problems creating a BMP file

[Kaspar]

Hello,
 
 
    I am getting screen shot data from various instruments with the VISA read command, which outputs a string of data.  How do I convert this to a 2d array so that I create a BMP file?
 
Regards,
 
Kaspar

[smercurio_fc]

Well, that depends on the format of the 2D data, and what the 2D data represents. This should be documented in the instrument's manual, which we don't have.

[Kaspar]

Hello,
 
   I am getting BMP data from 2 differenet manufacturers. I will contact them to get the format. So once I get the format  how would I convert the output of the VISA read (which is string data) to the input that the Write BMP File vi needs which is image data?
 
Regards,
 
Kaspar

[MikeS81]

Hi Kaspar,
i think your "string" data is a binary byte stream. If you know the format you can convert your data to an array of U8 and build your picture of it.
Hope it helps.Mike

[Kaspar]

Hello,
 
  Yes your are correct this is a binary data string from the instrument. I will try what you suggested. thank you!
Regards,
 
Kaspar
 
 

[Dennis Knutson]

And have you tried simply saving the data directly to disk?

[Kaspar]

Hello,
   Yes I have tried writing the data directly to a file and have looked at it with binary file viewers. The file created does not have the BMP header info, it appears to just have the bitmap data. So it looks like I have to figure out how to convert  from the output of the VISA read, which is the binary data to image data, which is what the Write BMP file needs for a input.
Regards,
 
Kaspar
 
 
  

[Mythilt]

Something like the vi attached is probably what you need.
You will need to modify it according to the specifics of your data.
 


ConvertStringtoBitmapExample.vi:
http://forums.ni.com/attachments/ni/170/347105/1/ConvertStringtoBitmapExample.vi

[Kaspar]

Hello,
 
  I am using Labview 8.2, the vi you attached is in 8.5. Could you PLEASE (I have used the magic word) save the vi in 8.2 and post it?
Regards,
 
Kaspar

[Mythilt]

Soitanly.
 
v8.2 version attached.


ConvertStringtoBitmapExample.vi:
http://forums.ni.com/attachments/ni/170/347132/1/ConvertStringtoBitmapExample.vi

[Kaspar]

Hello,
 
  Thanks for posting the 8.2 version. Now I have to contact the vendors to get the image res and size of the screenshot data.  Presently the programmers guides just state BMP format, there is no indication of res and/or size.
 
Regards,
 
Kaspar
 

[Kaspar]

Hello,
  Success....drum roll please (I have used the magic word). I have been able to get a screen shot from a TDS2022 scope. I have attached the vi to this E-mail, it is written in Labview 8.2. If you have questions, please reply to this forum.
Regards,
 
Kaspar
 
  


tds2022_screen_capture.vi:
http://forums.ni.com/attachments/ni/170/348247/1/tds2022_screen_capture.vi

[Kaspar]

Hello,
 
   I got so excited about fixing the screenshot with the TDS2022 that I forgot to save the vi to disk before I appended it to the website. So here it is again, this time it is the vi that works. Sorry for the confusion.
 
Regards, Kaspar
 


tds2022_screen_capture.vi:
http://forums.ni.com/attachments/ni/170/348336/1/tds2022_screen_capture.vi

[Mythilt]

So the program works now?  Excellent, and good job.

[Kaspar]

Hello,
 
  The vi I supplied above works at least for me in my program. Hopefully someone else will use it in their program to get a screenshot of the scope.
Regards,
 
Kaspar

[smercurio_fc]

I think an easier solution is to use the Flatten Pixmap function to generate that cluster. You just need to know what bit-depth you're dealing with so you wire to the appropriate input.

[Kaspar]

Hello,
 
  I have used the "String to byte Array" vi to convert from the string output of a VISA read to a u8 1d array. Unfortunately, the Flatten Pixmap vi, requires a 2d array input. So how would I convert this into a 2 day array for the flatten pixmap vi?
Regards,
 
Kaspar

[Mythilt]

Kaspar wrote:

Hello,
 
  I have used the "String to byte Array" vi to convert from the string output of a VISA read to a u8 1d array. Unfortunately, the Flatten Pixmap vi, requires a 2d array input. So how would I convert this into a 2 day array for the flatten pixmap vi?
Regards,
 
Kaspar


If you know the size of the image (width / Height) you use the reshape array function.

[smercurio_fc]

I have used the "String to byte Array" vi to
convert from the string output of a VISA read to a u8 1d array.
Unfortunately, the Flatten Pixmap vi, requires a 2d array input. So how
would I convert this into a 2 day array for the flatten pixmap vi?
<img src="Loading Image..."> Message Edited by smercurio_fc on 08-06-2008 10:44 AM


reshape array.png:
http://forums.ni.com/attachments/ni/170/347133/1/reshape array.png