Ensure modulate can co-exist with other colour ops #1958

docs/changelog.md

@@ -14,6 +14,9 @@ Requires libvips v8.8.1.
   [#1952](https://github.com/lovell/sharp/pull/1952)
   [@pouya-eghbali](https://github.com/pouya-eghbali)
 
+* Ensure `modulate` and other colour-based operations can co-exist.
+  [#1958](https://github.com/lovell/sharp/issues/1958)
+
 #### v0.23.2 - 28<sup>th</sup> October 2019
 
 * Add `background` option to tile output operation.

src/operations.cc

@@ -191,12 +191,20 @@ namespace sharp {
       VImage alpha = image[image.bands() - 1];
       return RemoveAlpha(image)
         .colourspace(VIPS_INTERPRETATION_LCH)
-        .linear({brightness, saturation, 1}, {0, 0, static_cast<double>(hue)})
+        .linear(
+          { brightness, saturation, 1},
+          { 0.0, 0.0, static_cast<double>(hue) }
+        )
+        .colourspace(VIPS_INTERPRETATION_sRGB)
         .bandjoin(alpha);
     } else {
       return image
         .colourspace(VIPS_INTERPRETATION_LCH)
-        .linear({brightness, saturation, 1}, {0, 0, static_cast<double>(hue)});
+        .linear(
+          { brightness, saturation, 1 },
+          { 0.0, 0.0, static_cast<double>(hue) }
+        )
+        .colourspace(VIPS_INTERPRETATION_sRGB);
     }
   }
 

test/unit/modulate.js

@@ -122,4 +122,21 @@ describe('Modulate', function () {
       });
     });
   });
+
+  it('should be able to use linear and modulate together', function () {
+    const base = 'modulate-linear.jpg';
+    const actual = fixtures.path('output.' + base);
+    const expected = fixtures.expected(base);
+
+    const contrast = 1.5;
+    const brightness = 0.5;
+
+    return sharp(fixtures.testPattern)
+      .linear(contrast, -(128 * contrast) + 128)
+      .modulate({ brightness })
+      .toFile(actual)
+      .then(function () {
+        fixtures.assertMaxColourDistance(actual, expected);
+      });
+  });
 });