hdevalence
Posts: 3
Joined: Sat Nov 16, 2013 9:18 am

Impossible to set white balance?

Sat Nov 16, 2013 9:42 am

Hi, I'm using raspistill to take a bunch of pictures in time-lapse mode. However, the pictures aren't very useful for my purposes because they have flicker in the WB/AE. It seems from my reading that it's impossible to prevent the camera from redoing the WB/AE calculations every shot.

I would like to be able to have the time lapse mode lock the exposure and white balance from the first shot, but from what I can see, it's not possible to do this: in particular, there seems to be no way to set a custom white balance. (Exposure flicker seems to be less of a problem in practice).

Is there something I'm missing? Does anyone know of a workaround?

Cheers.

ethanol100
Posts: 648
Joined: Wed Oct 02, 2013 12:28 pm

Re: Impossible to set white balance?

Sat Nov 16, 2013 10:21 am

Have you tried to set the awb to a specific mode? You can try to use i.e. "-awb sun" to get less variation in the white balance(there is still some auto white balance I guess). What type of scene do you capture. For the exposure you can use the -ss option to force a constant exposure.

And yes there does not exist a way to specify a custom whitebalance right now or to fix to a realy constant value.

hdevalence
Posts: 3
Joined: Sat Nov 16, 2013 9:18 am

Re: Impossible to set white balance?

Sat Nov 16, 2013 9:25 pm

Yes, I've tried to set the AWB to a specific mode. It doesn't help, and sometimes it makes the problem worse.

The issue with manually setting the exposure is that it doesn't seem like raspistill exposes the meter, and if you can't meter, you can't set the exposure.

It's really disappointing that really basic camera settings like a light meter and white balance aren't available, and that on an "open educational platform" I can't fix it myself, since it's a proprietary blob.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26833
Joined: Sat Jul 30, 2011 7:41 pm

Re: Impossible to set white balance?

Sun Nov 17, 2013 8:01 am

Except those are not *really* basic features....at least for the majority of the 80k camera's bought. Most people use AWB, or one of the presets.

It's on my list of stuff to fix. Which is unfortunately quite long.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

hdevalence
Posts: 3
Joined: Sat Nov 16, 2013 9:18 am

Re: Impossible to set white balance?

Mon Nov 18, 2013 1:26 am

Well, to be fair, it's perhaps not surprising that people don't use settings that aren't implemented. But I've seen a bunch of other posts in this forum talking about the issue in one way or another (e.g., saying that the AWB settings need more hysteresis).

I would really appreciate it if there was a way to set the white balance, or just have the AWB be more consistent from shot to shot. It's just unfortunate that due to the decision to keep the guts of the camera controller locked down and proprietary, this work has to be done by you alone. I would be happy to do it myself, if the option were available, but it's not.

In an ideal world, there would be APIs to control these settings manually, but I guess that would be more work for you. At the bare minimum, would it be possible to have a WB/AE lock setting?

poing
Posts: 1132
Joined: Thu Mar 08, 2012 3:32 pm

Re: Impossible to set white balance?

Mon Nov 18, 2013 9:26 am

hdevalence wrote:The issue with manually setting the exposure is that it doesn't seem like raspistill exposes the meter, and if you can't meter, you can't set the exposure.
I do not really understand that; If you want to set the exposure accurately you have to make a test image anyway. Just seeing a through-the-lens light level based on an algorithm doesn't tell you much without deep insight into said algorithm and a thorough knowledge of the scene.

That said manual WB is on top of my priority list although I'm not sure James' list is the same and it's a pity that it seems deeply buried into the GPU code.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26833
Joined: Sat Jul 30, 2011 7:41 pm

Re: Impossible to set white balance?

Mon Nov 18, 2013 9:29 am

hdevalence wrote:Well, to be fair, it's perhaps not surprising that people don't use settings that aren't implemented. But I've seen a bunch of other posts in this forum talking about the issue in one way or another (e.g., saying that the AWB settings need more hysteresis).

I would really appreciate it if there was a way to set the white balance, or just have the AWB be more consistent from shot to shot. It's just unfortunate that due to the decision to keep the guts of the camera controller locked down and proprietary, this work has to be done by you alone. I would be happy to do it myself, if the option were available, but it's not.

In an ideal world, there would be APIs to control these settings manually, but I guess that would be more work for you. At the bare minimum, would it be possible to have a WB/AE lock setting?
I wouldn't call it a 'decision' to have it locked down. It's a consequence of using the chosen SoC rather than a concious decision. And in fact, even that choice is limited - I am not aware of any open source ISP's.

As for DIY, I reckon it would take someone about 3 months minimum, after getting the source, to be able to do anything useful with it. I've been working in this stuff for 5 years, and I still have to ask for help from the guys who wrote the code.

As for the issue itself, it's on my list. It would be nice to have an API but it's a lot of work to get information from the ARM in to the right part of the GPU. Mostly boiler plate and a right PITA.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

User avatar
Burngate
Posts: 6328
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
Contact: Website

Re: Impossible to set white balance?

Mon Nov 18, 2013 12:26 pm

.... and when you've done that, can we connect one of these to the Pi?
http://www.sony.co.uk/pro/product/broad ... 0/overview
Image
As far as I know, it's just a 485 connection ...

Ok, I'm being silly.

Return to “Camera board”