Changes the "Sharpen" effect to Blitz::sharpen() instead of
Blitz::gaussianSharpen(), in order to avoid parameters that are currently
set in a dangerously adhoc fashion (radius, sigma, repeat).

Unfortunately, the results do not look good.

2007-08-14 20:35


Index: imagelib/effects/kpEffectBlurSharpen.cpp
===================================================================
--- imagelib/effects/kpEffectBlurSharpen.cpp	(revision 699849)
+++ imagelib/effects/kpEffectBlurSharpen.cpp	(working copy)
@@ -26,7 +26,7 @@
 */
 
 
-#define DEBUG_KP_EFFECT_BLUR_SHARPEN 0
+#define DEBUG_KP_EFFECT_BLUR_SHARPEN 1
 
 
 #include <kpEffectBlurSharpen.h>
@@ -46,18 +46,10 @@
 #endif
 
 
-static QImage BlurQImage (const QImage qimage_, int strength)
+static int RadiusForStrength (int strength)
 {
-    QImage qimage = qimage_;
-    if (strength == 0)
-        return qimage;
-
-
-    // The numbers that follow were picked by experimentation to try to get
-    // an effect linearly proportional to <strength> and at the same time,
-    // be fast enough.
-    //
-    // I still have no idea what "radius" means.
+    // (must be in range and not 0)
+    Q_ASSERT (strength > 0 && strength <= kpEffectBlurSharpen::MaxStrength);
 
     const double RadiusMin = 1;
     const double RadiusMax = 10;
@@ -67,92 +59,36 @@ static QImage BlurQImage (const QImage q
         (kpEffectBlurSharpen::MaxStrength - 1);
 
 #if DEBUG_KP_EFFECT_BLUR_SHARPEN
-    kDebug () << "kpEffectBlurSharpen.cpp:BlurQImage(strength=" << strength << ")"
+    kDebug () << "kpEffectBlurSharpen.cpp:RadiusForStrength(strength=" << strength << ")"
                << " radius=" << radius
                << endl;
 #endif
 
-
-    qimage = Blitz::blur (qimage, qRound (radius));
-
-
-    return qimage;
+    return qRound (radius);
 }
 
-static QImage SharpenQImage (const QImage &qimage_, int strength)
+
+static QImage BlurQImage (const QImage qimage_, int strength)
 {
     QImage qimage = qimage_;
     if (strength == 0)
         return qimage;
 
 
-    // The numbers that follow were picked by experimentation to try to get
-    // an effect linearly proportional to <strength> and at the same time,
-    // be fast enough.
-    //
-    // I still have no idea what "radius" and "sigma" mean.
-
-    const double RadiusMin = .1;
-    const double RadiusMax = 2.5;
-    const double radius = RadiusMin +
-       (strength - 1) *
-       (RadiusMax - RadiusMin) /
-       (kpEffectBlurSharpen::MaxStrength - 1);
-
-    const double SigmaMin = .5;
-    const double SigmaMax = 3.0;
-    const double sigma = SigmaMin +
-        (strength - 1) *
-        (SigmaMax - SigmaMin) /
-        (kpEffectBlurSharpen::MaxStrength - 1);
-
-    const double RepeatMin = 1;
-    const double RepeatMax = 2;
-    const double repeat = qRound (RepeatMin +
-        (strength - 1) *
-        (RepeatMax - RepeatMin) /
-        (kpEffectBlurSharpen::MaxStrength - 1));
+    qimage = Blitz::blur (qimage, ::RadiusForStrength (strength));
 
-// I guess these values are more proper as they use an auto-calculated
-// radius but they cause sharpen() to be too slow.
-#if 0
-    const double radius = 0/*auto-calculate*/;
-
-    const double SigmaMin = .6;
-    const double SigmaMax = 1.0;
-    const double sigma = SigmaMin +
-        (strength - 1) *
-        (SigmaMax - SigmaMin) /
-        (kpEffectBlurSharpen::MaxStrength - 1);
 
-    const double RepeatMin = 1;
-    const double RepeatMax = 3;
-    const double repeat = qRound (RepeatMin +
-        (strength - 1) *
-        (RepeatMax - RepeatMin) /
-        (kpEffectBlurSharpen::MaxStrength - 1));
-#endif
+    return qimage;
+}
 
-#if DEBUG_KP_EFFECT_BLUR_SHARPEN
-    kDebug () << "kpEffectBlurSharpen.cpp:SharpenQImage(strength=" << strength << ")"
-               << " radius=" << radius
-               << " sigma=" << sigma
-               << " repeat=" << repeat
-               << endl;
-#endif
+static QImage SharpenQImage (const QImage &qimage_, int strength)
+{
+    QImage qimage = qimage_;
+    if (strength == 0)
+        return qimage;
 
 
-    for (int i = 0; i < repeat; i++)
-    {
-    #if DEBUG_KP_EFFECT_BLUR_SHARPEN
-	QTime timer; timer.start ();
-    #endif
-        qimage = Blitz::gaussianSharpen (qimage, radius, sigma);
-    #if DEBUG_KP_EFFECT_BLUR_SHARPEN
-        kDebug () << "\titeration #" + QString::number (i)
-                  << ": " + QString::number (timer.elapsed ()) << "ms" << endl;
-    #endif
-    }
+    qimage = Blitz::sharpen (qimage, ::RadiusForStrength (strength) * 10);
 
 
     return qimage;