Thermal transfer technology is generally considered to be a relatively mature technology; yet advancements continue to occur. Most recently, thermal technology has begun to transition from 300 dpi to 600 dpi. The increased resolution has resulted in a significant improvement in image quality that is apparent in photos, bar codes, text, and Kanji characters.
Mark B. Mizen, "Improvements in the Image Quality of Thermally Printed Security Cards" in Proc. IS&T Printing for Fabrication: Int'l Conf. on Digital Printing Technologies (NIP34), 2018, pp 208 - 210, https://doi.org/10.2352/ISSN.2169-4451.2018.34.208