search

spitschan / SilentSubstitutionToolbox

Toolbox to simulate colorimetric observers for evaluation of photoreceptor isolation
Other
7 stars 5 forks source link

T_energy not quite right, I think #28

Closed DavidBrainard closed 7 years ago

DavidBrainard commented 7 years ago

Joris and I are looking at SST object makeSpectralSensitivities.

On lines 94-95 we found:

%% Convert to energy fundamentals T_energy = EnergyToQuanta(obj.S,T_quantalAbsorptionsNormalized')';

So the returned T_energy fundamentals compute absorptions rather than isomerizations. I don't think there is any reason ever to want absorptions, the biophysically meaningful quantity is isomerizations.

We are changing this, but posting an issue so you can disagree if there is a reason why really it should be absorptions. Note that for computation of contrast, which is what we've mostly cared about in the past, this doesn't change anything, since the difference between absorptions and isomerizations is just multiplication by a single scalar representing the quantal efficiency of an absoprtion producing an isomerization.

DavidBrainard commented 7 years ago

Made the same change in the other two makeSpectralSensitivities functions.

And added comments that my recommendation is that the STT object not return the absorptions functions, or the normalized quantal fundamentals (see comments in SSTReceptorHuman.

DavidBrainard commented 7 years ago

While we're here, we should track back and verify whether pupil diameter is taken into account in the isomerization fundamentals.

DavidBrainard commented 7 years ago

Actually, things were even deeper. The previous energy fundamentals were being computed from normalized absorptions, which makes their units really odd. Now we are computing from quantalIsomerizations.

spitschan commented 7 years ago

Where "previous" means GetHumanPhotoreceptorSS? Presumably this had never been a problem b/c contrast is invariant to the scalar.

On 27 October 2017 6:17:10 pm David Brainard notifications@github.com wrote:

Actually, things were even deeper. The previous energy fundamentals were being computed from normalized absorptions, which makes their units really odd. Now we are computing from quantalIsomerizations.

-- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/spitschan/SilentSubstitutionToolbox/issues/28#issuecomment-340009682