Impute TIFF xres/yres from withMetadata({density})

lovell · Nov 8, 2021 · 342de36 · 342de36
1 parent b33231d
commit 342de36
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diff --git a/docs/api-output.md b/docs/api-output.md
@@ -379,6 +379,8 @@ Returns **Sharp**
 
 Use these TIFF options for output image.
 
+The `density` can be set in pixels/inch via [withMetadata][1] instead of providing `xres` and `yres` in pixels/mm.
+
 ### Parameters
 
 *   `options` **[Object][6]?** output options

diff --git a/docs/search-index.json b/docs/search-index.json
diff --git a/lib/output.js b/lib/output.js
@@ -637,6 +637,8 @@ function trySetAnimationOptions (source, target) {
 /**
  * Use these TIFF options for output image.
  *
+ * The `density` can be set in pixels/inch via {@link withMetadata} instead of providing `xres` and `yres` in pixels/mm.
+ *
  * @example
  * // Convert SVG input to LZW-compressed, 1 bit per pixel TIFF output
  * sharp('input.svg')

diff --git a/src/pipeline.cc b/src/pipeline.cc
@@ -1496,6 +1496,9 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->tiffTileHeight = sharp::AttrAsUint32(options, "tiffTileHeight");
   baton->tiffXres = sharp::AttrAsDouble(options, "tiffXres");
   baton->tiffYres = sharp::AttrAsDouble(options, "tiffYres");
+  if (baton->tiffXres == 1.0 && baton->tiffYres == 1.0 && baton->withMetadataDensity > 0) {
+    baton->tiffXres = baton->tiffYres = baton->withMetadataDensity / 25.4;
+  }
   // tiff compression options
   baton->tiffCompression = static_cast<VipsForeignTiffCompression>(
   vips_enum_from_nick(nullptr, VIPS_TYPE_FOREIGN_TIFF_COMPRESSION,

diff --git a/test/unit/tiff.js b/test/unit/tiff.js
@@ -188,6 +188,26 @@ describe('TIFF', function () {
       )
   );
 
+  it('TIFF imputes xres and yres from withMetadataDensity if not explicitly provided', async () => {
+    const data = await sharp(fixtures.inputTiff)
+      .resize(8, 8)
+      .tiff()
+      .withMetadata({ density: 600 })
+      .toBuffer();
+    const { density } = await sharp(data).metadata();
+    assert.strictEqual(600, density);
+  });
+
+  it('TIFF uses xres and yres over withMetadataDensity if explicitly provided', async () => {
+    const data = await sharp(fixtures.inputTiff)
+      .resize(8, 8)
+      .tiff({ xres: 1000, yres: 1000 })
+      .withMetadata({ density: 600 })
+      .toBuffer();
+    const { density } = await sharp(data).metadata();
+    assert.strictEqual(25400, density);
+  });
+
   it('TIFF invalid xres value should throw an error', function () {
     assert.throws(function () {
       sharp().tiff({ xres: '1000.0' });