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Simplify pHash/SSIM code by using matching threshold, not difference
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@kristiankoskimaki
kristiankoskimaki committed May 24, 2019
1 parent edcf29a commit bb3f425
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Showing 5 changed files with 36 additions and 46 deletions.
53 changes: 23 additions & 30 deletions comparison.cpp
View file
Expand Up @@ -20,8 +20,7 @@ Comparison::Comparison(const QVector<Video *> &userVideos, const Prefs &userPref

if(_prefs._ComparisonMode == _prefs._SSIM)
ui->selectSSIM->setChecked(true);
_prefs._thresholdPhashOriginal = _prefs._thresholdPhash;
ui->thresholdSlider->setValue(64 - _prefs._thresholdPhash);
ui->thresholdSlider->setValue(QVariant(_prefs._thresholdSSIM * 100).toInt());
ui->progressBar->setMaximum(_videos.count() * (_videos.count() - 1) / 2);

on_nextVideo_clicked();
Expand Down Expand Up @@ -154,14 +153,14 @@ bool Comparison::bothVideosMatch(const Video *left, const Video *right)
_phashSimilarity = phashSimilarity(left, right);
if(_prefs._ComparisonMode == _prefs._PHASH)
{
if(_phashSimilarity <= _prefs._thresholdPhash)
if(_phashSimilarity >= _prefs._thresholdPhash)
return true;
return false;
} //ssim comparison takes long time, only do it if pHash somewhat matches
else if(_phashSimilarity <= qMax(_prefs._thresholdPhash, 20))
} //ssim comparison takes long time, only do it if pHash differs at most 20 bits of 64
else if(_phashSimilarity >= qMax(_prefs._thresholdPhash, 64 - 20))
{
_ssimSimilarity = ssim(left->grayThumb, right->grayThumb, _prefs._ssimBlockSize);
_ssimSimilarity = _ssimSimilarity + _durationModifier / 64.0;
_ssimSimilarity = _ssimSimilarity + _durationModifier / 64.0; // b/64 bits (phash) <=> p/100 % (ssim)
if(_ssimSimilarity > _prefs._thresholdSSIM)
return true;
}
Expand All @@ -170,21 +169,21 @@ bool Comparison::bothVideosMatch(const Video *left, const Video *right)

int Comparison::phashSimilarity(const Video *left, const Video *right)
{
int distance = 0;
uint64_t differentBits = left->hash ^ right->hash; //XOR to value (only ones for differing bits)
int distance = 64;
uint64_t differentBits = left->hash ^ right->hash; //XOR to value (only ones for differing bits)
while(differentBits != 0)
{
differentBits &= differentBits - 1; //count number of bits of value
distance++;
differentBits &= differentBits - 1; //count number of bits of value
distance--;
}

if( qAbs(left->duration - right->duration) <= 1000 )
_durationModifier = 0 - _prefs._sameDurationModifier; //lower distance if both durations within 1s
_durationModifier = 0 + _prefs._sameDurationModifier; //lower distance if both durations within 1s
else
_durationModifier = 0 + _prefs._differentDurationModifier; //raise distance if both durations differ 1s
_durationModifier = 0 - _prefs._differentDurationModifier; //raise distance if both durations differ 1s

distance = distance + _durationModifier;
return distance > 0? distance : 0; //negative value would wrap into huge value because return value is int
return distance > 64? 64 : distance;
}

void Comparison::showVideo(const QString &side) const
Expand Down Expand Up @@ -369,10 +368,9 @@ void Comparison::updateUI()
}

if(_prefs._ComparisonMode == _prefs._PHASH)
ui->identicalBits->setText(QStringLiteral("%1/64 different bits").arg(_phashSimilarity));
ui->identicalBits->setText(QStringLiteral("%1/64 same bits").arg(_phashSimilarity));
if(_prefs._ComparisonMode == _prefs._SSIM)
ui->identicalBits->setText(QStringLiteral("%1 SSIM index").arg(QString::number(_ssimSimilarity, 'f', 3)));

ui->identicalBits->setText(QStringLiteral("%1 SSIM index").arg(QString::number(qMin(_ssimSimilarity, 1.0), 'f', 3)));
_zoomLevel = 0;
ui->progressBar->setValue(comparisonsSoFar());
}
Expand Down Expand Up @@ -607,22 +605,17 @@ void Comparison::on_swapFilenames_clicked() const

void Comparison::on_thresholdSlider_valueChanged(const int &value)
{
const int differentBits = 64 - value;
const int percentage = 100 * value / 64;

const QString thresholdMessage = QStringLiteral("pHash threshold: %1% (%2/64 bits may differ),"
" was originally %3%\nSSIM threshold: %4").
arg(percentage).arg(differentBits).arg(100 * (64 - _prefs._thresholdPhashOriginal) / 64).
arg(value / 64.0);
_prefs._thresholdSSIM = value / 100.0;
const int matchingBitsOf64 = static_cast<int>(round(64 * _prefs._thresholdSSIM));
_prefs._thresholdPhash = matchingBitsOf64;

const QString thresholdMessage = QStringLiteral(
"Threshold: %1% (%2/64 bits = match) Default: 89%\n"
"Smaller: less strict, can match different videos (false positive)\n"
"Larger: more strict, can miss identical videos (false negative)").arg(value).arg(matchingBitsOf64);
ui->thresholdSlider->setToolTip(thresholdMessage);

if(differentBits != _prefs._thresholdPhash) //function also called when constructor sets slider
{
_prefs._thresholdPhash = 64 - value;
_prefs._thresholdSSIM = value / 64.0;
}

emit adjustThresholdSlider(64 - _prefs._thresholdPhash);
emit adjustThresholdSlider(ui->thresholdSlider->value());
}

void Comparison::resizeEvent(QResizeEvent *event)
Expand Down
3 changes: 1 addition & 2 deletions comparison.ui
View file
Expand Up @@ -78,7 +78,7 @@
<number>1</number>
</property>
<property name="maximum">
<number>64</number>
<number>100</number>
</property>
<property name="orientation">
<enum>Qt::Horizontal</enum>
Expand Down Expand Up @@ -920,7 +920,6 @@
<customwidgets>
<customwidget>
<class>ClickableLabel</class>
<extends>QWidget</extends>
</customwidget>
</customwidgets>
<resources/>
Expand Down
15 changes: 7 additions & 8 deletions mainwindow.cpp
View file
Expand Up @@ -37,7 +37,7 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWi
ui->selectThumbnails->addItem(thumb.modeName(i));
ui->selectThumbnails->setCurrentIndex(3);

for(int i=0; i<=9; i++)
for(int i=0; i<=5; i++)
{
ui->differentDurationCombo->addItem(QStringLiteral("%1").arg(i));
ui->sameDurationCombo->addItem(QStringLiteral("%1").arg(i));
Expand Down Expand Up @@ -122,16 +122,15 @@ bool MainWindow::detectffmpeg() const

void MainWindow::calculateThreshold(const int &value)
{
const int differentBits = 64 - value; //two video's hashes may only differ this many bits
const int percentage = 100 * value / 64; //to be considered having the the same content
_prefs._thresholdSSIM = value / 100.0;
const int matchingBitsOf64 = static_cast<int>(round(64 * _prefs._thresholdSSIM));
_prefs._thresholdPhash = matchingBitsOf64;

const QString thresholdMessage = QStringLiteral(
"Threshold: %1% (%2/64 bits may differ)\n"
"Default is: 89% (7/64 bits may differ)\n"
"Threshold: %1% (%2/64 bits = match) Default: 89%\n"
"Smaller: less strict, can match different videos (false positive)\n"
"Larger: more strict, can miss identical videos (false negative)").arg(percentage).arg(differentBits);
"Larger: more strict, can miss identical videos (false negative)").arg(value).arg(matchingBitsOf64);
ui->thresholdSlider->setToolTip(thresholdMessage);
_prefs._thresholdPhash = differentBits;
_prefs._thresholdSSIM = value / 64.0;
}

void MainWindow::on_browseFolders_clicked() const
Expand Down
4 changes: 2 additions & 2 deletions mainwindow.ui
View file
Expand Up @@ -251,13 +251,13 @@
<number>1</number>
</property>
<property name="maximum">
<number>64</number>
<number>100</number>
</property>
<property name="pageStep">
<number>8</number>
</property>
<property name="value">
<number>57</number>
<number>89</number>
</property>
<property name="orientation">
<enum>Qt::Horizontal</enum>
Expand Down
7 changes: 3 additions & 4 deletions prefs.h
View file
Expand Up @@ -10,12 +10,11 @@ class Prefs
int _ComparisonMode = _PHASH;
int _thumbnails = thumb4;

int _thresholdPhash = 7;
int _thresholdPhashOriginal = 7;

double _thresholdSSIM = 0.90;
int _ssimBlockSize = 16;

double _thresholdSSIM = 0.89;
int _thresholdPhash = 57;

int _differentDurationModifier = 4;
int _sameDurationModifier = 1;
};
Expand Down

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