Does anyone have any experience with luminance changes in a visual display?

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Adam Vilanova-Goldstein 2020-12-13

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评论： Image Analyst 2020-12-15

I am a visual cognitive psychologist and I use Matlab and PsychToolBox for some visual search experiments. I am attempting to change the luminance of black stimuli at random intervals. I have considered using a grey as the baseline and then changing the color to make it darker or lighter randomly but have been unable to get the color to change. Any suggestions on how I should think about this?

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Image Analyst 2020-12-14

When you mean "color" you mean the brightness (intensity) of a gray scale image, right? Not the color like a non-gray/tinted RGB image?

Also, when you say "random intervals" do you mean intervals of gray level, or time intervals?

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Matt Gaidica 2020-12-13

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在 MATLAB Online 中打开

'Value' is, I believe, the same as 'luminance' in your case. If so, you could create images based on HSV values and change the value variable dynamically.

h = zeros(200,200);
s = zeros(200,200);
v = ones(200,200);
RGB1 = hsv2rgb(h,s,v*0.3);
RGB2 = hsv2rgb(h,s,v*0.5);
RGB3 = hsv2rgb(h,s,v*0.8);
close all
montage({RGB1,RGB2,RGB3},'Size',[1,3]);

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Matt Gaidica 2020-12-15

编辑：Matt Gaidica 2020-12-15

在 MATLAB Online 中打开

LumMid = repmat(63.75, [5,3]);
LumMult = [0; 0.5;1;1.5;1.95];
multiList = LumMult .* LumMid;
if thing1
    ovalColors = LumMid(1:3,:);
elseif thing2
    ovalColors = multiList(randi([1,5],3,1),:);
else
    % cover other cases here
end

I mean, totally agree this will need calibration, but if it's just concepting a paradigm... Could also just initialize ovalColors and cover remaining cases.

ovalColors = LumMid(1:3,:);
if thing2
    ovalColors = multiList(randi([1,5],3,1),:);
else
    % cover other cases here
end

Image Analyst 2020-12-15

For super precise experiments, you might need to use a calibrated gray scale monitor like they use in radiology. Barco makes respected monitors:

https://www.barco.com/en/product/nio-5mp-led-mdng-5221

https://www.barco.com/en/glossary/healthcare/dicom-calibration

https://www.imaging-resource.com/ARTS/MONCAL/CALIBRATE.HTM

https://pubmed.ncbi.nlm.nih.gov/17333412/

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Image Analyst 2020-12-13

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You should probably calibrate your displays with this device:

https://www.xrite.com/categories/calibration-profiling/i1-solutions/i1display-pro-plus

In addition, there are ASTM guidelines for viewing (target brightesses, surround brightness, clothing, room brightness, etc.) that you may want to look at.