Inverting values of raster file using QGIS?

I ran a proximity (raster distance) function and I would like to invert the result.

Is there a simple way to do this with out converting it back to vector format and editing the attribute table?

Answer

Thanks to Mr. Stimson I used the expression 1000-(raster layer) to get the inverted raster result. I chose 1000 because it didn't have to be an exact invert and I didn't want negative numbers. I need to run it through r.cost algorithm which creates an error if there is a negative number.

If you are wondering what number to use try this link How to extract pixel value counts from a raster in QGIS?