To collate the info above into a single post, which should help others understand how ColourSpace works for manual calibration.
First, all measurements within ColourSpace need to reference back to a 0-1 range. This is associated with LUT generation.
(This is all because the main ColourSpace code enables any 'profile' to be used to generate a LUT, and ColourSpace ZRO is a sup-set of the main code. We are NOT going to modify ZRO so it deviates from the main code base.)
This does mean all 'source' patch data needs to use a 0-1 range.
For manual calibration this means the defined patches need to be 0-255 range, with any rescaling performed via the graphics card under EIDID control, or using the Patch Scale option, etc.
So any .csv sequence needs to also be 0-1 range.
This because the Target values will always assume black is an internal patch of 0, not 16.
And white is 255, not 235.
Yes there will be some 'rounding' of the 8 bit values.
That is expected.
Is it an issue?
No display/probe combination is ever more stable than the rounding error.
You can prove the rounding issues by taking single step measurements, as you will see on occasion same 16-235 output value for 2 adjacent 0-255 input values.
But, you never do that in manual calibration.
You use a few 'grey-scale' points, likely 10 or 20(ish) throughout the 016-235 range.
So in reality it is not an actual issue.
(You could make a .csv that is a full set of 255 steps, but the display/probe instability would cause far more measurement errors than the 16-235 rounding!)
But, we will we adding 10, 12, 14, 26 bit 'bit depth' options in the future.
(Presently being worked on...)
That will greatly alter the rounding issues.
Additionally, it is likely we will add some form of 'Sub-Range' capability.
But, that introduces issues with LUT generation, as outlined above... so is not likely to happen quickly, as we will need to make the code base compatible across the main ColourSpace program, as well as ZRO.
So in reality, this is a non-issue in the real world.
Mob Boss at Light Illusion