Trying to combine an image with a Plot

Question

I've got this picture:

The image has a resolution of 2001x2001. The left most pixel has an x-value of -2, and the right most pixel has an x-value of 2. Same goes for the y-values. Now I am trying to load this image into Mathematica and get it on the right scale inside a graphics environment. I've tried using inset like this:

julia = Import["https://i.stack.imgur.com/NLMXG.png"];
Graphics[{Blue, Rectangle[{-2, -2}, {2, 2}], 
    Inset[julia, Center, Center, 4]}, PlotRange -> {{-3, 3}, {-3, 3}}, 
  Axes -> True, AxesStyle -> Orange]

This still gives a little blue border around some sides, giving me the impression that it is not centered properly. Is there a better way to do this?

Answer 1

Inset is not suitable for reliable and precise positioning. Use Raster to include bitmap data in an image. It lets you specify the coordinates of the corners:

Graphics[
 Raster[ImageData[julia], {{-2, -2}, {2, 2}}],
 Frame -> True,
 GridLines -> Automatic,
 Method -> {"GridLinesInFront" -> True}
]

Note: the Graphics Method option I used is undocumented, so it might change in the future. It is used by functions like DensityPlot to make sure the grid lines are not obscured by other graphics elements.