331 lines
13 KiB
C
331 lines
13 KiB
C
|
/*****************************************************************************
|
||
|
|
|
||
|
|
quantize.c - quantize a high resolution image into lower one
|
||
|
|
|
||
|
|
Based on: "Color Image Quantization for frame buffer Display", by
|
||
|
|
Paul Heckbert SIGGRAPH 1982 page 297-307.
|
||
|
|
|
||
|
|
This doesn't really belong in the core library, was undocumented,
|
||
|
|
and was removed in 4.2. Then it turned out some client apps were
|
||
|
|
actually using it, so it was restored in 5.0.
|
||
|
|
|
||
|
|
******************************************************************************/
|
||
|
|
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include "gif_lib.h"
|
||
|
|
#include "gif_lib_private.h"
|
||
|
|
|
||
|
|
#define ABS(x) ((x) > 0 ? (x) : (-(x)))
|
||
|
|
|
||
|
|
#define COLOR_ARRAY_SIZE 32768
|
||
|
|
#define BITS_PER_PRIM_COLOR 5
|
||
|
|
#define MAX_PRIM_COLOR 0x1f
|
||
|
|
|
||
|
|
static int SortRGBAxis;
|
||
|
|
|
||
|
|
typedef struct QuantizedColorType {
|
||
|
|
GifByteType RGB[3];
|
||
|
|
GifByteType NewColorIndex;
|
||
|
|
long Count;
|
||
|
|
struct QuantizedColorType *Pnext;
|
||
|
|
} QuantizedColorType;
|
||
|
|
|
||
|
|
typedef struct NewColorMapType {
|
||
|
|
GifByteType RGBMin[3], RGBWidth[3];
|
||
|
|
unsigned int NumEntries; /* # of QuantizedColorType in linked list below */
|
||
|
|
unsigned long Count; /* Total number of pixels in all the entries */
|
||
|
|
QuantizedColorType *QuantizedColors;
|
||
|
|
} NewColorMapType;
|
||
|
|
|
||
|
|
static int SubdivColorMap(NewColorMapType * NewColorSubdiv,
|
||
|
|
unsigned int ColorMapSize,
|
||
|
|
unsigned int *NewColorMapSize);
|
||
|
|
static int SortCmpRtn(const void *Entry1, const void *Entry2);
|
||
|
|
|
||
|
|
/******************************************************************************
|
||
|
|
Quantize high resolution image into lower one. Input image consists of a
|
||
|
|
2D array for each of the RGB colors with size Width by Height. There is no
|
||
|
|
Color map for the input. Output is a quantized image with 2D array of
|
||
|
|
indexes into the output color map.
|
||
|
|
Note input image can be 24 bits at the most (8 for red/green/blue) and
|
||
|
|
the output has 256 colors at the most (256 entries in the color map.).
|
||
|
|
ColorMapSize specifies size of color map up to 256 and will be updated to
|
||
|
|
real size before returning.
|
||
|
|
Also non of the parameter are allocated by this routine.
|
||
|
|
This function returns GIF_OK if successful, GIF_ERROR otherwise.
|
||
|
|
******************************************************************************/
|
||
|
|
int
|
||
|
|
GifQuantizeBuffer(unsigned int Width,
|
||
|
|
unsigned int Height,
|
||
|
|
int *ColorMapSize,
|
||
|
|
GifByteType * RedInput,
|
||
|
|
GifByteType * GreenInput,
|
||
|
|
GifByteType * BlueInput,
|
||
|
|
GifByteType * OutputBuffer,
|
||
|
|
GifColorType * OutputColorMap) {
|
||
|
|
|
||
|
|
unsigned int Index, NumOfEntries;
|
||
|
|
int i, j, MaxRGBError[3];
|
||
|
|
unsigned int NewColorMapSize;
|
||
|
|
long Red, Green, Blue;
|
||
|
|
NewColorMapType NewColorSubdiv[256];
|
||
|
|
QuantizedColorType *ColorArrayEntries, *QuantizedColor;
|
||
|
|
|
||
|
|
ColorArrayEntries = (QuantizedColorType *)malloc(
|
||
|
|
sizeof(QuantizedColorType) * COLOR_ARRAY_SIZE);
|
||
|
|
if (ColorArrayEntries == NULL) {
|
||
|
|
return GIF_ERROR;
|
||
|
|
}
|
||
|
|
|
||
|
|
for (i = 0; i < COLOR_ARRAY_SIZE; i++) {
|
||
|
|
ColorArrayEntries[i].RGB[0] = i >> (2 * BITS_PER_PRIM_COLOR);
|
||
|
|
ColorArrayEntries[i].RGB[1] = (i >> BITS_PER_PRIM_COLOR) &
|
||
|
|
MAX_PRIM_COLOR;
|
||
|
|
ColorArrayEntries[i].RGB[2] = i & MAX_PRIM_COLOR;
|
||
|
|
ColorArrayEntries[i].Count = 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Sample the colors and their distribution: */
|
||
|
|
for (i = 0; i < (int)(Width * Height); i++) {
|
||
|
|
Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
|
||
|
|
(2 * BITS_PER_PRIM_COLOR)) +
|
||
|
|
((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
|
||
|
|
BITS_PER_PRIM_COLOR) +
|
||
|
|
(BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR));
|
||
|
|
ColorArrayEntries[Index].Count++;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Put all the colors in the first entry of the color map, and call the
|
||
|
|
* recursive subdivision process. */
|
||
|
|
for (i = 0; i < 256; i++) {
|
||
|
|
NewColorSubdiv[i].QuantizedColors = NULL;
|
||
|
|
NewColorSubdiv[i].Count = NewColorSubdiv[i].NumEntries = 0;
|
||
|
|
for (j = 0; j < 3; j++) {
|
||
|
|
NewColorSubdiv[i].RGBMin[j] = 0;
|
||
|
|
NewColorSubdiv[i].RGBWidth[j] = 255;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Find the non empty entries in the color table and chain them: */
|
||
|
|
for (i = 0; i < COLOR_ARRAY_SIZE; i++)
|
||
|
|
if (ColorArrayEntries[i].Count > 0)
|
||
|
|
break;
|
||
|
|
QuantizedColor = NewColorSubdiv[0].QuantizedColors = &ColorArrayEntries[i];
|
||
|
|
NumOfEntries = 1;
|
||
|
|
while (++i < COLOR_ARRAY_SIZE)
|
||
|
|
if (ColorArrayEntries[i].Count > 0) {
|
||
|
|
QuantizedColor->Pnext = &ColorArrayEntries[i];
|
||
|
|
QuantizedColor = &ColorArrayEntries[i];
|
||
|
|
NumOfEntries++;
|
||
|
|
}
|
||
|
|
QuantizedColor->Pnext = NULL;
|
||
|
|
|
||
|
|
NewColorSubdiv[0].NumEntries = NumOfEntries; /* Different sampled colors */
|
||
|
|
NewColorSubdiv[0].Count = ((long)Width) * Height; /* Pixels */
|
||
|
|
NewColorMapSize = 1;
|
||
|
|
if (SubdivColorMap(NewColorSubdiv, *ColorMapSize, &NewColorMapSize) !=
|
||
|
|
GIF_OK) {
|
||
|
|
free((char *)ColorArrayEntries);
|
||
|
|
return GIF_ERROR;
|
||
|
|
}
|
||
|
|
if (NewColorMapSize < *ColorMapSize) {
|
||
|
|
/* And clear rest of color map: */
|
||
|
|
for (i = NewColorMapSize; i < *ColorMapSize; i++)
|
||
|
|
OutputColorMap[i].Red = OutputColorMap[i].Green =
|
||
|
|
OutputColorMap[i].Blue = 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Average the colors in each entry to be the color to be used in the
|
||
|
|
* output color map, and plug it into the output color map itself. */
|
||
|
|
for (i = 0; i < NewColorMapSize; i++) {
|
||
|
|
if ((j = NewColorSubdiv[i].NumEntries) > 0) {
|
||
|
|
QuantizedColor = NewColorSubdiv[i].QuantizedColors;
|
||
|
|
Red = Green = Blue = 0;
|
||
|
|
while (QuantizedColor) {
|
||
|
|
QuantizedColor->NewColorIndex = i;
|
||
|
|
Red += QuantizedColor->RGB[0];
|
||
|
|
Green += QuantizedColor->RGB[1];
|
||
|
|
Blue += QuantizedColor->RGB[2];
|
||
|
|
QuantizedColor = QuantizedColor->Pnext;
|
||
|
|
}
|
||
|
|
OutputColorMap[i].Red = (Red << (8 - BITS_PER_PRIM_COLOR)) / j;
|
||
|
|
OutputColorMap[i].Green = (Green << (8 - BITS_PER_PRIM_COLOR)) / j;
|
||
|
|
OutputColorMap[i].Blue = (Blue << (8 - BITS_PER_PRIM_COLOR)) / j;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Finally scan the input buffer again and put the mapped index in the
|
||
|
|
* output buffer. */
|
||
|
|
MaxRGBError[0] = MaxRGBError[1] = MaxRGBError[2] = 0;
|
||
|
|
for (i = 0; i < (int)(Width * Height); i++) {
|
||
|
|
Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
|
||
|
|
(2 * BITS_PER_PRIM_COLOR)) +
|
||
|
|
((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
|
||
|
|
BITS_PER_PRIM_COLOR) +
|
||
|
|
(BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR));
|
||
|
|
Index = ColorArrayEntries[Index].NewColorIndex;
|
||
|
|
OutputBuffer[i] = Index;
|
||
|
|
if (MaxRGBError[0] < ABS(OutputColorMap[Index].Red - RedInput[i]))
|
||
|
|
MaxRGBError[0] = ABS(OutputColorMap[Index].Red - RedInput[i]);
|
||
|
|
if (MaxRGBError[1] < ABS(OutputColorMap[Index].Green - GreenInput[i]))
|
||
|
|
MaxRGBError[1] = ABS(OutputColorMap[Index].Green - GreenInput[i]);
|
||
|
|
if (MaxRGBError[2] < ABS(OutputColorMap[Index].Blue - BlueInput[i]))
|
||
|
|
MaxRGBError[2] = ABS(OutputColorMap[Index].Blue - BlueInput[i]);
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef DEBUG
|
||
|
|
fprintf(stderr,
|
||
|
|
"Quantization L(0) errors: Red = %d, Green = %d, Blue = %d.\n",
|
||
|
|
MaxRGBError[0], MaxRGBError[1], MaxRGBError[2]);
|
||
|
|
#endif /* DEBUG */
|
||
|
|
|
||
|
|
free((char *)ColorArrayEntries);
|
||
|
|
|
||
|
|
*ColorMapSize = NewColorMapSize;
|
||
|
|
|
||
|
|
return GIF_OK;
|
||
|
|
}
|
||
|
|
|
||
|
|
/******************************************************************************
|
||
|
|
Routine to subdivide the RGB space recursively using median cut in each
|
||
|
|
axes alternatingly until ColorMapSize different cubes exists.
|
||
|
|
The biggest cube in one dimension is subdivide unless it has only one entry.
|
||
|
|
Returns GIF_ERROR if failed, otherwise GIF_OK.
|
||
|
|
*******************************************************************************/
|
||
|
|
static int
|
||
|
|
SubdivColorMap(NewColorMapType * NewColorSubdiv,
|
||
|
|
unsigned int ColorMapSize,
|
||
|
|
unsigned int *NewColorMapSize) {
|
||
|
|
|
||
|
|
int MaxSize;
|
||
|
|
unsigned int i, j, Index = 0, NumEntries, MinColor, MaxColor;
|
||
|
|
long Sum, Count;
|
||
|
|
QuantizedColorType *QuantizedColor, **SortArray;
|
||
|
|
|
||
|
|
while (ColorMapSize > *NewColorMapSize) {
|
||
|
|
/* Find candidate for subdivision: */
|
||
|
|
MaxSize = -1;
|
||
|
|
for (i = 0; i < *NewColorMapSize; i++) {
|
||
|
|
for (j = 0; j < 3; j++) {
|
||
|
|
if ((((int)NewColorSubdiv[i].RGBWidth[j]) > MaxSize) &&
|
||
|
|
(NewColorSubdiv[i].NumEntries > 1)) {
|
||
|
|
MaxSize = NewColorSubdiv[i].RGBWidth[j];
|
||
|
|
Index = i;
|
||
|
|
SortRGBAxis = j;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (MaxSize == -1)
|
||
|
|
return GIF_OK;
|
||
|
|
|
||
|
|
/* Split the entry Index into two along the axis SortRGBAxis: */
|
||
|
|
|
||
|
|
/* Sort all elements in that entry along the given axis and split at
|
||
|
|
* the median. */
|
||
|
|
SortArray = (QuantizedColorType **)malloc(
|
||
|
|
sizeof(QuantizedColorType *) *
|
||
|
|
NewColorSubdiv[Index].NumEntries);
|
||
|
|
if (SortArray == NULL)
|
||
|
|
return GIF_ERROR;
|
||
|
|
for (j = 0, QuantizedColor = NewColorSubdiv[Index].QuantizedColors;
|
||
|
|
j < NewColorSubdiv[Index].NumEntries && QuantizedColor != NULL;
|
||
|
|
j++, QuantizedColor = QuantizedColor->Pnext)
|
||
|
|
SortArray[j] = QuantizedColor;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Because qsort isn't stable, this can produce differing
|
||
|
|
* results for the order of tuples depending on platform
|
||
|
|
* details of how qsort() is implemented.
|
||
|
|
*
|
||
|
|
* We mitigate this problem by sorting on all three axes rather
|
||
|
|
* than only the one specied by SortRGBAxis; that way the instability
|
||
|
|
* can only become an issue if there are multiple color indices
|
||
|
|
* referring to identical RGB tuples. Older versions of this
|
||
|
|
* sorted on only the one axis.
|
||
|
|
*/
|
||
|
|
qsort(SortArray, NewColorSubdiv[Index].NumEntries,
|
||
|
|
sizeof(QuantizedColorType *), SortCmpRtn);
|
||
|
|
|
||
|
|
/* Relink the sorted list into one: */
|
||
|
|
for (j = 0; j < NewColorSubdiv[Index].NumEntries - 1; j++)
|
||
|
|
SortArray[j]->Pnext = SortArray[j + 1];
|
||
|
|
SortArray[NewColorSubdiv[Index].NumEntries - 1]->Pnext = NULL;
|
||
|
|
NewColorSubdiv[Index].QuantizedColors = QuantizedColor = SortArray[0];
|
||
|
|
free((char *)SortArray);
|
||
|
|
|
||
|
|
/* Now simply add the Counts until we have half of the Count: */
|
||
|
|
Sum = NewColorSubdiv[Index].Count / 2 - QuantizedColor->Count;
|
||
|
|
NumEntries = 1;
|
||
|
|
Count = QuantizedColor->Count;
|
||
|
|
while (QuantizedColor->Pnext != NULL &&
|
||
|
|
(Sum -= QuantizedColor->Pnext->Count) >= 0 &&
|
||
|
|
QuantizedColor->Pnext->Pnext != NULL) {
|
||
|
|
QuantizedColor = QuantizedColor->Pnext;
|
||
|
|
NumEntries++;
|
||
|
|
Count += QuantizedColor->Count;
|
||
|
|
}
|
||
|
|
/* Save the values of the last color of the first half, and first
|
||
|
|
* of the second half so we can update the Bounding Boxes later.
|
||
|
|
* Also as the colors are quantized and the BBoxes are full 0..255,
|
||
|
|
* they need to be rescaled.
|
||
|
|
*/
|
||
|
|
MaxColor = QuantizedColor->RGB[SortRGBAxis]; /* Max. of first half */
|
||
|
|
/* coverity[var_deref_op] */
|
||
|
|
MinColor = QuantizedColor->Pnext->RGB[SortRGBAxis]; /* of second */
|
||
|
|
MaxColor <<= (8 - BITS_PER_PRIM_COLOR);
|
||
|
|
MinColor <<= (8 - BITS_PER_PRIM_COLOR);
|
||
|
|
|
||
|
|
/* Partition right here: */
|
||
|
|
NewColorSubdiv[*NewColorMapSize].QuantizedColors =
|
||
|
|
QuantizedColor->Pnext;
|
||
|
|
QuantizedColor->Pnext = NULL;
|
||
|
|
NewColorSubdiv[*NewColorMapSize].Count = Count;
|
||
|
|
NewColorSubdiv[Index].Count -= Count;
|
||
|
|
NewColorSubdiv[*NewColorMapSize].NumEntries =
|
||
|
|
NewColorSubdiv[Index].NumEntries - NumEntries;
|
||
|
|
NewColorSubdiv[Index].NumEntries = NumEntries;
|
||
|
|
for (j = 0; j < 3; j++) {
|
||
|
|
NewColorSubdiv[*NewColorMapSize].RGBMin[j] =
|
||
|
|
NewColorSubdiv[Index].RGBMin[j];
|
||
|
|
NewColorSubdiv[*NewColorMapSize].RGBWidth[j] =
|
||
|
|
NewColorSubdiv[Index].RGBWidth[j];
|
||
|
|
}
|
||
|
|
NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] =
|
||
|
|
NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] +
|
||
|
|
NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] - MinColor;
|
||
|
|
NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] = MinColor;
|
||
|
|
|
||
|
|
NewColorSubdiv[Index].RGBWidth[SortRGBAxis] =
|
||
|
|
MaxColor - NewColorSubdiv[Index].RGBMin[SortRGBAxis];
|
||
|
|
|
||
|
|
(*NewColorMapSize)++;
|
||
|
|
}
|
||
|
|
|
||
|
|
return GIF_OK;
|
||
|
|
}
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
Routine called by qsort to compare two entries.
|
||
|
|
*****************************************************************************/
|
||
|
|
|
||
|
|
static int
|
||
|
|
SortCmpRtn(const void *Entry1,
|
||
|
|
const void *Entry2) {
|
||
|
|
QuantizedColorType *entry1 = (*((QuantizedColorType **) Entry1));
|
||
|
|
QuantizedColorType *entry2 = (*((QuantizedColorType **) Entry2));
|
||
|
|
|
||
|
|
/* sort on all axes of the color space! */
|
||
|
|
int hash1 = entry1->RGB[SortRGBAxis] * 256 * 256
|
||
|
|
+ entry1->RGB[(SortRGBAxis+1) % 3] * 256
|
||
|
|
+ entry1->RGB[(SortRGBAxis+2) % 3];
|
||
|
|
int hash2 = entry2->RGB[SortRGBAxis] * 256 * 256
|
||
|
|
+ entry2->RGB[(SortRGBAxis+1) % 3] * 256
|
||
|
|
+ entry2->RGB[(SortRGBAxis+2) % 3];
|
||
|
|
|
||
|
|
return hash1 - hash2;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* end */
|