thomasc
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Registered:1557938099 Posts: 3
Posted 1559651362
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#1
Would anyone be kind enough to share how the calculation for "Pixels per degree " on the NIMH ML dashboard (V2) is performed using the following inputs :
- Resolution - Diagonal size (cm) - Viewing Distance (cm) Thanks, Thomas
Jaewon
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Registered:1435685587 Posts: 971
Posted 1559700340
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#2
See the get.PixelsPerDegree function in mlconfig.m
thomasc
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Registered:1557938099 Posts: 3
Posted 1559728738
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#3
Hi Jaewon, Thanks for pointing me to the calculation in mlconfig.m. Estimates from horizontal and vertical pixel distances using the same methodology in get.PixelsPerDegree give differing estimates of "Pixels per degree" (for x and y axes). Is the diagonal pixel distance used instead of the horizontal and vertical pixel distances simply to yield a single estimate? Thanks, Thomas
Jaewon
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Posted 1559753164
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#4
It is something I inherited from the original ML, but I think it is a reasonable way to get the estimate. If you want to be so obsessive about this, be my guest. But the difference between screen width and height is just one source of error. For example, the monitor screen is flat, not curved like a sphere, so technically you need to stretch out your stimuli when you present them on the periphery, to compensate the curvature difference. Also you don't poke the ruler through the subject's eye, so your viewing distance measure is not perfect either.
thomasc
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Registered:1557938099 Posts: 3
Posted 1560228171
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#5
Thank you Jaewon