diff --git a/CanlabCore/@image_vector/render_on_surface.m b/CanlabCore/@image_vector/render_on_surface.m
index a7c26d91..8c735d79 100644
--- a/CanlabCore/@image_vector/render_on_surface.m
+++ b/CanlabCore/@image_vector/render_on_surface.m
@@ -478,7 +478,7 @@
     set(surface_handles(i), 'EdgeColor', 'none');
     
     if doscaledtrans
-        z = c/max(abs(c));
+        z = c/max(abs(datvec));
         z = enhance_contrast(z);
         set(surface_handles(i), 'FaceVertexAlphaData',abs(z));
         set(surface_handles(i), 'FaceAlpha', 'interp');
diff --git a/CanlabCore/fmridisplay_helper_functions/render_blobs.m b/CanlabCore/fmridisplay_helper_functions/render_blobs.m
index 8a91154b..d8d7d3c4 100644
--- a/CanlabCore/fmridisplay_helper_functions/render_blobs.m
+++ b/CanlabCore/fmridisplay_helper_functions/render_blobs.m
@@ -621,13 +621,14 @@
                 
                 if dotrans
                     % Set transparency
+                                        
+                    if dotrans
+                        s = max(abs(Z(Z~=0 & ~isnan(Z))));
+                        Z(~isnan(Z)) = enhance_contrast(Z(~isnan(Z))/s)*s;
+                    end
                     
                     if ~docolormap || dosplitcolor, Zscaled = abs(Z); end
                     
-                    Zscaled(isnan(Zscaled)) = 0;
-                    Zscaled = enhance_contrast(Zscaled);
-                    Zscaled = abs(Zscaled);
-                    
                     if ~isempty(transvalue)
                         % constant transparency value
                         set(h, 'AlphaDataMapping', 'scaled', 'AlphaData', transvalue .* double(abs(Z) > 0), 'FaceAlpha', 'interp')
@@ -637,6 +638,7 @@
                         % Note: changed by Tor, 2015. Zscaled values > 1
                         % were messing up transparency scale for underlay.
                         % Max should be 1.
+                        
                         set(h, 'AlphaDataMapping', 'scaled', 'AlphaData', Zscaled ./ max(abs(Zscaled(:))), 'FaceAlpha', 'interp');
                     end