I have a PDF figure created with Export[] in Mathematica 11.0.1.0 on Mac OSX
The figure has these improper white-lines when I zoom-out and make the image smaller (The size it will appear in the document).
I have seen a previous post Avoiding white lines inside filled area in RegionPlot exported as PDF or PS but this does not resolve this issue.
The code used to generate the image is:
f21fps = Show[SmoothDensityHistogram[data21fps, PlotRange -> {{0, 200}, {0, 200}}, ColorFunction -> "SunsetColors", FrameLabel -> {Text[ Style["t2-t1", FontSize -> 14, Italic], FormatType -> StandardForm], Text[Style["t1", FontSize -> 14, Italic], FormatType -> StandardForm]}, PlotLabel -> "FPS", LabelStyle -> {FontFamily -> "Times", 14}, PlotLegends -> BarLegend[Automatic, LegendFunction -> f, LegendMarkerSize -> 368] , Mesh -> 0 ], Plot[x, {x, 0, 200}], ImageSize -> 400, PlotRangePadding -> 0] Export["f21fps.pdf",f21fps]; where data21fps is a list of {x,y} values. How could I avoid the undesired white lines when reducing the size of the pdf image?
EDITED 1
Due to comment of @march, I am trying to rasterize the plot but not the axes as it is explained in the post Rasterized image together with vector-graphics axes
which uses this code to make it
rasterizeBackground[g_, res_: 450] := Show[Rasterize[ Show[g, PlotRangePadding -> 0, ImagePadding -> 0, ImageMargins -> 0, LabelStyle -> Opacity[0], FrameTicksStyle -> Opacity[0], FrameStyle -> Opacity[0], AxesStyle -> Opacity[0], TicksStyle -> Opacity[0], PlotRangeClipping -> False], ImageResolution -> res] /. Raster[data_, rect_, rest__] :> Raster[data, Transpose@OptionValue[AbsoluteOptions[g, PlotRange], PlotRange], rest], Sequence @@ Options[g], Sequence @@ Options[g, PlotRange]] I have been testing it but gives me error
f21fpsR = rasterizeBackground[f21fps] Rule::argr: Rule called with 1 argument; 2 arguments are expected. How could I fix this and make it work with my image?
Thank you very much

contourDensityPlotfunction. That's the one I use. Furthermore, it accepts the same options as ContourPLot and DensityPlot $\endgroup$SmoothDensityHistogram[]plotting a data set of{x,y}points. $\endgroup$