Decolmor

Gem for converting color spaces from/to: HEX/RGB/HSL/HSV/HSB/HSI/CMYK
The Alpha channel (transparency) is supported.
There is also a simple RGB generator.

News . Recent releases . Changelog . Wiki

Install

Add the following line to Gemfile:

gem 'decolmor'

and run bundle install from your shell.

To install the gem manually from your shell, run:

gem install decolmor

Supported Rubies

Using

require 'decolmor'

rgb = [29, 128, 86]
Decolmor.rgb_to_hsb(rgb)
=> [154.5, 77.3, 50.2]

or include into class:

class SomeClass
  include Decolmor
end
SomeClass.rgb_to_hsb(rgb)
=> [154.5, 77.3, 50.2]

Gem methods will be available as class methods.

See WIKI for more examples.

Rounding for HSL/HSV/HSB/HSI/CMYK

By default, rounding 1 is used to convert to HSL/HSV/HSB/HSI/CMYK.
This is enough to loselessly convert RGB -> HSL/HSV/HSB/HSI/CMYK -> RGB: * for HSI this is not quite true ~2k (of 16.6M) RGB colors will be slightly different, rounding 2 fixes this.

rgb = [224, 23, 131]  
    hsl = Decolmor.rgb_to_hsl(rgb)  # => [327.8, 81.4, 48.4]
    hsv = Decolmor.rgb_to_hsv(rgb)  # => [327.8, 89.7, 87.8]
    Decolmor.hsv_to_rgb(hsv)  # => [224, 23, 131]
    Decolmor.hsl_to_rgb(hsl)  # => [224, 23, 131]

If you convert between HSL <==> HSV (HSB) with a rounding of 2, you can get more accurate results.
This can also be useful if you use HSL/HSB for intermediate changes and then go back to RGB.
You can change rounding globally:

Decolmor.hsx_round = 2
    Decolmor.rgb_to_hsl(rgb)  # => [154.55, 63.06, 30.78]
    Decolmor.hsx_round        # => 2

You can also specify rounding as a second argument when calling the method:

Decolmor.rgb_to_hsl(rgb, 3)  # => [154.545, 63.057, 30.784]

In this case, the global rounding will be ignored. If you need to get integers, use 0.

HEX to

Alpha channel

When converting from HEX to RGBA Alpha channel is converted to a value from the range 0..1 with rounding 3:
- 3 digits is enough for a lossless conversion 0..255 -> 0..1 -> 0..255

Decolmor.hex_to_rgb('#19988BB8')           # => [25, 152, 139, 0.722]
    Decolmor.hex_to_rgb([25, 152, 139, 0.722)  # => "#19988BB8"

Consequently, when converting to HEX from RGBA, Alpha from the range 0..1 is assumed.
But you can set range 0..255 for alpha channel:

Decolmor.hex_to_rgb('#19988BB8', alpha_255: true)          # => [25, 152, 139, 184]
    Decolmor.rgb_to_hex([25, 152, 139, 184], alpha_255: true)  # => "#19988BB8"

You can also set rounding for Alpha channel as a second argument:

Decolmor.hex_to_rgb('#19988BB8', 2)  # => [25, 152, 139, 0.72]

This only works for converting from HEX.
In other cases (conversions between RGB/HSL/HSV/HSB/HSI/CMYK) Alpha channel remains unchanged.

HSL, HSI, HSV or HSB

HSL, HSI, HSV - are three different color spaces.
They have only one common parameter HUE.
S - Suturation, despite the same name, is different in all three spaces,
like the last component: Lightness / Intensity / Value (Brightness).

HSB is an alternative name for HSV, it is the same thing.
However, for convenience, aliasing methods are made for HSB from HSV.

rgb = [255, 109, 55]  
    Decolmor.rgb_to_hsv(rgb)  # => [16.2, 78.4, 100.0]
    Decolmor.rgb_to_hsb(rgb)  # => [16.2, 78.4, 100.0]

HSL/HSV/HSB to RGB conversion

HSL/HSV/HSB to RGB conversion has two implementations, the gem includes both: - hsl_to_rgb - hsv_to_rgb - hsb_to_rgb

or
- hsl_to_rgb_alt - hsv_to_rgb_alt - hsb_to_rgb_alt

The results of the two implementations are identical, but the alternative versions (postfix _alt) are slightly slower.

Attention for CMYK !

Unfortunately, there is no simple formula for linear RGB to/from CMYK conversion.
This implementation is a simplified/dirty/simulation.
CMYK is used for printing and the correct conversion will be non-linear, based on the color profile for the particular printing device.
Therefore, the CMYK conversion results will not match Adobe products.
BUT:
Conversion from/to HEX/RGB/HSL/HSV/HSB/HSI is simple and is described by formulas.
Read more: Supported Methods

License

MIT License
Copyright © 2021 ChildrenofkoRn
LICENSE