Compare Camera Images

[Fwehne]

Hi Idriss,

without any picture i have no clue what you are talking about in point 1).

When i open your vi, it seems that you are running it on a myRIO. Anyway, same issue as with 1), i need more informations. What is your expected Framerate, what is the Image Size in Pixels, on what system are you running your code?

[moidrissou]

Hey Fabian,

thank you for your reply.

I am using the myRio FPGA module with Labview 2016. the camera  i use to acquire the ímages is Basler acA2000 and it can take 50 Frames per second. the sizes are 360x640. 

the PNG-Image attached Shows you what  my Problems are: the first two Images are the Images to be compare, acquired with the camera. the 3rd is the result of the subtration. it seams to be 0. but when i applied my Loop to get all the Pixels which are greater than 0, it seams like all of them exceed 0. thats also the reason why the vi is slow, because it must be reading more than 100000 adresses in the while-Loop for the Highlight. even when i used a threeshold like ( > 10) i get the same results.

thank you for taking your time to help me.

Idriss

[Fwehne]

Hy Idriss,

please attach the images you want to compare as png. Most likely you are suffering from the camera noise, which will prevent a succesful operation without further modifications.

cheers

[moidrissou]

i didn't save the Images. i am acquiring them direct from the camera in my while-Loop. or do you mean i should save those Images as PNG and send them to you?

[Fwehne]

Please Save two images and attach them to this post.

[moidrissou]

Hey Fabian,

sorry if i didn't reply yesterday, i have had some Problems the configuration of my camera.

now i am trying to save the camera Images, can you please tell me why i am getting this error ? It should be working.

[Fwehne]

Hey Idriss,

you are trying to use the windows os file path convention on a linux rt os (your my rio).

This is why you are getting this error.

Check out this link:

http://www.ni.com/tutorial/14669/en/

After you have saved the image on your myRIO you have to transfer it to your pc:

http://digital.ni.com/public.nsf/allkb/4EBE45E8A816B19386257B6C0071D025

I will be on vocation until the beginning of september from tomorrow, if you upload the images, i can have a look at them today.

cheers

[moidrissou]

Hey Fabian,

Here are the Pictures from my camera.

[Fwehne]

Hey Idriss,

you are suffering from the normal camera noise one would expect in such a situation (See Image Compare.vi):

If you want to compare the two images you have to account for this. Depending on your settings, the color channel you want to use you have to find the proper threshold. Personally i would start by simply calculating the standard deviation (append the negative array, to get the symmetric value) multiply this times 3 (99,9 something % of all points of the noise distribution reside within this window)  (See Image Compare.vi for this). I dont know if this is a valuable threshold for you, this is something you have to figure out on your own.

Anyway, your second issue regarding the performance. You are executing your code on a myrio, which is running the real-time code on a Cortex A9 chip. The decrease in performance is expected here. If you want to be faster you have to spend more money for a faster real-time system...

As already said, i will be on vacation, so please dont expect any more support here the next time. If you have further questions please contact the NI Technical Support.

cheers

[moidrissou]

Thank you very much for your Support. I wish you nice Holidays.