bitmap_rgbaf.lua

--floating point RGBA bitmap types for HDR storage and internal processing.
local bitmap = require'bitmap'
local glue = require'glue'
local ffi = require'ffi'

bitmap.colortypes.rgbaf = {channels = 'rgba', max = 1}

bitmap.formats.rgbaf = glue.merge({bpp = 32 * 4, ctype = ffi.typeof'float',
	colortype = 'rgbaf', bitmap.formats.rgba8})

bitmap.formats.rgbad = glue.merge({bpp = 64 * 4, ctype = ffi.typeof'double',
	colortype = 'rgbaf', bitmap.formats.rgba8})

bitmap.converters.rgbaf = {}

function bitmap.converters.rgbaf.rgba8(r, g, b, a)
	return r * 255, g * 255, b * 255, a * 255
end

function bitmap.converters.rgba8.rgbaf(r, g, b, a)
	return r * (1 / 255), g * (1 / 255), b * (1 / 255), a * (1 / 255)
end

function bitmap.converters.rgbaf.rgba16(r, g, b, a)
	return r * 65535, g * 65535, b * 65535, a * 65535
end

function bitmap.converters.rgba16.rgbaf(r, g, b, a)
	return r * (1 / 65535), g * (1 / 65535), b * (1 / 65535), a * (1 / 65535)
end

function bitmap.converters.rgbaf.ga8(r, g, b, a)
	return bitmap.rgb2g(r, g, b) * 255, a
end

function bitmap.converters.ga8.rgbaf(g, a)
	g = g / 255
	a = a / 255
	return g, g, g, a
end

function bitmap.converters.rgbaf.ga16(r, g, b, a)
	return bitmap.rgb2g(r, g, b) * 65535, a
end

function bitmap.converters.ga16.rgbaf(g, a)
	g = g / 65535
	a = a / 65535
	return g, g, g, a
end

function bitmap.converters.cmyk8.rgbaf(c, m, y, k)
	return c * k / 65535, m * k / 65535, y * k / 65535, 1
end

function bitmap.converters.ycck8.rgbaf(y, cb, cr, k)
	return
		(y                        + 1.402   * (cr - 128)) / 255,
		(y - 0.34414 * (cb - 128) - 0.71414 * (cr - 128)) / 255,
      (y + 1.772   * (cb - 128)                       ) / 255,
		1
end


if not ... then require'bitmap_demo' end