diff --git a/tests/benchmarks/image.cpp b/tests/benchmarks/image.cpp
index 327a4e4cde..15fc4ebaf5 100644
--- a/tests/benchmarks/image.cpp
+++ b/tests/benchmarks/image.cpp
@@ -65,7 +65,7 @@ static const wxImage& GetTestImage()
     if ( !s_triedToLoad )
     {
         s_triedToLoad = true;
-        s_image.LoadFile("horse.bmp");
+        s_image.LoadFile(Bench::GetStringParameter("horse.bmp"));
     }
 
     return s_image;
@@ -73,20 +73,32 @@ static const wxImage& GetTestImage()
 
 BENCHMARK_FUNC(EnlargeNormal)
 {
-    return GetTestImage().Scale(300, 300, wxIMAGE_QUALITY_NORMAL).IsOk();
+    const wxImage& image = GetTestImage();
+    const double factor = Bench::GetNumericParameter(150) / 100.;
+    return image.Scale(factor*image.GetWidth(), factor*image.GetHeight(),
+                       wxIMAGE_QUALITY_NORMAL).IsOk();
 }
 
 BENCHMARK_FUNC(EnlargeHighQuality)
 {
-    return GetTestImage().Scale(300, 300, wxIMAGE_QUALITY_HIGH).IsOk();
+    const wxImage& image = GetTestImage();
+    const double factor = Bench::GetNumericParameter(150) / 100.;
+    return image.Scale(factor*image.GetWidth(), factor*image.GetHeight(),
+                       wxIMAGE_QUALITY_HIGH).IsOk();
 }
 
 BENCHMARK_FUNC(ShrinkNormal)
 {
-    return GetTestImage().Scale(50, 50, wxIMAGE_QUALITY_NORMAL).IsOk();
+    const wxImage& image = GetTestImage();
+    const double factor = Bench::GetNumericParameter(50) / 100.;
+    return image.Scale(factor*image.GetWidth(), factor*image.GetHeight(),
+                       wxIMAGE_QUALITY_NORMAL).IsOk();
 }
 
 BENCHMARK_FUNC(ShrinkHighQuality)
 {
-    return GetTestImage().Scale(50, 50, wxIMAGE_QUALITY_HIGH).IsOk();
+    const wxImage& image = GetTestImage();
+    const double factor = Bench::GetNumericParameter(50) / 100.;
+    return image.Scale(factor*image.GetWidth(), factor*image.GetHeight(),
+                       wxIMAGE_QUALITY_HIGH).IsOk();
 }