CrImage::Color

Standard colors

Color bit depth constants

Common named colors (CSS/Web colors)

YCbCr to RGB conversion coefficients (scaled by 65536)

Cb/Cr conversion coefficients

RGB to YCbCr rounding adjustment: 257 << 15

YCbCr conversion constants (JFIF specification) Y' = 0.2990R + 0.5870G + 0.1140*B Note: 19595 + 38470 + 7471 = 65536

YY1 multiplier for YCbCr to RGB: Y' * 0x10101

Blend two colors together with a ratio. Ratio of 0.0 returns c1, ratio of 1.0 returns c2.

blended = Color.blend(Color::RED, Color::BLUE, 0.5) # => Purple

converts a CMYK quadruple to an RGB triple.

Get a contrasting color (black or white) for text on this background.

text_color = Color.contrasting(background_color)

Check if a color is considered "dark" (luminance <= 0.5).

Color.dark?(Color::BLACK) # => true
Color.dark?(Color::WHITE) # => false

Darken a color by a percentage (0.0 to 1.0).

darker = Color.darken(Color::RED, 0.2) # => Darker red

Calculate Euclidean distance between two colors in RGB space. Returns a value between 0.0 (identical) and ~441.67 (black to white).

dist = Color.distance(Color::RED, Color::BLUE) # => ~360.62

Create grayscale color

Color.gray(128) # => 50% gray

Create RGBA color from hex integer

Color.hex(0xFF0000FF) # => Red with full alpha
Color.hex(0xFF0000)   # => Red (alpha = 255)

Alias for blend - interpolate between two colors.

mid = Color.interpolate(Color::RED, Color::BLUE, 0.5) # => Purple

Check if a color is considered "light" (luminance > 0.5). Useful for determining text color on backgrounds.

Color.light?(Color::WHITE) # => true
Color.light?(Color::BLACK) # => false

Lighten a color by a percentage (0.0 to 1.0).

lighter = Color.lighten(Color::RED, 0.2) # => Lighter red

Calculate perceived luminance of a color (0.0 to 1.0). Uses standard luminance coefficients (ITU-R BT.709).

lum = Color.luminance(Color::WHITE) # => 1.0
lum = Color.luminance(Color::BLACK) # => 0.0

Mix multiple colors together (average).

mixed = Color.mix([Color::RED, Color::GREEN, Color::BLUE])

Parse a color from various string formats:

• Hex: "#RRGGBB", "#RRGGBBAA", "#RGB", "#RGBA"
• CSS: "rgb(r, g, b)", "rgba(r, g, b, a)"
• Named: "red", "blue", "green", etc.

Examples:

Color.parse("#FF0000")            # => Red
Color.parse("#FF0000FF")          # => Red with alpha
Color.parse("#F00")               # => Red (short form)
Color.parse("rgb(255, 0, 0)")     # => Red
Color.parse("rgba(255, 0, 0, 1)") # => Red with alpha
Color.parse("red")                # => Red

Create RGB color (alpha = 255)

Color.rgb(255, 0, 0) # => Red

converts an RGB triple to a CMYK quadruple.

converts an RGB triple to a Y'CbCr triple.

Create RGBA color

Color.rgba(255, 0, 0, 128) # => Semi-transparent red

Create a new color with a different alpha value. Alpha should be 0-255 for 8-bit or 0-65535 for 16-bit.

semi_red = Color.with_alpha(Color::RED, 128) # => Semi-transparent red

Helper method to convert YCbCr values to RGB components (16-bit) Returns RGB values in 16-bit range (0-65535) This is used internally for fast YCbCr to RGB conversion