rgb                package:grDevices                R Documentation

_R_G_B _C_o_l_o_r _S_p_e_c_i_f_i_c_a_t_i_o_n

_D_e_s_c_r_i_p_t_i_o_n:

     This function creates "colors" corresponding to the given
     intensities (between 0 and 'max') of the red, green and blue
     primaries.

     An alpha transparency value can also be specified (0 means fully
     transparent and 'max' means opaque). If 'alpha' is not specified,
     an opaque colour is generated.

     The names argument may be used to provide names for the colors.

     The values returned by these functions can be used with a 'col='
     specification in graphics functions or in 'par'.

_U_s_a_g_e:

     rgb(red, green, blue, alpha, names = NULL, maxColorValue = 1)

_A_r_g_u_m_e_n_t_s:

red, blue, green, alpha: vectors of same length with values in [0, M]
          where M is 'maxColorValue'. When this is '255', the 'red',
          'blue', 'green', and 'alpha' values are coerced to integers
          in '0:255' and the result is computed most efficiently.

   names: character. The names for the resulting vector.

maxColorValue: number giving the maximum of the color values range, see
          above.

_S_e_e _A_l_s_o:

     'col2rgb' the "inverse" for translating R colors to RGB vectors;
     'rainbow', 'hsv', 'gray'.

_E_x_a_m_p_l_e_s:

     rgb(0,1,0)
     (u01 <- seq(0,1, length=11))
     stopifnot(rgb(u01,u01,u01) == gray(u01))
     reds <- rgb((0:15)/15, g=0,b=0, names=paste("red",0:15,sep="."))
     reds

     rgb(0, 0:12, 0, max = 255)# integer input

