Originally Posted by Light Illusion
If Farthest Point patch sets really bring an improvement, we will add them to LightSpace.
Nothing to do with any other calibration system, as the concept is well know, and has been for years.
(Credit to those that defined the concept in the first place, including the paper miki linked to.)
We have not bothered with it as yet, as any benefits have not previously shown to be worth while.
(For most, and Anisometric approach works very well.)
The WOLED tests LightSpace users are doing may show enough of a benefit...
Especially with the sorting approach bobof has implemented.
We will see.
Having said that, the fact LightSpace can work with any patch set a user wants is probably enough.
That allows the user to define whatever patch set they want, for themselves - sourcing from anywhere.
I'm not sure how much benefit the patch sorting brings over the current ansio sequence in real testing. I don't actually have an OLED display - I only did this as the theory was interesting to me and it helped some friends out.
It is definitely possible to get better drift behaviour than the current revised ansio patch sequence by careful control of the preroll and patch order, but the current ansio sequence has a relatively soft curve to it I believe so the drift algo is likely able to deal with most of it.
For anyone interested one of the threads on this at the LS forum:
This was drift from the original ansio sequence (no longer in use):
An analysis I did of what I thought was the original patch sequence power over the course of the sequence. This analysis puts the RGB patch values through gamma function to work out amount of light and has an algo to try and work out WRGB subpixel values (approx):
This is what I think the current sequence looks like through the same analysis - note the gentle curve trend. A bit spikey too.
This is a patch sequence for the same analysis after being pushed through my "algorithm" to try and keep the average total plus WRGB levels constant on a rolling basis through the patch sequence. (note - ignore the difference in y scale, just look at the shape)
Of course it is likely my very basic model for WRGB mixing is flawed, and really you should adjust for the deviance from native panel white point for the display in it's profiled state, as that will affect the WRGB mixing employed for a given patch value. The proof in the pudding though that this seems to be "enough" is that when appropriately pre-rolled these sets processed thus seem to exhibit very small levels of drift.
One other issue to be aware of - if you have variable patch display times (because you have longer integration times for darker patches, or averaging below certain nit levels) this algorithm won't work as well. Ideally you would understand the effect of the patch value on the patch display time and also use that as a factor in your sorting algorithm. However, that is beyond the scope of what I can probably be bothered with (not even having an OLED to play with!!!
). For some meters this can't be worked around - eg for the Basiccolor Discus the variable read times can't be defeated.
This is a typical drift plot for a sorted sequence measured with a K10A set up for constant patch display time. I think it is about as flat as you're likely to get for a consumer OLED without taking this to an extreme such as power profiling the actual display in advance of running the actual profile, and using that power profile to sort the patch set.