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I found some more possible improvements for performance...


git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@1142 416bcca6-2ee7-4201-b75f-2eb2f807beb1
This commit is contained in:
Adrien Destugues 2009-11-02 19:27:12 +00:00
parent 7efea41231
commit db8111373d
1 changed files with 171 additions and 98 deletions
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267
op_c.c
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@ -28,6 +28,8 @@
#include "op_c.h" #include "op_c.h"
#include "errors.h" #include "errors.h"
/// Convert RGB to HSL.
/// Both input and output are in the 0..255 range to use in the palette screen
void RGB_to_HSL(int r,int g,int b,byte * hr,byte * sr,byte* lr) void RGB_to_HSL(int r,int g,int b,byte * hr,byte * sr,byte* lr)
{ {
double rd,gd,bd,h,s,l,max,min; double rd,gd,bd,h,s,l,max,min;
@ -37,9 +39,6 @@ void RGB_to_HSL(int r,int g,int b,byte * hr,byte * sr,byte* lr)
gd = g / 255.0; gd = g / 255.0;
bd = b / 255.0; bd = b / 255.0;
// compute L
// l=(rd*0.30)+(gd*0.59)+(bd*0.11);
// compute maximum of rd,gd,bd // compute maximum of rd,gd,bd
if (rd>=gd) if (rd>=gd)
{ {
@ -97,6 +96,8 @@ void RGB_to_HSL(int r,int g,int b,byte * hr,byte * sr,byte* lr)
*sr = (s*255.0); *sr = (s*255.0);
} }
/// Convert HSL back to RGB
/// Input and output are all in range 0..255
void HSL_to_RGB(byte h,byte s,byte l, byte* r, byte* g, byte* b) void HSL_to_RGB(byte h,byte s,byte l, byte* r, byte* g, byte* b)
{ {
float rf =0 ,gf = 0,bf = 0; float rf =0 ,gf = 0,bf = 0;
@ -162,10 +163,14 @@ void HSL_to_RGB(byte h,byte s,byte l, byte* r, byte* g, byte* b)
*b = bf * (255); *b = bf * (255);
} }
///////////////////////////////////////////////////////////////////////////// // Conversion table handlers
///////////////////////////// Méthodes de gestion des tables de conversion // // The conversion table is built after a run of the median cut algorithm and is
///////////////////////////////////////////////////////////////////////////// // used to find the best color index for a given (RGB) color. GIMP avoids
// creating the whole table and only create parts of it when they are actually
// needed. This may or may not be faster
/// Creates a new conversion table
/// params: bumber of bits for R, G, B (precision)
T_Conversion_table * CT_new(int nbb_r,int nbb_g,int nbb_b) T_Conversion_table * CT_new(int nbb_r,int nbb_g,int nbb_b)
{ {
T_Conversion_table * n; T_Conversion_table * n;
@ -174,31 +179,34 @@ T_Conversion_table * CT_new(int nbb_r,int nbb_g,int nbb_b)
n=(T_Conversion_table *)malloc(sizeof(T_Conversion_table)); n=(T_Conversion_table *)malloc(sizeof(T_Conversion_table));
if (n!=NULL) if (n!=NULL)
{ {
// On recopie les paramŠtres demand‚s // Copy the passed parameters
n->nbb_r=nbb_r; n->nbb_r=nbb_r;
n->nbb_g=nbb_g; n->nbb_g=nbb_g;
n->nbb_b=nbb_b; n->nbb_b=nbb_b;
// On calcule les autres // Calculate the others
// Value ranges (max value actually)
n->rng_r=(1<<nbb_r); n->rng_r=(1<<nbb_r);
n->rng_g=(1<<nbb_g); n->rng_g=(1<<nbb_g);
n->rng_b=(1<<nbb_b); n->rng_b=(1<<nbb_b);
// Shifts
n->dec_r=nbb_g+nbb_b; n->dec_r=nbb_g+nbb_b;
n->dec_g=nbb_b; n->dec_g=nbb_b;
n->dec_b=0; n->dec_b=0;
// Reductions (how many bits are lost)
n->red_r=8-nbb_r; n->red_r=8-nbb_r;
n->red_g=8-nbb_g; n->red_g=8-nbb_g;
n->red_b=8-nbb_b; n->red_b=8-nbb_b;
// On tente d'allouer la table // Allocate the table
size=(n->rng_r)*(n->rng_g)*(n->rng_b); size=(n->rng_r)*(n->rng_g)*(n->rng_b);
n->table=(byte *)malloc(size); n->table=(byte *)malloc(size, 1);
if (n->table!=NULL) if (n->table == NULL)
// C'est bon!
memset(n->table,0,size); // Inutile, mais plus propre
else
{ {
// Table impossible … allouer // Not enough memory
free(n); free(n);
n=NULL; n=NULL;
} }
@ -207,27 +215,33 @@ T_Conversion_table * CT_new(int nbb_r,int nbb_g,int nbb_b)
return n; return n;
} }
/// Delete a conversion table and release its memory
void CT_delete(T_Conversion_table * t) void CT_delete(T_Conversion_table * t)
{ {
free(t->table); free(t->table);
free(t); free(t);
} }
/// Get the best palette index for an (R, G, B) color
byte CT_get(T_Conversion_table * t,int r,int g,int b) byte CT_get(T_Conversion_table * t,int r,int g,int b)
{ {
int index; int index;
// On réduit le nombre de bits par couleur // Reduce the number of bits to the table precision
r=(r>>t->red_r); r=(r>>t->red_r);
g=(g>>t->red_g); g=(g>>t->red_g);
b=(b>>t->red_b); b=(b>>t->red_b);
// On recherche la couleur la plus proche dans la table de conversion // Find the nearest color
index=(r<<t->dec_r) | (g<<t->dec_g) | (b<<t->dec_b); index=(r<<t->dec_r) | (g<<t->dec_g) | (b<<t->dec_b);
return t->table[index]; return t->table[index];
} }
/// Set an entry of the table, index (RGB), value i
void CT_set(T_Conversion_table * t,int r,int g,int b,byte i) void CT_set(T_Conversion_table * t,int r,int g,int b,byte i)
{ {
int index; int index;
@ -237,19 +251,21 @@ void CT_set(T_Conversion_table * t,int r,int g,int b,byte i)
} }
// Handlers for the occurences tables
// This table is used to count the occurence of an (RGB) pixel value in the
// source 24bit image. These count are then used by the median cut algorithm to
// decide which cluster to split.
///////////////////////////////////////////////////////////////////////////// /// Initialize an occurence table
/////////////////////////////// M‚thodes de gestion des tables d'occurence //
/////////////////////////////////////////////////////////////////////////////
void OT_init(T_Occurrence_table * t) void OT_init(T_Occurrence_table * t)
{ {
int size; int size;
size=(t->rng_r)*(t->rng_g)*(t->rng_b)*sizeof(int); size=(t->rng_r)*(t->rng_g)*(t->rng_b)*sizeof(int);
memset(t->table,0,size); // On initialise … 0 memset(t->table,0,size); // Set it to 0
} }
/// Allocate an occurence table for given number of bits
T_Occurrence_table * OT_new(int nbb_r,int nbb_g,int nbb_b) T_Occurrence_table * OT_new(int nbb_r,int nbb_g,int nbb_b)
{ {
T_Occurrence_table * n; T_Occurrence_table * n;
@ -258,12 +274,12 @@ T_Occurrence_table * OT_new(int nbb_r,int nbb_g,int nbb_b)
n=(T_Occurrence_table *)malloc(sizeof(T_Occurrence_table)); n=(T_Occurrence_table *)malloc(sizeof(T_Occurrence_table));
if (n!=0) if (n!=0)
{ {
// On recopie les paramŠtres demand‚s // Copy passed parameters
n->nbb_r=nbb_r; n->nbb_r=nbb_r;
n->nbb_g=nbb_g; n->nbb_g=nbb_g;
n->nbb_b=nbb_b; n->nbb_b=nbb_b;
// On calcule les autres // Compute others
n->rng_r=(1<<nbb_r); n->rng_r=(1<<nbb_r);
n->rng_g=(1<<nbb_g); n->rng_g=(1<<nbb_g);
n->rng_b=(1<<nbb_b); n->rng_b=(1<<nbb_b);
@ -274,15 +290,12 @@ T_Occurrence_table * OT_new(int nbb_r,int nbb_g,int nbb_b)
n->red_g=8-nbb_g; n->red_g=8-nbb_g;
n->red_b=8-nbb_b; n->red_b=8-nbb_b;
// On tente d'allouer la table // Allocate the table
size=(n->rng_r)*(n->rng_g)*(n->rng_b)*sizeof(int); size=(n->rng_r)*(n->rng_g)*(n->rng_b)*sizeof(int);
n->table=(int *)malloc(size); n->table=(int *)calloc(size, 1);
if (n->table!=0) if (n->table == NULL)
// C'est bon! On initialise … 0
OT_init(n);
else
{ {
// Table impossible … allouer // Not enough memory !
free(n); free(n);
n=0; n=0;
} }
@ -291,31 +304,42 @@ T_Occurrence_table * OT_new(int nbb_r,int nbb_g,int nbb_b)
return n; return n;
} }
/// Delete a table and free the memory
void OT_delete(T_Occurrence_table * t) void OT_delete(T_Occurrence_table * t)
{ {
free(t->table); free(t->table);
free(t); free(t);
} }
/// Get number of occurences for a given color
int OT_get(T_Occurrence_table * t, int r, int g, int b) int OT_get(T_Occurrence_table * t, int r, int g, int b)
{ {
int index; int index;
// Drop bits as needed
index=(r<<t->dec_r) | (g<<t->dec_g) | (b<<t->dec_b); index=(r<<t->dec_r) | (g<<t->dec_g) | (b<<t->dec_b);
return t->table[index]; return t->table[index];
} }
/// Add 1 to the count for a color
void OT_inc(T_Occurrence_table * t,int r,int g,int b) void OT_inc(T_Occurrence_table * t,int r,int g,int b)
{ {
int index; int index;
// Drop bits as needed
r=(r>>t->red_r); r=(r>>t->red_r);
g=(g>>t->red_g); g=(g>>t->red_g);
b=(b>>t->red_b); b=(b>>t->red_b);
// Compute the address
index=(r<<t->dec_r) | (g<<t->dec_g) | (b<<t->dec_b); index=(r<<t->dec_r) | (g<<t->dec_g) | (b<<t->dec_b);
t->table[index]++; t->table[index]++;
} }
/// Count the use of each color in a 24bit picture and fill in the table
void OT_count_occurrences(T_Occurrence_table* t, T_Bitmap24B image, int size) void OT_count_occurrences(T_Occurrence_table* t, T_Bitmap24B image, int size)
{ {
T_Bitmap24B ptr; T_Bitmap24B ptr;
@ -325,11 +349,13 @@ void OT_count_occurrences(T_Occurrence_table* t, T_Bitmap24B image, int size)
OT_inc(t, ptr->R, ptr->G, ptr->B); OT_inc(t, ptr->R, ptr->G, ptr->B);
} }
/// Count the total number of pixels in an occurence table
int OT_count_colors(T_Occurrence_table * t) int OT_count_colors(T_Occurrence_table * t)
{ {
int val; // Valeur de retour int val; // Computed return value
int nb; // Nombre de couleurs … tester int nb; // Number of colors to test
int i; // Compteur de couleurs test‚es int i; // Loop index
val = 0; val = 0;
nb=(t->rng_r)*(t->rng_g)*(t->rng_b); nb=(t->rng_r)*(t->rng_g)*(t->rng_b);
@ -341,25 +367,41 @@ int OT_count_colors(T_Occurrence_table * t)
} }
// Cluster management
// Clusters are boxes in the RGB spaces, defined by 6 corner coordinates :
// Rmax, Rmin, Vmax (or Gmax), Vmin, Rmax, Rmin
// The median cut algorithm start with a single cluster covering the whole
// colorspace then split it in two smaller clusters on the longest axis until
// there are 256 non-empty clusters (with some tricks if the original image
// actually has less than 256 colors)
// Each cluster also store the number of pixels that are inside and the
// rmin, rmax, vmin, vmax, bmin, bmax values are the first/last values that
// actually are used by a pixel in the cluster
// When you split a big cluster there may be some space between the splitting
// plane and the first pixel actually in a cluster
/////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////// M‚thodes de gestion des clusters //
/////////////////////////////////////////////////////////////////////////////
/// Pack a cluster, ie compute its {r,v,b}{min,max} values
void Cluster_pack(T_Cluster * c,T_Occurrence_table * to) void Cluster_pack(T_Cluster * c,T_Occurrence_table * to)
{ {
int rmin,rmax,vmin,vmax,bmin,bmax; int rmin,rmax,vmin,vmax,bmin,bmax;
int r,g,b; int r,g,b;
// On cherche les mins et les maxs de chaque composante sur la couverture // Find min. and max. values actually used for each component in this cluster
// int nbocc; // Pre-shift everything to avoid using OT_Get and be faster. This will only
// work if the occurence table actually has full precision, that is a
// On prédécale tout pour éviter de faire trop de bazar en se forçant à utiliser OT_get, plus rapide // 256^3*sizeof(int) = 64MB table. If your computer has less free ram and
// malloc fails, this will not work at all !
// GIMP use only 6 bits for G and B components in this table.
rmin=c->rmax <<16; rmax=c->rmin << 16; rmin=c->rmax <<16; rmax=c->rmin << 16;
vmin=c->vmax << 8; vmax=c->vmin << 8; vmin=c->vmax << 8; vmax=c->vmin << 8;
bmin=c->bmax; bmax=c->bmin; bmin=c->bmax; bmax=c->bmin;
c->occurences=0; c->occurences=0;
// Unoptimized code kept here for documentation purpose because the optimized
// one is unreadable : run over the whole cluster and find the min and max,
// and count the occurences at the same time.
/* /*
for (r=c->rmin<<16;r<=c->rmax<<16;r+=1<<16) for (r=c->rmin<<16;r<=c->rmax<<16;r+=1<<16)
for (g=c->vmin<<8;g<=c->vmax<<8;g+=1<<8) for (g=c->vmin<<8;g<=c->vmax<<8;g+=1<<8)
@ -379,9 +421,9 @@ void Cluster_pack(T_Cluster * c,T_Occurrence_table * to)
} }
*/ */
// On recherche le minimum et le maximum en parcourant le cluster selon chaque composante, // Optimized version : find the extremums one at a time, so we can reduce the
// ça évite des accès mémoires inutiles, de plus chaque boucle est plus petite que la // area to seek for the next one. Start at the edges of the cluster and go to
// précédente puisqu'on connait une borne supplémentaire // the center until we find a pixel.
for(r=c->rmin<<16;r<=c->rmax<<16;r+=1<<16) for(r=c->rmin<<16;r<=c->rmax<<16;r+=1<<16)
for(g=c->vmin<<8;g<=c->vmax<<8;g+=1<<8) for(g=c->vmin<<8;g<=c->vmax<<8;g+=1<<8)
@ -449,7 +491,8 @@ BMAX:
} }
} }
ENDCRUSH: ENDCRUSH:
// Il faut quand même parcourir la partie utile du cluster, pour savoir combien il y a d'occurences // We still need to seek the internal part of the cluster to count pixels
// inside it
for(r=rmin;r<=rmax;r+=1<<16) for(r=rmin;r<=rmax;r+=1<<16)
for(g=vmin;g<=vmax;g+=1<<8) for(g=vmin;g<=vmax;g+=1<<8)
for(b=bmin;b<=bmax;b++) for(b=bmin;b<=bmax;b++)
@ -457,11 +500,14 @@ ENDCRUSH:
c->occurences+=to->table[r + g + b]; // OT_get c->occurences+=to->table[r + g + b]; // OT_get
} }
// Unshift the values and put them in the cluster info
c->rmin=rmin>>16; c->rmax=rmax>>16; c->rmin=rmin>>16; c->rmax=rmax>>16;
c->vmin=vmin>>8; c->vmax=vmax>>8; c->vmin=vmin>>8; c->vmax=vmax>>8;
c->bmin=bmin; c->bmax=bmax; c->bmin=bmin; c->bmax=bmax;
// On regarde la composante qui a la variation la plus grande // Find the longest axis to know which way to split the cluster
// This multiplications are supposed to improve the result, but may or may not
// work, actually.
r=(c->rmax-c->rmin)*299; r=(c->rmax-c->rmin)*299;
g=(c->vmax-c->vmin)*587; g=(c->vmax-c->vmin)*587;
b=(c->bmax-c->bmin)*114; b=(c->bmax-c->bmin)*114;
@ -496,6 +542,9 @@ ENDCRUSH:
} }
} }
/// Split a cluster on its longest axis.
/// c = source cluster, c1, c2 = output after split
void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue, void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
T_Occurrence_table * to) T_Occurrence_table * to)
{ {
@ -503,10 +552,12 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
int cumul; int cumul;
int r, g, b; int r, g, b;
// Split criterion: each of the cluster will have the same number of pixels
limit = c->occurences / 2; limit = c->occurences / 2;
cumul = 0; cumul = 0;
if (hue == 0) if (hue == 0) // split on red
{ {
// Run over the cluster until we reach the requested number of pixels
for (r = c->rmin<<16; r<=c->rmax<<16; r+=1<<16) for (r = c->rmin<<16; r<=c->rmax<<16; r+=1<<16)
{ {
for (g = c->vmin<<8; g<=c->vmax<<8; g+=1<<8) for (g = c->vmin<<8; g<=c->vmax<<8; g+=1<<8)
@ -527,9 +578,11 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
r>>=16; r>>=16;
g>>=8; g>>=8;
// We tried to split on red, but found half of the pixels with r = rmin
// so we enforce some split to happen anyway, instead of creating an empty
// c2 and c1 == c
if (r==c->rmin) if (r==c->rmin)
r++; r++;
// R est la valeur de d‚but du 2nd cluster
c1->Rmin=c->Rmin; c1->Rmax=r-1; c1->Rmin=c->Rmin; c1->Rmax=r-1;
c1->rmin=c->rmin; c1->rmax=r-1; c1->rmin=c->rmin; c1->rmax=r-1;
@ -546,7 +599,7 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
c2->bmin=c->bmin; c2->bmax=c->bmax; c2->bmin=c->bmin; c2->bmax=c->bmax;
} }
else else
if (hue==1) if (hue==1) // split on green
{ {
for (g=c->vmin<<8;g<=c->vmax<<8;g+=1<<8) for (g=c->vmin<<8;g<=c->vmax<<8;g+=1<<8)
@ -570,7 +623,6 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
if (g==c->vmin) if (g==c->vmin)
g++; g++;
// G est la valeur de d‚but du 2nd cluster
c1->Rmin=c->Rmin; c1->Rmax=c->Rmax; c1->Rmin=c->Rmin; c1->Rmax=c->Rmax;
c1->rmin=c->rmin; c1->rmax=c->rmax; c1->rmin=c->rmin; c1->rmax=c->rmax;
@ -586,7 +638,7 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
c2->Bmin=c->Bmin; c2->Bmax=c->Bmax; c2->Bmin=c->Bmin; c2->Bmax=c->Bmax;
c2->bmin=c->bmin; c2->bmax=c->bmax; c2->bmin=c->bmin; c2->bmax=c->bmax;
} }
else else // split on blue
{ {
for (b=c->bmin;b<=c->bmax;b++) for (b=c->bmin;b<=c->bmax;b++)
@ -610,7 +662,6 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
if (b==c->bmin) if (b==c->bmin)
b++; b++;
// B est la valeur de d‚but du 2nd cluster
c1->Rmin=c->Rmin; c1->Rmax=c->Rmax; c1->Rmin=c->Rmin; c1->Rmax=c->Rmax;
c1->rmin=c->rmin; c1->rmax=c->rmax; c1->rmin=c->rmin; c1->rmax=c->rmax;
@ -628,6 +679,8 @@ void Cluster_split(T_Cluster * c, T_Cluster * c1, T_Cluster * c2, int hue,
} }
} }
/// Compute the mean R, G, B (for palette generation) and H, L (for palette sorting)
void Cluster_compute_hue(T_Cluster * c,T_Occurrence_table * to) void Cluster_compute_hue(T_Cluster * c,T_Occurrence_table * to)
{ {
int cumul_r,cumul_g,cumul_b; int cumul_r,cumul_g,cumul_b;
@ -657,10 +710,11 @@ void Cluster_compute_hue(T_Cluster * c,T_Occurrence_table * to)
} }
// Cluster set management
// A set of clusters in handled as a list, the median cut algorithm pops a
// cluster from the list, split it, and pushes back the two splitted clusters
// until the lit grows to 256 items
/////////////////////////////////////////////////////////////////////////////
//////////////////////////// M‚thodes de gestion des ensembles de clusters //
/////////////////////////////////////////////////////////////////////////////
// Debug helper : check if a cluster set has the right count value // Debug helper : check if a cluster set has the right count value
/* /*
@ -679,6 +733,7 @@ void CS_Check(T_Cluster_set* cs)
*/ */
/// Setup the first cluster before we start the operations /// Setup the first cluster before we start the operations
/// This one covers the full palette range
void CS_Init(T_Cluster_set * cs, T_Occurrence_table * to) void CS_Init(T_Cluster_set * cs, T_Occurrence_table * to)
{ {
cs->clusters->Rmin = cs->clusters->rmin = 0; cs->clusters->Rmin = cs->clusters->rmin = 0;
@ -700,25 +755,23 @@ T_Cluster_set * CS_New(int nbmax, T_Occurrence_table * to)
n=(T_Cluster_set *)malloc(sizeof(T_Cluster_set)); n=(T_Cluster_set *)malloc(sizeof(T_Cluster_set));
if (n != NULL) if (n != NULL)
{ {
// On recopie les paramŠtres demand‚s // Copy requested params
n->nb_max = OT_count_colors(to); n->nb_max = OT_count_colors(to);
// On vient de compter le nombre de couleurs existantes, s'il est plus grand // If the number of colors asked is > 256, we ceil it because we know we
// que 256 on limite à 256 // don't want more
// (nombre de couleurs voulu au final)
if (n->nb_max > nbmax) if (n->nb_max > nbmax)
{ {
n->nb_max = nbmax; n->nb_max = nbmax;
} }
// On tente d'allouer le premier cluster // Allocate the first cluster
n->clusters=(T_Cluster *)malloc(sizeof(T_Cluster)); n->clusters=(T_Cluster *)malloc(sizeof(T_Cluster));
if (n->clusters != NULL) if (n->clusters != NULL)
// C'est bon! On initialise
CS_Init(n, to); CS_Init(n, to);
else else
{ {
// Table impossible … allouer // No memory free ! Sorry !
free(n); free(n);
n = NULL; n = NULL;
} }
@ -740,12 +793,18 @@ void CS_Delete(T_Cluster_set * cs)
free(cs); free(cs);
} }
/// Pop a cluster from the cluster list
void CS_Get(T_Cluster_set * cs, T_Cluster * c) void CS_Get(T_Cluster_set * cs, T_Cluster * c)
{ {
T_Cluster* current = cs->clusters; T_Cluster* current = cs->clusters;
T_Cluster* prev = NULL; T_Cluster* prev = NULL;
// Search a cluster with at least 2 distinct colors so we can split it // Search a cluster with at least 2 distinct colors so we can split it
// Clusters are sorted by number of occurences, so a cluster may end up
// with a lot of pixelsand on top of the list, but only one color. We can't
// split it in that case. It should probably be stored on a list of unsplittable
// clusters to avoid running on it again on each iteration.
do do
{ {
if ( (current->rmin < current->rmax) || if ( (current->rmin < current->rmax) ||
@ -771,12 +830,14 @@ void CS_Get(T_Cluster_set * cs, T_Cluster * c)
current = NULL; current = NULL;
} }
/// Push a cluster in the list
void CS_Set(T_Cluster_set * cs,T_Cluster * c) void CS_Set(T_Cluster_set * cs,T_Cluster * c)
{ {
T_Cluster* current = cs->clusters; T_Cluster* current = cs->clusters;
T_Cluster* prev = NULL; T_Cluster* prev = NULL;
// Search the first cluster that is smaller than ours // Search the first cluster that is smaller than ours (less pixels)
while (current && current->occurences > c->occurences) while (current && current->occurences > c->occurences)
{ {
prev = current; prev = current;
@ -795,41 +856,44 @@ void CS_Set(T_Cluster_set * cs,T_Cluster * c)
cs->nb++; cs->nb++;
} }
// Détermination de la meilleure palette en utilisant l'algo Median Cut : /// This is the main median cut algorithm and the function actually called to
// 1) On considère l'espace (R,G,B) comme 1 boîte /// reduce the palette. We get the number of pixels for each collor in the
// 2) On cherche les extrêmes de la boîte en (R,G,B) /// occurence table and generate the cluster set from it.
// 3) On trie les pixels de l'image selon l'axe le plus long parmi (R,G,B) // 1) RGB space is a big box
// 4) On coupe la boîte en deux au milieu, et on compacte pour que chaque bord // 2) We seek the pixels with extreme values
// corresponde bien à un pixel extreme // 3) We split the box in 2 parts on its longest axis
// 5) On recommence à couper selon le plus grand axe toutes boîtes confondues // 4) We pack the 2 resulting boxes again to leave no empty space between the box border and the first pixel
// 6) On s'arrête quand on a le nombre de couleurs voulu // 5) We take the box with the biggest number of pixels inside and we split it again
// 6) Iterate until there are 256 boxes. Associate each of them to its middle color
void CS_Generate(T_Cluster_set * cs, T_Occurrence_table * to) void CS_Generate(T_Cluster_set * cs, T_Occurrence_table * to)
{ {
T_Cluster current; T_Cluster current;
T_Cluster Nouveau1; T_Cluster Nouveau1;
T_Cluster Nouveau2; T_Cluster Nouveau2;
// Tant qu'on a moins de 256 clusters // There are less than 256 boxes
while (cs->nb<cs->nb_max) while (cs->nb<cs->nb_max)
{ {
// On récupère le plus grand cluster // Get the biggest one
CS_Get(cs,&current); CS_Get(cs,&current);
// On le coupe en deux // Split it
Cluster_split(&current, &Nouveau1, &Nouveau2, current.plus_large, to); Cluster_split(&current, &Nouveau1, &Nouveau2, current.plus_large, to);
// On compacte ces deux nouveaux (il peut y avoir un espace entre l'endroit // Pack the 2 new clusters (the split may leave some empty space between the
// de la coupure et les premiers pixels du cluster) // box border and the first actual pixel)
Cluster_pack(&Nouveau1, to); Cluster_pack(&Nouveau1, to);
Cluster_pack(&Nouveau2, to); Cluster_pack(&Nouveau2, to);
// On les remet dans le set // Put them back in the list
CS_Set(cs,&Nouveau1); CS_Set(cs,&Nouveau1);
CS_Set(cs,&Nouveau2); CS_Set(cs,&Nouveau2);
} }
} }
/// Compute the color associated to each box in the list
void CS_Compute_colors(T_Cluster_set * cs, T_Occurrence_table * to) void CS_Compute_colors(T_Cluster_set * cs, T_Occurrence_table * to)
{ {
T_Cluster * c; T_Cluster * c;
@ -838,6 +902,11 @@ void CS_Compute_colors(T_Cluster_set * cs, T_Occurrence_table * to)
Cluster_compute_hue(c,to); Cluster_compute_hue(c,to);
} }
// We sort the clusters on two criterions to get a somewhat coherent palette.
// TODO : It would be better to do this in one single pass.
/// Sort the clusters by chrominance value
void CS_Sort_by_chrominance(T_Cluster_set * cs) void CS_Sort_by_chrominance(T_Cluster_set * cs)
{ {
T_Cluster* nc; T_Cluster* nc;
@ -866,10 +935,12 @@ void CS_Sort_by_chrominance(T_Cluster_set * cs)
prev = NULL; prev = NULL;
} }
// Put the new list bavk in place // Put the new list back in place
cs->clusters = newlist; cs->clusters = newlist;
} }
/// Sort the clusters by luminance value
void CS_Sort_by_luminance(T_Cluster_set * cs) void CS_Sort_by_luminance(T_Cluster_set * cs)
{ {
T_Cluster* nc; T_Cluster* nc;
@ -903,6 +974,8 @@ void CS_Sort_by_luminance(T_Cluster_set * cs)
cs->clusters = newlist; cs->clusters = newlist;
} }
/// Generates the palette from the clusters, then the conversion table to map (RGB) to a palette index
void CS_Generate_color_table_and_palette(T_Cluster_set * cs,T_Conversion_table * tc,T_Components * palette) void CS_Generate_color_table_and_palette(T_Cluster_set * cs,T_Conversion_table * tc,T_Components * palette)
{ {
int index; int index;
@ -1028,8 +1101,7 @@ void GS_Generate(T_Gradient_set * ds,T_Cluster_set * cs)
} }
/// Compute best palette for given picture.
T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size, T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size,
T_Components * palette, int r, int g, int b) T_Components * palette, int r, int g, int b)
{ {
@ -1038,7 +1110,7 @@ T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size,
T_Cluster_set * cs; T_Cluster_set * cs;
T_Gradient_set * ds; T_Gradient_set * ds;
// Création des éléments nécessaires au calcul de palette optimisée: // Allocate all the elements
to = 0; tc = 0; cs = 0; ds = 0; to = 0; tc = 0; cs = 0; ds = 0;
to = OT_new(r, g, b); to = OT_new(r, g, b);
@ -1052,7 +1124,7 @@ T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size,
return 0; return 0;
} }
// Première étape : on compte les pixels de chaque couleur pour pouvoir trier là dessus // Count pixels for each color
OT_count_occurrences(to, image, size); OT_count_occurrences(to, image, size);
cs = CS_New(256, to); cs = CS_New(256, to);
@ -1063,13 +1135,13 @@ T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size,
return 0; return 0;
} }
//CS_Check(cs); //CS_Check(cs);
// C'est bon, on a pu tout allouer // Ok, everything was allocated
// On génère les clusters (avec l'algo du median cut) // Generate the cluster set with median cut algorithm
CS_Generate(cs, to); CS_Generate(cs, to);
//CS_Check(cs); //CS_Check(cs);
// On calcule la teinte de chaque pixel (Luminance et chrominance) // Compute the color data for each cluster (palette entry + HL)
CS_Compute_colors(cs, to); CS_Compute_colors(cs, to);
//CS_Check(cs); //CS_Check(cs);
@ -1079,15 +1151,13 @@ T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size,
GS_Generate(ds, cs); GS_Generate(ds, cs);
GS_Delete(ds); GS_Delete(ds);
} }
// Enfin on trie les clusters (donc les couleurs de la palette) dans un ordre // Sort the clusters on L and H to get a nice palette
// sympa : par couleur, et par luminosité pour chaque couleur
CS_Sort_by_luminance(cs); CS_Sort_by_luminance(cs);
//CS_Check(cs); //CS_Check(cs);
CS_Sort_by_chrominance(cs); CS_Sort_by_chrominance(cs);
//CS_Check(cs); //CS_Check(cs);
// Enfin on génère la palette et la table de correspondance entre chaque // And finally generate the conversion table to map RGB > pal. index
// couleur 24b et sa couleur palette associée.
CS_Generate_color_table_and_palette(cs, tc, palette); CS_Generate_color_table_and_palette(cs, tc, palette);
//CS_Check(cs); //CS_Check(cs);
@ -1096,6 +1166,8 @@ T_Conversion_table * Optimize_palette(T_Bitmap24B image, int size,
return tc; return tc;
} }
/// Change a value with proper ceiling and flooring
int Modified_value(int value,int modif) int Modified_value(int value,int modif)
{ {
value+=modif; value+=modif;
@ -1110,10 +1182,11 @@ int Modified_value(int value,int modif)
return value; return value;
} }
/// Convert a 24b image to 256 colors (with a given palette and conversion table)
/// This destroys the 24b picture !
/// Uses floyd steinberg dithering.
void Convert_24b_bitmap_to_256_Floyd_Steinberg(T_Bitmap256 dest,T_Bitmap24B source,int width,int height,T_Components * palette,T_Conversion_table * tc) void Convert_24b_bitmap_to_256_Floyd_Steinberg(T_Bitmap256 dest,T_Bitmap24B source,int width,int height,T_Components * palette,T_Conversion_table * tc)
// Cette fonction dégrade au fur et à mesure le bitmap source, donc soit on ne
// s'en ressert pas, soit on passe à la fonction une copie de travail du
// bitmap original.
{ {
T_Bitmap24B current; T_Bitmap24B current;
T_Bitmap24B c_plus1; T_Bitmap24B c_plus1;
@ -1205,6 +1278,8 @@ void Convert_24b_bitmap_to_256_Floyd_Steinberg(T_Bitmap256 dest,T_Bitmap24B sour
} }
} }
/// Converts from 24b to 256c without dithering, using given conversion table
void Convert_24b_bitmap_to_256_nearest_neighbor(T_Bitmap256 dest, void Convert_24b_bitmap_to_256_nearest_neighbor(T_Bitmap256 dest,
T_Bitmap24B source, int width, int height, __attribute__((unused)) T_Components * palette, T_Bitmap24B source, int width, int height, __attribute__((unused)) T_Components * palette,
T_Conversion_table * tc) T_Conversion_table * tc)
@ -1241,6 +1316,8 @@ void Convert_24b_bitmap_to_256_nearest_neighbor(T_Bitmap256 dest,
} }
// These are the allowed precisions for all the tables.
// For some of them only the first one may work because of ugly optimizations
static const byte precision_24b[]= static const byte precision_24b[]=
{ {
8,8,8, 8,8,8,
@ -1257,11 +1334,7 @@ static const byte precision_24b[]=
3,3,2}; 3,3,2};
// Convertie avec le plus de précision possible une image 24b en 256c // Give this one a 24b source, get back the 256c bitmap and its palette
// Renvoie s'il y a eu une erreur ou pas..
// Cette fonction utilise l'algorithme "median cut" (Optimize_palette) pour trouver la palette, et diffuse les erreurs avec floyd-steinberg.
int Convert_24b_bitmap_to_256(T_Bitmap256 dest,T_Bitmap24B source,int width,int height,T_Components * palette) int Convert_24b_bitmap_to_256(T_Bitmap256 dest,T_Bitmap24B source,int width,int height,T_Components * palette)
{ {
T_Conversion_table * table; // table de conversion T_Conversion_table * table; // table de conversion