Improve changelog

aleju · Jan 11, 2020 · 18fc510 · 18fc510
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diff --git a/changelogs/master/20200107_improved_blending.md b/changelogs/master/20200107_improved_blending.md
@@ -1,34 +1,86 @@
-# Improved Blending #462 #556
+# More Choices for Image Blending #462 #556
 
-* Added `imgaug.augmenters.blend.BlendAlphaMask`, which uses a mask generator
-  instance to generate per batch alpha masks and then alpha-blends using
-  these masks.
-* Added `imgaug.augmenters.blend.IBatchwiseMaskGenerator`, an interface for
-  classes generating masks on a batch-by-batch basis.
-* Added `imgaug.augmenters.blend.StochasticParameterMaskGen`, a mask generator
-  helper for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.SomeColorsMaskGen`, a colorwise
-  mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.HorizontalLinearGradientMaskGen`, a linear
-  gradient mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.VerticalLinearGradientMaskGen`, a linear
-  gradient mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.RegularGridMaskGen`, a checkerboard-like
-  mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.CheckerboardMaskGen`, a checkerboard-like
-  mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.SegMapClassIdsMaskGen`, a segmentation
-  map-based mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.BoundingBoxesMaskGen`, a bounding box-based
-  mask generator for `BlendAlphaMask`.
-* Added `imgaug.augmenters.blend.InvertMaskGen`, an mask-inverting mask
-  generator for `BlendAlphaMask`.
+The available augmenters for alpha-blending of images were
+significantly extended. There are now new blending
+augmenters available to alpha-blend acoording to:
+* Some randomly chosen colors. (`BlendAlphaSomeColors`)
+* Linear gradients. (`BlendAlphaHorizontalLinearGradient`,
+  `BlendAlphaVerticalLinearGradient`)
+* Regular grids and checkerboard patterns. (`BlendAlphaRegularGrid`,
+  `BlendAlphaCheckerboard`)
+* Only at locations that overlap with specific segmentation class
+  IDs (or the inverse of that). (`BlendAlphaSegMapClassIds`)
+* Only within bounding boxes with specific labels (or the inverse
+  of that). (`BlendAlphaBoundingBoxes`)
+
+This allows to e.g. randomly remove some colors while leaving
+other colors unchanged (`BlendAlphaSomeColors(Grayscale(1.0))`),
+to change the color of some objects
+(`BlendAlphaSegMapClassIds(AddToHue((-256, 256)))`), to add
+cloud-patterns only to the top of images
+(`BlendAlphaVerticalLinearGradient(Clouds())`) or to apply
+augmenters in some coarse rectangular areas (e.g.
+`BlendAlphaRegularGrid(Multiply(0.0))` to achieve a similar
+effect to `CoarseDropout` or
+`BlendAlphaRegularGrid(AveragePooling(8))` to pool in equally
+coarse image sub-regions).
+
+Other mask-based alpha blending techniques can be achieved by
+subclassing `IBatchwiseMaskGenerator` and providing an
+instance of such a class to `BlendAlphaMask`.
+
+This patch also changes the naming of the blending augmenters
+as follows:
+* `Alpha` -> `BlendAlpha`
+* `AlphaElementwise` -> `BlendAlphaElementwise`
+* `SimplexNoiseAlpha` -> `BlendAlphaSimplexNoise`
+* `FrequencyNoiseAlpha` -> `BlendAlphaFrequencyNoise`
+The old names are now deprecated.
+Furthermore, the parameters `first` and `second`, which were
+used by all blending augmenters, have now the names `foreground`
+and `background`.
+
+List of changes:
+* Added `imgaug.augmenters.blend.BlendAlphaMask`, which uses
+  a mask generator instance to generate per batch alpha masks and
+  then alpha-blends using these masks.
+* Added `imgaug.augmenters.blend.BlendAlphaSomeColors`.
+* Added `imgaug.augmenters.blend.BlendAlphaHorizontalLinearGradient`.
+* Added `imgaug.augmenters.blend.BlendAlphaVerticalLinearGradient`.
+* Added `imgaug.augmenters.blend.BlendAlphaRegularGrid`.
+* Added `imgaug.augmenters.blend.BlendAlphaCheckerboard`.
+* Added `imgaug.augmenters.blend.BlendAlphaSegMapClassIds`.
+* Added `imgaug.augmenters.blend.BlendAlphaBoundingBoxes`.
+* Added `imgaug.augmenters.blend.IBatchwiseMaskGenerator`,
+  an interface for classes generating masks on a batch-by-batch
+  basis.
+* Added `imgaug.augmenters.blend.StochasticParameterMaskGen`,
+  a helper to generate masks from `StochasticParameter` instances.
+* Added `imgaug.augmenters.blend.SomeColorsMaskGen`, a generator
+  that produces masks marking randomly chosen colors in images.
+* Added `imgaug.augmenters.blend.HorizontalLinearGradientMaskGen`,
+  a linear gradient mask generator.
+* Added `imgaug.augmenters.blend.VerticalLinearGradientMaskGen`,
+  a linear gradient mask generator.
+* Added `imgaug.augmenters.blend.RegularGridMaskGen`,
+  a checkerboard-like mask generator where every grid cell has
+  a random alpha value.
+* Added `imgaug.augmenters.blend.CheckerboardMaskGen`,
+  a checkerboard-like mask generator where every grid cell has
+  the opposite alpha value of its 4-neighbours.
+* Added `imgaug.augmenters.blend.SegMapClassIdsMaskGen`, a
+  segmentation map-based mask generator.
+* Added `imgaug.augmenters.blend.BoundingBoxesMaskGen`, a bounding
+  box-based mask generator.
+* Added `imgaug.augmenters.blend.InvertMaskGen`, an mask generator
+  that inverts masks produces by child generators.
 * Changed `imgaug.parameters.SimplexNoise` and
-  `imgaug.parameters.FrequencyNoise` to also accept `(H, W, C)` sampling
-  shapes, instead of only `(H, W)`.
-* Refactored `AlphaElementwise` to be a wrapper around `BlendAlphaMask`.
+  `imgaug.parameters.FrequencyNoise` to also accept `(H, W, C)`
+  sampling shapes, instead of only `(H, W)`.
+* Refactored `AlphaElementwise` to be a wrapper around
+  `BlendAlphaMask`.
 * Renamed `Alpha` to `BlendAlpha`.
-  `AlphaElementwise` is now deprecated.
+  `Alpha` is now deprecated.
 * Renamed `AlphaElementwise` to `BlendAlphaElementwise`.
   `AlphaElementwise` is now deprecated.
 * Renamed `SimplexNoiseAlpha` to `BlendAlphaSimplexNoise`.
@@ -38,13 +90,6 @@
 * Renamed arguments `first` and `second` to `foreground` and `background`
   in `BlendAlpha`, `BlendAlphaElementwise`, `BlendAlphaSimplexNoise` and
   `BlendAlphaFrequencyNoise`.
-* Added `imgaug.augmenters.blend.BlendAlphaSomeColors`.
-* Added `imgaug.augmenters.blend.BlendAlphaHorizontalLinearGradient`.
-* Added `imgaug.augmenters.blend.BlendAlphaVerticalLinearGradient`.
-* Added `imgaug.augmenters.blend.BlendAlphaRegularGrid`.
-* Added `imgaug.augmenters.blend.BlendAlphaCheckerboard`.
-* Added `imgaug.augmenters.blend.BlendAlphaSegMapClassIds`.
-* Added `imgaug.augmenters.blend.BlendAlphaBoundingBoxes`.
 * Changed `imgaug.parameters.handle_categorical_string_param()` to allow
   parameter `valid_values` to be `None`.
 * Fixed a wrong error message in