Question: How to remove the white lines in a plot

Hi,

 

I am using densityplot function to produce different plots of a function. The function depends on two variables q and yi .

densityplot(f, q = 0 .. 1, yi = 0 .. 1, grid = [100, 100], style = patchnogrid, color = "Red", axes = boxed, axesfont = [Times, Roman, 15], labelfont = [Times, Roman, 15])


I pass the command style = patchnogrid, but still I get these white lines which I believe are grid lines. 
In the example provided in maple tutorial, when they used this command, all gridlines were removed. Why are they not removed in my plots?

if the plot is not visible, click the link

https://www.dropbox.com/s/7xxfefv8n1arr4q/Example.jpg?dl=0

plot

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