The reason D-Sub and VGA interfaces cannot easily be converted into HDMI and most DVI formats is the difference in type of transmission.
VGA and D-Sub are analog connectors, while the HDMI and DVI (DVI-D at least) are digital. In order to create an adapter that can connect a cable of one type to a port of the other type, a signal converter has to be crammed inside somewhere.
The TEC HDCOM-001, found in Tokyo's Akihabara shopping district (Japan), can do this for D-Sub and HDMI.
The adapter can convert signals both ways and can carry both video and up to 6 channels of audio, which the dongle treats as analog audio outputs.
The display resolution can be of up to 1920 x 1080 pixels (Full HD) with 60 Hz refresh rate. The price is of 5,480 JPY (US $68 / 53 Euro).