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JPEG tweaks and optimization (thanks to digitall)

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svn-id: r46522
This commit is contained in:
Scott Thomas 2009-12-24 08:26:13 +00:00
parent 65dcc0b2a3
commit b63cbe2577
2 changed files with 53 additions and 31 deletions
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82
graphics/jpeg.cpp
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@ -57,6 +57,15 @@ JPEG::JPEG() :
_huff[i].sizes = NULL;
_huff[i].codes = NULL;
}
// Initialize sqrt_2 and cosine lookups
_sqrt_2 = sqrt(2.0f);
debug(2, "JPEG: _sqrt_2: %f", _sqrt_2);
for(byte i = 0; i < 32; i++) {
_cosine_32[i] = cos(i * PI / 16);
debug(2, "JPEG: _cosine_32[%d]: %f", i, _cosine_32[i]);
}
}
JPEG::~JPEG() {
@ -151,19 +160,30 @@ bool JPEG::read(Common::SeekableReadStream *str) {
}
bool JPEG::readJFIF() {
/* uint16 length = */ _str->readUint16BE();
uint16 length = _str->readUint16BE();
uint32 tag = _str->readUint32BE();
if (tag != MKID_BE('JFIF'))
if (tag != MKID_BE('JFIF')) {
warning("JPEG::readJFIF() tag mismatch");
return false;
_str->readByte(); // NULL
/* byte majorVersion = */ _str->readByte();
/* byte minorVersion = */ _str->readByte();
}
if (_str->readByte() != 0) { // NULL
warning("JPEG::readJFIF() NULL mismatch");
return false;
}
byte majorVersion = _str->readByte();
byte minorVersion = _str->readByte();
if(majorVersion != 1 || minorVersion != 1)
warning("JPEG::readJFIF() Non-v1.1 JPEGs may not be handled correctly!");
/* byte densityUnits = */ _str->readByte();
/* uint16 xDensity = */ _str->readUint16BE();
/* uint16 yDensity = */ _str->readUint16BE();
byte thumbW = _str->readByte();
byte thumbH = _str->readByte();
_str->seek(thumbW * thumbH * 3, SEEK_CUR); // Ignore thumbnail
if (length != (thumbW * thumbH * 3) + 16) {
warning("JPEG::readJFIF() length mismatch");
return false;
}
return true;
}
@ -325,10 +345,6 @@ bool JPEG::readSOS() {
// Initialize the DC predictor
_scanComp[c]->DCpredictor = 0;
}
// Initialize the scan surfaces
for (int c = 0; c < _numScanComp; c++)
_scanComp[c]->surface.create(_w, _h, 1);
// Start of spectral selection
if (_str->readByte() != 0) {
@ -356,16 +372,28 @@ bool JPEG::readSOS() {
uint16 yMCU = _h / (_maxFactorV * 8);
// Check for non- multiple-of-8 dimensions
if (_w % 8 != 0)
if (_w % (_maxFactorH * 8) != 0)
xMCU++;
if (_h % 8 != 0)
if (_h % (_maxFactorV * 8) != 0)
yMCU++;
// Initialize the scan surfaces
for (uint16 c = 0; c < _numScanComp; c++) {
_scanComp[c]->surface.create(xMCU * _maxFactorH * 8, yMCU * _maxFactorV * 8, 1);
}
bool ok = true;
for (int y = 0; ok && (y < yMCU); y++)
for (int y = 0; ok && (y < yMCU); y++)
for (int x = 0; ok && (x < xMCU); x++)
ok = readMCU(x, y);
// Trim Component surfaces back to image height and width
// Note: Code using jpeg must use surface.pitch correctly...
for (uint16 c = 0; c < _numScanComp; c++) {
_scanComp[c]->surface.w = _w;
_scanComp[c]->surface.h = _h;
}
return ok;
}
@ -415,15 +443,15 @@ bool JPEG::readMCU(uint16 xMCU, uint16 yMCU) {
}
float JPEG::idct(int x, int y, int weight, int fx, int fy) {
float vx = cos((2 * x + 1) * fx * PI / 16);
float vy = cos((2 * y + 1) * fy * PI / 16);
float ret = (float)weight * vx * vy;
byte vx_in = ((int32)((2 * x) + 1) * fx) % 32;
byte vy_in = ((int32)((2 * y) + 1) * fy) % 32;
float ret = (float)weight * _cosine_32[vx_in] * _cosine_32[vy_in];
if (fx == 0)
ret /= sqrt(2.0f);
ret /= _sqrt_2;
if (fy == 0)
ret /= sqrt(2.0f);
ret /= _sqrt_2;
return ret;
}
@ -443,7 +471,7 @@ bool JPEG::readDataUnit(uint16 x, uint16 y) {
// Calculate the DCT coefficients from the input sequence
int16 DCT[64];
for (int i = 0; i < 64; i++) {
for (uint8 i = 0; i < 64; i++) {
// Dequantize
int16 val = readData[i];
int16 quant = _quant[_currentComp->quantTableSelector][i];
@ -455,7 +483,7 @@ bool JPEG::readDataUnit(uint16 x, uint16 y) {
// Shortcut the IDCT for DC component
float result[64];
for (int i = 0; i < 64; i++)
for (uint8 i = 0; i < 64; i++)
result[i] = DCT[0] / 2;
// Apply the IDCT (PAG31)
@ -486,21 +514,13 @@ bool JPEG::readDataUnit(uint16 x, uint16 y) {
x <<= 3;
y <<= 3;
// Handle non- multiple-of-8 dimensions
byte xLim = 8;
byte yLim = 8;
if (x*scalingH + 8 > _w)
xLim -= (x*scalingH + 8 - _w);
if (y*scalingV + 8 > _h)
yLim -= (y*scalingV + 8 - _h);
for (int j = 0; j < yLim; j++) {
for (int sV = 0; sV < scalingV; sV++) {
for (uint8 j = 0; j < 8; j++) {
for (uint16 sV = 0; sV < scalingV; sV++) {
// Get the beginning of the block line
byte *ptr = (byte *)_currentComp->surface.getBasePtr(x * scalingH, (y + j) * scalingV + sV);
for (int i = 0; i < xLim; i++) {
for (uint8 sH = 0; sH < scalingH; sH++) {
for (uint8 i = 0; i < 8; i++) {
for (uint16 sH = 0; sH < scalingH; sH++) {
*ptr = (byte)(result[j * 8 + i]);
ptr++;
}