Data.Colour.Word8

This module provides Colour8, which stores linear RGB (red, green, blue) colour values where each channel is a Word8. It also provides arithmetic over such colours, and a few predefined colours.

It is the general intention that "most" work will be done with Data.Colour.Double, with values converted to Colour8 only as a final step. However, full arithmetic is supported anyway, in case anybody wants to work that way. It is slightly less efficient and flexible, however.

Beware that "most" RGB data found in external sources is in the (non-linear) sRGB colour space, not the linear RGB colour space used here. See Data.Colour.Nonlinear for conversion functions.

Documentation

data Colour8

The integral colour. It stores three channels (red, green and blue) as linear Word8 values ranging from 0 to 255. (0 represents minimum intensity, 255 represents maximum. Black is therefore Colour8 0 0 0 and white is Colour8 255 255 255.)

The channel values are stored as strict, unboxed fields, so operating on Colour8s should be quite efficient in time and space.

The Num and Fractional instances provide arithmetic for Colour8s. Note that (*) acts channel-wise; this is usually what is wanted.

Constructors

Colour8

Fields

red8 :: !Word8

green8 :: !Word8

blue8 :: !Word8

Instances

Eq Colour8

Num Colour8

Ord Colour8

Show Colour8

c8map :: (Word8 -> Word8) -> Colour8 -> Colour8

Apply a function to every channel of a Colour8. (Mostly used internally; exposed here in case it might be useful.)

c8zip :: (Word8 -> Word8 -> Word8) -> Colour8 -> Colour8 -> Colour8

The colour equivilent of zipWith. (Mostly used internally; exposed here in case it might be useful.)

c8fold :: (Word8 -> Word8 -> Word8) -> Colour8 -> Word8

Use a function to fold the three values in a Colour8 into a single value. No particular order of application is promised.

grey8 :: Word8 -> Colour8

Convert a Word8 into a shade of grey.

c8scale :: Word8 -> Colour8 -> Colour8

Scale a Colour8 by the specified amount. Recall that 0x00 means zero, and 0xFF means one. This means that it is impossible to make a colour brighter, only darker. It also means this operation is modestly inefficient due to the renormalisation steps.

unpack8 :: Colour8 -> (Word8, Word8, Word8)

Convert a Colour8 to a tuple.

pack8 :: (Word8, Word8, Word8) -> Colour8

Convert a tuple to a Colour8.

c8Black :: Colour8

Constant: Black.

c8Red :: Colour8

Constant: Red.

c8Yellow :: Colour8

Constant: Yellow.

c8Green :: Colour8

Constant: Green.

c8Cyan :: Colour8

Constant: Cyan.

c8Blue :: Colour8

Constant: Blue.

c8Magenta :: Colour8

Constant: Magenta.

c8White :: Colour8

Constant: White.