PROPixx Demo 5 – Displaying Gabor patches at 480 Hz¶
In this demo, we design a stimuli to run at 480 Hz on the PROPixx. To display at 480 Hz, we limit our resolution to 1/4 of the screen to display 4 times faster. Indeed, your stimulus needs to be created as follows:
Quadrant 1 |
Quadrant 2 |
Quadrant 3 |
Quadrant 4 |
We simply generate a window of size (960, 540) and we move it to the right quadrant. In one frame, we animate the stimulus 4 times, once for each quadrant. We send a 120 Hz signal that has 4 frames of information, allowing us to display at 480 Hz.
For 1440 Hz display, the technique is the same, but we use the colour information of each quadrant to create the equivalent of twelve frames in one. Frame 1 would be Quadrant 1 Red, frame 2 is Quadrant 2 Red, and on until green and then finally quadrant 1 to 4 blue.
To set the PROPixx in a different mode, we use a sequencer, Datapixx('SetPropixxDlpSequenceProgram', 2);
, the 2 is for 480 Hz,
5 for 1440 Hz, 0 for normal display.
In this demo we create a Gabors that we scale for every Gabors we want, then we move them randomly in the resolution. We animate the Gabors 4 times per frame to create the 480 Hz animation. We animate everything as in Quadrant 1 and move them to the respective quadrant.
At the end of the script, we must put back the normal sequencer, Datapixx('SetPropixxDlpSequenceProgram', 0);
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 | function DatapixxShowGabor(frames, nbr_of_Gabor, win)
% function DatapixxShowGabor(frames = 4800, nbr_of_Gabor = 200, win)
%
% This has been inspired by GaboriumDemo.m from Psychtoolbox.
%
% This demo constructs a gabor aquarium at 480 Hz. It displays the Gabor
% for a set amount of frames given by the frames argument. The number of gabor
% is determined by nbr_of_Gabor and the max amount depends on the speed
% of your computer.
%
% frames -- Number of frames to animate the stimuli for (optional,
% default is 4800)
% nbr_of_Gabor -- Number of Gabor to be in the stimuli (optional, default
% is 200)
% win -- Handle to the win (optional, default is full screen)
%
% Oct 29, 2014 dml Written
% Mar 23, 2018 dml Updated
% Initialize the PROPixx to 480 Hz
Datapixx('Open');
Datapixx('SetPropixxDlpSequenceProgram', 2); % 2 for 480, 5 for 1440 Hz, 0 for normal
Datapixx('RegWrRd');
if nargin < 3 || isempty(win)
PsychImaging('PrepareConfiguration');
PsychImaging('AddTask', 'General', 'FloatingPoint32BitIfPossible');
screenid = max(Screen('Screens'));
[win win_rect] = PsychImaging('OpenWindow', screenid, 128);
end
if nargin < 2 || isempty(nbr_of_Gabor)
nbr_of_Gabor = 100;
end
if nargin < 1 || isempty(frames)
frames = 4800;
end
% Set the transparency for gabor patch
Screen('BlendFunction', win, GL_SRC_ALPHA, GL_ONE);
% Get refresh rate
ifi = Screen('GetFlipInterval', win);
%Generate a Gabor patch (from GaboriumDemo.m)
s = 32;
res = 2*[s s];
phase = 0;
sc = 5;
freq = 0.05;
tilt = 0;
contrast = 5;
x=res(1)/2;
y=res(2)/2;
sf = freq;
[gab_x gab_y] = meshgrid(0:(res(1)-1), 0:(res(2)-1));
a=cos(deg2rad(tilt))*sf*360;
b=sin(deg2rad(tilt))*sf*360;
multConst=1/(sqrt(2*pi)*sc);
x_factor=-1*(gab_x-x).^2;
y_factor=-1*(gab_y-y).^2;
sinWave=sin(deg2rad(a*(gab_x - x) + b*(gab_y - y)+phase));
varScale=2*sc^2;
m=contrast*(multConst*exp(x_factor/varScale+y_factor/varScale).*sinWave)';
%Transform the gabors into texture
gabortex=Screen('MakeTexture', win, m, [], [], 2);
texrect = Screen('Rect', gabortex);
inrect = repmat(texrect', 1, nbr_of_Gabor);
% Create the array for the 4 quadrants gabor
dstRects = zeros(4, nbr_of_Gabor);
dstRects_q2 = zeros(4, nbr_of_Gabor);
dstRects_q3 = zeros(4, nbr_of_Gabor);
dstRects_q4 = zeros(4, nbr_of_Gabor);
srcRects = [];
rotAngles = rand(1, nbr_of_Gabor) * 360;
% Create the right amount of gabors, and scale them randomly
for i=1:nbr_of_Gabor
scale(i) = 2*(0.1 + 0.9 * randn);
dstRects(:, i) = CenterRectOnPoint(texrect * scale(i), rand * 1920/2, rand * 1080/2)';
end
% Initial flip
vbl = Screen('Flip', win);
number_of_frames = 1;
% Stimulus
while number_of_frames < frames
% FRAME 1
if number_of_frames > frames
vbl = Screen('Flip', win, vbl + 0.5 * ifi);
break;
end
Screen('DrawTextures', win, gabortex, srcRects, dstRects, rotAngles, [], 0.5, [], [], 0);
number_of_frames = number_of_frames + 1;
% Animate
rotAngles = rotAngles + 1 * randn(1, nbr_of_Gabor);
[x y] = RectCenterd(dstRects);
x = mod(x + cos(rotAngles/360*2*pi), 1920/2);
y = mod(y + sin(rotAngles/360*2*pi), 1080/2);
dstRects_q2 = CenterRectOnPointd(inrect .* repmat(scale,4,1), x, y);
% Move to Q2
dstRects_q2(1,:) = dstRects_q2(1,:) + 1920/2;
dstRects_q2(3,:) = dstRects_q2(3,:) + 1920/2;
% FRAME 2
if number_of_frames > frames
vbl = Screen('Flip', win, vbl + 0.5 * ifi);
break;
end
Screen('DrawTextures', win, gabortex, srcRects, dstRects_q2, rotAngles, [], 0.5, [], [], 0);
number_of_frames = number_of_frames + 1;
% animate
rotAngles = rotAngles + 1 * randn(1, nbr_of_Gabor);
[x y] = RectCenterd(dstRects_q2);
x = mod(x + cos(rotAngles/360*2*pi), 1920/2);
y = mod(y + sin(rotAngles/360*2*pi), 1080/2);
dstRects_q3 = CenterRectOnPointd(inrect .* repmat(scale,4,1), x, y);
% Move to Q3
dstRects_q3(2,:) = dstRects_q3(2,:) + 1080/2;
dstRects_q3(4,:) = dstRects_q3(4,:) + 1080/2;
% FRAME 3
if number_of_frames > frames
vbl = Screen('Flip', win, vbl + 0.5 * ifi);
break;
end
Screen('DrawTextures', win, gabortex, srcRects, dstRects_q3, rotAngles, [], 0.5, [], [], 0);
number_of_frames = number_of_frames + 1;
% Animate
rotAngles = rotAngles + 1 * randn(1, nbr_of_Gabor);
[x y] = RectCenterd(dstRects_q3);
x = mod(x + cos(rotAngles/360*2*pi), 1920/2);
y = mod(y + sin(rotAngles/360*2*pi), 1080/2);
dstRects_q4 = CenterRectOnPointd(inrect .* repmat(scale,4,1), x, y);
% Move to Q4
dstRects_q4(1,:) = dstRects_q4(1,:) + 1920/2;
dstRects_q4(2,:) = dstRects_q4(2,:) + 1080/2;
dstRects_q4(3,:) = dstRects_q4(3,:) + 1920/2;
dstRects_q4(4,:) = dstRects_q4(4,:) + 1080/2;
% FRAME 4
if number_of_frames > frames
vbl = Screen('Flip', win, vbl + 0.5 * ifi);
break;
end
Screen('DrawTextures', win, gabortex, srcRects, dstRects_q4, rotAngles, [], 0.5, [], [], 0);
number_of_frames = number_of_frames + 1;
% animate for next frame
rotAngles = rotAngles + 1 * randn(1, nbr_of_Gabor);
[x y] = RectCenterd(dstRects_q4);
x = mod(x + cos(rotAngles/360*2*pi), 1920/2);
y = mod(y + sin(rotAngles/360*2*pi), 1080/2);
dstRects = CenterRectOnPointd(inrect .* repmat(scale,4,1), x, y);
% Update the four Qudrants
vbl = Screen('Flip', win, vbl + 0.5 * ifi);
[pressed dummy keycode] = KbCheck;
if pressed
break;
end
end
% Blank screen
Screen('Flip', win);
% Exit on escape
KbName('UnifyKeyNames');
escapeKey = KbName('ESCAPE');
while 1
% Check the state of the keyboard.
[ keyIsDown, ~, keyCode ] = KbCheck;
if keyIsDown
if keyCode(escapeKey)
Screen('CloseAll')
break;
end
end
end
%Restore PROPixx State
Datapixx('SetPropixxDlpSequenceProgram', 0);
Datapixx('RegWrRd');
Datapixx('close');
clear all;
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