# Measuring and controlling image luminance

**URL:** <https://forum.magicleap.cloud/t/measuring-and-controlling-image-luminance/7064>\
**Category:** General\
**Created:** [June 22, 2026, 10:27pm UTC](https://forum.magicleap.cloud/t/measuring-and-controlling-image-luminance/7064 "2026-06-22T22:27:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![apy](https://avatars.discourse-cdn.com/v4/letter/a/e56c9b/32.png) [@apy](https://forum.magicleap.cloud/u/apy)\
**Post date:** [June 22, 2026, 10:27pm UTC](https://forum.magicleap.cloud/t/measuring-and-controlling-image-luminance/7064/1 "2026-06-22T22:27:41Z")

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Dear Magic Leap community, I have a pupillometry experiment (in Magic Leap) with 2 colored image conditions. I want to measure image luminance of all of my images to: 1) check if there are significant luminance differences between my 2 conditions and 2) be able to account for luminance in my analyses to ensure that any pupil size differences \* condition are not due to luminance differences. I have tried measuring luminance with GIMP and in MATLAB (in 2D), but I am not getting convergent results and struggling to find what the gold standard approach would be in vision research / how can I get the best luminance measures of my stimuli on Magic Leap. Thanks a lot!!

PS: I already have extracted the ambient light sensor data from my experiment, but as I understand it this is measuring ambient light rather than light measured through the lenses (where you can see the objects presented).

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**Author:** ![jspire](https://avatars.discourse-cdn.com/v4/letter/j/8dc957/32.png) [@jspire](https://forum.magicleap.cloud/u/jspire)\
**Post date:** [July 16, 2026, 12:47am UTC](https://forum.magicleap.cloud/t/measuring-and-controlling-image-luminance/7064/2 "2026-07-16T00:47:53Z")

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Hi Apy,

Are you using linear or gamma space measurment with your app? If linear: The engine is doing the math linearly, but the display still applies a hardware gamma (typically ~2.2) If gamma: The engine and display are both working in non-linear curves.

You may need to calculate for the gamma curves to get the “true” intensity of the light.

Thank you,