Expose mozjpeg quant_table flag

docs/api-output.md

@@ -116,6 +116,8 @@ Use these JPEG options for output image.
     -   `options.progressive` **[Boolean][6]** use progressive (interlace) scan (optional, default `false`)
     -   `options.chromaSubsampling` **[String][1]** set to '4:4:4' to prevent chroma subsampling when quality <= 90 (optional, default `'4:2:0'`)
     -   `options.trellisQuantisation` **[Boolean][6]** apply trellis quantisation, requires mozjpeg (optional, default `false`)
+    -   `options.quantisationTable` **[Number][8]** [quantisation table][9] to use, integer 0-8 (optional, default `0`)
+    -   `options.quantizationTable` **[Number][8]** alternative spelling of quantisationTable (optional, default `0`)
     -   `options.overshootDeringing` **[Boolean][6]** apply overshoot deringing, requires mozjpeg (optional, default `false`)
     -   `options.optimiseScans` **[Boolean][6]** optimise progressive scans, forces progressive, requires mozjpeg (optional, default `false`)
     -   `options.optimizeScans` **[Boolean][6]** alternative spelling of optimiseScans (optional, default `false`)
@@ -312,3 +314,5 @@ Returns **Sharp**
 [7]: https://nodejs.org/api/buffer.html
 
 [8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number
+
+[9]:  https://jcupitt.github.io/libvips/API/current/VipsForeignSave.html#vips-jpegsave

lib/constructor.js

@@ -193,6 +193,7 @@ const Sharp = function (input, options) {
     jpegOvershootDeringing: false,
     jpegOptimiseScans: false,
     jpegOptimiseCoding: true,
+    jpegQuantisationTable: 0,
     pngProgressive: false,
     pngCompressionLevel: 9,
     pngAdaptiveFiltering: false,

lib/output.js

@@ -150,6 +150,8 @@ function withMetadata (withMetadata) {
  * @param {Boolean} [options.optimizeScans=false] - alternative spelling of optimiseScans
  * @param {Boolean} [options.optimiseCoding=true] - optimise Huffman coding tables
  * @param {Boolean} [options.optimizeCoding=true] - alternative spelling of optimiseCoding
+ * @param {Number} [options.quantisationTable=0] - quantization table to use, integer 0-8, requires mozjpeg
+ * @param {Number} [options.quantizationTable=0] - alternative spelling of quantisationTable
  * @param {Boolean} [options.force=true] - force JPEG output, otherwise attempt to use input format
  * @returns {Sharp}
  * @throws {Error} Invalid options
@@ -191,6 +193,14 @@ function jpeg (options) {
     if (is.defined(options.optimiseCoding)) {
       this._setBooleanOption('jpegOptimiseCoding', options.optimiseCoding);
     }
+    options.quantisationTable = is.number(options.quantizationTable) ? options.quantizationTable : options.quantisationTable;
+    if (is.defined(options.quantisationTable)) {
+      if (is.integer(options.quantisationTable) && is.inRange(options.quantisationTable, 0, 8)) {
+        this.options.jpegQuantisationTable = options.quantisationTable;
+      } else {
+        throw new Error('Invalid quantisation table (integer, 0-8) ' + options.quantisationTable);
+      }
+    }
   }
   return this._updateFormatOut('jpeg', options);
 }

src/pipeline.cc

@@ -733,6 +733,7 @@ class PipelineWorker : public Nan::AsyncWorker {
             ->set("interlace", baton->jpegProgressive)
             ->set("no_subsample", baton->jpegChromaSubsampling == "4:4:4")
             ->set("trellis_quant", baton->jpegTrellisQuantisation)
+            ->set("quant_table", baton->jpegQuantisationTable)
             ->set("overshoot_deringing", baton->jpegOvershootDeringing)
             ->set("optimize_scans", baton->jpegOptimiseScans)
             ->set("optimize_coding", baton->jpegOptimiseCoding)));
@@ -848,6 +849,7 @@ class PipelineWorker : public Nan::AsyncWorker {
             ->set("interlace", baton->jpegProgressive)
             ->set("no_subsample", baton->jpegChromaSubsampling == "4:4:4")
             ->set("trellis_quant", baton->jpegTrellisQuantisation)
+            ->set("quant_table", baton->jpegQuantisationTable)
             ->set("overshoot_deringing", baton->jpegOvershootDeringing)
             ->set("optimize_scans", baton->jpegOptimiseScans)
             ->set("optimize_coding", baton->jpegOptimiseCoding));
@@ -927,6 +929,7 @@ class PipelineWorker : public Nan::AsyncWorker {
               {"interlace", baton->jpegProgressive ? "TRUE" : "FALSE"},
               {"no_subsample", baton->jpegChromaSubsampling == "4:4:4" ? "TRUE": "FALSE"},
               {"trellis_quant", baton->jpegTrellisQuantisation ? "TRUE" : "FALSE"},
+              {"quant_table", std::to_string(baton->jpegQuantisationTable)},
               {"overshoot_deringing", baton->jpegOvershootDeringing ? "TRUE": "FALSE"},
               {"optimize_scans", baton->jpegOptimiseScans ? "TRUE": "FALSE"},
               {"optimize_coding", baton->jpegOptimiseCoding ? "TRUE": "FALSE"}
@@ -1266,6 +1269,7 @@ NAN_METHOD(pipeline) {
   baton->jpegProgressive = AttrTo<bool>(options, "jpegProgressive");
   baton->jpegChromaSubsampling = AttrAsStr(options, "jpegChromaSubsampling");
   baton->jpegTrellisQuantisation = AttrTo<bool>(options, "jpegTrellisQuantisation");
+  baton->jpegQuantisationTable = AttrTo<uint32_t>(options, "jpegQuantisationTable");
   baton->jpegOvershootDeringing = AttrTo<bool>(options, "jpegOvershootDeringing");
   baton->jpegOptimiseScans = AttrTo<bool>(options, "jpegOptimiseScans");
   baton->jpegOptimiseCoding = AttrTo<bool>(options, "jpegOptimiseCoding");

src/pipeline.h

@@ -102,6 +102,7 @@ struct PipelineBaton {
   bool jpegProgressive;
   std::string jpegChromaSubsampling;
   bool jpegTrellisQuantisation;
+  int jpegQuantisationTable;
   bool jpegOvershootDeringing;
   bool jpegOptimiseScans;
   bool jpegOptimiseCoding;
@@ -188,6 +189,7 @@ struct PipelineBaton {
     jpegProgressive(false),
     jpegChromaSubsampling("4:2:0"),
     jpegTrellisQuantisation(false),
+    jpegQuantisationTable(0),
     jpegOvershootDeringing(false),
     jpegOptimiseScans(false),
     jpegOptimiseCoding(true),

test/unit/io.js

@@ -389,6 +389,16 @@ describe('Input/output', function () {
     });
   });
 
+  describe('Invalid JPEG quantisation table', function () {
+    [-1, 88.2, 'test'].forEach(function (table) {
+      it(table.toString(), function () {
+        assert.throws(function () {
+          sharp().jpeg({ quantisationTable: table });
+        });
+      });
+    });
+  });
+
   it('Progressive JPEG image', function (done) {
     sharp(fixtures.inputJpg)
       .resize(320, 240)
@@ -856,6 +866,37 @@ describe('Input/output', function () {
       });
   });
 
+  it('Specifying quantisation table provides different JPEG', function (done) {
+    // First generate with default quantisation table
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .jpeg({ optimiseCoding: false })
+      .toBuffer(function (err, withDefaultQuantisationTable, withInfo) {
+        if (err) throw err;
+        assert.strictEqual(true, withDefaultQuantisationTable.length > 0);
+        assert.strictEqual(withDefaultQuantisationTable.length, withInfo.size);
+        assert.strictEqual('jpeg', withInfo.format);
+        assert.strictEqual(320, withInfo.width);
+        assert.strictEqual(240, withInfo.height);
+        // Then generate with different quantisation table
+        sharp(fixtures.inputJpg)
+          .resize(320, 240)
+          .jpeg({ optimiseCoding: false, quantisationTable: 3 })
+          .toBuffer(function (err, withQuantTable3, withoutInfo) {
+            if (err) throw err;
+            assert.strictEqual(true, withQuantTable3.length > 0);
+            assert.strictEqual(withQuantTable3.length, withoutInfo.size);
+            assert.strictEqual('jpeg', withoutInfo.format);
+            assert.strictEqual(320, withoutInfo.width);
+            assert.strictEqual(240, withoutInfo.height);
+
+            // Verify image is same (as mozjpeg may not be present) size or less
+            assert.strictEqual(true, withQuantTable3.length <= withDefaultQuantisationTable.length);
+            done();
+          });
+      });
+  });
+
   it('Convert SVG to PNG at default 72DPI', function (done) {
     sharp(fixtures.inputSvg)
       .resize(1024)