So for example, if I set the minimum accurate measurement range to 0.15 cd/m2, once Argyll reads a patch with a luminance of 0.15 cd/m2, it then records it as the lowest valid reading. It would skip all patch measurments between 0.00-0.15 cd/m2 and in just evenly space any remaining luminance measurements below 0.15cd/m2 (since Argyll appears to calculate the native gamma of the the display, it should be able to make a reasonably accurate guess of where those low luminance values would likely fall on the gamma curve) while using the same R:B:G ratio that was found when measured at 0.15cd/m2.
Heuristics are often fragile, and it would make for a great deal of complexity to provide some sort of estimate of the minimum reliable reading of each type of instrument in each type of mode, particularly if the mode is dynamic (true of many of the colorimeters that are based on Light to Frequency sensors). There's no real telling what a display does as it goes to black either - my CRT has quite large "dead" zones, and interpolating the readings would give a poor correlation to its actual behavior (it doesn't go below 0.1 though). Why don't you try the adaptive mode and see what you think: spotread -e vs. display mode: spotread -d
Now before getting too far astray, can you say a little more about how that -V parameter will work? Will the -V parameter have a number value after it? If not, then I assume it just tells Argyll to disable heuristics?
It just tells Argyll to use the emissive mode of the instrument rather than display mode. For the i1pro emissive mode uses adaptive integration and gain. For most other types of instruments there is no difference between these modes. Graeme Gill.