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.

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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

• 2.4
• 2.5
• 2.6
• 2.7
• 3.0

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.

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.

• with & without prefix #
• short HEX are supported (including Alpha)
• can be set rounding for the 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 - 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 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.

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: https://en.wikipedia.org/wiki/HSL_and_HSV
The results when rounded to an integer will be the same as when using graphics editors, such as CorelDRAW or Adobe Photoshop.

• Setter global rounding for conversion to HSL/HSV/HSB/CMYK
  • hsx_round =
• HEX <==> RGB(A)
  • hex_to_rgb
  • rgb_to_hex
• Simple generator RGB, you can set any channel(s)
  • new_rgb
• RGB(A) to HSL/HSV/HSB/HSI
  • rgb_to_hsl
  • rgb_to_hsv
  • rgb_to_hsb
  • rgb_to_hsi
• HSL/HSV/HSB/HSI to RGB(A)
  • hsl_to_rgb
  • hsv_to_rgb
  • hsb_to_rgb
  • hsi_to_rgb
• Alternative implementation HSL/HSV/HSB to RGB(A) (a little slower)
  • hsl_to_rgb_alt
  • hsv_to_rgb_alt
  • hsb_to_rgb_alt
• HSL <==> HSV (HSB)
  • hsl_to_hsv
  • hsl_to_hsb
  • hsv_to_hsl
  • hsb_to_hsl
• RGB(A) <==> CMYK
  • rgb_to_cmyk
  • cmyk_to_rgb
• HEX => HSL/HSV/HSB/HSI/CMYK
  • hex_to_hsl
  • hex_to_hsv
  • hex_to_hsb
  • hex_to_hsi
  • hex_to_cmyk
• HSL/HSV/HSB/HSI/CMYK => HEX
  • hsl_to_hex
  • hsv_to_hex
  • hsb_to_hex
  • hsi_to_hex
  • cmyk_to_hex

MIT License
Copyright (c) 2021 ChildrenofkoRn
LICENSE