<< return to Pixycam.com

Adjust brightness with auto exposure correction disabled

Pixy Software
#1

Hi,

I’m trying to detect an LED in an outdoor setting with changing light conditions. For this I wanted to disable the auto exposure correction in PixyMon so that the brightness of the LED itself is consistent. As it is documented the brightness slider at the tuning tab doesn’t work with auto exposure correction disabled. Is there any other way to adjust the brightness?

The brightness is at a good level and stable when I disable auto exposure correction but as soon as I click the apply button the brightness is reset to a standard value which is way too bright for my application. I’m not sure if I’m doing something wrong or if this is a bug. Or maybe it’s not possible to save the brightness level with auto exposure correction disabled?

I’m using
PixyMon v2 version 3.0.24
Pixy2 firmware version 3.0.18 general build
Pixy2 hardware version 2.3.0

Thank you very much for your help,
Nik

#2

I think I found a workaround that lets me store the brightness setting. I can save the Pixy parameters into a prm file with auto exposure correction active, edit the file to disable it and then load the file in PixyMon again.
Set auto exposure correction to 0:
data value=“0” key=“Auto Exposure Correction” type=“INT8”
data value=“589856” key=“AEC Value” type=“INT32”

The AEC Value seems to be responsible for the brightness. Is there some documentation what this parameter means? Does this parameter set the gain/offset of the camera sensor?

Thank you,
Nik

#3

Hello,
The current brightness level should be saved as fixed (unchanging) when you disable auto exposure. So for example if you want low exposure, lower the brightness before disabling auto exposure. It sounds like you’re saying that when you disable it, the exposure ends up being set too high. Are you using Pixy2 and the latest firmware version?

Edward

#4

Hi Edward,

The procedure you’re describing works until I click on the “Apply” button. After disabling auto exposure the brightness is fixed at the correct low level like you say. But as soon as I click the “Apply” button the brightness is reset to some standard value.
I’m using:
PixyMon v2 version 3.0.24
Pixy2 firmware version 3.0.18 general build
Pixy2 hardware version 2.3.0

Thanks,
Nik

#5

Hello,
This appears to be bug. Here’s a workaround: From PixyMon, save the parameters from the File menu. Then go into the .prm file with a text editor and change the “AEC Value” to 262146.

<data key="AEC Value" value="262146" type="INT32"/>

Then save the text file and load the same prm file into PixyMon.

The AEC value are two 16-bit values stuck together, so it’s not as simple as “small is dark”, “large is bright”. Let me know if this is too dark and I can suggest some other values (524296 is slightly brighter).

Edward

#6

Thanks, I’ll try this.

Cheers,
Nik