matlab2tikz creating external png

hi there, I am using matlab2tikz to export my graphics and use them in latex documents. However, when I have a raster image background in my figures matlab2tikz creates an external png to save this background image. Problem is that I am using latex (rather than pdflatex) and all of my images are in eps so the png images are throwing the bounding box error and I cant switch to pdflatex. I tried to use the "imagesAsPng" flag in matlab2tikz to save the output image as a matrix of pixels but it gave an error. If you can help pointing me in the right direction I would be grateful.

thanks H