topic Re: problems creating a BMP file in LabVIEW

problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 14:23:28 GMT

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

Re: problems creating a BMP file

smercurio_fc — Wed, 06 Aug 2008 14:31:09 GMT

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.

Re: problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 14:42:09 GMT

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

Re: problems creating a BMP file

MikeS81 — Wed, 06 Aug 2008 14:47:01 GMT

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

Re: problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 14:51:53 GMT

Hello,

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

Regards,

Kaspar

Re: problems creating a BMP file

Dennis_Knutson — Wed, 06 Aug 2008 14:57:24 GMT

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

Re: problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 15:07:07 GMT

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

Re: problems creating a BMP file

Mythilt — Wed, 06 Aug 2008 15:19:18 GMT

Something like the vi attached is probably what you need.

You will need to modify it according to the specifics of your data.

Re: problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 15:22:15 GMT

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

Re: problems creating a BMP file

smercurio_fc — Wed, 06 Aug 2008 15:24:38 GMT

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.

Re: problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 15:41:34 GMT

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

Re: problems creating a BMP file

Mythilt — Wed, 06 Aug 2008 15:42:51 GMT

Soitanly.

v8.2 version attached.

Re: problems creating a BMP file

smercurio_fc — Wed, 06 Aug 2008 15:44:02 GMT

Message Edited by smercurio_fc on 08-06-2008 10:44 AM

Re: problems creating a BMP file

Mythilt — Wed, 06 Aug 2008 15:44:33 GMT

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.

Re: problems creating a BMP file

Kaspar — Wed, 06 Aug 2008 15:51:24 GMT

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

Re: problems creating a BMP file

Kaspar — Mon, 11 Aug 2008 13:41:30 GMT

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

Re: problems creating a BMP file

Kaspar — Mon, 11 Aug 2008 16:47:12 GMT

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

Re: problems creating a BMP file

Mythilt — Mon, 11 Aug 2008 21:13:16 GMT

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

Re: problems creating a BMP file

Kaspar — Tue, 12 Aug 2008 12:06:27 GMT

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

Re: problems creating a BMP file

Kaspar — Wed, 03 Sep 2008 16:37:27 GMT

Hello,

Attached to the reply is a vi that creates a BMP file from the E4411B spectrum analyzer, this is why I was asking all of the questions in the forum.

Regards,

Kaspar