# Is the intensity reading by pixel proportional to the photon count?

**URL:** <https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355>\
**Category:** OpenMV Boards\
**Created:** [May 23, 2023, 10:40pm UTC](https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355 "2023-05-23T22:40:08Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![simonfissette](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@simonfissette](https://forums.openmv.io/u/simonfissette)\
**Post date:** [May 23, 2023, 10:40pm UTC](https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355/1 "2023-05-23T22:40:08Z")

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To be more precise, I would like to know for example if I double the integration time, will the reading by pixel will double as well or there is some kind of gamma correction or else processed on board?

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**Author:** ![kwagyeman](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/kwagyeman/32/4_2.png) [@kwagyeman](https://forums.openmv.io/u/kwagyeman)\
**Post date:** [May 24, 2023, 5:55pm UTC](https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355/2 "2023-05-24T17:55:20Z")

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The camera ISP applies gamma correction. It’s a normal step.

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**Author:** ![simonfissette](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@simonfissette](https://forums.openmv.io/u/simonfissette)\
**Post date:** [May 24, 2023, 9:01pm UTC](https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355/3 "2023-05-24T21:01:34Z")

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I understand. However, is it possible to access the raw data without the gamma correction? The ones that should be proportional to the photon count or the absolute luminosity?

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**Author:** ![kwagyeman](https://yyz1.discourse-cdn.com/flex029/user_avatar/forums.openmv.io/kwagyeman/32/4_2.png) [@kwagyeman](https://forums.openmv.io/u/kwagyeman)\
**Post date:** [May 24, 2023, 9:12pm UTC](https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355/4 "2023-05-24T21:12:57Z")

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Yes, use the RAW BAYER image.

Set the pic format to BAYER.

Note, on the OV5640 the raw bayer image is still processed by default. If you have a MT9V034 sensor then this will be unprocessed.

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**Author:** ![simonfissette](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@simonfissette](https://forums.openmv.io/u/simonfissette)\
**Post date:** [May 26, 2023, 3:31pm UTC](https://forums.openmv.io/t/is-the-intensity-reading-by-pixel-proportional-to-the-photon-count/8355/5 "2023-05-26T15:31:15Z")

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Thanks for the quick reply. I will look for the MT9V034 and test if the readings are linear with the exposure time for a constant light source.