private void ApplyWhiteBalance(MagickImage image)
{
using (MagickImage mask = image.Clone())
{
mask.ColorSpace = ColorSpace.HSB;
mask.Negate(Channels.Green);
using (MagickImage newMask = mask.Separate(Channels.Green).First())
{
using (MagickImage maskBlue = mask.Separate(Channels.Blue).First())
{
newMask.Composite(maskBlue, CompositeOperator.Multiply);
}
newMask.ContrastStretch((Percentage)0, WhiteBalance);
newMask.InverseOpaque(new MagickColor("white"), new MagickColor("black"));
double maskMean = GetMean(newMask);
double redRatio = GetRatio(image, Channels.Red, newMask, maskMean);
double greenRatio = GetRatio(image, Channels.Green, newMask, maskMean);
double blueRatio = GetRatio(image, Channels.Blue, newMask, maskMean);
ColorMatrix matrix = new ColorMatrix(3, redRatio, 0, 0, 0, greenRatio, 0, 0, 0, blueRatio);
image.ColorMatrix(matrix);
}
}
}
private void EnhanceImage(MagickImage image)
{
if (Enhance == TextCleanerEnhance.Stretch)
{
image.ContrastStretch((Percentage)0);
}
else if (Enhance == TextCleanerEnhance.Normalize)
{
image.Normalize();
}
}
public IEnumerable <byte> PreProcess(IEnumerable <byte> bitmap)
{
using (var processed = new MagickImage(bitmap.ToArray()))
{
processed.ContrastStretch(new Percentage(0));
processed.Morphology(MorphologyMethod.Dilate, Kernel.Diamond, Constants.HighlightIntensity);
processed.Threshold(new Percentage(20));
return(processed.ToByteArray());
}
}
private void EnhanceImage(MagickImage image)
{
if (Enhance == WhiteboardEnhancements.None)
{
return;
}
if (Enhance.HasFlag(WhiteboardEnhancements.Stretch))
{
image.ContrastStretch((Percentage)0, (Percentage)0);
}
if (Enhance.HasFlag(WhiteboardEnhancements.Whitebalance))
{
ApplyWhiteBalance(image);
}
}
private void CopyOpacity(MagickImage image)
{
image.Alpha(AlphaOption.Off);
using (MagickImage gray = image.Clone())
{
gray.ColorSpace = ColorSpace.Gray;
gray.Negate();
gray.AdaptiveThreshold(FilterSize, FilterSize, FilterOffset);
gray.ContrastStretch((Percentage)0);
if (Threshold.HasValue)
{
gray.Blur((double)Threshold.Value / 100.0, Quantum.Max);
gray.Level(Threshold.Value, new Percentage(100));
}
image.Composite(gray, CompositeOperator.CopyAlpha);
image.Opaque(MagickColor.Transparent, BackgroundColor);
image.Alpha(AlphaOption.Off);
}
}
private void RemoveNoise(MagickImage image)
{
using (MagickImage second = image.Clone())
{
second.ColorSpace = ColorSpace.Gray;
second.Negate();
second.AdaptiveThreshold(FilterSize, FilterSize, FilterOffset);
second.ContrastStretch((Percentage)0);
if (SmoothingThreshold != null)
{
second.Blur(SmoothingThreshold.Value.ToDouble() / 100, Quantum.Max);
second.Level(SmoothingThreshold.Value, new Percentage(100));
}
image.Composite(second, CompositeOperator.CopyAlpha);
}
image.Opaque(MagickColor.FromRgba(255, 255, 255, 0), BackgroundColor);
image.Alpha(AlphaOption.Off);
}