Using the same photon map even if I increase the resolution?

[iduna79]

If I save a photon map and final gathering map can I still use them if I increase the resolution? With the same quality. Or do I have to render them out again?

[bart]

You can reuse them because they store the 3D location along with their values. However, there may be decreased quality in detailed illumination areas because of not enough illumination information now that you have increased resolution.

That said, often the default values over-calculate the number of photons or FG points needed, so it might look OK.
Try it first, and trust your eyes.