Implement brightness, saturation and hue modulation #609 #1601

Goues · 2019-03-05T23:32:44Z

Hello, I've read about feature request #609 because this is what I would like to be able to do too. I have no experience in C/C++ but I followed all advice I could find to stitch those changes.

Can you please look at it and point me to all the missing pieces I should do as well?

Thank you very much!
Goues

Goues · 2019-03-05T23:41:45Z

p.s. Unit tests are not passing, because it claims that output is not similar enough to expected output, should I just set a higher threshold?

coveralls · 2019-03-06T07:05:08Z

Coverage increased (+0.03%) to 98.522% when pulling a90d8b6 on Goues:feature-modulate into 18afcf5 on lovell:master.

lovell · 2019-03-06T21:20:39Z

Thank you very much for this PR Jakub. It looks good from a quick scan and I expect to have some time to take a proper look at it next week.

It's always pleasure to see tests - perhaps try assertMaxColourDistance instead of assertSimilar as this feature is all about colours, plus that might avoid some of those threshold problems you mentioned.

There should probably also be some verification in the JavaScript to throw Errors for things like invalid property values (there are a few examples of this in other operations).

Goues · 2019-03-08T20:44:14Z

I've updated to include input validation and error throwing. Also, I made it work with PNG with alpha channel, which wasn't the case in the first implementation.

Looks like I need some help with actually making test assertions right.

lovell

Thanks again for the PR Jakub and apologies for the delay getting around to reviewing this properly.

I've left a couple of comments inline around input validation.

I think the remaining test failures can be resolved by switching to use the lossless PNG format. (There are slight variations in the lossy JPEG decoder on different platforms.)

lib/operation.js

lovell · 2019-03-17T10:30:08Z

lib/operation.js

+    if (is.number(options.saturation) && options.saturation >= 0) {
+      this.options.saturation = options.saturation;
+    } else {
+      throw new Error('Invalid saturation ' + options.brightness);


I think this error message should refer to options.saturation (ditto for the hue message below). There's an is.invalidParameterError helper function that might be useful here too.

lovell · 2019-03-17T10:31:35Z

src/operations.cc

@@ -309,6 +309,20 @@ namespace sharp {
          0.0, 0.0, 0.0, 1.0));
  }

+  VImage Modulate(VImage image, double const brightness, double const saturation, double const hue) {
+    image = image.colourspace(VIPS_INTERPRETATION_LCH);


It might be slightly more efficient to perform the colourspace conversion after the removal of alpha channel.

src/operations.cc

- otherwise linear expects a vector of size 4

Goues · 2019-03-19T07:15:14Z

Thank you for the review, I've updated the PR and rebased over master.

lovell · 2019-03-19T22:35:37Z

Thanks for all the updates, this is looking great. Were you able to experiment with using PNG input (and output) for the tests to avoid having to set a threshold?

Goues · 2019-03-20T06:35:09Z

Yes, I added this file for testing hue rotation https://github.com/lovell/sharp/blob/bed50294bd59fb5f1a22c1edbd98414c85f733c6/test/fixtures/test-pattern.png with hue from 30 to 360 by steps of 30degs. It came exactly as css filter: hue-rotate(30deg) does, because I was testing all those three transforms against css filters.

Also I had this branch in my app for about a week already and QA didn't find anything wrong with uploaded images.

lovell

One small change to make hue integral rather than floating-point and this will be good to merge, thank you.

lovell · 2019-03-24T14:06:04Z

lib/operation.js

+    if (is.number(options.hue)) {
+      this.options.hue = options.hue % 360;
+    } else {
+      throw is.invalidParameterError('saturation', 'number', options.saturation);


The validation error for hue incorrectly refers to saturation.

lovell · 2019-03-24T14:07:15Z

lib/operation.js

+    }
+  }
+  if ('hue' in options) {
+    if (is.number(options.hue)) {


I think hue needs to be an integer value (can use is.integer check for this) as it is additive.

lovell · 2019-03-24T14:09:31Z

src/pipeline.h

@@ -87,6 +87,9 @@ struct PipelineBaton {
  std::vector<double> flattenBackground;
  bool negate;
  double blurSigma;
+  double brightness;
+  double saturation;
+  double hue;


I think hue can be a int (signed, as negative values are acceptable).

I actally started out with hue as an integer, but I don't know how to make it work in C type system. linear expects vectors with doubles, so it fails with: error: non-constant-expression cannot be narrowed from type 'int' to 'double' in initializer list [-Wc++11-narrowing]

Should I somehow convert int back to double in operations.cc?

Try something like {0.0, 0.0, static_cast<double>(hue)} in the call to linear(), which the compiler should be able to use to initialise a std::vector<double>.

lovell · 2019-03-25T07:44:44Z

Fantastic, thanks again for this Jakub, it will be in v0.22.1.

Goues force-pushed the feature-modulate branch from 246abdd to f750f1b Compare March 5, 2019 23:33

lovell added the enhancement label Mar 6, 2019

lovell requested changes Mar 17, 2019

View reviewed changes

Goues added 11 commits March 19, 2019 08:14

Implement brightness, saturation and hue modulation lovell#609

fe14792

Add docs

9d092d2

Fix double file extension

ad6e6b4

Add JSDoc

8c19211

Remove only from tests

9cb4ffd

Auto generate docs from code

e86f4e8

Make modulation work when there is an extra channel and improve testing

228f0ce

- otherwise linear expects a vector of size 4

Add parameter validation

c44a74a

Fix error messages

790361e

Improve validation messages

8109c1b

Apply colourspace after removing alpha

b89d4b9

Goues force-pushed the feature-modulate branch from 77d156e to b89d4b9 Compare March 19, 2019 07:14

Goues added 3 commits March 19, 2019 10:40

Fix extra semicolon

2afd49a

Change max colour distance in tests

9d4704a

Further increase of max colour distance

bed5029

lovell added this to the v0.22.1 milestone Mar 19, 2019

lovell reviewed Mar 24, 2019

View reviewed changes

Goues added 2 commits March 24, 2019 16:48

Fix error message

d4db2f2

Change hue to expect an integer

a90d8b6

lovell merged commit b494b2e into lovell:master Mar 25, 2019

lovell added a commit that referenced this pull request Mar 25, 2019

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Implement brightness, saturation and hue modulation #609 #1601

Implement brightness, saturation and hue modulation #609 #1601

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Implement brightness, saturation and hue modulation #609 #1601

Implement brightness, saturation and hue modulation #609 #1601

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