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Diffstat (limited to 'xicc/bt1886.c')
| -rw-r--r-- | xicc/bt1886.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/xicc/bt1886.c b/xicc/bt1886.c new file mode 100644 index 0000000..3f94dbe --- /dev/null +++ b/xicc/bt1886.c @@ -0,0 +1,351 @@ + +/* + * Author: Graeme W. Gill + * Date: 16/8/13 + * Version: 1.00 + * + * Copyright 2013, 2014 Graeme W. Gill + * All rights reserved. + * + * This material is licenced under the GNU AFFERO GENERAL PUB LICENSE Version 3 :- + * see the License.txt file for licencing details. + * + */ + +/* BT.1886 stype input offset transfer curve, */ +/* + general gamma + input + output offset curve support. */ + +#include <sys/types.h> +#include <string.h> +#include <ctype.h> +#ifdef __sun +#include <unistd.h> +#endif +#if defined(__IBMC__) && defined(_M_IX86) +#include <float.h> +#endif +#include "numlib.h" +#include "icc.h" /* definitions for this library */ +#include "bt1886.h" /* definitions for this library */ + +#undef DEBUG + +/* BT.1886 support */ +/* This is both a EOTF curve, and a white point */ +/* adjustment. */ + +/* Compute technical gamma from effective gamma in BT.1886 style */ + +/* Info for optimization */ +typedef struct { + double wp; /* 100% input target */ + double thyr; /* 50% input target */ + double bp; /* 0% input target */ +} gam_fits; + +/* gamma + input offset function handed to powell() */ +static double gam_fit(void *dd, double *v) { + gam_fits *gf = (gam_fits *)dd; + double gamma = v[0]; + double a, b; + double rv = 0.0; + double t1, t2; + + if (gamma < 0.0) { + rv += 100.0 * -gamma; + gamma = 1e-4; + } + + t1 = pow(gf->bp, 1.0/gamma); + t2 = pow(gf->wp, 1.0/gamma); + b = t1/(t2 - t1); /* Offset */ + a = pow(t2 - t1, gamma); /* Gain */ + + /* Comput 50% output for this technical gamma */ + /* (All values are without output offset being added in) */ + t1 = a * pow((0.5 + b), gamma); + t1 = t1 - gf->thyr; + rv += t1 * t1; + + return rv; +} + +/* Given the effective gamma and the output offset Y, */ +/* return the technical gamma needed for the correct 50% response. */ +static double xicc_tech_gamma( + double egamma, /* effective gamma needed */ + double off, /* Output offset required */ + double outoprop /* Prop. of offset to be accounted for on output */ +) { + gam_fits gf; + double outo; + double op[1], sa[1], rv; + + if (off <= 0.0) { + return egamma; + } + + /* We set up targets without outo being added */ + outo = off * outoprop; /* Offset acounted for in output */ + gf.bp = off - outo; /* Black value for 0 % input */ + gf.wp = 1.0 - outo; /* White value for 100% input */ + gf.thyr = pow(0.5, egamma) - outo; /* Advetised 50% target */ + + op[0] = egamma; + sa[0] = 0.1; + + if (powell(&rv, 1, op, sa, 1e-6, 500, gam_fit, (void *)&gf, NULL, NULL) != 0) + warning("Computing effective gamma and input offset is inaccurate"); + + return op[0]; +} + +/* Set the bt1886_info to a default do nothing state */ +void bt1886_setnop(bt1886_info *p) { + icmXYZ2XYZ(p->w, icmD50); + p->ingo = 0.0; + p->outsc = 1.0; + p->outo = 0.0; + p->outL = 0.0; + p->tab[1] = 0.0; + p->tab[2] = 0.0; +} + +/* Setup the bt1886_info for the given target black point, proportion of */ +/* offset to be accounted for on output, and gamma. */ +/* wp XYZ simply sets the L*a*b* reference */ +/* Pure BT.1886 will have outopro = 0.0 and gamma = 2.4 */ +void bt1886_setup( +bt1886_info *p, +icmXYZNumber *w, /* wp used for L*a*b* conversion */ +double *XYZbp, /* normalised bp used for black offset and black point hue "bend" */ +double outoprop, /* 0..1 proportion of output black point compensation */ +double gamma, /* technical or effective gamma */ +int effg /* nz if effective gamma, z if technical gamma */ +) { + double Lab[3], ino, bkipow, wtipow; + + icmXYZ2XYZ(p->w, *w); + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886_setup wp.Y %f, bp.Y %f, outprop %f, gamma %f, effg %d", p->w.Y, XYZbp[1], outoprop, gamma, effg); +#endif + + if (effg) { + p->gamma = xicc_tech_gamma(gamma, XYZbp[1], outoprop); +#ifdef DEBUG + a1logd(g_log, 2, "bt1886_setup tgamma %f", p->gamma); +#endif + } else { + p->gamma = gamma; + } + + icmXYZ2Lab(&p->w, Lab, XYZbp); + + p->outL = Lab[0]; /* For bp blend comp. */ + p->tab[0] = Lab[1]; /* a* b* correction needed */ + p->tab[1] = Lab[2]; +#ifdef DEBUG + a1logd(g_log, 2, "bt1886_setup bend Lab = %f %f %f", p->outL, p->tab[0], p->tab[1]); +#endif + + if (XYZbp[1] < 0.0) + XYZbp[1] = 0.0; + + + p->outo = XYZbp[1] * outoprop; /* Offset acounted for in output */ + ino = XYZbp[1] - p->outo; /* Balance of offset accounted for in input */ + + bkipow = pow(ino, 1.0/p->gamma); /* Input offset black to 1/pow */ + wtipow = pow((1.0 - p->outo), 1.0/p->gamma); /* Input offset white to 1/pow */ + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886_setup outo %f, ino %f, bkipow %f, wtipow %f", p->outo, ino, bkipow, wtipow); +#endif + + p->ingo = bkipow/(wtipow - bkipow); /* non-linear Y that makes input offset */ + /* proportion of black point */ + p->outsc = pow(wtipow - bkipow, p->gamma); /* Scale to make input of 1 map to */ + /* 1.0 - p->outo */ + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886_setup ingo %f, outsc %f", p->ingo, p->outsc); +#endif +} + +/* Apply BT.1886 eotf curve to the device RGB value */ +/* to produce a linear light RGB. We pass xvYCC out of range values through. */ +void bt1886_fwd_curve(bt1886_info *p, double *out, double *in) { + int j; + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 Dev RGB in %f %f %f, pow %f\n", in[0],in[1],in[2], p->gamma); + a1logd(g_log, 2, "outo %f, outsc %f, pow %f\n", p->outo, p->outsc, 1.0/p->gamma); + a1logd(g_log, 2, "ingo %f, pow %f, outsc %f, outo %f\n", p->ingo, p->gamma, p->outsc,p->outo); +#endif + + for (j = 0; j < 3; j++) { + int neg = 0; + double vv = in[j]; + + if (vv < 0.0) { /* Allow for xvYCC */ + neg = 1; + vv = -vv; + } + /* Apply input offset */ + vv += p->ingo; + + /* Apply power and scale */ + if (vv > 0.0) + vv = p->outsc * pow(vv, p->gamma); + + /* Apply output portion of offset */ + vv += p->outo; + + if (neg) + vv = -vv; + + out[j] = vv; + } + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 linear RGB out %f %f %f\n", out[0],out[1],out[2]); +#endif +} + +/* Apply inverse BT.1886 eotf curve to the linear light RGB to produce */ +/* device RGB values. We pass xvYCC out of range values through. */ +void bt1886_bwd_curve(bt1886_info *p, double *out, double *in) { + int j; + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 linear RGB in %f %f %f\n", in[0],in[1],in[2]); + a1logd(g_log, 2, "outo %f, outsc %f, pow %f, ingo %f\n", p->outo, p->outsc, 1.0/p->gamma,p->ingo); +#endif + + for (j = 0; j < 3; j++) { + int neg = 0; + double vv = in[j]; + + if (vv < 0.0) { /* Allow for xvYCC */ + neg = 1; + vv = -vv; + } + + /* Un-apply output portion of offset */ + vv -= p->outo; + + /* Un-apply power and scale */ + if (vv > 0.0) + vv = pow(vv/p->outsc, 1.0/p->gamma); + + /* Un-apply input offset */ + vv -= p->ingo; + + if (neg) + vv = -vv; + + out[j] = vv; + } + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 Dev RGB out %f %f %f\n", in[0],in[1],in[2]); +#endif +} + +/* Apply BT.1886 processing black point hue adjustment to the XYZ value */ +void bt1886_wp_adjust(bt1886_info *p, double *out, double *in) { + double vv; + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 XYZ wp adj. in %f %f %f\n", in[0],in[1],in[2]); +#endif + + icmXYZ2Lab(&p->w, out, in); + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 Lab wp adj. in %f %f %f\n", out[0],out[1],out[2]); +#endif + + /* Blend ab to required black point offset p->tab[] as L approaches black. */ + vv = (out[0] - p->outL)/(100.0 - p->outL); /* 0 at bp, 1 at wp */ + vv = 1.0 - vv; + if (vv < 0.0) + vv = 0.0; + else if (vv > 1.0) + vv = 1.0; + vv = pow(vv, 40.0); + + out[1] += vv * p->tab[0]; + out[2] += vv * p->tab[1]; + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 Lab after wp adj. %f %f %f\n", out[0],out[1],out[2]); +#endif + + icmLab2XYZ(&p->w, out, out); + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 XYZ after wp adj. %f %f %f\n", out[0],out[1],out[2]); +#endif +} + + +/* Apply inverse BT.1886 processing black point hue adjustment to the XYZ value */ +void bt1886_inv_wp_adjust(bt1886_info *p, double *out, double *in) { + double vv; + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 XYZ inv. wp adj. in %f %f %f\n", in[0],in[1],in[2]); +#endif + + icmXYZ2Lab(&p->w, out, in); + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 Lab inv. wp adj. in %f %f %f\n", out[0],out[1],out[2]); +#endif + + /* Blend ab to required black point offset p->tab[] as L approaches black. */ + vv = (out[0] - p->outL)/(100.0 - p->outL); /* 0 at bp, 1 at wp */ + vv = 1.0 - vv; + if (vv < 0.0) + vv = 0.0; + else if (vv > 1.0) + vv = 1.0; + vv = pow(vv, 40.0); + + out[1] -= vv * p->tab[0]; + out[2] -= vv * p->tab[1]; + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 Lab after inv. wp adj. %f %f %f\n", out[0],out[1],out[2]); +#endif + + icmLab2XYZ(&p->w, out, out); + +#ifdef DEBUG + a1logd(g_log, 2, "bt1886 XYZ after inv. wp adj. %f %f %f\n", out[0],out[1],out[2]); +#endif +} + + + + + + + + + + + + + + + + + + + + + + |