Tuned up display calibration instructions & tweaked openScreen so that

.display.gamma could be manually overridden without messing with rigPrefs directly
- for some reason, merely setting .display.gamma = [] wasn't actually overriding
existing .display.gamma.power values
- updated precidence in openScreen and instructions in calibDisplay_...m to explain
how & why those must be overridden during calibration

@pldaps/openScreen.m

@@ -160,10 +160,14 @@
 
 %% Color correction
 % Must be initialized before PTB screen opened, correction parameters are loaded/applied below
-if isfield(p.trial.display, 'gamma') && isfield(p.trial.display.gamma, 'power')
-    PsychImaging('AddTask', 'FinalFormatting', 'DisplayColorCorrection', 'SimpleGamma');
-else
-	PsychImaging('AddTask', 'FinalFormatting', 'DisplayColorCorrection', 'LookupTable');
+if isfield(p.trial.display, 'gamma')
+    if isfield(p.trial.display.gamma, 'power') && ~isempty(p.trial.display.gamma.power)
+        PsychImaging('AddTask', 'FinalFormatting', 'DisplayColorCorrection', 'SimpleGamma');
+    elseif isfield(p.trial.display.gamma, 'table') && ~isempty(p.trial.display.gamma.table)
+        PsychImaging('AddTask', 'FinalFormatting', 'DisplayColorCorrection', 'LookupTable');
+    end
+% else
+% 	PsychImaging('AddTask', 'FinalFormatting', 'DisplayColorCorrection', 'LookupTable');
 end
 
 % Functional modifications to PsychImaging prior to PTB screen creation
@@ -466,15 +470,12 @@
 
 
 %% Apply display calibration (e.g. gamma encoding or lookup table)
-if isfield(p.trial.display, 'gamma')
+if isfield(p.trial.display, 'gamma') 
     % disp('****************************************************************')
     fprintLineBreak
-    fprintf('Applying display color correction ');
-    if isfield(p.trial.display.gamma, 'table')
-        fprintf('via lookup table\n');
-        PsychColorCorrection('SetLookupTable', p.trial.display.ptr, p.trial.display.gamma.table, 'FinalFormatting');
-    elseif isfield(p.trial.display.gamma, 'power')
-        fprintf('via gamma power %3.3f\n', p.trial.display.gamma.power);
+    if isfield(p.trial.display.gamma, 'power') && ~isempty(p.trial.display.gamma.power)
+        % allow .power correction to take precident
+        fprintf('Applying display color correction via gamma power %3.3f\n', p.trial.display.gamma.power);
         PsychColorCorrection('SetEncodingGamma', p.trial.display.ptr, p.trial.display.gamma.power, 'FinalFormatting');
         % Extended gamma parameters
         if all( isfield(p.trial.display.gamma, {'bias', 'minL', 'maxL', 'gain'}) )
@@ -484,10 +485,20 @@
             gain=p.trial.display.gamma.gain;
             PsychColorCorrection('SetExtendedGammaParameters', p.trial.display.ptr, minL, maxL, gain, bias);
         end
+
+    elseif isfield(p.trial.display.gamma, 'table') && ~isempty(p.trial.display.gamma.table)
+        % [old] direct lookup table approach
+        fprintf('Applying display color correction via lookup table\n');
+        PsychColorCorrection('SetLookupTable', p.trial.display.ptr, p.trial.display.gamma.table, 'FinalFormatting');
+
+    else
+        fprintf('No luminance/color linearization to apply\n');    
     end
 else
-    %set a linear gamma
-    PsychColorCorrection('SetLookupTable', ptr, linspace(0,1,p.trial.display.info.realBitDepth)'*[1, 1, 1], 'FinalFormatting');
+    % do nothing, direct pass through to device while allowing PTB to 'ClampOnly' by default
+    fprintf('No luminance/color linearization to apply\n');
+    %     %set a linear gamma
+    %     PsychColorCorrection('SetLookupTable', ptr, linspace(0,1,p.trial.display.info.realBitDepth)'*[1, 1, 1], 'FinalFormatting');
 end
 
 % % This seems redundant. Is it necessary?

SupportFunctions/Utils/calibDisplay_pldaps.m

@@ -14,13 +14,25 @@
 %  Must be run after pausing a running PLDAPS session.
 %  - This is a feature, not a bug, because it ensures that measurements are made under
 %    the exact same setup conditions as your experiment.
-%  - This is not the stereo-specific version of the calibration code
+%  This is not the stereo-specific version of the calibration code
 %    - its *not* INcompatible with stereo displays, but it doesn't make/fit
 %      separate monocular calibrations, or do any binocular crosstalk measurements
 % 
+%  When making initial calibration measurements, its important to be sure that 
+%  all other/prior calibrations are disabled when the new measurements are made.
+%  - e.g. linearization via gamma table or power, or binocular crosstalk corrections
+%  - Otherwise the result will be confounded by [unknown] prior display corrections
+%  - Easiest way to do this is to make sure the .display.gamma.power field is empty
+%    before your code executes p.run
+%  - In the modularDemo, you would want to set:  pss.display.gamma.power = [];
+%  
 %  Save the returned greyscale [simpleGamma] value in your rigPrefs as:
 %       .display.gamma.power
 % 
+%  AFTER you've run your calibration & added the results to your rigPrefs,
+%  run this calibration function again to validate. This will help ensure that your
+%  validation is performed in EXACTLY the same state as your experiment.
+% 
 % 
 % EXAMPLE:
 % ---
@@ -43,6 +55,7 @@
 %   % [ follow command window instructions to apply & save new rigPrefs values ]
 % 
 %   % Done! Future experiments on this rig will apply this gamma correction automatically
+%   % Rerun the calibration measurements with the new settings applied to validate your results
 % ---
 % 
 % 

SupportFunctions/Utils/calibDisplay_pldapsRb3d.m

@@ -19,9 +19,21 @@
 %    & binocular crosstalk correction
 %  - ...still needs [more] commenting & explanation on how to properly use/implement (TBC 2021)
 % 
+%  When making initial calibration measurements, its important to be sure that 
+%  all other/prior calibrations are disabled when the new measurements are made.
+%  - e.g. linearization via gamma table or power, or binocular crosstalk corrections
+%  - Otherwise the result will be confounded by [unknown] prior display corrections
+%  - Easiest way to do this is to make sure the .display.gamma.power field is empty
+%    before your code executes p.run
+%  - In the modularDemo, you would want to set:  pss.display.gamma.power = [];
+%  
 %  Save the returned greyscale [simpleGamma] value in your rigPrefs as:
 %       .display.gamma.power
 % 
+%  AFTER you've run your calibration & added the results to your rigPrefs,
+%  run this calibration function again to validate. This will help ensure that your
+%  validation is performed in EXACTLY the same state as your experiment.
+% 
 % 
 % EXAMPLE:
 %   p = yourPldapsExperiment;
@@ -43,6 +55,7 @@
 %   % [ follow command window instructions to apply & save new rigPrefs values ]
 %   
 %   % Done! Future experiments on this rig will apply this gamma correction automatically
+%   % Rerun the calibration measurements with the new settings applied to validate your results
 % ---
 % 
 % 

tutorial/+modularDemo/doRfPos_gabGrid.m

@@ -107,7 +107,7 @@
 % pss.display.screenSize = [];
 % pss.display.scrnNum = 0;
 
-pss.display.stereoMode = 4; % 0==mono 2D; 3-or-4==freeFuse 3D;  See Screen('OpenWindow?')
+pss.display.stereoMode = 0; % 0==mono 2D; 3-or-4==freeFuse 3D;  See Screen('OpenWindow?')
 
 pss.display.useGL = 1;
 pss.display.multisample = 2;