !== "svg" || !this.options.svgAllowUpscale) {
             resizeOptions.withoutEnlargement = true;
           }
-          if(this.options.fixOrientation || this.needsRotation(metadata.orientation)) {
-            sharpInstance.rotate();
-          }
+
           sharpInstance.resize(resizeOptions);
-        } else if (metadata.format !== "svg") {
-          if(this.options.fixOrientation || stat.width === metadata.width && this.needsRotation(metadata.orientation)) {
-            sharpInstance.rotate();
-          }
         }
 
         if(!this.options.dryRun) {

package.json

@@ -49,7 +49,8 @@
     "@11ty/eleventy": "^2.0.1",
     "@11ty/eleventy-plugin-webc": "^0.11.1",
     "ava": "^5.3.1",
-    "eslint": "^8.52.0"
+    "eslint": "^8.52.0",
+    "pixelmatch": "^5.3.0"
   },
   "ava": {
     "failFast": false,

test/test.js

@@ -3,6 +3,8 @@ const test = require("ava");
 const fs = require("fs");
 const { URL } = require("url");
 const eleventyImage = require("../");
+const sharp = require("sharp");
+const pixelmatch = require('pixelmatch');
 
 // Remember that any outputPath tests must use path.join to work on Windows
 
@@ -846,6 +848,32 @@ test("Maintains orientation #132", async t => {
 });
 
 // Broken test cases from https://github.com/recurser/exif-orientation-examples
+test("#158: Test EXIF orientation data landscape (3)", async t => {
+  let stats = await eleventyImage("./test/exif-Landscape_3.jpg", {
+    widths: [200, "auto"],
+    formats: ['auto'],
+    useCache: false,
+    dryRun: true,
+  });
+
+  t.is(stats.jpeg.length, 2);
+  t.is(stats.jpeg[0].width, 200);
+  t.is(stats.jpeg[1].width, 1800);
+  t.is(Math.floor(stats.jpeg[0].height), 133);
+  t.is(stats.jpeg[1].height, 1200);
+
+  // This orientation (180º rotation) preserves image dimensions and requires an image diff
+  const readToRaw = async input => {
+    // pixelmatch requires 4 bytes/pixel, hence alpha
+    return sharp(input).ensureAlpha().toFormat(sharp.format.raw).toBuffer();
+  };
+  for (const [inSrc, outStat] of [["./test/exif-Landscape_3-bakedOrientation-200.jpg", stats.jpeg[0]], ["./test/exif-Landscape_3-bakedOrientation.jpg", stats.jpeg[1]]]) {
+    const inRaw = await readToRaw(inSrc);
+    const outRaw = await readToRaw(outStat.buffer);
+    t.is(pixelmatch(inRaw, outRaw, null, outStat.width, outStat.height, { threshold: 0.15 }), 0);
+  }
+});
+
 test("#132: Test EXIF orientation data landscape (5)", async t => {
   let stats = await eleventyImage("./test/exif-Landscape_5.jpg", {
     widths: [400, "auto"],
@@ -892,7 +920,20 @@ test("#132: Test EXIF orientation data landscape (8)", async t => {
     widths: [400],
     formats: ['auto'],
     outputDir: "./test/img/",
-    // dryRun: true,
+    dryRun: true,
+  });
+
+  t.is(stats.jpeg.length, 1);
+  t.is(stats.jpeg[0].width, 400);
+  t.is(Math.floor(stats.jpeg[0].height), 266);
+});
+
+test("#158: Test EXIF orientation data landscape (15)", async t => {
+  let stats = await eleventyImage("./test/exif-Landscape_15.jpg", {
+    widths: [400],
+    formats: ['auto'],
+    outputDir: "./test/img/",
+    dryRun: true,
   });
 
   t.is(stats.jpeg.length, 1);