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gdalmediancut.cpp
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gdalmediancut.cpp
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/******************************************************************************
*
* Project: CIETMap Phase 2
* Purpose: Use median cut algorithm to generate an near-optimal PCT for a
* given RGB image. Implemented as function GDALComputeMedianCutPCT.
* Author: Frank Warmerdam, warmerdam@pobox.com
*
******************************************************************************
* Copyright (c) 2001, Frank Warmerdam
* Copyright (c) 2007-2010, Even Rouault <even dot rouault at spatialys.com>
*
* SPDX-License-Identifier: MIT
******************************************************************************
*
* This code was based on the tiffmedian.c code from libtiff (www.libtiff.org)
* which was based on a paper by Paul Heckbert:
*
* "Color Image Quantization for Frame Buffer Display", Paul
* Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.
*
*/
#include "cpl_port.h"
#include "gdal_alg.h"
#include "gdal_alg_priv.h"
#include <climits>
#include <cstring>
#include <algorithm>
#include <limits>
#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_progress.h"
#include "cpl_vsi.h"
#include "gdal.h"
#include "gdal_priv.h"
template <typename T> static T *HISTOGRAM(T *h, int n, int r, int g, int b)
{
const int index = (r * n + g) * n + b;
return &h[index];
}
#ifndef MAKE_COLOR_CODE_defined
#define MAKE_COLOR_CODE_defined
static int MAKE_COLOR_CODE(int r, int g, int b)
{
return r | (g << 8) | (b << 16);
}
#endif
// NOTE: If changing the size of this structure, edit
// MEDIAN_CUT_AND_DITHER_BUFFER_SIZE_65536 in gdal_alg_priv.h and take into
// account ColorIndex in gdaldither.cpp.
typedef struct
{
GUInt32 nColorCode;
int nCount;
GUInt32 nColorCode2;
int nCount2;
GUInt32 nColorCode3;
int nCount3;
} HashHistogram;
typedef struct colorbox
{
struct colorbox *next, *prev;
int rmin, rmax;
int gmin, gmax;
int bmin, bmax;
GUIntBig total;
} Colorbox;
template <class T>
static void splitbox(Colorbox *ptr, const T *histogram,
const HashHistogram *psHashHistogram, int nCLevels,
Colorbox **pfreeboxes, Colorbox **pusedboxes,
GByte *pabyRedBand, GByte *pabyGreenBand,
GByte *pabyBlueBand, T nPixels);
template <class T>
static void shrinkbox(Colorbox *box, const T *histogram, int nCLevels);
static Colorbox *largest_box(Colorbox *usedboxes);
/************************************************************************/
/* GDALComputeMedianCutPCT() */
/************************************************************************/
/**
* Compute optimal PCT for RGB image.
*
* This function implements a median cut algorithm to compute an "optimal"
* pseudocolor table for representing an input RGB image. This PCT could
* then be used with GDALDitherRGB2PCT() to convert a 24bit RGB image into
* an eightbit pseudo-colored image.
*
* This code was based on the tiffmedian.c code from libtiff (www.libtiff.org)
* which was based on a paper by Paul Heckbert:
*
* \verbatim
* "Color Image Quantization for Frame Buffer Display", Paul
* Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.
* \endverbatim
*
* The red, green and blue input bands do not necessarily need to come
* from the same file, but they must be the same width and height. They will
* be clipped to 8bit during reading, so non-eight bit bands are generally
* inappropriate.
*
* @param hRed Red input band.
* @param hGreen Green input band.
* @param hBlue Blue input band.
* @param pfnIncludePixel function used to test which pixels should be included
* in the analysis. At this time this argument is ignored and all pixels are
* utilized. This should normally be NULL.
* @param nColors the desired number of colors to be returned (2-256).
* @param hColorTable the colors will be returned in this color table object.
* @param pfnProgress callback for reporting algorithm progress matching the
* GDALProgressFunc() semantics. May be NULL.
* @param pProgressArg callback argument passed to pfnProgress.
*
* @return returns CE_None on success or CE_Failure if an error occurs.
*/
extern "C" int CPL_STDCALL GDALComputeMedianCutPCT(
GDALRasterBandH hRed, GDALRasterBandH hGreen, GDALRasterBandH hBlue,
int (*pfnIncludePixel)(int, int, void *), int nColors,
GDALColorTableH hColorTable, GDALProgressFunc pfnProgress,
void *pProgressArg)
{
VALIDATE_POINTER1(hRed, "GDALComputeMedianCutPCT", CE_Failure);
const int nXSize = GDALGetRasterBandXSize(hRed);
const int nYSize = GDALGetRasterBandYSize(hRed);
if (nYSize == 0)
return CE_Failure;
if (static_cast<GUInt32>(nXSize) <
std::numeric_limits<GUInt32>::max() / static_cast<GUInt32>(nYSize))
{
return GDALComputeMedianCutPCTInternal(
hRed, hGreen, hBlue, nullptr, nullptr, nullptr, pfnIncludePixel,
nColors, 5, static_cast<GUInt32 *>(nullptr), hColorTable,
pfnProgress, pProgressArg);
}
else
{
return GDALComputeMedianCutPCTInternal(
hRed, hGreen, hBlue, nullptr, nullptr, nullptr, pfnIncludePixel,
nColors, 5, static_cast<GUIntBig *>(nullptr), hColorTable,
pfnProgress, pProgressArg);
}
}
#ifndef IsColorCodeSet_defined
#define IsColorCodeSet_defined
static inline bool IsColorCodeSet(GUInt32 nColorCode)
{
return (nColorCode >> 31) == 0;
}
#endif
static inline int FindColorCount(const HashHistogram *psHashHistogram,
GUInt32 nColorCode)
{
GUInt32 nIdx = nColorCode % PRIME_FOR_65536;
while (true)
{
if (!IsColorCodeSet(psHashHistogram[nIdx].nColorCode))
{
return 0;
}
if (psHashHistogram[nIdx].nColorCode == nColorCode)
{
return psHashHistogram[nIdx].nCount;
}
if (!IsColorCodeSet(psHashHistogram[nIdx].nColorCode2))
{
return 0;
}
if (psHashHistogram[nIdx].nColorCode2 == nColorCode)
{
return psHashHistogram[nIdx].nCount2;
}
if (!IsColorCodeSet(psHashHistogram[nIdx].nColorCode3))
{
return 0;
}
if (psHashHistogram[nIdx].nColorCode3 == nColorCode)
{
return psHashHistogram[nIdx].nCount3;
}
do
{
nIdx += 257;
if (nIdx >= PRIME_FOR_65536)
nIdx -= PRIME_FOR_65536;
} while (IsColorCodeSet(psHashHistogram[nIdx].nColorCode) &&
psHashHistogram[nIdx].nColorCode != nColorCode &&
IsColorCodeSet(psHashHistogram[nIdx].nColorCode2) &&
psHashHistogram[nIdx].nColorCode2 != nColorCode &&
IsColorCodeSet(psHashHistogram[nIdx].nColorCode3) &&
psHashHistogram[nIdx].nColorCode3 != nColorCode);
}
}
static inline int *FindAndInsertColorCount(HashHistogram *psHashHistogram,
GUInt32 nColorCode)
{
GUInt32 nIdx = nColorCode % PRIME_FOR_65536;
while (true)
{
if (psHashHistogram[nIdx].nColorCode == nColorCode)
{
return &(psHashHistogram[nIdx].nCount);
}
if (!IsColorCodeSet(psHashHistogram[nIdx].nColorCode))
{
psHashHistogram[nIdx].nColorCode = nColorCode;
psHashHistogram[nIdx].nCount = 0;
return &(psHashHistogram[nIdx].nCount);
}
if (psHashHistogram[nIdx].nColorCode2 == nColorCode)
{
return &(psHashHistogram[nIdx].nCount2);
}
if (!IsColorCodeSet(psHashHistogram[nIdx].nColorCode2))
{
psHashHistogram[nIdx].nColorCode2 = nColorCode;
psHashHistogram[nIdx].nCount2 = 0;
return &(psHashHistogram[nIdx].nCount2);
}
if (psHashHistogram[nIdx].nColorCode3 == nColorCode)
{
return &(psHashHistogram[nIdx].nCount3);
}
if (!IsColorCodeSet(psHashHistogram[nIdx].nColorCode3))
{
psHashHistogram[nIdx].nColorCode3 = nColorCode;
psHashHistogram[nIdx].nCount3 = 0;
return &(psHashHistogram[nIdx].nCount3);
}
do
{
nIdx += 257;
if (nIdx >= PRIME_FOR_65536)
nIdx -= PRIME_FOR_65536;
} while (IsColorCodeSet(psHashHistogram[nIdx].nColorCode) &&
psHashHistogram[nIdx].nColorCode != nColorCode &&
IsColorCodeSet(psHashHistogram[nIdx].nColorCode2) &&
psHashHistogram[nIdx].nColorCode2 != nColorCode &&
IsColorCodeSet(psHashHistogram[nIdx].nColorCode3) &&
psHashHistogram[nIdx].nColorCode3 != nColorCode);
}
}
template <class T>
int GDALComputeMedianCutPCTInternal(
GDALRasterBandH hRed, GDALRasterBandH hGreen, GDALRasterBandH hBlue,
GByte *pabyRedBand, GByte *pabyGreenBand, GByte *pabyBlueBand,
int (*pfnIncludePixel)(int, int, void *), int nColors, int nBits,
T *panHistogram, // NULL, or >= size (1<<nBits)^3 * sizeof(T) bytes.
GDALColorTableH hColorTable, GDALProgressFunc pfnProgress,
void *pProgressArg)
{
VALIDATE_POINTER1(hRed, "GDALComputeMedianCutPCT", CE_Failure);
VALIDATE_POINTER1(hGreen, "GDALComputeMedianCutPCT", CE_Failure);
VALIDATE_POINTER1(hBlue, "GDALComputeMedianCutPCT", CE_Failure);
CPLErr err = CE_None;
/* -------------------------------------------------------------------- */
/* Validate parameters. */
/* -------------------------------------------------------------------- */
const int nXSize = GDALGetRasterBandXSize(hRed);
const int nYSize = GDALGetRasterBandYSize(hRed);
if (GDALGetRasterBandXSize(hGreen) != nXSize ||
GDALGetRasterBandYSize(hGreen) != nYSize ||
GDALGetRasterBandXSize(hBlue) != nXSize ||
GDALGetRasterBandYSize(hBlue) != nYSize)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"Green or blue band doesn't match size of red band.");
return CE_Failure;
}
if (pfnIncludePixel != nullptr)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"GDALComputeMedianCutPCT() doesn't currently support "
"pfnIncludePixel function.");
return CE_Failure;
}
if (nColors <= 0)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"GDALComputeMedianCutPCT(): "
"nColors must be strictly greater than 1.");
return CE_Failure;
}
if (nColors > 256)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"GDALComputeMedianCutPCT(): "
"nColors must be lesser than or equal to 256.");
return CE_Failure;
}
if (pfnProgress == nullptr)
pfnProgress = GDALDummyProgress;
/* ==================================================================== */
/* STEP 1: create empty boxes. */
/* ==================================================================== */
if (static_cast<GUInt32>(nXSize) >
std::numeric_limits<T>::max() / static_cast<GUInt32>(nYSize))
{
CPLError(CE_Warning, CPLE_AppDefined,
"GDALComputeMedianCutPCTInternal() not called "
"with large enough type");
}
T nPixels = 0;
if (nBits == 8 && pabyRedBand != nullptr && pabyGreenBand != nullptr &&
pabyBlueBand != nullptr &&
static_cast<GUInt32>(nXSize) <=
std::numeric_limits<T>::max() / static_cast<GUInt32>(nYSize))
{
nPixels = static_cast<T>(nXSize) * static_cast<T>(nYSize);
}
const int nCLevels = 1 << nBits;
const int nCLevelsCube = nCLevels * nCLevels * nCLevels;
T *histogram = nullptr;
HashHistogram *psHashHistogram = nullptr;
if (panHistogram)
{
if (nBits == 8 && static_cast<GUIntBig>(nXSize) * nYSize <= 65536)
{
// If the image is small enough, then the number of colors
// will be limited and using a hashmap, rather than a full table
// will be more efficient.
histogram = nullptr;
psHashHistogram = reinterpret_cast<HashHistogram *>(panHistogram);
memset(psHashHistogram, 0xFF,
sizeof(HashHistogram) * PRIME_FOR_65536);
}
else
{
histogram = panHistogram;
memset(histogram, 0, nCLevelsCube * sizeof(T));
}
}
else
{
histogram =
static_cast<T *>(VSI_CALLOC_VERBOSE(nCLevelsCube, sizeof(T)));
if (histogram == nullptr)
{
return CE_Failure;
}
}
Colorbox *box_list =
static_cast<Colorbox *>(CPLMalloc(nColors * sizeof(Colorbox)));
Colorbox *freeboxes = box_list;
freeboxes[0].next = &freeboxes[1];
freeboxes[0].prev = nullptr;
for (int i = 1; i < nColors - 1; ++i)
{
freeboxes[i].next = &freeboxes[i + 1];
freeboxes[i].prev = &freeboxes[i - 1];
}
freeboxes[nColors - 1].next = nullptr;
freeboxes[nColors - 1].prev = &freeboxes[nColors - 2];
/* ==================================================================== */
/* Build histogram. */
/* ==================================================================== */
/* -------------------------------------------------------------------- */
/* Initialize the box datastructures. */
/* -------------------------------------------------------------------- */
Colorbox *freeboxes_before = freeboxes;
freeboxes = freeboxes_before->next;
if (freeboxes)
freeboxes->prev = nullptr;
Colorbox *usedboxes = freeboxes_before;
usedboxes->next = nullptr;
usedboxes->rmin = 999;
usedboxes->gmin = 999;
usedboxes->bmin = 999;
usedboxes->rmax = -1;
usedboxes->gmax = -1;
usedboxes->bmax = -1;
usedboxes->total =
static_cast<GUIntBig>(nXSize) * static_cast<GUIntBig>(nYSize);
/* -------------------------------------------------------------------- */
/* Collect histogram. */
/* -------------------------------------------------------------------- */
// TODO(schwehr): Move these closer to usage after removing gotos.
const int nColorShift = 8 - nBits;
int nColorCounter = 0;
GByte anRed[256] = {};
GByte anGreen[256] = {};
GByte anBlue[256] = {};
GByte *pabyRedLine = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
GByte *pabyGreenLine = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
GByte *pabyBlueLine = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
if (pabyRedLine == nullptr || pabyGreenLine == nullptr ||
pabyBlueLine == nullptr)
{
err = CE_Failure;
goto end_and_cleanup;
}
for (int iLine = 0; iLine < nYSize; iLine++)
{
if (!pfnProgress(iLine / static_cast<double>(nYSize),
"Generating Histogram", pProgressArg))
{
CPLError(CE_Failure, CPLE_UserInterrupt, "User Terminated");
err = CE_Failure;
goto end_and_cleanup;
}
err = GDALRasterIO(hRed, GF_Read, 0, iLine, nXSize, 1, pabyRedLine,
nXSize, 1, GDT_Byte, 0, 0);
if (err == CE_None)
err = GDALRasterIO(hGreen, GF_Read, 0, iLine, nXSize, 1,
pabyGreenLine, nXSize, 1, GDT_Byte, 0, 0);
if (err == CE_None)
err = GDALRasterIO(hBlue, GF_Read, 0, iLine, nXSize, 1,
pabyBlueLine, nXSize, 1, GDT_Byte, 0, 0);
if (err != CE_None)
goto end_and_cleanup;
for (int iPixel = 0; iPixel < nXSize; iPixel++)
{
const int nRed = pabyRedLine[iPixel] >> nColorShift;
const int nGreen = pabyGreenLine[iPixel] >> nColorShift;
const int nBlue = pabyBlueLine[iPixel] >> nColorShift;
usedboxes->rmin = std::min(usedboxes->rmin, nRed);
usedboxes->gmin = std::min(usedboxes->gmin, nGreen);
usedboxes->bmin = std::min(usedboxes->bmin, nBlue);
usedboxes->rmax = std::max(usedboxes->rmax, nRed);
usedboxes->gmax = std::max(usedboxes->gmax, nGreen);
usedboxes->bmax = std::max(usedboxes->bmax, nBlue);
bool bFirstOccurrence;
if (psHashHistogram)
{
int *pnColor = FindAndInsertColorCount(
psHashHistogram, MAKE_COLOR_CODE(nRed, nGreen, nBlue));
bFirstOccurrence = (*pnColor == 0);
(*pnColor)++;
}
else
{
T *pnColor =
HISTOGRAM(histogram, nCLevels, nRed, nGreen, nBlue);
bFirstOccurrence = (*pnColor == 0);
(*pnColor)++;
}
if (bFirstOccurrence)
{
if (nColorShift == 0 && nColorCounter < nColors)
{
anRed[nColorCounter] = static_cast<GByte>(nRed);
anGreen[nColorCounter] = static_cast<GByte>(nGreen);
anBlue[nColorCounter] = static_cast<GByte>(nBlue);
}
nColorCounter++;
}
}
}
if (!pfnProgress(1.0, "Generating Histogram", pProgressArg))
{
CPLError(CE_Failure, CPLE_UserInterrupt, "User Terminated");
err = CE_Failure;
goto end_and_cleanup;
}
if (nColorShift == 0 && nColorCounter <= nColors)
{
#if DEBUG_VERBOSE
CPLDebug("MEDIAN_CUT", "%d colors found <= %d", nColorCounter, nColors);
#endif
for (int iColor = 0; iColor < nColorCounter; iColor++)
{
const GDALColorEntry sEntry = {static_cast<GByte>(anRed[iColor]),
static_cast<GByte>(anGreen[iColor]),
static_cast<GByte>(anBlue[iColor]),
255};
GDALSetColorEntry(hColorTable, iColor, &sEntry);
}
goto end_and_cleanup;
}
/* ==================================================================== */
/* STEP 3: continually subdivide boxes until no more free */
/* boxes remain or until all colors assigned. */
/* ==================================================================== */
while (freeboxes != nullptr)
{
auto ptr = largest_box(usedboxes);
if (ptr != nullptr)
splitbox(ptr, histogram, psHashHistogram, nCLevels, &freeboxes,
&usedboxes, pabyRedBand, pabyGreenBand, pabyBlueBand,
nPixels);
else
freeboxes = nullptr;
}
/* ==================================================================== */
/* STEP 4: assign colors to all boxes */
/* ==================================================================== */
{
Colorbox *ptr = usedboxes;
for (int i = 0; ptr != nullptr; ++i, ptr = ptr->next)
{
const GDALColorEntry sEntry = {
static_cast<GByte>(((ptr->rmin + ptr->rmax) << nColorShift) /
2),
static_cast<GByte>(((ptr->gmin + ptr->gmax) << nColorShift) /
2),
static_cast<GByte>(((ptr->bmin + ptr->bmax) << nColorShift) /
2),
255};
GDALSetColorEntry(hColorTable, i, &sEntry);
}
}
end_and_cleanup:
CPLFree(pabyRedLine);
CPLFree(pabyGreenLine);
CPLFree(pabyBlueLine);
// We're done with the boxes now.
CPLFree(box_list);
freeboxes = nullptr;
usedboxes = nullptr;
if (panHistogram == nullptr)
CPLFree(histogram);
return err;
}
/************************************************************************/
/* largest_box() */
/************************************************************************/
static Colorbox *largest_box(Colorbox *usedboxes)
{
Colorbox *b = nullptr;
for (Colorbox *p = usedboxes; p != nullptr; p = p->next)
{
if ((p->rmax > p->rmin || p->gmax > p->gmin || p->bmax > p->bmin) &&
(b == nullptr || p->total > b->total))
{
b = p;
}
}
return b;
}
static void shrinkboxFromBand(Colorbox *ptr, const GByte *pabyRedBand,
const GByte *pabyGreenBand,
const GByte *pabyBlueBand, GUIntBig nPixels)
{
int rmin_new = 255;
int rmax_new = 0;
int gmin_new = 255;
int gmax_new = 0;
int bmin_new = 255;
int bmax_new = 0;
for (GUIntBig i = 0; i < nPixels; i++)
{
const int iR = pabyRedBand[i];
const int iG = pabyGreenBand[i];
const int iB = pabyBlueBand[i];
if (iR >= ptr->rmin && iR <= ptr->rmax && iG >= ptr->gmin &&
iG <= ptr->gmax && iB >= ptr->bmin && iB <= ptr->bmax)
{
if (iR < rmin_new)
rmin_new = iR;
if (iR > rmax_new)
rmax_new = iR;
if (iG < gmin_new)
gmin_new = iG;
if (iG > gmax_new)
gmax_new = iG;
if (iB < bmin_new)
bmin_new = iB;
if (iB > bmax_new)
bmax_new = iB;
}
}
CPLAssert(rmin_new >= ptr->rmin && rmin_new <= rmax_new &&
rmax_new <= ptr->rmax);
CPLAssert(gmin_new >= ptr->gmin && gmin_new <= gmax_new &&
gmax_new <= ptr->gmax);
CPLAssert(bmin_new >= ptr->bmin && bmin_new <= bmax_new &&
bmax_new <= ptr->bmax);
ptr->rmin = rmin_new;
ptr->rmax = rmax_new;
ptr->gmin = gmin_new;
ptr->gmax = gmax_new;
ptr->bmin = bmin_new;
ptr->bmax = bmax_new;
}
static void shrinkboxFromHashHistogram(Colorbox *box,
const HashHistogram *psHashHistogram)
{
if (box->rmax > box->rmin)
{
for (int ir = box->rmin; ir <= box->rmax; ++ir)
{
for (int ig = box->gmin; ig <= box->gmax; ++ig)
{
for (int ib = box->bmin; ib <= box->bmax; ++ib)
{
if (FindColorCount(psHashHistogram,
MAKE_COLOR_CODE(ir, ig, ib)) != 0)
{
box->rmin = ir;
goto have_rmin;
}
}
}
}
}
have_rmin:
if (box->rmax > box->rmin)
{
for (int ir = box->rmax; ir >= box->rmin; --ir)
{
for (int ig = box->gmin; ig <= box->gmax; ++ig)
{
for (int ib = box->bmin; ib <= box->bmax; ++ib)
{
if (FindColorCount(psHashHistogram,
MAKE_COLOR_CODE(ir, ig, ib)) != 0)
{
box->rmax = ir;
goto have_rmax;
}
}
}
}
}
have_rmax:
if (box->gmax > box->gmin)
{
for (int ig = box->gmin; ig <= box->gmax; ++ig)
{
for (int ir = box->rmin; ir <= box->rmax; ++ir)
{
for (int ib = box->bmin; ib <= box->bmax; ++ib)
{
if (FindColorCount(psHashHistogram,
MAKE_COLOR_CODE(ir, ig, ib)) != 0)
{
box->gmin = ig;
goto have_gmin;
}
}
}
}
}
have_gmin:
if (box->gmax > box->gmin)
{
for (int ig = box->gmax; ig >= box->gmin; --ig)
{
for (int ir = box->rmin; ir <= box->rmax; ++ir)
{
int ib = box->bmin;
for (; ib <= box->bmax; ++ib)
{
if (FindColorCount(psHashHistogram,
MAKE_COLOR_CODE(ir, ig, ib)) != 0)
{
box->gmax = ig;
goto have_gmax;
}
}
}
}
}
have_gmax:
if (box->bmax > box->bmin)
{
for (int ib = box->bmin; ib <= box->bmax; ++ib)
{
for (int ir = box->rmin; ir <= box->rmax; ++ir)
{
for (int ig = box->gmin; ig <= box->gmax; ++ig)
{
if (FindColorCount(psHashHistogram,
MAKE_COLOR_CODE(ir, ig, ib)) != 0)
{
box->bmin = ib;
goto have_bmin;
}
}
}
}
}
have_bmin:
if (box->bmax > box->bmin)
{
for (int ib = box->bmax; ib >= box->bmin; --ib)
{
for (int ir = box->rmin; ir <= box->rmax; ++ir)
{
for (int ig = box->gmin; ig <= box->gmax; ++ig)
{
if (FindColorCount(psHashHistogram,
MAKE_COLOR_CODE(ir, ig, ib)) != 0)
{
box->bmax = ib;
goto have_bmax;
}
}
}
}
}
have_bmax:;
}
/************************************************************************/
/* splitbox() */
/************************************************************************/
template <class T>
static void splitbox(Colorbox *ptr, const T *histogram,
const HashHistogram *psHashHistogram, int nCLevels,
Colorbox **pfreeboxes, Colorbox **pusedboxes,
GByte *pabyRedBand, GByte *pabyGreenBand,
GByte *pabyBlueBand, T nPixels)
{
T hist2[256] = {};
int first = 0;
int last = 0;
enum
{
RED,
GREEN,
BLUE
} axis;
// See which axis is the largest, do a histogram along that axis. Split at
// median point. Contract both new boxes to fit points and return.
{
int i = ptr->rmax - ptr->rmin;
if (i >= ptr->gmax - ptr->gmin && i >= ptr->bmax - ptr->bmin)
axis = RED;
else if (ptr->gmax - ptr->gmin >= ptr->bmax - ptr->bmin)
axis = GREEN;
else
axis = BLUE;
}
// Get histogram along longest axis.
const GUInt32 nIters = (ptr->rmax - ptr->rmin + 1) *
(ptr->gmax - ptr->gmin + 1) *
(ptr->bmax - ptr->bmin + 1);
switch (axis)
{
case RED:
{
if (nPixels != 0 && nIters > nPixels)
{
const int rmin = ptr->rmin;
const int rmax = ptr->rmax;
const int gmin = ptr->gmin;
const int gmax = ptr->gmax;
const int bmin = ptr->bmin;
const int bmax = ptr->bmax;
for (T iPixel = 0; iPixel < nPixels; iPixel++)
{
int iR = pabyRedBand[iPixel];
int iG = pabyGreenBand[iPixel];
int iB = pabyBlueBand[iPixel];
if (iR >= rmin && iR <= rmax && iG >= gmin && iG <= gmax &&
iB >= bmin && iB <= bmax)
{
hist2[iR]++;
}
}
}
else if (psHashHistogram)
{
T *histp = &hist2[ptr->rmin];
for (int ir = ptr->rmin; ir <= ptr->rmax; ++ir)
{
*histp = 0;
for (int ig = ptr->gmin; ig <= ptr->gmax; ++ig)
{
for (int ib = ptr->bmin; ib <= ptr->bmax; ++ib)
{
*histp += FindColorCount(
psHashHistogram, MAKE_COLOR_CODE(ir, ig, ib));
}
}
histp++;
}
}
else
{
T *histp = &hist2[ptr->rmin];
for (int ir = ptr->rmin; ir <= ptr->rmax; ++ir)
{
*histp = 0;
for (int ig = ptr->gmin; ig <= ptr->gmax; ++ig)
{
const T *iptr =
HISTOGRAM(histogram, nCLevels, ir, ig, ptr->bmin);
for (int ib = ptr->bmin; ib <= ptr->bmax; ++ib)
*histp += *iptr++;
}
histp++;
}
}
first = ptr->rmin;
last = ptr->rmax;
break;
}
case GREEN:
{
if (nPixels != 0 && nIters > nPixels)
{
const int rmin = ptr->rmin;
const int rmax = ptr->rmax;
const int gmin = ptr->gmin;
const int gmax = ptr->gmax;
const int bmin = ptr->bmin;
const int bmax = ptr->bmax;
for (T iPixel = 0; iPixel < nPixels; iPixel++)
{
const int iR = pabyRedBand[iPixel];
const int iG = pabyGreenBand[iPixel];
const int iB = pabyBlueBand[iPixel];
if (iR >= rmin && iR <= rmax && iG >= gmin && iG <= gmax &&
iB >= bmin && iB <= bmax)
{
hist2[iG]++;
}
}
}
else if (psHashHistogram)
{
T *histp = &hist2[ptr->gmin];
for (int ig = ptr->gmin; ig <= ptr->gmax; ++ig)
{
*histp = 0;
for (int ir = ptr->rmin; ir <= ptr->rmax; ++ir)
{
for (int ib = ptr->bmin; ib <= ptr->bmax; ++ib)
{
*histp += FindColorCount(
psHashHistogram, MAKE_COLOR_CODE(ir, ig, ib));
}
}
histp++;
}
}
else
{
T *histp = &hist2[ptr->gmin];
for (int ig = ptr->gmin; ig <= ptr->gmax; ++ig)
{
*histp = 0;
for (int ir = ptr->rmin; ir <= ptr->rmax; ++ir)
{
const T *iptr =
HISTOGRAM(histogram, nCLevels, ir, ig, ptr->bmin);
for (int ib = ptr->bmin; ib <= ptr->bmax; ++ib)
*histp += *iptr++;
}
histp++;
}
}
first = ptr->gmin;
last = ptr->gmax;
break;
}
case BLUE:
{
if (nPixels != 0 && nIters > nPixels)
{
const int rmin = ptr->rmin;
const int rmax = ptr->rmax;
const int gmin = ptr->gmin;
const int gmax = ptr->gmax;
const int bmin = ptr->bmin;
const int bmax = ptr->bmax;
for (T iPixel = 0; iPixel < nPixels; iPixel++)
{
const int iR = pabyRedBand[iPixel];
const int iG = pabyGreenBand[iPixel];
const int iB = pabyBlueBand[iPixel];
if (iR >= rmin && iR <= rmax && iG >= gmin && iG <= gmax &&
iB >= bmin && iB <= bmax)
{
hist2[iB]++;
}
}
}
else if (psHashHistogram)
{
T *histp = &hist2[ptr->bmin];
for (int ib = ptr->bmin; ib <= ptr->bmax; ++ib)
{
*histp = 0;
for (int ir = ptr->rmin; ir <= ptr->rmax; ++ir)
{
for (int ig = ptr->gmin; ig <= ptr->gmax; ++ig)
{
*histp += FindColorCount(
psHashHistogram, MAKE_COLOR_CODE(ir, ig, ib));
}
}
histp++;
}
}
else
{
T *histp = &hist2[ptr->bmin];
for (int ib = ptr->bmin; ib <= ptr->bmax; ++ib)
{
*histp = 0;
for (int ir = ptr->rmin; ir <= ptr->rmax; ++ir)
{
const T *iptr =
HISTOGRAM(histogram, nCLevels, ir, ptr->gmin, ib);
for (int ig = ptr->gmin; ig <= ptr->gmax; ++ig)
{
*histp += *iptr;
iptr += nCLevels;
}
}
histp++;
}
}
first = ptr->bmin;
last = ptr->bmax;
break;
}
}
// Find median point.
T *histp = &hist2[first];
int i = first; // TODO(schwehr): Rename i.
{
T sum = 0;
T sum2 = static_cast<T>(ptr->total / 2);
for (; i <= last && (sum += *histp++) < sum2; ++i)
{
}
}
if (i == first)
i++;
// Create new box, re-allocate points.
Colorbox *new_cb = *pfreeboxes;
*pfreeboxes = new_cb->next;
if (*pfreeboxes)
(*pfreeboxes)->prev = nullptr;
if (*pusedboxes)