void color_init() {
double x, y, z, r, g, b;
struct colourSystem* cs = &SMPTEsystem;
for(int ii = 0; ii < TEMP_ENTRIES; ++ii) {
double temp = base_temp + step * ii;
bbTemp = temp;
spectrum_to_xyz(bb_spectrum, &x, &y, &z);
xyz_to_rgb(cs, x, y, z, &r, &g, &b);
constrain_rgb(&r, &g, &b);
norm_rgb(&r, &g, &b);
temp_table[ii][0] = r;
temp_table[ii][1] = g;
temp_table[ii][2] = b;
}
}
void spectrum(double t1, double t2, int N, unsigned char *d)
{
int i,j,dj;
double X,Y,Z,R,G,B,L,M,S, Lw, Mw, Sw;
struct colourSystem *cs = &CIEsystem;
j = 0; dj = 1;
if (t1<t2) {
double t = t1;
t1 = t2;
t2 = t;
j = N-1; dj=-1;
}
for (i=0; i<N; i++) {
bbTemp = t1 + (t2-t1)/N*i;
// integrate blackbody radiation spectrum to XYZ
spectrum_to_xyz(bb_spectrum, &X, &Y, &Z);
// normalize highest temperature to white (in LMS system)
xyz_to_lms(X,Y,Z,&L,&M,&S);
if (i==0) {
Lw=1/L; Mw=1/M; Sw=1/S;
}
L *= Lw; M *= Mw; S *= Sw;
lms_to_xyz(L,M,S,&X,&Y,&Z);
// convert to RGB
xyz_to_rgb(cs, X, Y, Z, &R, &G, &B);
constrain_rgb(&R, &G, &B);
norm_rgb(&R, &G, &B);
d[(j<<2)] = (unsigned char) ((double)R*255);
d[(j<<2)+1] = (unsigned char) ((double)G*255);
d[(j<<2)+2] = (unsigned char) ((double)B*255);
d[(j<<2)+3] = (B>0.1)? B*255 : 0;
j += dj;
}
}
int main()
{
float t, x, y, z, r, g, b;
struct colourSystem *cs = &SMPTEsystem;
printf("Temperature x y z R G B\n");
printf("----------- ------ ------ ------ ----- ----- -----\n");
for (t = 1000; t <= 10000; t+= 500) {
bbTemp = t;
spectrum_to_xyz(bb_spectrum, &x, &y, &z);
xyz_to_rgb(cs, x, y, z, &r, &g, &b);
printf(" %5.0f K %.4f %.4f %.4f ", t, x, y, z);
if (constrain_rgb(&r, &g, &b)) {
norm_rgb(&r, &g, &b);
printf("%.3f %.3f %.3f (Approximation)\n", r, g, b);
} else {
norm_rgb(&r, &g, &b);
printf("%.3f %.3f %.3f\n", r, g, b);
}
}
return 0;
}
static void
plotMonochromeWavelengths(
pixel ** const pixels,
int const pixcols,
int const pixrows,
pixval const maxval,
const struct colorSystem * const cs,
bool const upvp,
int const xBias,
int const yBias) {
int const pxcols = pixcols - xBias;
int const pxrows = pixrows - yBias;
int x; /* The wavelength we're plotting */
for (x = (upvp? 420 : 450);
x <= 650;
x += (upvp? 10 : (x > 470 && x < 600) ? 5 : 10)) {
pixel rgbcolor;
/* Ick. Drop legends that overlap and twiddle position
so they appear at reasonable positions with respect to
the tongue.
*/
if (!overlappingLegend(upvp, x)) {
double cx, cy, cz, jr, jg, jb, jmax;
char wl[20];
int bx = 0, by = 0, tx, ty, r, g, b;
int icx, icy; /* Location of the color on the tongue */
if (x < 520) {
bx = Sz(-22);
by = Sz(2);
} else if (x < 535) {
bx = Sz(-8);
by = Sz(-6);
} else {
bx = Sz(4);
}
computeMonochromeColorLocation(x, pxcols, pxrows, upvp,
&icx, &icy);
/* Draw the tick mark */
PPM_ASSIGN(rgbcolor, maxval, maxval, maxval);
tx = icx + ((x < 520) ? Sz(-2) : ((x >= 535) ? Sz(2) : 0));
ty = icy + ((x < 520) ? 0 : ((x >= 535) ? Sz(-1) : Sz(-2)));
ppmd_line(pixels, pixcols, pixrows, Maxval,
B(icx, icy), B(tx, ty),
PPMD_NULLDRAWPROC, (char *) &rgbcolor);
/* The following flailing about sets the drawing color to
the hue corresponding to the pure wavelength (constrained
to the display gamut). */
if (upvp) {
double up, vp;
up = ((double) icx) / (pxcols - 1);
vp = 1.0 - ((double) icy) / (pxrows - 1);
upvp_to_xy(up, vp, &cx, &cy);
cz = 1.0 - (cx + cy);
} else {
cx = ((double) icx) / (pxcols - 1);
cy = 1.0 - ((double) icy) / (pxrows - 1);
cz = 1.0 - (cx + cy);
}
xyz_to_rgb(cs, cx, cy, cz, &jr, &jg, &jb);
(void) constrain_rgb(&jr, &jg, &jb);
/* Scale to max(rgb) = 1 */
jmax = MAX(jr, MAX(jg, jb));
if (jmax > 0) {
jr = jr / jmax;
jg = jg / jmax;
jb = jb / jmax;
}
/* gamma correct from linear rgb to nonlinear rgb. */
gamma_correct_rgb(cs, &jr, &jg, &jb);
r = Maxval * jr;
g = Maxval * jg;
b = Maxval * jb;
PPM_ASSIGN(rgbcolor, (pixval) r, (pixval) g, (pixval) b);
sprintf(wl, "%d", x);
ppmd_text(pixels, pixcols, pixrows, Maxval,
B(icx + bx, icy + by), Sz(6), 0, wl,
PPMD_NULLDRAWPROC, (char *) &rgbcolor);
}
}
}
static void
fillInTongue(pixel ** const pixels,
int const pixcols,
int const pixrows,
pixval const maxval,
const struct colorSystem * const cs,
bool const upvp,
int const xBias,
int const yBias,
bool const highlightGamut) {
int const pxcols = pixcols - xBias;
int const pxrows = pixrows - yBias;
int y;
/* Scan the image line by line and fill the tongue outline
with the RGB values determined by the color system for the x-y
co-ordinates within the tongue.
*/
for (y = 0; y < pxrows; ++y) {
bool present; /* There is some tongue on this line */
int leftEdge; /* x position of leftmost pixel in tongue on this line */
int rightEdge; /* same, but rightmost */
findTongue(pixels, pxcols, xBias, y, &present, &leftEdge, &rightEdge);
if (present) {
int x;
for (x = leftEdge; x <= rightEdge; ++x) {
double cx, cy, cz, jr, jg, jb, jmax;
int r, g, b, mx;
if (upvp) {
double up, vp;
up = ((double) x) / (pxcols - 1);
vp = 1.0 - ((double) y) / (pxrows - 1);
upvp_to_xy(up, vp, &cx, &cy);
cz = 1.0 - (cx + cy);
} else {
cx = ((double) x) / (pxcols - 1);
cy = 1.0 - ((double) y) / (pxrows - 1);
cz = 1.0 - (cx + cy);
}
xyz_to_rgb(cs, cx, cy, cz, &jr, &jg, &jb);
mx = Maxval;
/* Check whether the requested color is within the
gamut achievable with the given color system. If
not, draw it in a reduced intensity, interpolated
by desaturation to the closest within-gamut color. */
if (constrain_rgb(&jr, &jg, &jb)) {
mx = highlightGamut ? Maxval : ((Maxval + 1) * 3) / 4;
}
/* Scale to max(rgb) = 1. */
jmax = MAX(jr, MAX(jg, jb));
if (jmax > 0) {
jr = jr / jmax;
jg = jg / jmax;
jb = jb / jmax;
}
/* gamma correct from linear rgb to nonlinear rgb. */
gamma_correct_rgb(cs, &jr, &jg, &jb);
r = mx * jr;
g = mx * jg;
b = mx * jb;
PPM_ASSIGN(Bixels(y, x), (pixval) r, (pixval) g, (pixval) b);
}
}
}
}
