Picture Control to Waveform Graph

Hello everyone,
I'm utilizing the Draw Text at Point VI to display the string "eo" on the picture control. To put the fear of intense imagining behind, I bring up the question, is there any way to convert the Picture Control, and it's contents, to Waveform graphs? I could have sworn I worked with intensity graphs and did conversions in this fashion but for the life of me I cannot remember how it was done.
If not, is there any simple way to bring up actual text in a waveform graph for laser imaging to follow?
Thanks for any help...
Regards

Hi Steve,
I had a colleague transfer an image into a Waveform Graph. What came out was not at all the original picture. The IMAQ driver was used. I don't know of a method like what you have described.
Kevin S.
Applications Engineer
National Instruments

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Publication Quality Image Files [.TIFFs] of Waveform Graphs or Waveform Charts?

I'm familiar with the Knowledge Base Article 2PP7CM7Y, How Can I Save a Front Panel Control to a JPEG, PNG, or BMP File?
My problem is that the resulting pictures are nowhere near publication quality [i.e. the kind of thing you could import into Acrobat for submission to an academic or technical journal]. For instance, I've attached a PNG of an Electrocardiogram [ECG], called "ecg.png", that, in all honesty, doesn't deserve to be posted on a website, much less imported into an Acrobat document. As far as I can tell, I'm using all the high
est settings [24-bit color, no compression].
Does Labview have any other utilities for saving to industry standard image formats, especially high-resolution TIFFs? I know the information is there, because when I print the VI's Front Panel to our 600dpi laser print, I get really beautiful, publication quality prints. My suspicion is that whoever wrote the "Invoke Node/Get Image" VI [and/or the various "Graphics Format/Write File" VIs] simply took a snapshot of the graphic card's [VERY low resolution] video buffer, rather than calling the underlying software logic that gets invoked when you print to a 600DPI laser printer. Is there any way I can get access to that underlying software logic?
Thanks!
Attachments:
ecg.png ‏693 KB

Okay, I installed the HP PostScript drivers, but, as far as I can tell, there is no option to 'Save to File.' [Such an option may be there somewhere, but I looked all over the place, and I couldn't find it...]
Besides, the idea of saving to PostScript, and then running some program like 'ps2png' or 'ps2tiff' is not very appealing to me, for at least two reasons:
1) It's very batch-file-ish in nature, i.e. I've got to download some monstrosity like Ghostscript, get it installed, get it configured [no trivial task in and of itself, believe you me], then write some batch-file-ish thingamabob to open the PostScript file and process it - I'd much prefer to [at the very worst] make a call straight to a DLL from within a Labview VI. But that's o
nly the start of my woes; once I've got a PostScript file, I've got to figure out some way to cut just the picture of the Waveform Graph from the larger picture of the VI window - I suppose I could use some sort of a Clipping Path or an Encapsulated PostScript Bounding Box, but at this point we've clearly crossed over into the realm of what I would call 'hideously ugly, grotesquely inelegant, batch-file-ish hack.' Plus, my gut instinct is that it would take a bare minimum of a week or more to get such a thing up and running efficiently, when, if I could make a call straight to the Labview printing infrastructure, I could do it in just a few minutes.
2) It's very, very difficult to venture into the realm of PostScript software [especially Ghostscript] and keep your project from becoming contaminated by the GPL, or worse [the Aladdin license agreement ain't exactly a stroll on the beach].

Dispaying a waveform graph with control of the cursor in the document.

I would like to be able to control the cursor when I save my waveform graph in html. I'm currently saving the graph through the report vi's

I am not sure I understand your question. Do you want to simply control where the cursor is on the picture you are appending to the html report. If so then when you use the Append Control Image to Report VI it basically takes a snap shot at that moment and displays it. Therefore you just need to place the cursor where you wnat it before you add the image.
To programttically control the cursor you will need to use property nodes of the Waveform Graph. A good start would be the property cursor>>cursor position>>all elements.

Limit control to property of a waveform graph

I have a waveform graph in which I would like to limit practically all the property of the contextual menu. Such as:
Visible items, Auto scale X and Y...
There is a way to do that. By setting "Disabled" to 1.
My problem: I would still like to let the user change the Y scale by double clicking it.
Thanks
Nitrof

Nitrol,
Unless I'm mistaken (it happens), the only way to really do this is completely disable all functionality and add the functionality back through your front panel. I would suggest a very easy approach by putting two digital controls (or one array with two elements, or a cluster, or...) which would be the min and max of the Y scale. You can even make it more simple by just adding a Property Node of the graph, selecting the Y scale, and creating a control. That would save you a lot of work. It wouldn't be as neat and tidy, but it would get the job done with the least amount of work.
If you want to know how to do this exactly as you specified, here goes:
Place a picture control over the y scale of the graph. Make the picture invisible (the "T"
color for the frame and the drawing area. Then, with the picture selected, move it to the front. Next, in the diagram, get the mouse down data from the Mouse property in a while loop. Throw the mouse down data into a shift register. Make the loop have a delay (wait) of about 200ms. AND the output of the mouse down button with the previous one. When the output is true (of the AND), stop the loop. You have detected a double click of the Y scale. NOW, you have to add a subVI that pops up (dialog) options for the Y scale. The user will change the scale, and then you can input these into the Y scale of the graphs property node. Yes, its quite complicated, but the results are exactly what you are looking for.
Of course, I always recommend the KISS principle (Keep It Simple Stupid).
Good luck

BCG Brightness Contrast Gamma - Looking for BCG function returning color table / lookup table coded in pure G and applicable to Intensity Graph or Picture Control

Looking for BCG function returning color table / lookup table coded in
pure G and applicable to 8-bit Intensity Graph or Picture Control. Do
not want to use IMAQ Vision is this particular application. Any
help is appreciated.
Sincerely,
Don

Take a look at this color model software I put together. (Don't concern yourself much with the basic programming at this point.). The color component generator subVI is borrowed from a LabVIEW example.
First look at test_color2.vi. If you adjust the sliders of the various controls, you will see how it works. You can see that for pure B&W images, brightness, contrast, and gamma (which I think I have coded correctly) are all fairly straightforward to modify.
Now look at test_color3.vi. Here we try to adjust BCG for color images using the color model shown here where current color component clusters are carried into the BCG event cases via shift registers. You can see that once color is introduced into the image, it becomes difficult to mix the colorizing with the BCG model. And this is pretty much where I am right now.
Would be interested in comments / suggestions.
Sincerely,
Don
Attachments:
test_color2.llb ‏2251 KB

Get image invoke method gives blank image when I try to capture waveform graph picture

Hello
I am facing problem when try to capture waveform graph picture using invoke method Get image and write JPEG function, some times it gives blank images.I am using these functions inside nested loops.
ObservationsWith reference to attached VI)
(1) Sometimes I found it captures images correctly when i run labview program first time but after that it starts writing blank images.
(2) Whenever i use flat sequence structure for waveform graph and get image node it always gives blank picture which indicates that execution of waveform graph and Get image should not be sequential.
(3) Whenever it gives blank image i checked the image data which is not valid data so it indicates problem is with Get image method or labview program flow(may be race condition between waveform graph and Get image method).
I have attached vi ,please change path name and folder name in which images are being saved.I'm using labview 8.5.1 .
Attachments:
image_capture_problem.lvproj ‏6 KB
image capture problem.JPG ‏149 KB
0.0_10__3.jpg ‏2 KB

Hi,
I have tried sequence structure.But sometimes it also gives blank images. I have attached new vi which is using flat sequence. Run this vi 7-8 times then you will observe blank images. I don't know why?Any help will be greatly appreciated.
Attachments:
image_capture_problem.vi ‏69 KB

Control Waveform Graph - Set Lower Limit and Autoscale Upper Limit

In a waveform graph is their a way to set the lower graph Y limit at zero and then have it autoscale the maximum Y limit as a percentage (150% for example) of the maximum Y graph value ?
Direction to examples or a starting point to read up on would be great !
Thanks,
Joe
Ireland
Solved!
Go to Solution.

Turn off autoscale and set the max with a property node based on the array max of the data.
LabVIEW Champion . Do more with less code and in less time .

Waveform graph - How can I get that functionality (picture inside)

Hi ...
When browsing through the examples yesterday I came across the screenshot below. Now my question ist: How do I get that 4-way-cursor-move-thing next to the waveform graph and how do I get that look of the Cursor Palette? I think I tried nearly every checkbox on the waveform graph, but I couldn't get that same look. Anyone here who wants to help?
Thanks in advance
Attachments:
capture_14092006_084304.jpg ‏63 KB

Oh, boy
The fact that this isn't a waveform graph but a XY Graph might explain it

How do I Get the value from a mouse click - on a waveform graph?

If I have made a plot into a Waveform Graph and later want to do a zoom of my data
(Not zoom into the Waveform Graph, but regenerate the data). How do I read the mouse
coordinate if I click on the graph window. I know how to put up the horiz and vert
cursors but don't know how to just read the mouse click. I would really like to
follow the windows standard that identifys a rectangle by clicking and draging and then
be able to read the corners of the rectangle. Thanks, Rick
PS: Using Labview 6i

I would recommend to 'translate' your graph in a picture and dislay it in a picture control (see picture examples in LV6).
Once you did it, pictures have an extremely useful property called Mouse that returns the mouse coordinates and click events when you place the cursor on the picture.
By this you can re-arrange the graph on picture appearance.
There are also other methods such as using a Window's API that returns the mouse position referred to the whole screen window, but I believe this would be much more difficult to implement.
Let me know if this was clear and if you need an example vi.
Good luck,
Alberto

A problem about saving the picture control'image in a child VI.

i want to use 'export image' method to get a picture control'image,so ,i have a child VI to use method 'export image',and a main VI to using the child VI,but when i run the main VI,there is no image is saved on the disk ,but if i open the child VI'frontpanel,then,i run the main VI,the image is saved on the disk,i want to know the reason why i can not get the image,when i run the main vi without the child 'frontpanel or blockdiagram is opened.
Solved!
Go to Solution.
Attachments:
child.vi ‏11 KB
main.vi ‏7 KB

The behavior that Simon describes is not a hard and fast rule, and the Export Image method used to be a bit of an exception. It would supposedly update the controls of unopened FPs that used the method. Reality never quite matched what was described in the documentation if I recall.
If you pore over the detailed help you discover that this method works fine in SubVIs with some controls and not others. Look at the characteristic 'Loads the Front Panel Into Memory', for a Picture control it is 'No', for a Waveform Graph, for instance, it is 'Yes'. Caveat: Relying on this level of detail to be correct in the LV help is a bit risky. Best to try it yourself. Not loading the FP is a good hint that the method is not going to behave in a SubVI.
As to the problem at hand, a Picture Indicator is an odd choice to me to use this method. You have VIs in the Picture palette to convert pictures to image data and then export the image data to a PNG or JPG or BMP file directly. Anything you would draw and then export could be exported directly without drawing.

How to add custom graphical features to cursors in Waveform Graphs

Hi all:
I´ve starting a project in LabView, in which I need to synchronise some events with a sound track.
To do this, I tought that LabView would be the tool of choice, but now that I´m working on it, I
found my self faced with some serious problems.
What I want to do, is to represent a .wav sound file in a Waveform graph, and then use the cursors
to mark some points in the desired places where I want things to happen, but, these events are
going to be on during some period of time.
So, it will be natural that some consecutive events might overlap in time, and I need to have
some control on this.
The best solution would be to have a rectangular strip attached to the cursors, with a lenght
representing the exact time duration of the event.
But this is only possible on my dreams, because I dont see any tools on LabView that aloud us to implement
any extra graphical features on the cursors.
But as I learned more about LabView, I found that a user can program blocks of software in C, to implement
things that LabView does´nt do by default.
And now I´m wondering if this could be the solution for my problem.
Is it possible to add new custom features such as the one that I need?
If yes, how?
I have atached an image to give a clear ideia of what I need.
I´ll apretiate any help.
Thanks
Attachments:
LV Custom.jpg ‏40 KB

No, you can't modify the cursors with either the native or C code. But I'm wondering if you can't get what you want with an XY graph instead of a regular graph. You can have multiple separate plots and some of them can be thick horizontal lines. I've attached a file with just some constants wired to an XY graph to show what I mean. Obviously, you'd have to calculate the values for the x and y arrays in your real situation. If you have to use a regular graph to display the .wav file, you could also overlay a transparent XY Graph on top. The other possiblity is to use a picture control to display your data. There's a couple of shipping examples (i.e. Waveform and XY Plots, XY Multi Plot) that show how data can be represented and Pen Attributes and Sub setting shows how you can draw lines of different widths.
Attachments:
Horizontal Bars.vi ‏30 KB

How to force waveform graph cursors to show Y value on more than one plot?

Hello
Is it possible to show more than one Y value on waveform graph cursors?
Thanks in advance.
Pawel

Hi Dennis
That is correct, on graph woth multiple plots I want to display multiple Y values of plots at the same X value.
I know I can use property node to access cursor list etc. and this is how I have done it, but my question was rather if it is possible to force the cursor legend to display more than one Y value (as a native display). As a default it displays one value and you can choose which plot you want to stick to, but it would be a great feature to have possibility to expand cursor legend to display more than one value.
The question has nice consequences. If it was possible, you could use a property node to export image of the graph, control sizes, or even simple "copy" data from the popup menu. Otherwise we need to "artificially" glue the exter
nal controls displaying Y values if we want to export pictures, etc.
But since you did not answer that I supose it is not possible, as I thought.
thanks anyways.
kind regards
Pawel

I would like to see the time in a waveform graph (real-time)

i need the x-axis of the waveform graph to show real time (from the computer clock). I have made a program with all the example. He read and log data when the chosen time has elapsed. the program work's well...but i dont't know why the x-axis blink every time he draw a point
i can see two x-axis in the same time.
i give you a picture of one of a part of my program, i hope someone can help me
Attachments:
my_software.JPG ‏128 KB

Hi,
I tried to reproduce what you were getting by building a simple VI but I havent had much luck (I have attached the VI).
Could you post your code so that I can take a look at it?
Feroz P
National Instruments
Attachments:
Graph.vi ‏39 KB

Transition measurement vi cursors displayed in waveform graph are moving outside of scale

Using a waveform graph to display pressure over time. I wanted to be able to calculate the fall time of the pressure over time so I'm using the Transition Measurement vi. I copied exactly what was in the example for transition measurement inside help and it is correctly determining the falling transition time but I am having a problem with the cursors on the waveform graph. I should be seeing a set of green vertical cursors marking out the fall start time and fall end time like in the picture I've attached (capture2) like in the example. The problem is they both always start at 3.43 (capture1) and after each sample period they increment by one (4.34, 5.34, 6.34) The come right out of the bundle from the transition measurement output as those numbers. The period of the signal I'm interested in is always less than 2 seconds, so I never see the vertical cursors.
I've tried substituting my daq signal with a sine wave generator and it does the same thing.
The block diagram is in the first capture
also I would be interested in finding out exactly how the numbers wired to the active cursor property of the property node for a waveform graph relate back to the actual cursors on the graph. Are they just automatically numbered starting with 0 from the top-down?
Wayland
Solved!
Go to Solution.
Attachments:
Capture.PNG ‏44 KB
Capture1.PNG ‏7 KB
Capture2.PNG ‏29 KB

Hi Wayland,
The reason the cursors are always apparent in the example VI for the Transition Measurement.vi, is because the signal being generated is always resetting. So, the signal resets to a 'new' signal for the cursors to go over and therefore always remain in the somewhat same location. The Waveform Graph is also configured in such a way that it will not move or continue to show new data coming in, the data cursors have moved onto. So in your case, you will want to right click the graph and make sure "Ignore Time Stamp" is not checked/selected. This will make it so the graph keeps up with your incoming data and the cursors. You can check this in the example file by removing the True Constant going to the waveform generator and changing the time stamp option previously mentioned.
In order to view the available cursors and their numbered position, you can right click on the Waveform Graph and select properties. In the properties window there is a Cursors tab, inside this tab at the top is a drop down menu that lists all of available cursors, indexed starting with 0 at the top.
-Jake B.

How do I change the data used by a Waveform graph dependent upon which tab window is active?

Hi,
First I want to say thank you in advanced!! Let me describe the situation a little bit. My front panel VI (see attachment) has a tab control and on each tab window I have an intensity chart with a free-drag cursor. Below the tab control window I am trying to display either the row or the column of data where the cursor is located, I can do this for each intensity chart individually. I am trying to clean the block diagram up a little bit and instead of using 4 Waveform Graphs, I want to use only one, can the data that is displayed in the wave form graph is associated with which page is active on the Tab Control. Can this be done? And how can I do it?
Thank you again,
~Daniel DeWitte
Solved!
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Attachments:
Changing Waveform graph data.JPG ‏123 KB

Simply wire the tab terminal to a case structure that switches the data going to the graph terminal
(sorry,posting by phone, cannot look at your code...)
LabVIEW Champion . Do more with less code and in less time .

Picture Control to Waveform Graph

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