losing the design of illustrations, photos, etc. HCC2D Researchers have proposed a new High Capacity Colored 2-Dimensional (HCC2D) Code, which builds upon a QR code basis for preserving the QR robustness to distortions and uses colors for increasing data density (as of 2014 it is still in prototyping phase). The HCC2D code specification is described in details in Querini et al. (2014), while techniques for color classification of HCC2D code cells are described in detail in Querini and Italiano (2014), which is an extended version of Querini and Italiano (2013). Introducing colors into QR codes requires addressing additional issues. In particular, during QR code reading only the brightness information is taken into account, while HCC2D codes have to cope with chromatic distortions during the decoding phase. In order to ensure adaptation to chromatic distortions which arise in each scanned code, HCC2D codes make use of an additional field: the Color Palette Pattern. This is because color cells of a Color Palette Pattern are supposed to be distorted in the same way as color cells of the Encoding Region. Replicated color palettes are used for training machine learning classifiers. License The use of QR code technology is freely licensed as long as users follow the standards for QR Code documented with JIS or ISO/IEC. Non-standardized codes may require special licensing. Denso Wave owns a number of patents on QR code technology, but has chosen to exercise them in a limited fashion. In order to promote widespread usage of the technology Denso Wave chose to waive its rights to a key patent in its possession for standardized codes only. In the US, the granted QR code patent is , and in Japan , both of which have expired. The European Patent Office granted patent to Denso Wave, which was then validated into French, UK, and German patents, all of which expired in March 2015. The text QR Code itself is a registered trademark and wordmark of Denso Wave Incorporated. In UK, the trademark is registered as E921775, the term QR Code, with a filing date of 3 September 1998. The UK version of the trademark is based on the Kabushiki Kaisha Denso (DENSO CORPORATION) trademark, filed as Trademark 000921775, the term QR Code, on 3 September 1998 and registered on 16 December 1999 with the European Union OHIM (Office for Harmonization in the Internal Market). The U.S. Trademark for the term QR