LifeCam USBCamera changing settings from Java

[robert1356]

I spent more time on it last night and discovered a few things. I looked at the source code for the USBCamera class - it's just a wrapper for the NIVision.IMAQ functions - that's not a bad thing, but it is good to know.

Info:

• The USBCamera constructors call 'openCamera' internally. You don't need to explicitly call openCamera unless you explicitly call closeCamera.

• UpdateSetting is automatically called by getImage() and getImageData() if one of the settings (exposure, brightness, fps, etc) had previously been changed. There is no need to call updateSettings() explicitly unless you are not using getImage() or getImageData().

• The setBrightness() and setExposure() functions do nothing but set a USBCamera member variable. The settings are not sent to the camera/driver until the updateSettings is called (which will be the next time you call getImage() or getImageData())
  • The getBrightness() does nothing but return that member variable.

It's good to know what the functions are actually doing

Bottom line - I removed the openCamera() call and removed my calls to updateSettings() and relied on the USBCamera class to manage it. This works better, but not perfectly. I can adjust the brightness and see things change, but exposure seems to have no effect.

I took it a step further. I created my own USBCamera class and added a getExposure() and modified the getBrightness() to get the values from the camera/driver using the NIVision.IMAQ calls. This proved to me that the exposure and brightness ARE getting changed, AND I validated that I am NOT in AutoExposure mode. Unfortunately, I still cannot get the exposure changes to show any appreciable effect on the LifeCam image. Brightness goes from a decent image with Brightness = 0, to a white image with Brightness = 100. Exposure changes seem to have no effect.

Has ANYONE been able to get images out of the life cam, using ANY method, that comes anywhere close to being as dark as the sample images for the FRC vision processing? I'm beginning to think that the LifeCam is simply not adjustable to that low of an exposure.

[Justin Buist]

Originally Posted by robert1356

Brightness goes from a decent image with Brightness = 0, to a white image with Brightness = 100. Exposure changes seem to have no effect.

Has ANYONE been able to get images out of the life cam, using ANY method, that comes anywhere close to being as dark as the sample images for the FRC vision processing? I'm beginning to think that the LifeCam is simply not adjustable to that low of an exposure.

The Javadoc notes that exposure and brightness go from 0 - 100 are completely wrong. I forget what the actual range is but this issue frustrated a room of students and mentors for most of a Saturday until we played with the MS software for the LifeCam which actually presents sane values for the 3 different settings. Brightness is something like -15 to 4 (don't trust that number, I'm going from rough memory) but not 0-100 at all. None of them documented to be 0-100 actually are.

[1024Programming]

Originally Posted by Justin Buist

The Javadoc notes that exposure and brightness go from 0 - 100 are completely wrong. I forget what the actual range is but this issue frustrated a room of students and mentors for most of a Saturday until we played with the MS software for the LifeCam which actually presents sane values for the 3 different settings. Brightness is something like -15 to 4 (don't trust that number, I'm going from rough memory) but not 0-100 at all. None of them documented to be 0-100 actually are.

I think it was mentioned in another post that the values actually go from 0-20,000. if that is the case, then using command will only max the value at 100/20,000.

[robert1356]

Using the NIVision IMAQ commands, the min/max values returned are 5 and 20,000 respectively. I duplicated the USB Camera class (too bad they made all the variable private instead of protected) and replaced the setExposureManual() with code that allowed me to set the value explicitly. It turns out that anything above about 40 or 50 will give you quite a bright image. I'm actually using 10 I think for the exposure and 10 for the brightness.

As for losing the settings - as long as you don't power the camera off, you will not lose the settings. It's tricky, but you can use Robot code to configure the camera, then disconnect, then run GRIP and it will have the setting you just set. There are some real caveats in all this and I think I finally have all the cases worked out. I'm probably going to post the code when I get it working.

Caveat #1 - The robot code cannot use CameraServer - if it does, GRIP will not be able to publish a stream. Unfortunately, while you CAN disconnect from the USBCamera, you CANNOT kill the CameraServer stream without rebooting the robot or manually killing the robot code.

Caveat #2 - don't forget that during development, if you use your robot code to set the settings, then launch GRIP, if you reload robot code, GRIP is still running and your robot code will throw an exception trying to connect to the USBCamera - you have to either reboot your roborio or kill the GRIP process. I've written code to kill the GRIP process if the USBCamera open() method throws and exception.

[ahartnet]

Just wanted to say thanks for reporting your findings on all of this. I've been busy taking care of some other mentor duties, and this is a life saver in allowing some students still get some help in trouble shooting what is going on with limited software experience

[medofbr]

Originally Posted by robert1356

Using the NIVision IMAQ commands, the min/max values returned are 5 and 20,000 respectively. I duplicated the USB Camera class (too bad they made all the variable private instead of protected) and replaced the setExposureManual() with code that allowed me to set the value explicitly. It turns out that anything above about 40 or 50 will give you quite a bright image. I'm actually using 10 I think for the exposure and 10 for the brightness.

As for losing the settings - as long as you don't power the camera off, you will not lose the settings. It's tricky, but you can use Robot code to configure the camera, then disconnect, then run GRIP and it will have the setting you just set. There are some real caveats in all this and I think I finally have all the cases worked out. I'm probably going to post the code when I get it working.

Caveat #1 - The robot code cannot use CameraServer - if it does, GRIP will not be able to publish a stream. Unfortunately, while you CAN disconnect from the USBCamera, you CANNOT kill the CameraServer stream without rebooting the robot or manually killing the robot code.

Caveat #2 - don't forget that during development, if you use your robot code to set the settings, then launch GRIP, if you reload robot code, GRIP is still running and your robot code will throw an exception trying to connect to the USBCamera - you have to either reboot your roborio or kill the GRIP process. I've written code to kill the GRIP process if the USBCamera open() method throws and exception.

When you say you can use the Robot code to configure the camera, then disconnect, then run GRIP, what do you mean by "then disconnect"? Does the mean calling the CloseCamera() function?