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gdaldither.cpp
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gdaldither.cpp
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/******************************************************************************
*
* Project: CIETMap Phase 2
* Purpose: Convert RGB (24bit) to a pseudo-colored approximation using
* Floyd-Steinberg dithering (error diffusion).
* Author: Frank Warmerdam, warmerdam@pobox.com
*
******************************************************************************
* Copyright (c) 2001, Frank Warmerdam
* Copyright (c) 2007, Even Rouault <even dot rouault at spatialys.com>
*
* SPDX-License-Identifier: MIT
******************************************************************************
*
* Notes:
*
* [1] Floyd-Steinberg dither:
* I should point out that the actual fractions we used were, assuming
* you are at X, moving left to right:
*
* X 7/16
* 3/16 5/16 1/16
*
* Note that the error goes to four neighbors, not three. I think this
* will probably do better (at least for black and white) than the
* 3/8-3/8-1/4 distribution, at the cost of greater processing. I have
* seen the 3/8-3/8-1/4 distribution described as "our" algorithm before,
* but I have no idea who the credit really belongs to.
* --
* Lou Steinberg
*/
#include "cpl_port.h"
#include "gdal_alg.h"
#include "gdal_alg_priv.h"
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_progress.h"
#include "cpl_vsi.h"
#include "gdal.h"
#include "gdal_priv.h"
#if defined(__x86_64) || defined(_M_X64)
#define USE_SSE2
#endif
#ifdef USE_SSE2
#include <emmintrin.h>
#define CAST_PCT(x) reinterpret_cast<GByte *>(x)
#define ALIGN_INT_ARRAY_ON_16_BYTE(x) \
(((reinterpret_cast<GUIntptr_t>(x) % 16) != 0) \
? reinterpret_cast<int *>(reinterpret_cast<GByte *>(x) + 16 - \
(reinterpret_cast<GUIntptr_t>(x) % 16)) \
: (x))
#else
#define CAST_PCT(x) x
#endif
#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
static void FindNearestColor(int nColors, int *panPCT, GByte *pabyColorMap,
int nCLevels);
static int FindNearestColor(int nColors, int *panPCT, int nRedValue,
int nGreenValue, int nBlueValue);
// Structure for a hashmap from a color code to a color index of the
// color table.
// 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 HashHistogram in gdalmediancut.cpp.
typedef struct
{
GUInt32 nColorCode;
GUInt32 nColorCode2;
GUInt32 nColorCode3;
GByte nIndex;
GByte nIndex2;
GByte nIndex3;
GByte nPadding;
} ColorIndex;
/************************************************************************/
/* GDALDitherRGB2PCT() */
/************************************************************************/
#ifndef IsColorCodeSet_defined
#define IsColorCodeSet_defined
static inline bool IsColorCodeSet(GUInt32 nColorCode)
{
return (nColorCode >> 31) == 0;
}
#endif
/**
* 24bit to 8bit conversion with dithering.
*
* This functions utilizes Floyd-Steinberg dithering in the process of
* converting a 24bit RGB image into a pseudocolored 8bit image using a
* provided color table.
*
* 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. Likewise the hTarget band will be written with 8bit values
* and must match the width and height of the source bands.
*
* The color table cannot have more than 256 entries.
*
* @param hRed Red input band.
* @param hGreen Green input band.
* @param hBlue Blue input band.
* @param hTarget Output band.
* @param hColorTable the color table to use with the output band.
* @param pfnProgress callback for reporting algorithm progress matching the
* GDALProgressFunc() semantics. May be NULL.
* @param pProgressArg callback argument passed to pfnProgress.
*
* @return CE_None on success or CE_Failure if an error occurs.
*/
int CPL_STDCALL GDALDitherRGB2PCT(GDALRasterBandH hRed, GDALRasterBandH hGreen,
GDALRasterBandH hBlue,
GDALRasterBandH hTarget,
GDALColorTableH hColorTable,
GDALProgressFunc pfnProgress,
void *pProgressArg)
{
return GDALDitherRGB2PCTInternal(hRed, hGreen, hBlue, hTarget, hColorTable,
5, nullptr, TRUE, pfnProgress,
pProgressArg);
}
int GDALDitherRGB2PCTInternal(
GDALRasterBandH hRed, GDALRasterBandH hGreen, GDALRasterBandH hBlue,
GDALRasterBandH hTarget, GDALColorTableH hColorTable, int nBits,
// NULL or at least 256 * 256 * 256 * sizeof(GInt16) bytes.
GInt16 *pasDynamicColorMap, int bDither, GDALProgressFunc pfnProgress,
void *pProgressArg)
{
VALIDATE_POINTER1(hRed, "GDALDitherRGB2PCT", CE_Failure);
VALIDATE_POINTER1(hGreen, "GDALDitherRGB2PCT", CE_Failure);
VALIDATE_POINTER1(hBlue, "GDALDitherRGB2PCT", CE_Failure);
VALIDATE_POINTER1(hTarget, "GDALDitherRGB2PCT", CE_Failure);
VALIDATE_POINTER1(hColorTable, "GDALDitherRGB2PCT", CE_Failure);
/* -------------------------------------------------------------------- */
/* 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 (GDALGetRasterBandXSize(hTarget) != nXSize ||
GDALGetRasterBandYSize(hTarget) != nYSize)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"GDALDitherRGB2PCT(): "
"Target band doesn't match size of source bands.");
return CE_Failure;
}
if (pfnProgress == nullptr)
pfnProgress = GDALDummyProgress;
/* -------------------------------------------------------------------- */
/* Setup more direct colormap. */
/* -------------------------------------------------------------------- */
int iColor;
#ifdef USE_SSE2
int anPCTUnaligned[256 + 4]; // 4 for alignment on 16-byte boundary.
int *anPCT = ALIGN_INT_ARRAY_ON_16_BYTE(anPCTUnaligned);
#else
int anPCT[256 * 4] = {};
#endif
const int nColors = GDALGetColorEntryCount(hColorTable);
if (nColors == 0)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"GDALDitherRGB2PCT(): "
"Color table must not be empty.");
return CE_Failure;
}
else if (nColors > 256)
{
CPLError(CE_Failure, CPLE_IllegalArg,
"GDALDitherRGB2PCT(): "
"Color table cannot have more than 256 entries.");
return CE_Failure;
}
iColor = 0;
do
{
GDALColorEntry sEntry;
GDALGetColorEntryAsRGB(hColorTable, iColor, &sEntry);
CAST_PCT(anPCT)[4 * iColor + 0] = static_cast<GByte>(sEntry.c1);
CAST_PCT(anPCT)[4 * iColor + 1] = static_cast<GByte>(sEntry.c2);
CAST_PCT(anPCT)[4 * iColor + 2] = static_cast<GByte>(sEntry.c3);
CAST_PCT(anPCT)[4 * iColor + 3] = 0;
iColor++;
} while (iColor < nColors);
#ifdef USE_SSE2
// Pad to multiple of 8 colors.
const int nColorsMod8 = nColors % 8;
if (nColorsMod8)
{
int iDest = nColors;
for (iColor = 0; iColor < 8 - nColorsMod8 && iDest < 256;
iColor++, iDest++)
{
anPCT[iDest] = anPCT[nColors - 1];
}
}
#endif
/* -------------------------------------------------------------------- */
/* Setup various variables. */
/* -------------------------------------------------------------------- */
const int nCLevels = 1 << nBits;
const int nCLevelsCube = nCLevels * nCLevels * nCLevels;
ColorIndex *psColorIndexMap = nullptr;
GByte *pabyRed = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
GByte *pabyGreen = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
GByte *pabyBlue = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
GByte *pabyIndex = static_cast<GByte *>(VSI_MALLOC_VERBOSE(nXSize));
int *panError =
static_cast<int *>(VSI_CALLOC_VERBOSE(sizeof(int), (nXSize + 2) * 3));
if (pabyRed == nullptr || pabyGreen == nullptr || pabyBlue == nullptr ||
pabyIndex == nullptr || panError == nullptr)
{
CPLFree(pabyRed);
CPLFree(pabyGreen);
CPLFree(pabyBlue);
CPLFree(pabyIndex);
CPLFree(panError);
return CE_Failure;
}
GByte *pabyColorMap = nullptr;
if (pasDynamicColorMap == nullptr)
{
/* --------------------------------------------------------------------
*/
/* Build a 24bit to 8 bit color mapping. */
/* --------------------------------------------------------------------
*/
pabyColorMap = static_cast<GByte *>(
VSI_MALLOC_VERBOSE(nCLevelsCube * sizeof(GByte)));
if (pabyColorMap == nullptr)
{
CPLFree(pabyRed);
CPLFree(pabyGreen);
CPLFree(pabyBlue);
CPLFree(pabyIndex);
CPLFree(panError);
CPLFree(pabyColorMap);
return CE_Failure;
}
FindNearestColor(nColors, anPCT, pabyColorMap, nCLevels);
}
else
{
pabyColorMap = nullptr;
if (nBits == 8 && static_cast<GIntBig>(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.
psColorIndexMap =
reinterpret_cast<ColorIndex *>(pasDynamicColorMap);
memset(psColorIndexMap, 0xFF, sizeof(ColorIndex) * PRIME_FOR_65536);
}
else
{
memset(pasDynamicColorMap, 0xFF, 256 * 256 * 256 * sizeof(GInt16));
}
}
/* ==================================================================== */
/* Loop over all scanlines of data to process. */
/* ==================================================================== */
CPLErr err = CE_None;
for (int iScanline = 0; iScanline < nYSize; iScanline++)
{
/* --------------------------------------------------------------------
*/
/* Report progress */
/* --------------------------------------------------------------------
*/
if (!pfnProgress(iScanline / static_cast<double>(nYSize), nullptr,
pProgressArg))
{
CPLError(CE_Failure, CPLE_UserInterrupt, "User Terminated");
CPLFree(pabyRed);
CPLFree(pabyGreen);
CPLFree(pabyBlue);
CPLFree(pabyIndex);
CPLFree(panError);
CPLFree(pabyColorMap);
return CE_Failure;
}
/* --------------------------------------------------------------------
*/
/* Read source data. */
/* --------------------------------------------------------------------
*/
CPLErr err1 = GDALRasterIO(hRed, GF_Read, 0, iScanline, nXSize, 1,
pabyRed, nXSize, 1, GDT_Byte, 0, 0);
if (err1 == CE_None)
err1 = GDALRasterIO(hGreen, GF_Read, 0, iScanline, nXSize, 1,
pabyGreen, nXSize, 1, GDT_Byte, 0, 0);
if (err1 == CE_None)
err1 = GDALRasterIO(hBlue, GF_Read, 0, iScanline, nXSize, 1,
pabyBlue, nXSize, 1, GDT_Byte, 0, 0);
if (err1 != CE_None)
{
CPLFree(pabyRed);
CPLFree(pabyGreen);
CPLFree(pabyBlue);
CPLFree(pabyIndex);
CPLFree(panError);
CPLFree(pabyColorMap);
return err1;
}
/* --------------------------------------------------------------------
*/
/* Apply the error from the previous line to this one. */
/* --------------------------------------------------------------------
*/
if (bDither)
{
for (int i = 0; i < nXSize; i++)
{
pabyRed[i] = static_cast<GByte>(std::max(
0, std::min(255, (pabyRed[i] + panError[i * 3 + 0 + 3]))));
pabyGreen[i] = static_cast<GByte>(std::max(
0,
std::min(255, (pabyGreen[i] + panError[i * 3 + 1 + 3]))));
pabyBlue[i] = static_cast<GByte>(std::max(
0, std::min(255, (pabyBlue[i] + panError[i * 3 + 2 + 3]))));
}
memset(panError, 0, sizeof(int) * (nXSize + 2) * 3);
}
/* --------------------------------------------------------------------
*/
/* Figure out the nearest color to the RGB value. */
/* --------------------------------------------------------------------
*/
int nLastRedError = 0;
int nLastGreenError = 0;
int nLastBlueError = 0;
for (int i = 0; i < nXSize; i++)
{
const int nRedValue =
std::max(0, std::min(255, pabyRed[i] + nLastRedError));
const int nGreenValue =
std::max(0, std::min(255, pabyGreen[i] + nLastGreenError));
const int nBlueValue =
std::max(0, std::min(255, pabyBlue[i] + nLastBlueError));
int iIndex = 0;
int nError = 0;
int nSixth = 0;
if (psColorIndexMap)
{
const GUInt32 nColorCode =
MAKE_COLOR_CODE(nRedValue, nGreenValue, nBlueValue);
GUInt32 nIdx = nColorCode % PRIME_FOR_65536;
while (true)
{
if (psColorIndexMap[nIdx].nColorCode == nColorCode)
{
iIndex = psColorIndexMap[nIdx].nIndex;
break;
}
if (!IsColorCodeSet(psColorIndexMap[nIdx].nColorCode))
{
psColorIndexMap[nIdx].nColorCode = nColorCode;
iIndex = FindNearestColor(nColors, anPCT, nRedValue,
nGreenValue, nBlueValue);
psColorIndexMap[nIdx].nIndex =
static_cast<GByte>(iIndex);
break;
}
if (psColorIndexMap[nIdx].nColorCode2 == nColorCode)
{
iIndex = psColorIndexMap[nIdx].nIndex2;
break;
}
if (!IsColorCodeSet(psColorIndexMap[nIdx].nColorCode2))
{
psColorIndexMap[nIdx].nColorCode2 = nColorCode;
iIndex = FindNearestColor(nColors, anPCT, nRedValue,
nGreenValue, nBlueValue);
psColorIndexMap[nIdx].nIndex2 =
static_cast<GByte>(iIndex);
break;
}
if (psColorIndexMap[nIdx].nColorCode3 == nColorCode)
{
iIndex = psColorIndexMap[nIdx].nIndex3;
break;
}
if (!IsColorCodeSet(psColorIndexMap[nIdx].nColorCode3))
{
psColorIndexMap[nIdx].nColorCode3 = nColorCode;
iIndex = FindNearestColor(nColors, anPCT, nRedValue,
nGreenValue, nBlueValue);
psColorIndexMap[nIdx].nIndex3 =
static_cast<GByte>(iIndex);
break;
}
do
{
nIdx += 257;
if (nIdx >= PRIME_FOR_65536)
nIdx -= PRIME_FOR_65536;
} while (
IsColorCodeSet(psColorIndexMap[nIdx].nColorCode) &&
psColorIndexMap[nIdx].nColorCode != nColorCode &&
IsColorCodeSet(psColorIndexMap[nIdx].nColorCode2) &&
psColorIndexMap[nIdx].nColorCode2 != nColorCode &&
IsColorCodeSet(psColorIndexMap[nIdx].nColorCode3) &&
psColorIndexMap[nIdx].nColorCode3 != nColorCode);
}
}
else if (pasDynamicColorMap == nullptr)
{
const int iRed = nRedValue * nCLevels / 256;
const int iGreen = nGreenValue * nCLevels / 256;
const int iBlue = nBlueValue * nCLevels / 256;
iIndex = pabyColorMap[iRed + iGreen * nCLevels +
iBlue * nCLevels * nCLevels];
}
else
{
const GUInt32 nColorCode =
MAKE_COLOR_CODE(nRedValue, nGreenValue, nBlueValue);
GInt16 *psIndex = &pasDynamicColorMap[nColorCode];
if (*psIndex < 0)
{
*psIndex = static_cast<GInt16>(FindNearestColor(
nColors, anPCT, nRedValue, nGreenValue, nBlueValue));
iIndex = *psIndex;
}
else
{
iIndex = *psIndex;
}
}
pabyIndex[i] = static_cast<GByte>(iIndex);
if (!bDither)
continue;
/* --------------------------------------------------------------------
*/
/* Compute Red error, and carry it on to the next error line.
*/
/* --------------------------------------------------------------------
*/
nError = nRedValue - CAST_PCT(anPCT)[4 * iIndex + 0];
nSixth = nError / 6;
panError[i * 3] += nSixth;
panError[i * 3 + 6] = nSixth;
panError[i * 3 + 3] += nError - 5 * nSixth;
nLastRedError = 2 * nSixth;
/* --------------------------------------------------------------------
*/
/* Compute Green error, and carry it on to the next error line.
*/
/* --------------------------------------------------------------------
*/
nError = nGreenValue - CAST_PCT(anPCT)[4 * iIndex + 1];
nSixth = nError / 6;
panError[i * 3 + 1] += nSixth;
panError[i * 3 + 6 + 1] = nSixth;
panError[i * 3 + 3 + 1] += nError - 5 * nSixth;
nLastGreenError = 2 * nSixth;
/* --------------------------------------------------------------------
*/
/* Compute Blue error, and carry it on to the next error line.
*/
/* --------------------------------------------------------------------
*/
nError = nBlueValue - CAST_PCT(anPCT)[4 * iIndex + 2];
nSixth = nError / 6;
panError[i * 3 + 2] += nSixth;
panError[i * 3 + 6 + 2] = nSixth;
panError[i * 3 + 3 + 2] += nError - 5 * nSixth;
nLastBlueError = 2 * nSixth;
}
/* --------------------------------------------------------------------
*/
/* Write results. */
/* --------------------------------------------------------------------
*/
err = GDALRasterIO(hTarget, GF_Write, 0, iScanline, nXSize, 1,
pabyIndex, nXSize, 1, GDT_Byte, 0, 0);
if (err != CE_None)
break;
}
pfnProgress(1.0, nullptr, pProgressArg);
/* -------------------------------------------------------------------- */
/* Cleanup */
/* -------------------------------------------------------------------- */
CPLFree(pabyRed);
CPLFree(pabyGreen);
CPLFree(pabyBlue);
CPLFree(pabyIndex);
CPLFree(panError);
CPLFree(pabyColorMap);
return err;
}
static int FindNearestColor(int nColors, int *panPCT, int nRedValue,
int nGreenValue, int nBlueValue)
{
#ifdef USE_SSE2
int nBestDist = 768;
int nBestIndex = 0;
int anDistanceUnaligned[16 + 4] =
{}; // 4 for alignment on 16-byte boundary.
int *anDistance = ALIGN_INT_ARRAY_ON_16_BYTE(anDistanceUnaligned);
const __m128i ff = _mm_set1_epi32(0xFFFFFFFF);
const __m128i mask_low = _mm_srli_epi64(ff, 32);
const __m128i mask_high = _mm_slli_epi64(ff, 32);
const unsigned int nColorVal =
MAKE_COLOR_CODE(nRedValue, nGreenValue, nBlueValue);
const __m128i thisColor = _mm_set1_epi32(nColorVal);
const __m128i thisColor_low = _mm_srli_epi64(thisColor, 32);
const __m128i thisColor_high = _mm_slli_epi64(thisColor, 32);
for (int iColor = 0; iColor < nColors; iColor += 8)
{
const __m128i pctColor =
_mm_load_si128(reinterpret_cast<__m128i *>(&panPCT[iColor]));
const __m128i pctColor2 =
_mm_load_si128(reinterpret_cast<__m128i *>(&panPCT[iColor + 4]));
_mm_store_si128(
reinterpret_cast<__m128i *>(anDistance),
_mm_sad_epu8(_mm_and_si128(pctColor, mask_low), thisColor_low));
_mm_store_si128(
reinterpret_cast<__m128i *>(anDistance + 4),
_mm_sad_epu8(_mm_and_si128(pctColor, mask_high), thisColor_high));
_mm_store_si128(
reinterpret_cast<__m128i *>(anDistance + 8),
_mm_sad_epu8(_mm_and_si128(pctColor2, mask_low), thisColor_low));
_mm_store_si128(
reinterpret_cast<__m128i *>(anDistance + 12),
_mm_sad_epu8(_mm_and_si128(pctColor2, mask_high), thisColor_high));
if (anDistance[0] < nBestDist)
{
nBestIndex = iColor;
nBestDist = anDistance[0];
}
if (anDistance[4] < nBestDist)
{
nBestIndex = iColor + 1;
nBestDist = anDistance[4];
}
if (anDistance[2] < nBestDist)
{
nBestIndex = iColor + 2;
nBestDist = anDistance[2];
}
if (anDistance[6] < nBestDist)
{
nBestIndex = iColor + 3;
nBestDist = anDistance[6];
}
if (anDistance[8 + 0] < nBestDist)
{
nBestIndex = iColor + 4;
nBestDist = anDistance[8 + 0];
}
if (anDistance[8 + 4] < nBestDist)
{
nBestIndex = iColor + 4 + 1;
nBestDist = anDistance[8 + 4];
}
if (anDistance[8 + 2] < nBestDist)
{
nBestIndex = iColor + 4 + 2;
nBestDist = anDistance[8 + 2];
}
if (anDistance[8 + 6] < nBestDist)
{
nBestIndex = iColor + 4 + 3;
nBestDist = anDistance[8 + 6];
}
}
return nBestIndex;
#else
int nBestDist = 768;
int nBestIndex = 0;
for (int iColor = 0; iColor < nColors; iColor++)
{
const int nThisDist = std::abs(nRedValue - panPCT[4 * iColor + 0]) +
std::abs(nGreenValue - panPCT[4 * iColor + 1]) +
std::abs(nBlueValue - panPCT[4 * iColor + 2]);
if (nThisDist < nBestDist)
{
nBestIndex = iColor;
nBestDist = nThisDist;
}
}
return nBestIndex;
#endif
}
/************************************************************************/
/* FindNearestColor() */
/* */
/* Finear near PCT color for any RGB color. */
/************************************************************************/
static void FindNearestColor(int nColors, int *panPCT, GByte *pabyColorMap,
int nCLevels)
{
/* -------------------------------------------------------------------- */
/* Loop over all the cells in the high density cube. */
/* -------------------------------------------------------------------- */
for (int iBlue = 0; iBlue < nCLevels; iBlue++)
{
for (int iGreen = 0; iGreen < nCLevels; iGreen++)
{
for (int iRed = 0; iRed < nCLevels; iRed++)
{
const int nRedValue = (iRed * 255) / (nCLevels - 1);
const int nGreenValue = (iGreen * 255) / (nCLevels - 1);
const int nBlueValue = (iBlue * 255) / (nCLevels - 1);
const int nBestIndex = FindNearestColor(
nColors, panPCT, nRedValue, nGreenValue, nBlueValue);
pabyColorMap[iRed + iGreen * nCLevels +
iBlue * nCLevels * nCLevels] =
static_cast<GByte>(nBestIndex);
}
}
}
}