Set explicit white balance values in Expo Camera?

[bmccann36]

My project involves taking two pictures and then comparing the rgb pixel data of the two. I would like to be able to take the first photo using the ‘auto’ white balance setting. When taking the second photo I do not want the WB to re-calibrate. I would like to capture the second photo with an identical WB setting to that used in the first.

I see from the camera example project that it is possible to toggle between presets such as ‘sunny’ and ‘fluorescent’. Is it possible to dial in a color temperature value such as 5500, or 4000 Kelvin etc…? It also seems that the auto setting is superior to any of the presets and yields the purest white. It seems to adjust the red, green, and blue as needed VS the presets which seem only to affect the relationship between red and blue.

So, is there a way to capture the specific rgb bias settings applied to white balance in the first photo and then apply those specific settings to another photo? Can it be done within the Expo environment?
thank you

[aalices]

@bmccann36 how about locking the WB? So the balance won’t change until you unlock it. I am not yet sure if this will work in Expo but I’ll try to give it a try and let you know if this works.

[bmccann36]

That sounds like it could be what I need. I suppose I would lock in the WB setting at the moment after the first picture was taken. As far as I can tell there is no method in react-native or expo that exposes this. It looks like it may involve writing a native module.
thanks