Using the map function along with the image function for geospatial data in R

I am trying to plot geospatial sea surface temperature correlation data on the world map (only Northern hemisphere). I am using the image function (plot correlation data) along with the map function (plot coastlines). On their own, I get them to work. My problem is I am not able to overlay the map on the image, the map just shows up as a small point at the left corner at the bottom of the plot. The packages I am using are graphics for the image function and maps for the map function.


Generate test data

    cor_nao_map = array(data=NA, dim=c(384,96))
    for(i in 1:384) {
       cor_nao_map_test[i,] = runif(96)  
    } 

Plot

    image(x=1:384,y=1:96,z=cor_nao_map,col=diverge_hcl(100),zlim=c(-0.43,0.43),xlab="Longitude in °",ylab="Latitude in °N")  

    map('world',projection="gilbert",add=T)