Crosstalk Algorithm - Optical system

In summary, I am having trouble getting good brightness values from my camera. I believe it is crosstalk but I don't know what to do to get rid of it.
  • #1
btb4198
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I have a camera that take pictures of square boxes that are really close to one another. There is a light that is Illuminating the boxes but when I try and isolate a single but in my picture, I am reading higher values then what I should be. If I remove the other boxes and only do one box, I am getting lower values. So I believe I have cross talking. What is the best Crosstalk Algorithm I can use?
 
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  • #2
Can you post some representative pictures and show your brightness data? Thanks.
 
  • #3
for the black part, I am getting value like 4.67 and they are lowest when I do not have the white or grey boxes. so when the picture is uniform
 

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  • #4
It could be crosstalk and it could be scattered light. What type of detector is it, and what is the detector architecture? Is it read out in a single array, or in multiple segments? Can you illuminate the detector with a small spot of light that you can move around? This is a good way to quantify crosstalk
 
  • #5
phyzguy said:
It could be crosstalk and it could be scattered light. What type of detector is it, and what is the detector architecture? Is it read out in a single array, or in multiple segments? Can you illuminate the detector with a small spot of light that you can move around? This is a good way to quantify crosstalk
Please see attachment. I am using a camera that has a CMOS image sensor. What do you mean by " illuminate the detector with a small spot of light" that can move around ? how small of a light ?
 
  • #6
When I put my cell phone in front of the camera everything turns white
 
  • #7
I don't think you are dealing with crosstalk. Try pointing the camera at a dark screen and point a laser pointer at the screen. You should see a spot of light in the camera. If it is crosstalk, you will see "ghost" images of the spot of light.
 
  • #8
So I am new to Optics, What is the different between crosstalk and scattered light? Do you believe that system is suffering from crosstalk ? Is there a test I can do for that ?
 
  • #9
Crosstalk is electrical coupling where the signal from reading out one pixel gets coupled into another pixel. You typically see a faint copy of one part of the image in a different part of the image. Since it is an electrical effect, the faint copy is an exact copy of the real image. If the real image is in focus, the crosstalk image is in focus, too. A test would be to do what I said. Have a bright spot in one area and the rest of the image dark. If it is crosstalk, you will see one or more copies of the bright spot in other parts of the image. Scattered light is an optical effect, not an electrical effect. It is light from the bright regions entering into the dark regions. In this case, the light scattered into the dark regions will typically be diffuse and out of focus. Look at the attached images. On the left, there is both crosstalk and scattered light. Notice how the ghosts of the numbers "2" and"5" are still in good focus. On the right, the crosstalk has been subtracted, but the scattered light remains, where there are fuzzy, out-of-focus copies of the bright regions in the dark areas. From what you've showed, I think your problem is scattered light, not crosstalk, but I don't know for sure.
crosstalk_subtraction_20150821.png
 
  • #10
Is there an Algorithm, I could use that could digital remove scattered light?

another question, in my picture, I never see any fuzzy, out-of-focus copies . I never seen any copies at all . but I still get lower values with uniform image vs one with the boxes like I show before. so I know it is there. why is that ?
 
  • #11
It depends on what the scattered light looks like. In the images I posted, those fuzzy out of focus images are actually reflections in the optical system, so they are not completely out of focus. It's also possible to have more diffuse scattered light, which you won't see easily. To subtract it off, you need to characterize what it looks like. For example, suppose you illuminate one part of the image, say white on the left and black on the right. Then, what do the counts in the dark region look like? Are they uniformly high? How much higher are they than a completely dark image? What if the bright region is 25% of the image vs 50% of the image? Does that reduce the counts in the dark region? Do the counts fall off as you move from the edge of the bright region to far away from the bright region? Once you can answer questions like these, you can build a model of the unwanted light and subtract it off.
 
  • #12
great! this has been a big help!
 
  • #13
Is that an Optical way to reduce scattered light ?
 

1. What is a crosstalk algorithm in an optical system?

A crosstalk algorithm in an optical system is a method used to minimize interference between multiple channels of information being transmitted through the same optical system. It ensures that signals intended for one channel do not affect or distort signals in other channels.

2. How does a crosstalk algorithm work?

A crosstalk algorithm works by using mathematical calculations and signal processing techniques to analyze and adjust the signals in each channel to minimize the effects of crosstalk. This can involve adjusting the signal strength, timing, or frequency of the signals.

3. Why is crosstalk a problem in optical systems?

Crosstalk can be a problem in optical systems because it can cause errors and distortions in the transmitted information. This can lead to reduced data transfer speeds, lower quality signals, and potentially even complete loss of information.

4. What are some common techniques used in crosstalk algorithms?

Some common techniques used in crosstalk algorithms include equalization, pre-emphasis, and post-equalization. These techniques help to compensate for signal distortions and minimize the effects of crosstalk.

5. How is crosstalk measured in optical systems?

Crosstalk in optical systems is typically measured using a metric called the crosstalk ratio, which compares the strength of the desired signal to the strength of the interfering signal. A higher crosstalk ratio indicates a lower level of interference and better performance of the crosstalk algorithm.

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