Gige camera image intensity changes every time I capture new frames

Hi,

I am using a gige camera to capture frames for certain duration. The issue is, everytime I use "getData" to acquire set of frames, the image characteristics change everytime. However, the charactertistics remain relatively constant for the set of frames acquired during one acquisition step. I have attached a plot here which shows three instances of camera acquisition, with x-axis is time and y-axis is the image contrast. I have made sure all the settings are changed to manual. Is there anything I am missing?

[Image Analyst]

Are you sure the lighting is not changing? Otherwise why would the blue and orange curves change so much over time.

[Akash Maity]

The lighting does not change because I am using a stabilized laser in otherwise dark room as my lighting source. The blue and the orange curve might change due to slight change in light intensity, but the change (+- 0.5) is still acceptable. On the contrary, between experiments, the contrast of the image change is a lot, which is something I don't understand.

Answer 1

[Sai Pavan]

Hello Akash,

I understand that you are trying to know the possible reasons for the discrepancies in image characteristics happening during several acquisitions.

Although lighting variations has been taken care of with the use of stabilized laser, there can be several other factors afftecting the image characteristics when using a GigE camera for image acquisition. These include:

• Buffer Clearing: Before starting a new acquisition, ensure that the camera's buffer is cleared. Leftover data in the buffer can sometimes cause issues with subsequent acquisitions.
• Camera Settings: Ensure that all relevant camera settings are set to manual and not just the exposure, gain, or white balance. This includes settings like iris, focus (if applicable), and any other automatic adjustments that the camera might be capable of performing.
• Warm-Up Time: Some cameras may require a warm-up period to reach a stable operating temperature, which can affect image characteristics. Ensure that the camera has had sufficient time to warm up before starting your acquisitions.
• Camera Initialization: Make sure that the camera is properly initialized before each acquisition. If the camera or the driver has some sort of state that isn't being reset between acquisitions, this could cause variability.
• MATLAB Variables: Check that any variables used in the acquisition process are properly reset or cleared between acquisitions to avoid any carryover of state or data.
• Camera Firmware: Ensure that your camera's firmware is up to date. Firmware issues can sometimes cause unexpected behavior.
• Software Settings: Check if there is any software-based image processing happening either on the camera or in MATLAB after you acquire the frames. This could include auto-contrast adjustments, gamma corrections, or other post-processing steps.

By systematically checking these factors, one should be able to identify and resolve the cause of the varying image characteristics between acquisitions.

Hope it helps!