Interesting. I have a pen-f and the high-res mode absolutely increases the resolution. Everything is very sharp when viewed at 100%. If the scene is stationary (no water or leaves blowing in the wind) I can't detect any stitching artifact.
I also think that the lenses have to be able to resolve this resolution. My 12mm prime looks somewhat sharper than my 8-25 zoom in high-res mode, even though there is no difference in regular mode.
I'm not sure how to quantify the increase in quality, but the details are sharp. However, I'd say that the real benefit of this mode is that the image is smoother than in the normal mode. Tonal transitions, in particular.
I can't find any specifics, but just taking a picture in this mode and looking at my watch, I think this particular camera takes 8 exposures.
I also think that the lenses have to be able to resolve this resolution. My 12mm prime looks somewhat sharper than my 8-25 zoom in high-res mode, even though there is no difference in regular mode.
I'm not sure how to quantify the increase in quality, but the details are sharp. However, I'd say that the real benefit of this mode is that the image is smoother than in the normal mode. Tonal transitions, in particular.
I can't find any specifics, but just taking a picture in this mode and looking at my watch, I think this particular camera takes 8 exposures.