Issues with subtracting Images

[University of South Carolina]

Hello everyone, I am relatively new to LabView and I have an huge order on my plate. I am using a Gige Cam with a 1394 cord to acquire images and there are several things that need to be done.

1) Turn on camera and take 1 image (this will be referred to as Original Image)

2) Take an arbitrary amount of ROI's and record the image and coordinates.

3) Now start a continuous image acquisition and subtracting the Original Image from the "latest image" to find the difference between the two and record that to avi and a sequence of images (slideshow). I also want to subtract the specific ROI's from each other by reapplying the same ROI to the "latest image" to find the specific difference in those areas.

4)For each different ROI subtraction that I do like Roi 1 of OI- Roi 1 latest image I would like to take that new subtracted image and turn it into an array of RGB values and save them to a spreadsheet with a time stamp. The spreadsheet will need to be organized by which ROI I chose as x axis, under that the three RGB values and on the Y axis time.

Right now I have completed steps 1 2 and I am stuck on 3 because whether I use IMAQ subtract Images or turn them to arrays and subtract or turn them to matrices and subtract I get whacked out subtractions. The two images are going to be of the same object so the numbers should be very close to each other thus I would assume the numbers should be very close to zero, but that aint happening.

I will try to post VI as soon as possible and if anyone has any suggestions on refining my other steps, it would be greatly appreciated.

[University of South Carolina]

This is the VI that I am working on A few things aren't being used and I am currently trying different ways of subtractions arrays, images, matricies.

[JtotheB]

What sort of images are you getting from these subtractions? Can you post those images? That might help us figure out what is going on.

[University of South Carolina]

Ok. The rainbow looking images are the result of subtractions with roi looking somewhat similar, the black green and blue images are from ROI very close to each other (had to construct them from hand with the draw rectangle VI).

[University of South Carolina]

Here's the rest.

[JtotheB]

What are the two original images that you are subtracting?

[University of South Carolina]

It is esentially a sample in a reactor and I want to detect changes in color values via subtraction and then convert that to arrays and so on.

[University of South Carolina]

Here's an update,

Averaging the images before the subtraction helps greatly reduce the noise that was there in my previous images. Putting the abs dif inside the for loop now prevents the image from flip flopping between two images. Here's the next problem that I'm going through now, how am I going to choose which ROI I specified and continuously apply it to the subtracted image. Applying it doesn't present a problem all I would have to do is apply the coordinates to IMAQ image to array.

P.S. Please disregard the name of the file it was agreed on by my boss for those who speak spanish.

[JtotheB]

If you move your ROI selection outside of the loop, and feed that into the loop. That will allow you to apply the same ROI to the subtracted image.

[University of South Carolina]

I hate to beat you to the punch ,but I actually have another update. The ROI selection has been solved. The VI will run ROI's 0 to n-1 and apply itself to the subtracted image also it will produce an average R  G  and B values for that ROI. It will run through all of them and becasue it is in the while loop it will run through the same ROI's again and give a slightly different average if there is change. One problem that I am experiencing now is saving this information to a spreadsheet. The order it needs to be is this..... Time        Roi0              Roi1                       Roi2 

                                                                                sec.   AVG.(R   G  B)   AVG.(R   G   B)   AVG.(R    G    B).

Each RGB should be its own column, But indicated by which ROI chosen. My attempts to save it to an spreadsheet or to an excel file have been unsucessful, though notepad will take it and that information can be transfered to excel though it is not properly formatted.Is there a way to just configure what the spreadsheet will look like in labview?

I will working on this issue with you guys to see if I can figure it out too. Probably should have posted that last time too.