Ensure create has correct bit depth and colourspace #3139

docs/api-operation.md

@@ -289,6 +289,20 @@ Produce the "negative" of the image.
 
     *   `options.alpha` **[Boolean][6]** Whether or not to negate any alpha channel (optional, default `true`)
 
+### Examples
+
+```javascript
+const output = await sharp(input)
+  .negate()
+  .toBuffer();
+```
+
+```javascript
+const output = await sharp(input)
+  .negate({ alpha: false })
+  .toBuffer();
+```
+
 Returns **Sharp** 
 
 ## normalise

docs/changelog.md

@@ -4,6 +4,11 @@
 
 Requires libvips v8.12.2
 
+### v0.30.4 - TBD
+
+* Ensure `create` input image has correct bit depth and colour space.
+  [#3139](https://github.com/lovell/sharp/issues/3139)
+
 ### v0.30.3 - 14th March 2022
 
 * Allow `sharpen` options to be provided more consistently as an Object.

lib/operation.js

@@ -420,6 +420,17 @@ function gamma (gamma, gammaOut) {
 
 /**
  * Produce the "negative" of the image.
+ *
+ * @example
+ * const output = await sharp(input)
+ *   .negate()
+ *   .toBuffer();
+ *
+ * @example
+ * const output = await sharp(input)
+ *   .negate({ alpha: false })
+ *   .toBuffer();
+ *
  * @param {Object} [options]
  * @param {Boolean} [options.alpha=true] Whether or not to negate any alpha channel
  * @returns {Sharp}

src/common.cc

@@ -375,12 +375,6 @@ namespace sharp {
               VImage::option()->set("mean", descriptor->createNoiseMean)->set("sigma", descriptor->createNoiseSigma)));
           }
           image = image.bandjoin(bands);
-          image = image.cast(VipsBandFormat::VIPS_FORMAT_UCHAR);
-          if (channels < 3) {
-            image = image.colourspace(VIPS_INTERPRETATION_B_W);
-          } else {
-            image = image.colourspace(VIPS_INTERPRETATION_sRGB);
-          }
         } else {
           std::vector<double> background = {
             descriptor->createBackground[0],
@@ -392,7 +386,8 @@ namespace sharp {
           }
           image = VImage::new_matrix(descriptor->createWidth, descriptor->createHeight).new_from_image(background);
         }
-        image.get_image()->Type = VIPS_INTERPRETATION_sRGB;
+        image.get_image()->Type = image.guess_interpretation();
+        image = image.cast(VIPS_FORMAT_UCHAR);
         imageType = ImageType::RAW;
       } else {
         // From filesystem

test/unit/negate.js

@@ -186,6 +186,22 @@ describe('Negate', function () {
       });
   });
 
+  it('negate create', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 10, g: 20, b: 30 }
+      }
+    })
+      .negate()
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r, g, b }, { r: 245, g: 235, b: 225 });
+  });
+
   it('invalid alpha value', function () {
     assert.throws(function () {
       sharp(fixtures.inputWebPWithTransparency).negate({ alpha: 'non-bool' });

test/unit/noise.js

@@ -19,7 +19,7 @@ describe('Gaussian noise', function () {
           sigma: 30
         }
       }
-    });
+    }).toColourspace('b-w');
     noise.toFile(output, function (err, info) {
       if (err) throw err;
       assert.strictEqual('png', info.format);
@@ -131,6 +131,7 @@ describe('Gaussian noise', function () {
       }
     });
     noise
+      .toColourspace('b-w')
       .toBuffer(function (err, data, info) {
         if (err) throw err;
         assert.strictEqual(1, info.channels);