Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV #4

Vindaar · 2019-08-05T14:30:39Z

I originally just wanted to add HCL (polar LUV) support to the library (as done in commit: c1d88d6).

However, while trying to add the inverse transformation RGB -> HCL, I realized it'd be nicer to add the required colorspaces that serve as the intermediate representations too. So I went and ported the relevant C code from the R library colorspaces (see here:
https://github.com/cran/colorspace/blob/master/src/colorspace.c)
to Nim.

I did some refactoring to keep the code somewhat clean. However, doing so probably has broken the docs somewhat.

There are now transformation procs according to <space1>_to_<space2> found in transformations.nim. These are called in as<space>, which convert SomeColor to <space>. Finally those are combined in a user faced to(c: SomeColor, toColor: typedesc) proc.

For convenience the old color space naming procs, e.g. hsl, rgb and their inverse color procs are still available, but are now generated using a macro.

Conversion from RGB to HCL is still missing, plus some explanations. Code is taken straight from R's grDevices module in color.c: https://svn.r-project.org/R/trunk/src/library/grDevices/src/colors.c

Some stuff is still broken and refactoring is necessary.

The definitions for the existint ColorHSL and the added HLS_to_RGB and RGB_to_HLS expect different color ranges. The latter taken from colorspaces.c (the R package's C code) takes the ranges from 0 to 1, for L and S, whereas the ColorHSL uses 0 to 100.

The ported code now states as such and is separated from the code already contained in chroma or new code.

Vindaar · 2019-08-09T17:59:53Z

I just noticed that at least some of the color transformations behave weirdly. I'll have to take a look at that, before I consider this ready to be merged.

Now also generate procs to define a color directly from the fields without having to create a Color<...> object first, e.g. ```nim proc hsl(h, s, l: float32): ColorHSL ```

Started comparing directly with the output of R colorspaces. Taking some 10 colors and calculate values in different color space. Then compare those.

Vindaar · 2019-08-10T20:20:21Z

I'll add more tests comparing the transformations with output from the R colorspace library in the next few days.
I fixed the main bug. I missed the linearization when converting RGB to XYZ values. But maybe more are lurking.

I also added an additional convenience proc, that mimics the existing rgb(r, g, b: uint8) proc for all types. For now I commented the equivalent rgb and rgba procs out, because otherwise we get a redefinition error. I wasn't sure whether you'd like to have those (for the sake of the docs) still in there or not. All macro generated procs obviously won't show up in the documentation.

Also, if you want I can add a travis script to run CI to this PR. Then you'd only have to activate the CI for the repository.

This proc is not automatically generated from the macro, because ColorHCL is an alias for ColorPolarLUV.

Sorry for the macro code here in a test case :/ It generates almostEqual comparisons for the `asXXX.asYYY...` transformations, `to(...).to(...)` trafos and a comparison of the `as...` with the `to...` transformation.

Vindaar · 2019-08-11T14:23:59Z

Ok, I fixed everything I could find for now. Every added transformation (plus HSL, HSV) now has a test case comparing it with the output of R's colorspace module and all match.

treeform · 2019-08-12T03:46:12Z

Wow this is big. This might take some time to review, but its going in.

treeform

I think it's my bug, some tests fail in JavaScript mode:

nim js -r test_colors.nim

[Suite] functions
  [FAILED] darken
  [OK] lighten
  [OK] saturate
  [OK] desaturate
  [FAILED] spin
  [OK] mix

But they pass in c mode - so maybe thats fine?

treeform · 2019-08-12T21:55:16Z

src/chroma.nim

-  result.b = float32(c.b) / 255
-  result.a = 1.0
-
+#proc rgb*(r, g, b: uint8): ColorRGB =


Maybe just remove it if we don't need it.

Yes, only left it in to not forget discussing this. Will remove it later.

treeform · 2019-08-12T21:55:27Z

src/chroma.nim

-  ## * rgba(0,0,255) -> blue
-  ## * rgba(0,0,0,255) -> opaque  black
-  ## * rgba(0,0,0,0) -> transparent black
+#proc rgba*(r, g, b, a: uint8): ColorRGBA =


same remove it?

treeform · 2019-08-12T21:57:02Z

src/chroma/colortypes.nim

+    b*: float32 ## blue (0-1)
+    a*: float32 ## alpha (0-1, 0 is fully transparent)
+
+  InvalidColor* = object of Exception


Maybe move this to the bottom, so that all color objects are in the same place?

treeform · 2019-08-12T21:58:54Z

tests/test_colors.nim

@@ -117,6 +119,223 @@ suite "spaces":
      #echo "YUV", c, " -> ", yuv(c)
      assert c.almostEqual(yuv(c).color())

+  test "Space transformations using `as*` procs":


Thank you for writing test.

Vindaar · 2019-08-13T18:47:13Z

Ok, I've addressed your comments regarding the procs and the exception.

I haven't checked the broken tests for the JS target yet. Do they work on the master branch?

treeform · 2019-08-13T19:01:25Z

I have checked the JS target and yes they are broken on master as well. Don't worry about them for now.

Vindaar · 2019-09-09T12:18:08Z

@treeform: anything else you'd like me to do for this? :)

treeform · 2020-11-28T18:23:16Z

Hey @Vindaar,

Using simple

proc rgba*(c: Color): ColorRGBA {.inline.} =
  ## Convert Color to ColorRGBA
  result.r = uint8(c.r * 255)
  result.g = uint8(c.g * 255)
  result.b = uint8(c.b * 255)
  result.a = uint8(c.a * 255)

proc color*(c: ColorRGBA): Color {.inline.} =
  ## Convert ColorRGBA to Color
  result.r = float32(c.r) / 255
  result.g = float32(c.g) / 255
  result.b = float32(c.b) / 255
  result.a = float32(c.a) / 255

Result in over 50% speed improvement over the macro generated code.

I tried adding inline to the macro generated code and its still kind of slow.

Do you have any ideas on how to improve performance of macro generated code?

Vindaar · 2020-11-30T18:11:34Z

Hm, this is peculiar. Sorry about that.

Not sure what's going on, but I suppose it's rather related to the fact that we have the intermediate to proc?

I'll try to take a look at it in the next few days. Please ping me again, if I forget.

Vindaar added 11 commits August 5, 2019 15:42

add HCL color space

c1d88d6

Conversion from RGB to HCL is still missing, plus some explanations. Code is taken straight from R's grDevices module in color.c: https://svn.r-project.org/R/trunk/src/library/grDevices/src/colors.c

WIP commit, adding XYZ, LAB, LUV, polarLAB, polarLUV conversions

6ac891a

finish adding the other ???_to_RGB and RGB_to_??? trafos, add tests

7e10d02

Some stuff is still broken and refactoring is necessary.

fix assignments in LAB <-> PolarLAB conversions

63e8be1

fix transformations of LUV <-> XYZ

e143766

trafos of RGB <-> PolrLUV also work

f14fafe

refactor into types, transformations submodules, refer to license

33969cf

The ported code now states as such and is separated from the code already contained in chroma or new code.

generate convenience procs using a macro working on SomeColor

0998894

remove debug output, add a couple of comments

825c0c7

update README about new color spaces

e4000b8

Vindaar changed the title ~~Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV~~ [WIP] Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV Aug 9, 2019

Vindaar added 5 commits August 10, 2019 19:21

fix omission of ColorXYZ in to proc

5e1e0f4

also gen ColorSpaceName(fieldName1: type,...) procs for all spaces

cc0bf99

Now also generate procs to define a color directly from the fields without having to create a Color<...> object first, e.g. ```nim proc hsl(h, s, l: float32): ColorHSL ```

add more tests showing things are still broken :)

db29f04

Started comparing directly with the output of R colorspaces. Taking some 10 colors and calculate values in different color space. Then compare those.

add linearization of RGB values when converting to XYZ and back

e56ba6c

add test task to nimble file

7e042f1

Vindaar added 3 commits August 11, 2019 16:15

add convenience hcl proc taking h, c, l individually

4442235

This proc is not automatically generated from the macro, because ColorHCL is an alias for ColorPolarLUV.

compare back / forth trafos using as, to, and ==(as, to)

5ab6506

Sorry for the macro code here in a test case :/ It generates almostEqual comparisons for the `asXXX.asYYY...` transformations, `to(...).to(...)` trafos and a comparison of the `as...` with the `to...` transformation.

add more tests comparing chroma.nim with R colorspace module

b889fdf

Vindaar changed the title ~~[WIP] Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV~~ Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV Aug 11, 2019

add final type of convenience procs to README, fix markdown

f4518ac

treeform requested changes Aug 12, 2019

View reviewed changes

remove dead rgb, rgba procs (gen. by macro), move InvalidColor

9cecd4b

treeform merged commit 415a4f2 into treeform:master Oct 16, 2019

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Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV #4

Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV #4

Vindaar commented Aug 5, 2019

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Vindaar commented Aug 13, 2019

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treeform commented Nov 28, 2020

Vindaar commented Nov 30, 2020

Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV #4

Add more color spaces: XYZ, LAB, polarLAB, LUV, polarLUV #4

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