D405 Color Instability in Indoor Lighting
Working with the D405 trying to solve other color issues such as variable auto-white balance performance, and over saturation I noticed that when under indoor lighting conditions the color stream from the camera changes setting quite rapidly and consistently. This is seen most obviously on red objects. Where the color changes between being a darker bluer shade and a lighter yellower shade.
I have this captured on video, but since I cannot upload it I will provide histograms showing this shift occur on a static scene. Overlaying the histograms there is definitely variations in how the camera is performing.
Steps to reproduce this behavior:
- setup in Indoor lighting (tried this outside as well)
- place the camera in a static scene with red, green, and blue objects
- Place something over the camera and remove it quickly triggering the camera to adjust
- repeat until colors become unstable and oscilate at a rate of 1-0.5 Hz
- Is this possibly caused by 60Hz lighting compensation breaking?
- Is there a possibility that the advanced color mode machine learning models are playing a role in this?
- Is there a way to get information about the current white balance in real time? (from what ive read the answer is no)
- Are there other settings I am not aware of that may be playing a role in this?
Hi Luke Bowersox I tested extensively with a D405 with your test method in the RealSense Viewer tool under indoor lighting but was unable to replicate the described oscillation effect. After uncovering the camera, there was a brief white flash each time and then the RGB image adjusted to normal. I conducted the tests under the power line frequency settings of Auto and then 60Hz.
Is the oscillation effect occurring for you in the RealSense Viewer or in a program script that you have written?
The power line frequency will typically be a factor in the camera's RGB performance if the camera is being used in a location with fluorescent lights, such as ceiling strip lights. This is because such lights contain a heated gas that flickers at a frequency that is difficult to see with the human eye.
The 60 Hz lighting power frequency will normally be used in North American regions, whilst European regions use the 50 Hz frequency. So if you have indoor ceiling strip lights and are located in Europe then it would be recommendable to set the power line frequency to 50 Hz instead of 60 in the Viewer or in your program if you are using your own script in order to better compensate for flickering on the image caused by 50 Hz lights.
As Advanced Mode settings are managed by machine learning algorithms and interact with each other in complex ways, it would be difficult to conclude whether they were a factor in your RGB issue. I was not able to replicate it in my own tests.
RGB auto-exposure metadata is not retrievable whilst auto-exposure is enabled. The same is true for RGB white balance metadata as far as I am aware.
The subject of white-balance metadata is discussed at the link below.
I think there is a bug in this forum, i keep having to retype my posts.
I have seen that page before and combed through it, good to know thats the end all be all.
- Could this be hardware related? This is one of the first D405s.
- Can you share more background on what the camera is doing to adjust for powerline freq, and how I might intentionally break it to try and reproduce this issue?
The described effect has not been previously reported by D405 users and I was not able to replicate it myself, though I do not have fluorescent lights in my location to test the possibility of whether they are a potential cause. My own D405 is an early model and has not experienced problems. It will therefore be useful for you to test several other D405 to see whether the issue can be replicated on more than one camera.
Power Line Frequency - which can be controlled with the SDK instruction RS2_OPTION_POWER_LINE_FREQUENCY - is an anti-flickering control that can be set to Off / 50Hz / 60Hz / Auto. There is no further documentation available for this function other than this summary description.
Does the issue still occur if auto-exposure is disabled? If the camera is being used indoors and the artificial lighting level is consistent throughout the day / night then it may not be necessary to have auto-exposure enabled in order to adjust for changes in lighting levels.
This is on my radar still I do think florescents play a big role in this! I won't have a chance to test this until I resolve other color issues. But if you or someone else has a chance to test in a warehouse type env with florescents. That may eliminate other factors like my setup being jacked up or HW etc.
The case at the link below may be a useful reference as it features a warehouse-like room with 60 Hz fluorescent lights.
Another reference is an underground car park with fluorescent lighting.
Please sign in to leave a comment.