From 13bbfb8b27e73e7ab59b847a077f281e712abf03 Mon Sep 17 00:00:00 2001 From: sam Date: Sat, 16 Aug 2008 00:53:54 +0000 Subject: [PATCH] * Start working on colour reduction with a constrained palette. git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2726 92316355-f0b4-4df1-b90c-862c8a59935f --- examples/img2rubik.c | 140 +++++++++++++++++++++++++++++++++++++++---- 1 file changed, 130 insertions(+), 10 deletions(-) diff --git a/examples/img2rubik.c b/examples/img2rubik.c index 815cbeb..2b0742e 100644 --- a/examples/img2rubik.c +++ b/examples/img2rubik.c @@ -4,26 +4,146 @@ #include #include #include +#include #include +#define Y(x) (0.299*(x)[0] + 0.587*(x)[1] + 0.114*(x)[2]) + +#define STEPS 16 +#define EPSILON (0.000001) + int main(int argc, char *argv[]) { - char *srcname = NULL, *dstname = NULL; - pipi_image_t *img; + double palette[][3] = + { + { 1.0, 0.0, 0.0 }, /* red */ + { 0.0, 1.0, 0.0 }, /* green */ + { 0.0, 0.0, 1.0 }, /* blue */ + { 1.0, 1.0, 1.0 }, /* white */ + { 1.0, 1.0, 0.0 }, /* yellow */ + { 1.0, 0.5, 0.0 }, /* orange */ + }; +#define NCOLORS ((int)(sizeof(palette)/sizeof(*palette))) - if(argc < 3) + double tmp; + int i, j; + + /* + * 1. Find the darkest and lightest colours + */ + double *dark = NULL, *light = NULL; + double min = 1.0, max = 0.0; + for(i = 0; i < NCOLORS; i++) { - fprintf(stderr, "%s: too few arguments\n", argv[0]); - return EXIT_FAILURE; + double p = Y(palette[i]); + if(p < min) + { + dark = palette[i]; + min = p; + } + if(p > max) + { + light = palette[i]; + max = p; + } } + printf("lightest (%g,%g,%g)\n", light[0], light[1], light[2]); + printf("darkest (%g,%g,%g)\n", dark[0], dark[1], dark[2]); + + /* + * 2. Find two base vectors for the chrominance planes + * FIXME: this doesn't work in all cases because u can be null + */ + double y[3], u[3], v[3]; + double ylen; + + y[0] = light[0] - dark[0]; + y[1] = light[1] - dark[1]; + y[2] = light[2] - dark[2]; + ylen = sqrt(y[0] * y[0] + y[1] * y[1] + y[2] * y[2]); + + u[0] = y[1]; + u[1] = -y[0]; + u[2] = 0; + tmp = sqrt(u[0] * u[0] + u[1] * u[1] + u[2] * u[2]); + u[0] /= tmp; u[1] /= tmp; u[2] /= tmp; + + v[0] = y[1] * u[2] - y[2] * u[1]; + v[1] = y[2] * u[0] - y[0] * u[2]; + v[2] = y[0] * u[1] - y[1] * u[0]; + tmp = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]); + v[0] /= tmp; v[1] /= tmp; v[2] /= tmp; + + printf("gray axis (%g,%g,%g) - length %g\n", y[0], y[1], y[2], ylen); + printf("u (%g,%g,%g)\n", u[0], u[1], u[2]); + printf("v (%g,%g,%g)\n", v[0], v[1], v[2]); + + /* + * 3. Browse the grey axis and do stuff + */ + double t; + for(t = 0.; t <= 1.0; t += 1. / STEPS) + { + double pts[NCOLORS*NCOLORS/2][3]; + double p0[3]; + int npts = 0; + + p0[0] = dark[0] + t * y[0]; + p0[1] = dark[1] + t * y[1]; + p0[2] = dark[2] + t * y[2]; + printf("%g,%g,%g\n", p0[0], p0[1], p0[2]); + + /* + * 3.1. Find all edges that intersect the t.y + (u,v) plane + */ + for(i = 0; i < NCOLORS; i++) + { + double k1[3]; + k1[0] = palette[i][0] - dark[0]; + k1[1] = palette[i][1] - dark[1]; + k1[2] = palette[i][2] - dark[2]; + tmp = sqrt(k1[0] * k1[0] + k1[1] * k1[1] + k1[2] * k1[2]); + + /* If k1.y > t.y.y, we don't want this point */ + double yk1 = y[0] * k1[0] + y[1] * k1[1] + y[2] * k1[2]; + if(yk1 > t * ylen * ylen + EPSILON) + continue; + + for(j = 0; j < NCOLORS; j++) + { + if(i == j) + continue; - srcname = argv[1]; - dstname = argv[2]; + double k2[3]; + k2[0] = palette[j][0] - dark[0]; + k2[1] = palette[j][1] - dark[1]; + k2[2] = palette[j][2] - dark[2]; + tmp = sqrt(k2[0] * k2[0] + k2[1] * k2[1] + k2[2] * k2[2]); - img = pipi_load(srcname); - pipi_save(img, dstname); - pipi_free(img); + /* If k2.y < t.y.y, we don't want this point */ + double yk2 = y[0] * k2[0] + y[1] * k2[1] + y[2] * k2[2]; + if(yk2 < t * ylen * ylen - EPSILON) + continue; + + if(yk2 < yk1) + continue; + + double s = yk1 == yk2 ? + 0.5 : (t * ylen * ylen - yk1) / (yk2 - yk1); + + pts[npts][0] = dark[0] + k1[0] + s * (k2[0] - k1[0]); + pts[npts][1] = dark[1] + k1[1] + s * (k2[1] - k1[1]); + pts[npts][2] = dark[2] + k1[2] + s * (k2[2] - k1[2]); + printf(" %i,%i: s = (%g,%g,%g)\n", i, j, pts[npts][0], pts[npts][1], pts[npts][2]); + npts++; + } + } + + /* + * 3.2. Find the barycentre of these points' convex hull. (TODO) + */ + } return 0; }