kolourpaint/patches/linear-sharpen-effect.diff

   1 Changes the "Sharpen" effect to Blitz::sharpen() instead of
   2 Blitz::gaussianSharpen(), in order to avoid parameters that are currently
   3 set in a dangerously adhoc fashion (radius, sigma, repeat).
   4
   5 Unfortunately, the results do not look good.
   6
   7 2007-08-14 20:35
   8
   9
  10 Index: imagelib/effects/kpEffectBlurSharpen.cpp
  11 ===================================================================
  12 --- imagelib/effects/kpEffectBlurSharpen.cpp    (revision 699849)
  13 +++ imagelib/effects/kpEffectBlurSharpen.cpp    (working copy)
  14 @@ -26,7 +26,7 @@
  15  */
  16
  17
  18 -#define DEBUG_KP_EFFECT_BLUR_SHARPEN 0
  19 +#define DEBUG_KP_EFFECT_BLUR_SHARPEN 1
  20
  21
  22  #include <kpEffectBlurSharpen.h>
  23 @@ -46,18 +46,10 @@
  24  #endif
  25
  26
  27 -static QImage BlurQImage (const QImage qimage_, int strength)
  28 +static int RadiusForStrength (int strength)
  29  {
  30 -    QImage qimage = qimage_;
  31 -    if (strength == 0)
  32 -        return qimage;
  33 -
  34 -
  35 -    // The numbers that follow were picked by experimentation to try to get
  36 -    // an effect linearly proportional to <strength> and at the same time,
  37 -    // be fast enough.
  38 -    //
  39 -    // I still have no idea what "radius" means.
  40 +    // (must be in range and not 0)
  41 +    Q_ASSERT (strength > 0 && strength <= kpEffectBlurSharpen::MaxStrength);
  42
  43      const double RadiusMin = 1;
  44      const double RadiusMax = 10;
  45 @@ -67,92 +59,36 @@ static QImage BlurQImage (const QImage q
  46          (kpEffectBlurSharpen::MaxStrength - 1);
  47
  48  #if DEBUG_KP_EFFECT_BLUR_SHARPEN
  49 -    kDebug () << "kpEffectBlurSharpen.cpp:BlurQImage(strength=" << strength << ")"
  50 +    kDebug () << "kpEffectBlurSharpen.cpp:RadiusForStrength(strength=" << strength << ")"
  51                 << " radius=" << radius
  52                 << endl;
  53  #endif
  54
  55 -
  56 -    qimage = Blitz::blur (qimage, qRound (radius));
  57 -
  58 -
  59 -    return qimage;
  60 +    return qRound (radius);
  61  }
  62
  63 -static QImage SharpenQImage (const QImage &qimage_, int strength)
  64 +
  65 +static QImage BlurQImage (const QImage qimage_, int strength)
  66  {
  67      QImage qimage = qimage_;
  68      if (strength == 0)
  69          return qimage;
  70
  71
  72 -    // The numbers that follow were picked by experimentation to try to get
  73 -    // an effect linearly proportional to <strength> and at the same time,
  74 -    // be fast enough.
  75 -    //
  76 -    // I still have no idea what "radius" and "sigma" mean.
  77 -
  78 -    const double RadiusMin = .1;
  79 -    const double RadiusMax = 2.5;
  80 -    const double radius = RadiusMin +
  81 -       (strength - 1) *
  82 -       (RadiusMax - RadiusMin) /
  83 -       (kpEffectBlurSharpen::MaxStrength - 1);
  84 -
  85 -    const double SigmaMin = .5;
  86 -    const double SigmaMax = 3.0;
  87 -    const double sigma = SigmaMin +
  88 -        (strength - 1) *
  89 -        (SigmaMax - SigmaMin) /
  90 -        (kpEffectBlurSharpen::MaxStrength - 1);
  91 -
  92 -    const double RepeatMin = 1;
  93 -    const double RepeatMax = 2;
  94 -    const double repeat = qRound (RepeatMin +
  95 -        (strength - 1) *
  96 -        (RepeatMax - RepeatMin) /
  97 -        (kpEffectBlurSharpen::MaxStrength - 1));
  98 +    qimage = Blitz::blur (qimage, ::RadiusForStrength (strength));
  99
 100 -// I guess these values are more proper as they use an auto-calculated
 101 -// radius but they cause sharpen() to be too slow.
 102 -#if 0
 103 -    const double radius = 0/*auto-calculate*/;
 104 -
 105 -    const double SigmaMin = .6;
 106 -    const double SigmaMax = 1.0;
 107 -    const double sigma = SigmaMin +
 108 -        (strength - 1) *
 109 -        (SigmaMax - SigmaMin) /
 110 -        (kpEffectBlurSharpen::MaxStrength - 1);
 111
 112 -    const double RepeatMin = 1;
 113 -    const double RepeatMax = 3;
 114 -    const double repeat = qRound (RepeatMin +
 115 -        (strength - 1) *
 116 -        (RepeatMax - RepeatMin) /
 117 -        (kpEffectBlurSharpen::MaxStrength - 1));
 118 -#endif
 119 +    return qimage;
 120 +}
 121
 122 -#if DEBUG_KP_EFFECT_BLUR_SHARPEN
 123 -    kDebug () << "kpEffectBlurSharpen.cpp:SharpenQImage(strength=" << strength << ")"
 124 -               << " radius=" << radius
 125 -               << " sigma=" << sigma
 126 -               << " repeat=" << repeat
 127 -               << endl;
 128 -#endif
 129 +static QImage SharpenQImage (const QImage &qimage_, int strength)
 130 +{
 131 +    QImage qimage = qimage_;
 132 +    if (strength == 0)
 133 +        return qimage;
 134
 135
 136 -    for (int i = 0; i < repeat; i++)
 137 -    {
 138 -    #if DEBUG_KP_EFFECT_BLUR_SHARPEN
 139 -       QTime timer; timer.start ();
 140 -    #endif
 141 -        qimage = Blitz::gaussianSharpen (qimage, radius, sigma);
 142 -    #if DEBUG_KP_EFFECT_BLUR_SHARPEN
 143 -        kDebug () << "\titeration #" + QString::number (i)
 144 -                  << ": " + QString::number (timer.elapsed ()) << "ms" << endl;
 145 -    #endif
 146 -    }
 147 +    qimage = Blitz::sharpen (qimage, ::RadiusForStrength (strength) * 10);
 148
 149
 150      return qimage;