You can actually use the normal image handling of HISE in C++ projects. Just make sure that the image is loaded somewhere on your scripted interface before you export, then call
auto myImage = hise::raw::Pool::loadImage("{PROJECT_FOLDER}MyImage.png");https://docs.hise.audio/cpp_api/raw/classhise_1_1raw_1_1_pool.html
You get some benefits over the traditional BinaryData approach: the images are shared across plugin instances and are more compressed.