diff options
Diffstat (limited to 'libred_get_colour.3')
-rw-r--r-- | libred_get_colour.3 | 45 |
1 files changed, 40 insertions, 5 deletions
diff --git a/libred_get_colour.3 b/libred_get_colour.3 index afd0a7f..d6649d2 100644 --- a/libred_get_colour.3 +++ b/libred_get_colour.3 @@ -1,20 +1,23 @@ .TH LIBRED_GET_COLOUR 3 LIBRED .SH NAME -libred_get_colour \- Calculate a colour temperature +libred_get_colour \- Calculate the colour of a temperature .SH SYNOPSIS .nf #include <libred.h> int \fBlibred_get_colour\fP(long int \fItemp\fP, double *\fIr\fP, double *\fIg\fP, double *\fIb\fP); +int \fBlibred_get_colour_xy\fP(long int \fItemp\fP, double *\fIx\fP, double *\fIy\fP); .fi .PP Link with -.IR -lred . +.I -lred +.IR -lm . .SH DESCRIPTION .BR libred_get_colour () gets or interpolates the colour temperature for .I temp -kelvins, and returns the colour temperature in sRGB. The values, +kelvins, and returns the colour temperature in sRGB, with the +sRGB transfer function applied. The values, between 0.0 and 1.0, for the \(dqred\(dq, green, and blue channels are stored in .IR *r , @@ -49,14 +52,45 @@ ceiling .TP round to nearest .I (temp - LIBRED_LOWEST_TEMPERATURE + LIBRED_DELTA_TEMPERATURE / 2) / LIBRED_DELTA_TEMPERATURE * LIBRED_DELTA_TEMPERATURE + LIBRED_LOWEST_TEMPERATURE +.PP +The +.BR libred_get_colour_xy () +function is the same as the +.BR libred_get_colour () +except it uses the CIE xy colour space instead of sRGB +(of course without any transfer function). This means +that the chroma values x and y are stored in +.I *x +and +.IR *y , +and the CIE Y value shall be assumed to be 1 for +equivalence with the +.BR libred_get_colour () +function. +.PP +Neither +.IR r , +.IR g , +.IR b , +.IR x , +nor +.I y +may be +.IR NULL . .SH RETURN VALUE Upon successful completion, the .BR libred_get_colour () +and +.BR libred_get_colour_xy () function returns 0. On failure, the function returns -1 and sets .I errno to indicate the error. .SH ERRORS -The function may fail if: +The +.BR libred_get_colour () +and +.BR libred_get_colour_xy () +functions may fail if: .TP .B EDOM If @@ -67,4 +101,5 @@ is less than .SH SEE ALSO .BR libred.h (0), .BR libred (7), -.BR libred_get_solar_elevation (3) +.BR libred_get_temperature (3), +.BR libred_solar_elevation (3) |