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authorLars-Dominik Braun <lars@6xq.net>2015-05-02 21:36:31 +0200
committerLars-Dominik Braun <lars@6xq.net>2015-05-02 21:36:31 +0200
commitb2dfbdf4d9644c684c938cb2730deab66aa06d9b (patch)
tree2710c26a94f8c85887389619682892363303f9db /src/filters.c
parentfb1c90e18b0d77a8b4035461722b89c7db46db51 (diff)
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-/*
- FLAM3 - cosmic recursive fractal flames
- Copyright (C) 1992-2009 Spotworks LLC
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>.
-*/
-
-#include "filters.h"
-
-
-/*
- * filter function definitions
- * from Graphics Gems III code
- * and ImageMagick resize.c
- */
-
-
-double flam3_spatial_support[flam3_num_spatialfilters] = {
-
- 1.5, /* gaussian */
- 1.0, /* hermite */
- 0.5, /* box */
- 1.0, /* triangle */
- 1.5, /* bell */
- 2.0, /* b spline */
- 2.0, /* mitchell */
- 1.0, /* blackman */
- 2.0, /* catrom */
- 1.0, /* hanning */
- 1.0, /* hamming */
- 3.0, /* lanczos3 */
- 2.0, /* lanczos2 */
- 1.5 /* quadratic */
-};
-
-double flam3_hermite_filter(double t) {
- /* f(t) = 2|t|^3 - 3|t|^2 + 1, -1 <= t <= 1 */
- if(t < 0.0) t = -t;
- if(t < 1.0) return((2.0 * t - 3.0) * t * t + 1.0);
- return(0.0);
-}
-
-double flam3_box_filter(double t) {
- if((t > -0.5) && (t <= 0.5)) return(1.0);
- return(0.0);
-}
-
-double flam3_triangle_filter(double t) {
- if(t < 0.0) t = -t;
- if(t < 1.0) return(1.0 - t);
- return(0.0);
-}
-
-double flam3_bell_filter(double t) {
- /* box (*) box (*) box */
- if(t < 0) t = -t;
- if(t < .5) return(.75 - (t * t));
- if(t < 1.5) {
- t = (t - 1.5);
- return(.5 * (t * t));
- }
- return(0.0);
-}
-
-double flam3_b_spline_filter(double t) {
-
- /* box (*) box (*) box (*) box */
- double tt;
-
- if(t < 0) t = -t;
- if(t < 1) {
- tt = t * t;
- return((.5 * tt * t) - tt + (2.0 / 3.0));
- } else if(t < 2) {
- t = 2 - t;
- return((1.0 / 6.0) * (t * t * t));
- }
- return(0.0);
-}
-
-double flam3_sinc(double x) {
- x *= M_PI;
- if(x != 0) return(sin(x) / x);
- return(1.0);
-}
-
-double flam3_blackman_filter(double x) {
- return(0.42+0.5*cos(M_PI*x)+0.08*cos(2*M_PI*x));
-}
-
-double flam3_catrom_filter(double x) {
- if (x < -2.0)
- return(0.0);
- if (x < -1.0)
- return(0.5*(4.0+x*(8.0+x*(5.0+x))));
- if (x < 0.0)
- return(0.5*(2.0+x*x*(-5.0-3.0*x)));
- if (x < 1.0)
- return(0.5*(2.0+x*x*(-5.0+3.0*x)));
- if (x < 2.0)
- return(0.5*(4.0+x*(-8.0+x*(5.0-x))));
- return(0.0);
-}
-
-double flam3_mitchell_filter(double t) {
- double tt;
-
- tt = t * t;
- if(t < 0) t = -t;
- if(t < 1.0) {
- t = (((12.0 - 9.0 * flam3_mitchell_b - 6.0 * flam3_mitchell_c) * (t * tt))
- + ((-18.0 + 12.0 * flam3_mitchell_b + 6.0 * flam3_mitchell_c) * tt)
- + (6.0 - 2 * flam3_mitchell_b));
- return(t / 6.0);
- } else if(t < 2.0) {
- t = (((-1.0 * flam3_mitchell_b - 6.0 * flam3_mitchell_c) * (t * tt))
- + ((6.0 * flam3_mitchell_b + 30.0 * flam3_mitchell_c) * tt)
- + ((-12.0 * flam3_mitchell_b - 48.0 * flam3_mitchell_c) * t)
- + (8.0 * flam3_mitchell_b + 24 * flam3_mitchell_c));
- return(t / 6.0);
- }
- return(0.0);
-}
-
-double flam3_hanning_filter(double x) {
- return(0.5+0.5*cos(M_PI*x));
-}
-
-double flam3_hamming_filter(double x) {
- return(0.54+0.46*cos(M_PI*x));
-}
-
-double flam3_lanczos3_filter(double t) {
- if(t < 0) t = -t;
- if(t < 3.0) return(flam3_sinc(t) * flam3_sinc(t/3.0));
- return(0.0);
-}
-
-double flam3_lanczos2_filter(double t) {
- if(t < 0) t = -t;
- if(t < 2.0) return(flam3_sinc(t) * flam3_sinc(t/2.0));
- return(0.0);
-}
-
-double flam3_gaussian_filter(double x) {
- return(exp((-2.0*x*x))*sqrt(2.0/M_PI));
-}
-
-double flam3_quadratic_filter(double x) {
- if (x < -1.5)
- return(0.0);
- if (x < -0.5)
- return(0.5*(x+1.5)*(x+1.5));
- if (x < 0.5)
- return(0.75-x*x);
- if (x < 1.5)
- return(0.5*(x-1.5)*(x-1.5));
- return(0.0);
-}
-
-double flam3_spatial_filter(int knum, double x) {
-
- if (knum==0)
- return flam3_gaussian_filter(x);
- else if (knum==1)
- return flam3_hermite_filter(x);
- else if (knum==2)
- return flam3_box_filter(x);
- else if (knum==3)
- return flam3_triangle_filter(x);
- else if (knum==4)
- return flam3_bell_filter(x);
- else if (knum==5)
- return flam3_b_spline_filter(x);
- else if (knum==6)
- return flam3_mitchell_filter(x);
- else if (knum==7)
- return flam3_sinc(x)*flam3_blackman_filter(x);
- else if (knum==8)
- return flam3_catrom_filter(x);
- else if (knum==9)
- return flam3_sinc(x)*flam3_hanning_filter(x);
- else if (knum==10)
- return flam3_sinc(x)*flam3_hamming_filter(x);
- else if (knum==11)
- return flam3_lanczos3_filter(x)*flam3_sinc(x/3.0);
- else if (knum==12)
- return flam3_lanczos2_filter(x)*flam3_sinc(x/2.0);
- else if (knum==13)
- return flam3_quadratic_filter(x);
-}
-
-int normalize_vector(double *v, int n) {
- double t = 0.0;
- int i;
- for (i = 0; i < n; i++)
- t += v[i];
- if (0.0 == t) return 1;
- t = 1.0 / t;
- for (i = 0; i < n; i++)
- v[i] *= t;
- return 0;
-}
-
-
-int flam3_create_spatial_filter(flam3_frame *spec, int field, double **filter) {
-
- int sf_kernel = spec->genomes[0].spatial_filter_select;
- int supersample = spec->genomes[0].spatial_oversample;
- double sf_radius = spec->genomes[0].spatial_filter_radius;
- double aspect_ratio = spec->pixel_aspect_ratio;
- double sf_supp = flam3_spatial_support[sf_kernel];
-
- double fw = 2.0 * sf_supp * supersample * sf_radius / aspect_ratio;
- double adjust, ii, jj;
-
- int fwidth = ((int) fw) + 1;
- int i,j;
-
-
- /* Make sure the filter kernel has same parity as oversample */
- if ((fwidth ^ supersample) & 1)
- fwidth++;
-
- /* Calculate the coordinate scaling factor for the kernel values */
- if (fw > 0.0)
- adjust = sf_supp * fwidth / fw;
- else
- adjust = 1.0;
-
- /* Calling function MUST FREE THE RETURNED KERNEL, lest ye leak memory */
- (*filter) = (double *)calloc(fwidth * fwidth,sizeof(double));
-
- /* fill in the coefs */
- for (i = 0; i < fwidth; i++)
- for (j = 0; j < fwidth; j++) {
-
- /* Calculate the function inputs for the kernel function */
- ii = ((2.0 * i + 1.0) / (double)fwidth - 1.0)*adjust;
- jj = ((2.0 * j + 1.0) / (double)fwidth - 1.0)*adjust;
-
- /* Scale for scanlines */
- if (field) jj *= 2.0;
-
- /* Adjust for aspect ratio */
- jj /= aspect_ratio;
-
- (*filter)[i + j * fwidth] =
- flam3_spatial_filter(sf_kernel,ii) * flam3_spatial_filter(sf_kernel,jj);
- }
-
-
- if (normalize_vector((*filter), fwidth * fwidth)) {
- fprintf(stderr, "Spatial filter value is too small: %g. Terminating.\n",sf_radius);
- return(-1);
- }
-
- return (fwidth);
-}
-
-flam3_de_helper flam3_create_de_filters(double max_rad, double min_rad, double curve, int ss) {
-
- flam3_de_helper de;
- double comp_max_radius, comp_min_radius;
- double num_de_filters_d;
- int num_de_filters,de_max_ind;
- int de_row_size, de_half_size;
- int filtloop;
- int keep_thresh=100;
-
- de.kernel_size=-1;
-
- if (curve <= 0.0) {
- fprintf(stderr,"estimator curve must be > 0\n");
- return(de);
- }
-
- if (max_rad < min_rad) {
- fprintf(stderr,"estimator must be larger than estimator_minimum.\n");
- fprintf(stderr,"(%f > %f) ? \n",max_rad,min_rad);
- return(de);
- }
-
- /* We should scale the filter width by the oversample */
- /* The '+1' comes from the assumed distance to the first pixel */
- comp_max_radius = max_rad*ss + 1;
- comp_min_radius = min_rad*ss + 1;
-
- /* Calculate how many filter kernels we need based on the decay function */
- /* */
- /* num filters = (de_max_width / de_min_width)^(1/estimator_curve) */
- /* */
- num_de_filters_d = pow( comp_max_radius/comp_min_radius, 1.0/curve );
- if (num_de_filters_d>1e7) {
- fprintf(stderr,"too many filters required in this configuration (%g)\n",num_de_filters_d);
- return(de);
- }
- num_de_filters = (int)ceil(num_de_filters_d);
-
- /* Condense the smaller kernels to save space */
- if (num_de_filters>keep_thresh) {
- de_max_ind = (int)ceil(DE_THRESH + pow(num_de_filters-DE_THRESH,curve))+1;
- de.max_filtered_counts = (int)pow( (double)(de_max_ind-DE_THRESH), 1.0/curve) + DE_THRESH;
- } else {
- de_max_ind = num_de_filters;
- de.max_filtered_counts = de_max_ind;
- }
-
- /* Allocate the memory for these filters */
- /* and the hit/width lookup vector */
- de_row_size = (int)(2*ceil(comp_max_radius)-1);
- de_half_size = (de_row_size-1)/2;
- de.kernel_size = (de_half_size+1)*(2+de_half_size)/2;
-
- de.filter_coefs = (double *) calloc (de_max_ind * de.kernel_size,sizeof(double));
- de.filter_widths = (double *) calloc (de_max_ind,sizeof(double));
-
- /* Generate the filter coefficients */
- de.max_filter_index = 0;
- for (filtloop=0;filtloop<de_max_ind;filtloop++) {
-
- double de_filt_sum=0.0, de_filt_d;
- double de_filt_h;
- int dej,dek;
- double adjloop;
- int filter_coef_idx;
-
- /* Calculate the filter width for this number of hits in a bin */
- if (filtloop<keep_thresh)
- de_filt_h = (comp_max_radius / pow(filtloop+1,curve));
- else {
- adjloop = pow(filtloop-keep_thresh,(1.0/curve)) + keep_thresh;
- de_filt_h = (comp_max_radius / pow(adjloop+1,curve));
- }
-
- /* Once we've reached the min radius, don't populate any more */
- if (de_filt_h <= comp_min_radius) {
- de_filt_h = comp_min_radius;
- de.max_filter_index = filtloop;
- }
-
- de.filter_widths[filtloop] = de_filt_h;
-
- /* Calculate norm of kernel separately (easier) */
- for (dej=-de_half_size; dej<=de_half_size; dej++) {
- for (dek=-de_half_size; dek<=de_half_size; dek++) {
-
- de_filt_d = sqrt( (double)(dej*dej+dek*dek) ) / de_filt_h;
-
- /* Only populate the coefs within this radius */
- if (de_filt_d <= 1.0) {
-
- /* Gaussian */
- de_filt_sum += flam3_spatial_filter(flam3_gaussian_kernel,
- flam3_spatial_support[flam3_gaussian_kernel]*de_filt_d);
-
- /* Epanichnikov */
-// de_filt_sum += (1.0 - (de_filt_d * de_filt_d));
- }
- }
- }
-
- filter_coef_idx = filtloop*de.kernel_size;
-
- /* Calculate the unique entries of the kernel */
- for (dej=0; dej<=de_half_size; dej++) {
- for (dek=0; dek<=dej; dek++) {
- de_filt_d = sqrt( (double)(dej*dej+dek*dek) ) / de_filt_h;
-
- /* Only populate the coefs within this radius */
- if (de_filt_d>1.0)
- de.filter_coefs[filter_coef_idx] = 0.0;
- else {
-
- /* Gaussian */
- de.filter_coefs[filter_coef_idx] = flam3_spatial_filter(flam3_gaussian_kernel,
- flam3_spatial_support[flam3_gaussian_kernel]*de_filt_d)/de_filt_sum;
-
- /* Epanichnikov */
-// de_filter_coefs[filter_coef_idx] = (1.0 - (de_filt_d * de_filt_d))/de_filt_sum;
- }
-
- filter_coef_idx ++;
- }
- }
-
- if (de.max_filter_index>0)
- break;
- }
-
- if (de.max_filter_index==0)
- de.max_filter_index = de_max_ind-1;
-
-
- return(de);
-}
-
-double flam3_create_temporal_filter(int numsteps, int filter_type, double filter_exp, double filter_width,
- double **temporal_filter, double **temporal_deltas) {
-
- double maxfilt = 0.0;
- double sumfilt = 0.0;
- double slpx,halfsteps;
- double *deltas, *filter;
-
- int i;
-
- /* Allocate memory - this must be freed in the calling routine! */
- deltas = (double *)malloc(numsteps*sizeof(double));
- filter = (double *)malloc(numsteps*sizeof(double));
-
- /* Deal with only one step */
- if (numsteps==1) {
- deltas[0] = 0;
- filter[0] = 1.0;
- *temporal_deltas = deltas;
- *temporal_filter = filter;
- return(1.0);
- }
-
- /* Define the temporal deltas */
- for (i = 0; i < numsteps; i++)
- deltas[i] = ((double)i /(double)(numsteps - 1) - 0.5)*filter_width;
-
- /* Define the filter coefs */
- if (flam3_temporal_exp == filter_type) {
-
- for (i=0; i < numsteps; i++) {
-
- if (filter_exp>=0)
- slpx = ((double)i+1.0)/numsteps;
- else
- slpx = (double)(numsteps - i)/numsteps;
-
- /* Scale the color based on these values */
- filter[i] = pow(slpx,fabs(filter_exp));
-
- /* Keep the max */
- if (filter[i]>maxfilt)
- maxfilt = filter[i];
- }
-
- } else if (flam3_temporal_gaussian == filter_type) {
-
- halfsteps = numsteps/2.0;
- for (i=0; i < numsteps; i++) {
-
- /* Gaussian */
- filter[i] = flam3_spatial_filter(flam3_gaussian_kernel,
- flam3_spatial_support[flam3_gaussian_kernel]*fabs(i - halfsteps)/halfsteps);
- /* Keep the max */
- if (filter[i]>maxfilt)
- maxfilt = filter[i];
- }
-
- } else { // (flam3_temporal_box)
-
- for (i=0; i < numsteps; i++)
- filter[i] = 1.0;
-
- maxfilt = 1.0;
-
- }
-
- /* Adjust the filter so that the max is 1.0, and */
- /* calculate the K2 scaling factor */
- for (i=0;i<numsteps;i++) {
- filter[i] /= maxfilt;
- sumfilt += filter[i];
- }
-
- sumfilt /= numsteps;
-
- *temporal_deltas = deltas;
- *temporal_filter = filter;
-
- return(sumfilt);
-}
-