Indeed, currently the converter don't take into account the image DPIs, even for image formats that have this information present, and assumes all as 72 DPI. I'm going to look into this. Probably with the addition of a new settings option, to take, or not, the image DPI info into account. And another to custom define the DPIs to use, forced or just when the information is not available in the images.
Thanks for mentioning the problem.