/* See LICENSE file for copyright and license details. */ #if defined(__GNUC__) # pragma GCC diagnostic push # pragma GCC diagnostic ignored "-Wunsuffixed-float-constants" #endif #ifndef LIBRED_COMPILING_PARSER # include "libred.h" # include # include # include /** * Colour temperatures in CIE xy (xyY without Y) */ static struct xy {double x, y;} xy_table[] = { # include "10deg-xy.i" }; /** * Colour temperatures in sRGB */ static struct rgb {double r, g, b;} rgb_table[] = { # include "10deg-rgb.i" }; #endif /** * Convert from CIE xyY to [0, 1] sRGB * * @param x The 'x' component * @param y The 'y' component * @param Y The 'Y' component * @param r Output parameter for the “red” value * (Seriously, sRGB red is orange, just look at it fullscreen) * @param g Output parameter for the green value * @param b Output parameter for the blue value */ static void ciexyy_to_srgb(double x, double y, double Y, double *r, double *g, double *b) { #define SRGB(C) (((C) <= 0.0031308) ? (12.92 * (C)) : ((1.0 + 0.055) * pow((C), 1.0 / 2.4) - 0.055)) double X, Z, max; #if __GNUC__ # pragma GCC diagnostic push # pragma GCC diagnostic ignored "-Wfloat-equal" #endif /* Convert CIE xyY to CIE XYZ */ X = Y * (y == 0.0 ? 0.0 : (x / y)); Z = Y * (y == 0.0 ? 0.0 : ((1.0 - x - y) / y)); #if __GNUC__ # pragma GCC diagnostic pop #endif /* Convert CIE XYZ to [0, 1] linear RGB (ciexyz_to_linear) */ *r = ( 3.240450 * X) + (-1.537140 * Y) + (-0.4985320 * Z); *g = (-0.969266 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z); *b = (0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z); /* Convert [0, 1] linear RGB to [0, 1] sRGB */ SRGB(*r), SRGB(*g), SRGB(*b); /* Adjust colours for use */ max = fmax(fmax(fabs(*r), fabs(*g)), fabs(*b)); #if __GNUC__ # pragma GCC diagnostic push # pragma GCC diagnostic ignored "-Wfloat-equal" #endif if (max != 0.0) *r /= max, *g /= max, *b /= max; #if __GNUC__ # pragma GCC diagnostic pop #endif *r = *r > 0.0 ? *r : 0.0; *g = *g > 0.0 ? *g : 0.0; *b = *b > 0.0 ? *b : 0.0; } #ifndef LIBRED_COMPILING_PARSER /** * Perform linear interpolation (considered very good) * 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 * * @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 r Output parameter for the “red” value * @param g Output parameter for the green value * @param b Output parameter for the blue value */ static void interpolate(double x1, double y1, double x2, double y2, double temp, double *r, double *g, double *b) { double weight = fmod(temp - (LIBRED_LOWEST_TEMPERATURE % LIBRED_DELTA_TEMPERATURE), (double)LIBRED_DELTA_TEMPERATURE) / (double)LIBRED_DELTA_TEMPERATURE; double x = x1 * (1 - weight) + x2 * weight; double y = y1 * (1 - weight) + y2 * weight; ciexyy_to_srgb(x, y, 1.0, r, g, b); } /** * 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 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) { 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(x1, y1, x2, y2, (double)temp, r, g, b); } else { *r = rgb_table[i].r; *g = rgb_table[i].g; *b = rgb_table[i].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 #if __GNUC__ # pragma GCC diagnostic pop #endif