N2 - Present paper is a continuation of works on evaluation of red, green, blue (RGB) to hue, saturation, intensity (HSI) colour space transformation in regard to digital image processing application in optical measurements methods. HSI colour space seems to be the most suitable domain for engineering applications due to its immunity to non-uniform lightning. Previous stages referred to the analysis of various RGB to HSI colour space transformations equivalence and programming platform configuration influence on the algorithms execution. The main purpose of this step is to understand the influence of computer processor architecture on the computing time, since analysis of images requires considerable computer resources. The technical development of computer components is very fast and selection of particular processor architecture can be an advantage for fastening the image analysis and then the measurements results. In this paper the colour space transformation algorithms, their complexity and execution time are discussed. The most common algorithms were compared with the authors own one. Computing time was considered as the main criterion taking into account a technical advancement of two computer processor architectures. It was shown that proposed algorithm was characterized by shorter execution time than in reported previously results. L1 - http://www.journals.pan.pl/Content/104049/PDF-MASTER/06_paper.pdf L2 - http://www.journals.pan.pl/Content/104049 PY - 2018 IS - No 1 DO - 10.1515/aoter-2018-0006 KW - Digital image processing KW - Optical measurement method KW - RGB to HSI colour space transformation KW - Linear transformation KW - Time performance KW - Relative computational time A1 - Ziemba, Andrzej A1 - Fornalik-Wajs, Elżbieta PB - The Committee of Thermodynamics and Combustion of the Polish Academy of Sciences and The Institute of Fluid-Flow Machinery Polish Academy of Sciences VL - vol. 39 DA - 2018.03.29 T1 - Time performance of RGB to HSI colour space transformation methods UR - http://www.journals.pan.pl/dlibra/publication/edition/104049 T2 - Archives of Thermodynamics