Can anyone tell me how the test target is constructed? There are 17 boxes, numbered from 0 to 255, and except for the final step to 255 they are evenly spaced (ie 16 apart).
Can these numbers be related to anything of interest for reflection densities when the target is printed? Do they, for example, represent a straight line of "densities" on a "negative" if we were to think of printing the target as the analogue of printing a negative of the target in a traditional darkroom?
I have a reflection/transmission densitometer. Out of curiosity I measured the densities of the 0 and 255 boxes when printed on hp premium plus mat and glossy papers with an hp7660 using the photo black cartridge. The differences between box 255 (almost pure white) and box 0 (apparently maximum black) are 2.48 for glossy and 2.31 for mat. Those of you who do silver printing will realize how impressive these figures are. I cannot guarantee that these figures are correct, since my X-rite relection standard is pretty old (although in good condition), but I couldn't find any of my prints on Ilford, Zone VI or (old) Seagull papers that came close to these values. [Range is not everything, of course!!]
test target "densities"
densitometer
I'm curious how the reflection densitometer works, I've never seen or used one. Does it integrate incident and/or reflected light over some substantial solid angle? Some materials, eg. glossy photo paper have a lot of specular reflection which I assume you don't want your densitometer to read, or you'd never get much density range.
--John Beale
--John Beale