How did you make the determination that the Kodak numbers are higher for both DR and SBR? When I compared the calculations with real plots for the two methods the DR and SBR were identical. The only practical difference between the two is that the Ilford G-Bar methos suggests a slightly higher EFS than Kodak's CI. This might, depending on the paper curve of the process, result in some differnce in the printing characteristics of the negative. But for all practical purposes the difference between G-Bar and CI is irrevelant.
Originally Posted by smieglitz
BTW, my reference is the 3rd edition of Beyond the Zone System and on page 29 Davis explains how Average Gradient, or G-Bar and CI (Contrast Index) are determined. It is same as one finds in Kodak and Ilford literature.