Exponential regression rule for Pixelate scale

src/effects/Pixelate.cpp

@@ -33,7 +33,7 @@
 using namespace openshot;
 
 /// Blank constructor, useful when using Json to load the effect properties
-Pixelate::Pixelate() : pixelization(0.7), left(0.0), top(0.0), right(0.0), bottom(0.0) {
+Pixelate::Pixelate() : pixelization(0.5), left(0.0), top(0.0), right(0.0), bottom(0.0) {
 	// Init effect properties
 	init_effect_details();
 }
@@ -68,7 +68,7 @@ std::shared_ptr<Frame> Pixelate::GetFrame(std::shared_ptr<Frame> frame, int64_t
 	std::shared_ptr<QImage> frame_image = frame->GetImage();
 
 	// Get current keyframe values
-	double pixelization_value = 1.0 - std::min(fabs(pixelization.GetValue(frame_number)), 1.0);
+	double pixelization_value = std::min(pow(0.001, fabs(pixelization.GetValue(frame_number))), 1.0);
 	double left_value = left.GetValue(frame_number);
 	double top_value = top.GetValue(frame_number);
 	double right_value = right.GetValue(frame_number);
@@ -82,8 +82,12 @@ std::shared_ptr<Frame> Pixelate::GetFrame(std::shared_ptr<Frame> frame, int64_t
 		QRect area(QPoint(0,0), frame_image->size());
 		area = area.marginsRemoved({int(left_value * w), int(top_value * h), int(right_value * w), int(bottom_value * h)});
 
+		int scale_to = (int) (area.width() * pixelization_value);
+		if (scale_to < 1) {
+			scale_to = 1; // Not less than one pixel
+		}
 		// Copy and scale pixels in area to be pixelated
-		auto frame_scaled = frame_image->copy(area).scaledToWidth(area.width() * pixelization_value, Qt::SmoothTransformation);
+		auto frame_scaled = frame_image->copy(area).scaledToWidth(scale_to, Qt::SmoothTransformation);
 
 		// Draw pixelated image back over original
 		QPainter painter(frame_image.get());