diff options
| -rw-r--r-- | Makefile | 14 | ||||
| -rw-r--r-- | blackbody.c | 190 | ||||
| -rw-r--r-- | libred.h | 76 | ||||
| -rw-r--r-- | libred_get_colour.3 | 37 | ||||
| l--------- | libred_get_colour_xy.3 | 1 | ||||
| -rw-r--r-- | libred_solar_elevation.3 | 6 |
6 files changed, 281 insertions, 43 deletions
@@ -11,7 +11,7 @@ include mk/$(OS).mk LIB_MAJOR = 1 -LIB_MINOR = 0 +LIB_MINOR = 1 LIB_VERSION = $(LIB_MAJOR).$(LIB_MINOR) @@ -22,9 +22,13 @@ OBJ =\ LOBJ = $(OBJ:.o=.lo) MAN0 = libred.h.0 -MAN3 = libred_get_colour.3 libred_solar_elevation.3 MAN7 = libred.7 +MAN3 =\ + libred_get_colour.3\ + libred_get_colour_xy.3\ + libred_solar_elevation.3 + all: libred.a libred.$(LIBEXT) solar.o: libred.h @@ -66,9 +70,9 @@ install: libred.a libred.$(LIBEXT) ln -sf -- libred.$(LIBMINOREXT) "$(DESTDIR)$(PREFIX)/lib/libred.$(LIBMAJOREXT)" ln -sf -- libred.$(LIBMAJOREXT) "$(DESTDIR)$(PREFIX)/lib/libred.$(LIBEXT)" cp -- libred.h "$(DESTDIR)$(PREFIX)/include" - cp -- $(MAN0) "$(DESTDIR)$(MANPREFIX)/man0" - cp -- $(MAN3) "$(DESTDIR)$(MANPREFIX)/man3" - cp -- $(MAN7) "$(DESTDIR)$(MANPREFIX)/man7" + cp -P -- $(MAN0) "$(DESTDIR)$(MANPREFIX)/man0" + cp -P -- $(MAN3) "$(DESTDIR)$(MANPREFIX)/man3" + cp -P -- $(MAN7) "$(DESTDIR)$(MANPREFIX)/man7" uninstall: -rm -f -- "$(DESTDIR)$(PREFIX)/lib/libred.a" diff --git a/blackbody.c b/blackbody.c index 6edc85a..78608c1 100644 --- a/blackbody.c +++ b/blackbody.c @@ -81,7 +81,7 @@ ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) /** * Perform linear interpolation (considered very good) - * between the CIE xyY values for two colour temperatures + * between the CIE xy values for two colour temperatures * and convert the result to sRGB. The two colours should * be the closest below the desired colour temperature, * and the closest above the desired colour temperature @@ -106,40 +106,29 @@ interpolate(double x1, double y1, double x2, double y2, double temp, double *r, } /** - * Get the [0, 1] sRGB values of a colour temperature - * - * libred has a table of colour temperature values, this - * function interpolates values that are missing. If you - * don't want any interpolation the `temp` parameter can - * be specified in one of the following ways: - * - * - floor: - * (temp - LIBRED_LOWEST_TEMPERATURE) / - * LIBRED_DELTA_TEMPERATURE * - * LIBRED_DELTA_TEMPERATURE + - * LIBRED_LOWEST_TEMPERATURE - * - * - ceiling: - * (temp - LIBRED_LOWEST_TEMPERATURE + - * LIBRED_DELTA_TEMPERATURE - 1) / - * LIBRED_DELTA_TEMPERATURE * - * LIBRED_DELTA_TEMPERATURE + - * LIBRED_LOWEST_TEMPERATURE - * - * - round to nearest: - * (temp - LIBRED_LOWEST_TEMPERATURE + - * LIBRED_DELTA_TEMPERATURE / 2) / - * LIBRED_DELTA_TEMPERATURE * - * LIBRED_DELTA_TEMPERATURE + - * LIBRED_LOWEST_TEMPERATURE + * Perform linear interpolation (considered very good) + * between the CIE xy values for two colour temperatures. + * The two colours should be the closest below the desired + * colour temperature, and the closest above the desired + * colour temperature * - * @param temp The desired colour temperature - * @param r Output parameter for the “red” value - * @param g Output parameter for the green value - * @param b Output parameter for the blue value - * @return 0 on succeess, -1 on error - * @throws EDOM The selected temperature is below 1000K + * @param x1 The 'x' component for the low colour + * @param y1 The 'y' component for the low colour + * @param x2 The 'x' component for the high colour + * @param y2 The 'y' component for the high colour + * @param temp The desired colour temperature + * @param x Output parameter for the CIE x value + * @param y Output parameter for the CIE y value */ +static void +interpolate_xy(double x1, double y1, double x2, double y2, double temp, double *x, double *y) +{ + double weight = fmod(temp - (LIBRED_LOWEST_TEMPERATURE % LIBRED_DELTA_TEMPERATURE), + (double)LIBRED_DELTA_TEMPERATURE) / (double)LIBRED_DELTA_TEMPERATURE; + *x = x1 * (1 - weight) + x2 * weight; + *y = y1 * (1 - weight) + y2 * weight; +} + int libred_get_colour(long int temp, double *r, double *g, double *b) { @@ -156,7 +145,7 @@ libred_get_colour(long int temp, double *r, double *g, double *b) } tmp = temp - LIBRED_LOWEST_TEMPERATURE; - + i = (size_t)(tmp / LIBRED_DELTA_TEMPERATURE); if (tmp % LIBRED_DELTA_TEMPERATURE) { x1 = xy_table[i].x; @@ -172,6 +161,139 @@ libred_get_colour(long int temp, double *r, double *g, double *b) return 0; } + +int +libred_get_colour_xy(long int temp, double *x, double *y) /* TODO test */ +{ + double x1, y1, x2, y2; + size_t i; + long int tmp; + + if (temp > LIBRED_HIGHEST_TEMPERATURE) + temp = LIBRED_HIGHEST_TEMPERATURE; + + if (temp < LIBRED_LOWEST_TEMPERATURE) { + errno = EDOM; + return -1; + } + + tmp = temp - LIBRED_LOWEST_TEMPERATURE; + + i = (size_t)(tmp / LIBRED_DELTA_TEMPERATURE); + if (tmp % LIBRED_DELTA_TEMPERATURE) { + x1 = xy_table[i].x; + y1 = xy_table[i].y; + x2 = xy_table[i + 1].x; + y2 = xy_table[i + 1].y; + interpolate_xy(x1, y1, x2, y2, (double)temp, x, y); + } else { + *x = xy_table[i].x; + *y = xy_table[i].y; + } + + return 0; +} + +double +libred_get_temperature_xy(double x, double y, double *x_error, double *y_error) /* TODO man, test */ +{ + size_t i, j; + double x1, y1, x2, y2, dx, dy, xd, yd, t, d2; + double best_temp = 0, best_d2 = INFINITY; + + if (!x_error) + x_error = &dx; + if (!y_error) + y_error = &dy; + + x1 = xy_table[0].x; + y1 = xy_table[0].y; + + for (j = 1; j < sizeof(xy_table) / sizeof(*xy_table); j++) { + x2 = xy_table[j].x; + y2 = xy_table[j].y; + dx = x2 - x1; + dy = y2 - y1; + + t = ((x - x1) * dx + (y - y1) * dy) / (dx * dx + dy * dy); + if (!isfinite(t)) + continue; + t = t < 0 ? 0 : t; + t = t > 1 ? 1 : t; + + xd = dx * t + x1 - x; + yd = dy * t + y1 - y; + d2 = xd * xd + yd * yd; + + if (d2 < best_d2) { + *x_error = xd; + *y_error = yd; + best_d2 = d2; + t *= (double)(j - i); + best_temp = (double)i + t; + } + } + + return best_temp * LIBRED_DELTA_TEMPERATURE + LIBRED_LOWEST_TEMPERATURE; +} + +/** + * Convert from [0, 1] sRGB to CIE xyY + * + * @param r The “red” value + * (Seriously, sRGB red is orange, just look at it fullscreen) + * @param g The green value + * @param b The blue value + * @param x Output parameter for The 'x' component + * @param y Output parameter for The 'y' component + * @param Y Output parameter for The 'Y' component + */ +static void +srgb_to_ciexyy(double r, double g, double b, double *x, double *y, double *Y) +{ + double s, z; + + r *= s = r < 0 ? -1 : 1; + r = s * (r <= 0.0031306684425217108 * 12.92 ? r * 12.92 : pow((r + 0.055) / 1.055, 2.4)); + g *= s = g < 0 ? -1 : 1; + g = s * (g <= 0.0031306684425217108 * 12.92 ? g * 12.92 : pow((g + 0.055) / 1.055, 2.4)); + b *= s = b < 0 ? -1 : 1; + b = s * (g <= 0.0031306684425217108 * 12.92 ? b * 12.92 : pow((b + 0.055) / 1.055, 2.4)); + + *x = (0.41245744558236758 * r) + (0.35757586524551588 * g) + (0.18043724782639967 * b); + *y = (0.21267337037840828 * r) + (0.71515173049103176 * g) + (0.07217489913055987 * b); + z = (0.01933394276167346 * r) + (0.11919195508183859 * g) + (0.95030283855237174 * b); + + *Y = *y; + s = *x + *y + z; + *x /= s; + *y /= s; + if (!isfinite(*x) || !isfinite(*y)) + *x = *y = 0; +} + +double +libred_get_temperature(double r, double g, double b, double *y, /* TODO man, test */ + double *r_error, double *g_error, double *b_error) +{ + double tx, ty, luma, x_error, y_error, ret; + + srgb_to_ciexyy(r, g, b, &tx, &ty, &luma); + ret = libred_get_temperature_xy(tx, ty, &x_error, &y_error); + ciexyy_to_srgb(x_error, y_error, luma, &r, &g, &b); + + if (y) + *y = luma; + if (r_error) + *r_error = r; + if (g_error) + *g_error = g; + if (b_error) + *b_error = b; + + return ret; +} + #endif @@ -212,6 +212,82 @@ int libred_check_timetravel(void); */ int libred_get_colour(long int, double *, double *, double *); +/** + * Get the CIE xy values of a colour temperature + * + * libred has a table of colour temperature values, this + * function interpolates values that are missing. If you + * don't want any interpolation the `temp` parameter can + * be specified in one of the following ways: + * + * - floor: + * (temp - LIBRED_LOWEST_TEMPERATURE) / + * LIBRED_DELTA_TEMPERATURE * + * LIBRED_DELTA_TEMPERATURE + + * LIBRED_LOWEST_TEMPERATURE + * + * - ceiling: + * (temp - LIBRED_LOWEST_TEMPERATURE + + * LIBRED_DELTA_TEMPERATURE - 1) / + * LIBRED_DELTA_TEMPERATURE * + * LIBRED_DELTA_TEMPERATURE + + * LIBRED_LOWEST_TEMPERATURE + * + * - round to nearest: + * (temp - LIBRED_LOWEST_TEMPERATURE + + * LIBRED_DELTA_TEMPERATURE / 2) / + * LIBRED_DELTA_TEMPERATURE * + * LIBRED_DELTA_TEMPERATURE + + * LIBRED_LOWEST_TEMPERATURE + * + * @param temp The desired colour temperature + * @param x Output parameter for the x value + * @param y Output parameter for the y value + * @return 0 on succeess, -1 on error + * + * @throws EDOM The selected temperature is below 1000K + */ +int libred_get_colour_xy(long int, double *, double *); + +/** + * Calculate the colour temperature from its CIE xy values + * + * @param x The CIE x value for the colour temperature + * @param y The CIE y value for the colour temperature + * @param x_error Output parameter for the absolute error in + * the CIE x value of the returned colour + * temperature; may be `NULL` + * @param y_error Output parameter for the absolute error in + * the CIE y value of the returned colour + * temperature; may be `NULL` + * @return The closest matching colour temperature + */ +double libred_get_temperature_xy(double, double, double *, double *); + +/** + * Calculate the colour temperature from its [0, 1] sRGB values + * + * @param r The sRGB “red” value for the colour temperature + * @param g The sRGB green value for the colour temperature + * @param b The sRGB blue value for the colour temperature + * @param y Output parameter for the CIE Y value for the + * provided sRGB colour, the sRGB error values must + * be multiplied by this value to correct them to + * match the brightness of the input sRGB colour; + * may be `NULL` + * @param r_error Output parameter for the absolute error in the + * “red” value of the returned colour temperature; + * may be `NULL` + * @param g_error Output parameter for the absolute error in the + * green value of the returned colour temperature; + * may be `NULL` + * @param b_error Output parameter for the absolute error in the + * blue value of the returned colour temperature; + * may be `NULL` + * @return The closest matching colour temperature + */ +double libred_get_temperature(double, double, double, double *, double *, double *, double *); + #endif diff --git a/libred_get_colour.3 b/libred_get_colour.3 index afd0a7f..61a62ff 100644 --- a/libred_get_colour.3 +++ b/libred_get_colour.3 @@ -6,6 +6,7 @@ libred_get_colour \- Calculate a colour temperature #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 @@ -14,7 +15,8 @@ Link with .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 +51,45 @@ 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 diff --git a/libred_get_colour_xy.3 b/libred_get_colour_xy.3 new file mode 120000 index 0000000..1d7ee17 --- /dev/null +++ b/libred_get_colour_xy.3 @@ -0,0 +1 @@ +libred_get_colour.3
\ No newline at end of file diff --git a/libred_solar_elevation.3 b/libred_solar_elevation.3 index 9bb4b0a..70587ca 100644 --- a/libred_solar_elevation.3 +++ b/libred_solar_elevation.3 @@ -27,11 +27,13 @@ Other values may or may not work, no error is thrown if used. .SH RETURN VALUE Upon successful completion, the .BR libred_solar_elevation () -return 0, on failure it returns -1 and sets +function returns 0, on failure it returns -1 and sets .I errno to indicate the error. .SH ERRORS -The function may fail for any reason specified for +The +.BR libred_solar_elevation () +function may fail for any reason specified for .BR clock_gettime (3). .SH SEE ALSO .BR libred.h (0), |