Fix new color propagation method (#6109)

* Fixed artifacts thanks to Alberto

* Added blur to Color propagation

* Clean format code - small improvments

* color propagation: Enable old mode at blur = 0

* Improve GUI

* color propagation: smooth progress bar for blur > 0

* change label

* Some cleanups

* color propagation: small speedup for blur > 0

* color propagation: speedup for blur > 0 when region with clipped highlights is small

* Speed-up for blur=1 - clean GUI code

* color propagation: cleanups

* Harmonize events in tonecurve.cc

* tonecurve.cc : cleanup

* Highlight reconstruction: small changes to gui

* Use Gtk::Box instead of Gtk::VBox

* Change maximum number of blur levels to 4

* Suppress BENCHFUN

* Suppress bad commit locallabtools

Co-authored-by: Desmis <jdesmis@gmail.com>
Co-authored-by: Ingo Weyrich <heckflosse67@gmx.de>

rtengine/rescale.h

@@ -35,23 +35,22 @@ inline float getBilinearValue(const array2D<float> &src, float x, float y)
     const int H = src.getHeight();
     
     // Get integer and fractional parts of numbers
-    int xi = x;
-    int yi = y;
-    float xf = x - xi;
-    float yf = y - yi;
-    int xi1 = std::min(xi + 1, W - 1);
-    int yi1 = std::min(yi + 1, H - 1);
+    const int xi = x;
+    const int yi = y;
+    const float xf = x - xi;
+    const float yf = y - yi;
+    const int xi1 = std::min(xi + 1, W - 1);
+    const int yi1 = std::min(yi + 1, H - 1);
 
-    float bl = src[yi][xi];
-    float br = src[yi][xi1];
-    float tl = src[yi1][xi];
-    float tr = src[yi1][xi1];
+    const float bl = src[yi][xi];
+    const float br = src[yi][xi1];
+    const float tl = src[yi1][xi];
+    const float tr = src[yi1][xi1];
 
     // interpolate
-    float b = xf * br + (1.f - xf) * bl;
-    float t = xf * tr + (1.f - xf) * tl;
-    float pxf = yf * t + (1.f - yf) * b;
-    return pxf;
+    const float b = intp(xf, br, bl);
+    const float t = intp(xf, tr, tl);
+    return intp(yf, t, b);
 }