_X_Q_u_e_r_y_C_o_l_o_r and _X_Q_u_e_r_y_C_o_l_o_r_s can generate _B_a_d_C_o_l_o_r and _B_a_d_V_a_l_u_e errors.
The _X_L_o_o_k_u_p_C_o_l_o_r function looks up the string name of a color with respect to the screen associated with the specified colormap. It returns both the exact color values and the closest values provided by the screen with respect to the visual type of the specified colormap. If the color name is not in the Host Portable Character Encoding, the result is implementation-dependent. Use of uppercase or lowercase does not matter. _X_L_o_o_k_u_p_C_o_l_o_r returns nonzero if the name is resolved; otherwise, it returns zero.
The _X_P_a_r_s_e_C_o_l_o_r function looks up the string name of a color with respect to the screen associated with the specified colormap. It returns the exact color value. If the color name is not in the Host Portable Character Encoding, the result is implementation-dependent. Use of uppercase or lowercase does not matter. _X_P_a_r_s_e_C_o_l_o_r returns nonzero if the name is resolved; otherwise, it returns zero.
_X_L_o_o_k_u_p_C_o_l_o_r and _X_P_a_r_s_e_C_o_l_o_r can generate _B_a_d_C_o_l_o_r error.
rgb:_<_r_e_d_>_/_<_g_r_e_e_n_>_/_<_b_l_u_e_>
_<_r_e_d_>, _<_g_r_e_e_n_>, _<_b_l_u_e_> := _h | _h_h | _h_h_h | _h_h_h_h
_h := single hexadecimal digits (case insignificant)
Note that _h indicates the value scaled in 4 bits, _h_h the value scaled in 8 bits, _h_h_h the value scaled in 12 bits, and _h_h_h_h the value scaled in 16 bits, respectively.
For backward compatibility, an older syntax for RGB Device is supported, but its continued use is not encouraged. The syntax is an initial sharp sign character followed by a numeric specification, in one of the following formats:
l l. #RGB (4 bits each) #RRGGBB (8 bits each) #RRRGGGBBB (12 bits each) #RRRRGGGGBBBB (16 bits each)
The R, G, and B represent single hexadecimal digits. When fewer than 16 bits each are specified, they represent the most significant bits of the value (unlike the ``rgb:'' syntax, in which values are scaled). For example, the string ``#3a7'' is the same as ``#3000a0007000''.
An RGB intensity specification is identified by the prefix ``rgbi:'' and conforms to the following syntax:
rgbi:_<_r_e_d_>_/_<_g_r_e_e_n_>_/_<_b_l_u_e_>
Note that red, green, and blue are floating-point values between 0.0 and 1.0, inclusive. The input format for these values is an optional sign, a string of numbers possibly containing a decimal point, and an optional exponent field containing an E or e followed by a possibly signed integer string.
The standard device-independent string specifications have the following syntax:
CIEXYZ:_<_X_>_/_<_Y_>_/_<_Z_> CIEuvY:_<_u_>_/_<_v_>_/_<_Y_> CIExyY:_<_x_>_/_<_y_>_/_<_Y_> CIELab:_<_L_>_/_<_a_>_/_<_b_> CIELuv:_<_L_>_/_<_u_>_/_<_v_> TekHVC:_<_H_>_/_<_V_>_/_<_C_>
All of the values (C, H, V, X, Y, Z, a, b, u, v, y, x) are floating-point values. The syntax for these values is an optional plus or minus sign, a string of digits possibly containing a decimal point, and an optional exponent field consisting of an ``E'' or ``e'' followed by an optional plus or minus followed by a string of digits.