Saving image data to text file - multiple columns

[CP Miika]

Hi,

I'm currently grabbing images using IMAQ functions and am computing the average of each image across the columns using IMAQ LinearAverages.vi. I am currently saving these values (ie a line profile size 1:N) to a text file. However I have a large amount of images (M) to capture, so I would like to output each image line profile data to an individual column.

At the moment the text file captures all data but in a single column-not very useful for post-processing purposes. Can anyone suggest a nice way of doing this? Is saving to a spreadsheet file better?

I'd appreciate any advice.

Kind regards,
Miika

[TiTou]

I'm not sure I fully understand what you're doing in your VI could you post some code to show exactly what you do so we can come up with appropriate ideas?

[CP Miika]

Hi TiTou,

Apologies for the delay; I have been at a conference meeting with limited internet. I hope you can still help me.

In the attached screen shot you can see the for loop within which I am saving the data to a text file - the N of the loop corresponds to how many images I wish to capture.  In this I am capturing an image with IMAQ, then I average along each column to obtain a line profile for this image and then these values I save to a text file.  However, the file is very big and it would make much more sense to save each line profile in a separate column rather then one after another. 

Averaging across the columns yields 1024 values (fixed). If I capture 1000 images and save each value, I would be ending up with 1000*1024 values, one after another in a .txt file.  It would be much easier for postprocessing if info from each image was in a separate column.

Any comments/suggestions are welcome!

Kind regards,
Miika

[TiTou]

Hi,

Sorry for coming back to you so late.

If you don't absolutely need a txt file I suggest to use TDMS files to save your data (binary file but you can open them in Excel if you install this), the advantage I see in this option is that you will have one column per image.

Hope this helps

[CP Miika]

Hi TiTou,

Thanks for the advice. I'll try your suggestion and post an update here in due course.

Miika

[CP Miika]

Hi TiTou,

I implemented what you suggested but I am encountering an error

Error 8 occurred at TDMS Open

Possible reason(s):

Labview: File permission error.  You do not have the correct permissions for the file.

============================================================

NI-488:  DMA hardware error detected.

Any idea why this is happening?

Miika

[TiTou]

Hmmm... surprising... can you check the file path you give and also connect an "open or create" constant to the open TDMS primitive?

[CP Miika]

My file path is just simply to a folder on the desktop.

I've selected open or create constant and connected it to TDMS open.  Still won't work.  It's strange - I am the admin on the computer I'm using so I don't see why it has permissions errors.

[TiTou]

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@CP Miika wrote:

My file path is just simply to a folder on the desktop.

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How do you form the file path? can you show you code please?

[CP Miika]

Hi TiTou,

I'm using a stacked sequence.  TDMS 1 shows the folder creation and TDMS 2 shows where this path is fed to TDMS open.vi via sequence local.

I hope you can help me.