Use floating point color values in [0,1]

Internal color representation is [0,1] now for every channel.

4 files changed, 37 insertions, 40 deletions

diff --git a/palettes.c b/palettes.c
index eb5700b..9251e93 100644
--- a/palettes.c
+++ b/palettes.c
@@ -58,9 +58,9 @@ static void parse_palettes(xmlNode *node) {
                   while (isspace( (int)val[c_idx]))
                      c_idx++;
 
-                  pal->colors[col_count][0] = r;
-                  pal->colors[col_count][1] = g;
-                  pal->colors[col_count][2] = b;
+                  pal->colors[col_count][0] = (double)r/255.0;
+                  pal->colors[col_count][1] = (double)g/255.0;
+                  pal->colors[col_count][2] = (double)b/255.0;
                   
                   col_count++;
                } while (col_count<count);
@@ -169,9 +169,9 @@ int flam3_get_palette(int n, flam3_palette c, double hue_rotation, randctx * con
             double4 rgb, hsv;
             
              rgb = (double4) {
-			       the_palettes[idx].colors[ii][0] / 255.0,
-				   the_palettes[idx].colors[ii][1] / 255.0,
-				   the_palettes[idx].colors[ii][2] / 255.0,
+			       the_palettes[idx].colors[ii][0],
+				   the_palettes[idx].colors[ii][1],
+				   the_palettes[idx].colors[ii][2],
 				   1.0,
 				   };
 	       
@@ -296,39 +296,39 @@ double4 flam3_calc_newrgb(double4 cbuf, double ls, double highpow) {
    
    /* Identify the most saturated channel */
    for (rgbi=0;rgbi<3;rgbi++) {
-      a = ls * (cbuf[rgbi]/PREFILTER_WHITE);
+      a = ls * (cbuf[rgbi]);
       if (a>maxa) {
          maxa = a;
-         maxc = cbuf[rgbi]/PREFILTER_WHITE;
+         maxc = cbuf[rgbi];
       }
    }
       
    /* If a channel is saturated and we have a non-negative highlight power */
    /* modify the color to prevent hue shift                                */
-   if (maxa>255 && highpow>=0.0) {
-      newls = 255.0/maxc;
+   if (maxa > 1.0 && highpow>=0.0) {
+      newls = 1.0/maxc;
       lsratio = pow(newls/ls,highpow);
 
       /* Calculate the max-value color (ranged 0 - 1) */
-	  double4 newrgb = newls*(cbuf/PREFILTER_WHITE)/255.0;
+	  double4 newrgb = newls*(cbuf);
 
       /* Reduce saturation by the lsratio */
       double4 newhsv = rgb2hsv(newrgb);
       newhsv[1] *= lsratio;
 
-      return hsv2rgb(newhsv) * 255.0;
+      return hsv2rgb(newhsv);
    } else {
-      newls = 255.0/maxc;
+      newls = 1.0/maxc;
       adjhlp = -highpow;
       if (adjhlp>1)
          adjhlp=1;
-      if (maxa<=255)
+      if (maxa<=1.0)
          adjhlp=1.0;
 
 	  /* Calculate the max-value color (ranged 0 - 1) interpolated with the old
 	   * behaviour */
 		
-      return ((1.0-adjhlp)*newls + adjhlp*ls)*(cbuf/PREFILTER_WHITE);
+      return ((1.0-adjhlp)*newls + adjhlp*ls)*(cbuf);
    }
 }
 
diff --git a/palettes.h b/palettes.h
index 97b9e94..3808f0c 100644
--- a/palettes.h
+++ b/palettes.h
@@ -23,7 +23,7 @@
 typedef struct {
     int number;
     char name[flam3_name_len];
-    unsigned char colors[256][3];
+    double colors[256][3];
 } lib_palette;
 
 #include "vector.h"
diff --git a/private.h b/private.h
index ff207e4..b568d8e 100644
--- a/private.h
+++ b/private.h
@@ -35,7 +35,6 @@
 
 #include <pthread.h>
 
-#define PREFILTER_WHITE 255
 #define EPS (1e-10)
 #define CMAP_SIZE 256
 #define CMAP_SIZE_M1 255
diff --git a/rect.c b/rect.c
index f06e382..5aee1d5 100644
--- a/rect.c
+++ b/rect.c
@@ -40,7 +40,6 @@
 /* allow this many iterations for settling into attractor */
 #define FUSE_27 15
 #define FUSE_28 100
-#define WHITE_LEVEL 255
 
 static void iter_thread(void *fth) {
    double sub_batch;
@@ -444,7 +443,7 @@ int render_rectangle(flam3_frame *spec, void *out,
          for (j = 0; j < CMAP_SIZE; j++) {
             dmap[j].index = cp.palette[(j * 256) / CMAP_SIZE].index / 256.0;
             for (k = 0; k < 4; k++)
-               dmap[j].color[k] = (cp.palette[(j * 256) / CMAP_SIZE].color[k] * WHITE_LEVEL) * color_scalar;
+               dmap[j].color[k] = cp.palette[(j * 256) / CMAP_SIZE].color[k] * color_scalar;
          }
 
          /* compute camera */
@@ -583,11 +582,11 @@ int render_rectangle(flam3_frame *spec, void *out,
 
       }
 
-      k1 =(cp.contrast * cp.brightness *
-      PREFILTER_WHITE * 268.0 * batch_filter[batch_num]) / 256;
+	  /* XXX: the original formula has a factor 268/256 in here, not sure why */
+      k1 = cp.contrast * cp.brightness * batch_filter[batch_num];
       area = image_width * image_height / (ppux * ppuy);
       k2 = (oversample * oversample * nbatches) /
-             (cp.contrast * area * WHITE_LEVEL * sample_density * sumfilt);
+             (cp.contrast * area * sample_density * sumfilt);
 #if 0
       printf("iw=%d,ih=%d,ppux=%f,ppuy=%f\n",image_width,image_height,ppux,ppuy);
       printf("contrast=%f, brightness=%f, PREFILTER=%d, temporal_filter=%f\n",
@@ -630,9 +629,9 @@ int render_rectangle(flam3_frame *spec, void *out,
       double linrange = cp.gam_lin_thresh;
 
       vibrancy /= vib_gam_n;
-      background[0] /= vib_gam_n/256.0;
-      background[1] /= vib_gam_n/256.0;
-      background[2] /= vib_gam_n/256.0;
+      background[0] /= vib_gam_n;
+      background[1] /= vib_gam_n;
+      background[2] /= vib_gam_n;
       
       /* If we're in the early clip mode, perform this first step to  */
       /* apply the gamma correction and clipping before the spat filt */
@@ -647,9 +646,9 @@ int render_rectangle(flam3_frame *spec, void *out,
                   alpha = 0.0;
                   ls = 0.0;
                } else {
-                  tmp=ac[3]/PREFILTER_WHITE;
+                  tmp=ac[3];
                   alpha = flam3_calc_alpha(tmp,g,linrange);
-                  ls = vibrancy * 256.0 * alpha / tmp;
+                  ls = vibrancy * alpha / tmp;
                   if (alpha<0.0) alpha = 0.0;
                   if (alpha>1.0) alpha = 1.0;
                }
@@ -660,7 +659,7 @@ int render_rectangle(flam3_frame *spec, void *out,
                   
                for (rgbi=0;rgbi<3;rgbi++) {
                   a = newrgb[rgbi];
-                  a += (1.0-vibrancy) * 256.0 * pow( t[rgbi] / PREFILTER_WHITE, g);
+                  a += (1.0-vibrancy) * pow( t[rgbi], g);
                   if (nchan<=3 || transp==0)
                      a += ((1.0 - alpha) * background[rgbi]);
                   else {
@@ -671,7 +670,7 @@ int render_rectangle(flam3_frame *spec, void *out,
                   }
 
                   /* Clamp here to ensure proper filter functionality */
-                  if (a>255) a = 255;
+                  if (a>1.0) a = 1.0;
                   if (a<0) a = 0;
                
                   /* Replace values in accumulation buffer with these new ones */
@@ -718,14 +717,14 @@ int render_rectangle(flam3_frame *spec, void *out,
             /* The old way, spatial filter first and then clip after gamma */
             if (!spec->earlyclip) {
             
-               tmp=t[3]/PREFILTER_WHITE;
+               tmp=t[3];
                
                if (t[3]<=0) {
                   alpha = 0.0;
                   ls = 0.0;
                } else { 
                   alpha = flam3_calc_alpha(tmp,g,linrange);
-                  ls = vibrancy * 256.0 * alpha / tmp;
+                  ls = vibrancy * alpha / tmp;
                   if (alpha<0.0) alpha = 0.0;
                   if (alpha>1.0) alpha = 1.0;
                }
@@ -734,7 +733,7 @@ int render_rectangle(flam3_frame *spec, void *out,
 
                for (rgbi=0;rgbi<3;rgbi++) {
                   a = newrgb[rgbi];
-                  a += (1.0-vibrancy) * 256.0 * pow( t[rgbi] / PREFILTER_WHITE, g);
+                  a += (1.0-vibrancy) * pow( t[rgbi], g);
                   if (nchan<=3 || transp==0)
                      a += ((1.0 - alpha) * background[rgbi]);
                   else {
@@ -745,7 +744,7 @@ int render_rectangle(flam3_frame *spec, void *out,
                   }
 
                   /* Clamp here to ensure proper filter functionality */
-                  if (a>255) a = 255;
+                  if (a>1.0) a = 1.0;
                   if (a<0) a = 0;
                
                   /* Replace values in accumulation buffer with these new ones */
@@ -758,16 +757,15 @@ int render_rectangle(flam3_frame *spec, void *out,
 
                a = t[rgbi];
 
-               if (a > 255)
-                  a = 255;
+               if (a > 1.0)
+                  a = 1.0;
                if (a < 0)
                   a = 0;
                
                if (2==bytes_per_channel) {
-                  a *= 256.0; /* Scales to [0-65280] */
-                  p16[rgbi] = (unsigned short) a;
+                  p16[rgbi] = nearbyint (a * 65535.0);
                } else {
-                  p8[rgbi] = (unsigned char) a;
+                  p8[rgbi] = nearbyint (a * 255.0);
                }
             }
 
@@ -781,9 +779,9 @@ int render_rectangle(flam3_frame *spec, void *out,
             if (nchan>3) {
                if (transp==1) {
                   if (2==bytes_per_channel)
-                     p16[3] = (unsigned short) (t[3] * 65535);
+                     p16[3] = nearbyint (t[3] * 65535.0);
                   else
-                     p8[3] = (unsigned char) (t[3] * 255);
+                     p8[3] = nearbyint (t[3] * 255);
                } else {
                   if (2==bytes_per_channel)
                      p16[3] = 65535;