ColorFilterHistogram Class Reference

Class that generates a histogram according to the current filter. More...

#include <ColorFilterHistogram.h>

Collaboration diagram for ColorFilterHistogram:

Public Member Functions
	ColorFilterHistogram ()
	Single constructor.
int	binFromPixel (const ColorFilter &filter, ColorFilterMode colorFilterMode, const QColor &pixel, const QRgb &rgbBackground) const
	Compute histogram bin number from pixel according to filter.
void	generate (const ColorFilter &filter, double histogramBins[], ColorFilterMode colorFilterMode, const QImage &image, int &maxBinCount) const
	Generate the histogram.
int	valueFromBin (const ColorFilter &filter, ColorFilterMode colorFilterMode, int bin)
	Inverse of binFromPixel.

Static Public Member Functions
static int	HISTOGRAM_BINS ()
	Number of histogram bins.

Detailed Description

Class that generates a histogram according to the current filter.

Definition at line 17 of file ColorFilterHistogram.h.

Constructor & Destructor Documentation

ColorFilterHistogram()

ColorFilterHistogram::ColorFilterHistogram

(

)

Single constructor.

Definition at line 13 of file ColorFilterHistogram.cpp.

{
}

Member Function Documentation

binFromPixel()

int ColorFilterHistogram::binFromPixel	(	const ColorFilter &	filter,
		ColorFilterMode	colorFilterMode,
		const QColor &	pixel,
		const QRgb &	rgbBackground ) const

Compute histogram bin number from pixel according to filter.

Definition at line 17 of file ColorFilterHistogram.cpp.

{
  // Instead of mapping from s=0 through 1 to bin=0 through HISTOGRAM_BINS-1, we
  // map it to bin=1 through HISTOGRAM_BINS-2 so first and last bin are zero. The
  // result is a peak at the start or end is complete and easier to read
  double s = filter.pixelToZeroToOneOrMinusOne (colorFilterMode,
                                                pixel,
                                                rgbBackground);
  ENGAUGE_ASSERT (s <= 1.0);
 
  int bin = -1;
 
  if (s >= 0) {
 
    bin = qFloor (FIRST_NON_EMPTY_BIN_AT_START () + s * (LAST_NON_EMPTY_BIN_AT_END () - FIRST_NON_EMPTY_BIN_AT_START ()));
 
  }
 
  return bin;
}

generate()

void ColorFilterHistogram::generate	(	const ColorFilter &	filter,
		double	histogramBins[],
		ColorFilterMode	colorFilterMode,
		const QImage &	image,
		int &	maxBinCount ) const

Generate the histogram.

The resolution is coarse since

1. finer resolution is not needed
2. this smooths out the curve

Definition at line 41 of file ColorFilterHistogram.cpp.

{
  // Initialize histogram bins
  int bin;
  for (bin = 0; bin < HISTOGRAM_BINS (); bin++) {
    histogramBins [bin] = 0;
  }
 
  QRgb rgbBackground = filter.marginColor(&image);
 
  // Populate histogram bins
  maxBinCount = 0;
  for (int x = 0; x < image.width(); x++) {
    for (int y = 0; y < image.height(); y++) {
 
      QColor pixel (image.pixel (x, y));
      int bin = binFromPixel (filter,
                              colorFilterMode,
                              pixel,
                              rgbBackground);
      if (bin >= 0) {
 
        ENGAUGE_ASSERT ((FIRST_NON_EMPTY_BIN_AT_START () <= bin) &&
                        (LAST_NON_EMPTY_BIN_AT_END () >= bin));
        ++(histogramBins [bin]);
 
        if (histogramBins [bin] > maxBinCount) {
          maxBinCount = qFloor (histogramBins [bin]);
        }
      }
    }
  }
}

HISTOGRAM_BINS()

int ColorFilterHistogram::HISTOGRAM_BINS ( )

inlinestatic

Number of histogram bins.

Definition at line 39 of file ColorFilterHistogram.h.

{ return 100; }

valueFromBin()

int ColorFilterHistogram::valueFromBin	(	const ColorFilter &	filter,
		ColorFilterMode	colorFilterMode,
		int	bin )

Inverse of binFromPixel.

Definition at line 79 of file ColorFilterHistogram.cpp.

{
  // Just do everything in binFromPixel backwards
  double s = double (bin - FIRST_NON_EMPTY_BIN_AT_START ()) / double (LAST_NON_EMPTY_BIN_AT_END () - FIRST_NON_EMPTY_BIN_AT_START ());
  s = qMin (qMax (s, 0.0), 1.0);
 
  return filter.zeroToOneToValue (colorFilterMode,
                                  s);
}

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The documentation for this class was generated from the following files:

• Color/ColorFilterHistogram.h
• Color/ColorFilterHistogram.cpp