Axes scaling and Intensity Graph

Hello,
I use a Intensity Graph to display measured data. Sometimes the X/Y-axis has to be transformed via the 1/x Operation and some other nonlinear transformations. Now I don't know how to let the Intensity Graph display the data correctly.
E.g. I use a normal X/Y Graph. After the 1/x operation the space between the data points are not equidistant anymore. This probably works because the XY-Graph needs the X AND Y Axis.
How can I do this with the Intensity Graph? Is there a simple solution or do I have to use the "picture" or somehting else?

Greetings!
You might need to use the arbitrary marker spacing. (click on the legend and look at the options) YOu can then assign a new color to each increment you select. You can also play around with the gradients, (color interpretation) but I suggest you only do that after you have your markers where you want them. I'm sure you can get nice results with the intensity graph.
Eric
Eric P. Nichols
P.O. Box 56235
North Pole, AK 99705

Similar Messages

Most efficient way to extract the amplitude of a signal and display on an intensity graph

Hi All,
I am having difficulty to display the amplitude of an voltage signal (voltage picked up by NI DAQ card).
what I am trying: Voltage signal (Dynamic data type)--> 2D array of dynamic data type (using 2 nested for loops) --> normal 2D array with scalar values --> intensity graph
I have difficulty to convert the dynamic 2D array to scalar 2D arry.
I only want to extract the amplitude of the imcoming signal.. any body can give some advice? thanks in advance..
Charlie

Hi Hillary,
Thanks for your reply.
Yes, I did tried to use Amplitude and Levels Express vi, it should be the one I am looking for, but I found it not work in my case, I need to put the value of amplitudes into a 2D array.
If I use Amplitude and Levels Express vi, it will give me a 3D array, I have found the solution, just convert the dynamic data to single scalar. (see pic attached)
Anybody can help me to solve the following 2 problems:
1. The speed of this program is too low, i think ii due to the DAQ assistant in the 2 for loops (for creating 2D array), it should be able to re-write using DAQmx (as "centerbolt" told me), I am working on this now, if anybody can help, I will appreciate that.
2. Is there any other way to creat the 2D array (for purpose of increasing speed also).
Thanks,
Charlie

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

Fix axes in intensity graph with cursor

Hi all,
I try to use the intensity graph as an xy-input device. The user should be allowed to drag the cursor to enter the value. However, the user can always move the cursor outside the plot area, which causes the corresponding axis to rescale. I want to have strictly fixed upper and lower limits. Is there any way to achieve this? One possible solution would be to reset the min/max values every time the cursor was moved (and coerce the cursor position back into the range). A simpler approach would be appreciated!
Regards,
Matthias

> I try to use the intensity graph as an xy-input device. The user
> should be allowed to drag the cursor to enter the value. However, the
> user can always move the cursor outside the plot area, which causes
> the corresponding axis to rescale. I want to have strictly fixed upper
> and lower limits. Is there any way to achieve this? One possible
> solution would be to reset the min/max values every time the cursor
> was moved (and coerce the cursor position back into the range). A
> simpler approach would be appreciated!
>
You don't say what version of LV you are using, but if it is relatively
recent, right click on the graph and go to Advanced and uncheck the
option to have Cursors Scroll Graph. The user can still drag and
release the cursor und
er the edge of the graph, but this will not change
the scales. You can pretty easily filter cursor points that are out of
range and even write back to the cursor value if you need to. I believe
that if there is data in the plot and the cursor is set to lock to the
plot, then it cannot be dragged outside the data either, and that is
another solution.
Greg McKaskle

MATLAB pcolor and LABVIEW Intensity Graph

Hello all
I have a data matrix which i want to plot using intensity graph of LABVIEW. My problem is that when i plot this matrix using MATLAB pcolor along with "shading interp" command, i got a very fine and smooth coloring graph of this matrix, however, using LABVIEW Intensity graph along with getcolor vi, i was not able to get a smooth coloring graph comparable to MATLAB pcolor. I have tried many setting but results were not satisfactory
Is this due to a limitation of LABVIEW intensity graph or i am missing something? Kindly help me
Best Regards
Asim

Thanks for providing that Asim, unfortunately the VI you provided is unusable as-is. There is a subVI missing, and while not critical, it's difficult to tell how you're setting up the intensity graph without that VI. Additionally, it doesn't appear that there is any graph data included in the VI you provided and a third-party software license would be required to use this VI. Could you upload the data you're handling in a format that works without any external tools?
As for thoughts on the differences in the plots; they are largely similar in appearance, although it does appear that you're using a different color scale in LabVIEW- the majority of your scale is in the blue-green range, rather than continuing linearly through yellow, orange, and red. You're going to lose a lot of visual resolution in the ranges you're highlighting due to this. The plot you're trying to achieve also appears to be interpolated or blurred around the edges of bins, are you actually plotting data between integers on the x-axis, or is this an artefact introduced by the software?
Regards,
Tom L.

I want to select a specific rectangular position from intensity graph to extract the x and y values

I want to select specfic rectangular postion from an intensity graph to extract the X and Y values at that specific position.
Is this possible using LabVIEW?
@nk

Hi nk,
Is this possible using LabVIEW?
Yes.
I want to select specfic rectangular postion from an intensity graph to extract the X and Y values at that specific position.
Just select the positions! What's your problem in doing so?
Btw. when you select positions you already know their XY values!? I don't get the point of your task...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

Recording Zoom factor and Pan position for intensity graph (LV8.2/8.5)

I'm using the zoom and pan features on the graph palette. I need a way to determine the zoom factor and pan position so as to reapply these to another intensity graph. Any way to do this?
Thanks,
Don

Can't you just copy over the Xscale.range.min|max and yscale.range.max|min?
LabVIEW Champion . Do more with less code and in less time .

Intensity graph and its "interpolate color" option

Dear Devs,
using LV2013.02f, my intensity graph never redraws correctly (it remains black), after I uncheck and check the "interpolate color" option in the right-click menu for the z-axis. Is this reproducible for anybody, please?
Note: There are more situations when the intensity graph remains black after changing some options, but I could not reproduce them systematically. Any ideas what to use instead of it to display 2D arrays of values?
Cheers,

Dear users,
dear GerdW
Related issue:
Intensity graph displays a black z-axis color bar
The issue(s) are connected to the positions of the markers on the color bar. I converted the VI to a 2010version (again, wrapped in a 7-Zip archive), I hope that helps for now.
Now, when I multiply my 2D array with a suitable high- and at the same time low-enough value (multiplier=1E+34) -- 1E+33 is too low, 1E+35 is already too high; then the markers of the color bar are visible suddenly. The "interpolate color" and the blackness of the graph can be now manipulated and adjusted.
So now, I have to remember that the default markers' positions are (0,50,100) and there is no way to change them before I extend the values of my array over this region suitably. Seriously, I went through all the right-click on the z-axis menu items and executed them one-by-one. None of those brought the z-axis color bar or the colors back into the graph again.
Q: How should a novice know about it? Isn't there a "reset all markers, distribute them equally and show all values in the default spectrum color" button somewhere, and did I missed it?!
Cheers,
Attachments:
2013-11-27 0946 buggy intensity graph.7z ‏133 KB

Scaling intensity graph Z-ramp with panel - how?

In LV7.1.1 is there any way to get the color ramp associated with an intensity graph to scale with changes in the VI panel size?
I've tried telling VI to scale the intensity graph indicator with the panel and that didn't work nor did telling it to scale all front-panel objects with the panel. The ramp always retains its original size.

I think you are stuck.
As for most of the controls, there is no way to change the size programmatically.
The only thing you could do as work around is to create a picture control (which size can be changed...) to mimick the graph scale...
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

Cursor Misalignment in Intensity Graph (LV6.1)

Howdy.
I have an Intensity Graph, with a 2D array of data (about 300x300) and a cursor. The cursor is locked to the plot, which for intensity graphs, means that the cursor is drawn at the lower left corner of the pixel that is being addressed.
Most of the time this works fine. However, sometimes, the cursor is drawn as being located at one pixel, but the values reported for the cursor are in fact a neighbor (usually the one to the right). The zoom level of the graph is such that a given pixel is larger than a screen pixel (about 3-5 times), so I wouldn't think that it was an aliasing problem, but the problem does go away if I zoom in a little further.
Has anyone else seen this? Does anyone have a fix?

I don't have a repeatable set of conditions that lead to this problem, so I don't have a demo vi that exhibits it.
As to unlocking the cursor, I think that in an intensity plot that is more confusing; the location and value reported for a cursor position are shifted half a pixel down and half left with respect to the way the plot is filled in. In other words, say we have a 10x10 plot shown in 100x100 pixel window. Each intensity value is 10 pixels wide. The axis values line up on the boundaries of these pixels. When the cursor is within half a unit (5 pixels) of the crossing point of these axes, that is, near the intersection of boundaries of four adjacent pixels, the value reported is the pixel location and value in the upper right of these four pixels. This means that with an unlocked cursor, I can be positioning it over (visually) the lower left pixel, but selecting the upper right. In fact 3/4 of any given pixel's visual representation is actually going to select some other pixel. So I've locked the cursor to remove that uncertainty; now it is supposed to be always in the lower left corner of the pixel selected.

Intensity Graph control using VC++ 6.0?

LabView supports an "Intensity Graph" control. Is there a way to accomplish the same thing with CNiGraph, CWGraph or CNiGraph3D?

Thank you for you answer. It was very helpful. One thing missing is the "intensity slider" that is part of the LabView control. It allows the user to adjust the image display. The other problem I have is that the 3D graph axes labelling always looks big and clunky no matter what I use for font type/size. What I am trying to emulate is shown in the attachment. Basically I am translating some LabView code into C++.
Attachments:
Image1.bmp ‏203 KB

Intensity graph Z cursor value

Greetings!
I am creating a scanning XY stage program using an intensity graph. I have a cursor to drag around that moves the XY stepper motor stages; zooms, adjusts Z colors & "contrast", etc. I have the data showing up fine.
However I can't figure out how to get the Z value (so I don't have to show the big cursor legend). As you know in the cursor legend as you move a cursor the X Y and Z values are shown.
Can't find a property node for the Z value... This must be simple
Thanks!
Steve
Solved!
Go to Solution.

Unless you use custom axis offsets and increments, it is just the value of the 2D array and the indices of the cursor positions, so index array should get what you want. If you use custom axis scaling, you need to apply the linear transform between cursor x, y values and corresponding array indices.
In a better world, the cursor index property should give both indices of the 2D array and the method would directly work also for cases where the axis scaling is custom. This is the reason for my old idea here, so please vote for it!
LabVIEW Champion . Do more with less code and in less time .

Image processing from .txt file onto an intensity graph

I am doing a mini project in my class and I was wondering if anyone could help me. It about image processing but I am bit stuck.
Heres the idea:
"An image is really nothing more than a 2D array of data. The value of every element in the array corresponds to the brightness of the image at that point.
In this project you will create a VI which loads a 2D array of data and then displays it on the screen using the Intensity Graph. Three example files (boats.txt, gordon.txt and parrot.txt) are available on the module webpage that you can use. However, you can also use any other black and white image you like, but will need to convert it to a “text image” first. To do this you can use some software called “ImageJ” which is available on the computers and is free to download.
You can vary the brightness of an image by adding the same value to every element in the array.
The contrast of an image is adjusted by multiplying every element in the array by the same value. Using numerical controls and simple array mathematics, you should adjust the brightness and contrast of your displayed image.
Some other ideas that you could try with image manipulation are:
o Invert an image (change black to white and white to black)"
First I am having problems putting my picture onto the graph. It is in the write file but the colours are not correct and the image has rotated 90 degrees. I will upload my VI so far when I get back onto my computer.
Would really appricate the help! Thank you for reading

Hi charlthedancer,
Here is an example to get you started.
Kind regards,
GajanS
Attachments:
Test.vi ‏14 KB

Programmatically disabling/enabling cursor in intensity graph

Hello all,
I am building a LV interface (LV2011) for a stepper XY stage. The system "scans" a surface, displaying it on the graph. I set up to cursors to zoom into a region of interest (ROI). Pressing a button resizes the scales to the ROI (zooming in on the area). Sections of code move the XY stage, and read a device. When done I want to zoom into a ROI and use a THIRD cursor to manually move the XY stage. I have this working with TWO graphs, based on the "region of interest.vi" I found in the dev zone.
What I would like to do is have a boolean toggle controlling ONE GRAPH between setting min/max (cursors 0 and 1) and manual stepper position (cursor 2). If cursor 2 is visible I want cursors 0 & 1 not showing and visa versa. Can I do this?
I attached the example - bascially what I did was add a cursor to the 2nd graph, grabbing the XY vales and sending to the stepper controllers. Works great! I am trying to "combine the two" by resizing the orig graph with a button click (works fine) and then click another button to show the XY stage cursor (and hiding the min/max cursors) - thats the brick wall
On a seond note - controlling a XY stage using the intensity graph's cursor is really nice; however it would be great if I can control the cursor similar to a slider's "coerce" - has anyone done this? I assume I have to write a routine in the event that performs some modulo function. Just curious!
Thanks,
Steve
Solved!
Go to Solution.
Attachments:
roi.llb ‏40 KB

Your exmaple works perfect. Howver I am having probs with Val(sngl) on the XY graph. On the example you gave, lets say I move the cursor with the mouse - event fires, everyone is happy. If I move the cursor with CODE - nada. I even read the "Value" of the graph and wrote it to "Val(sngl)" to try to fire the event. How does one force a trigger on an XY chart when you move a cursor (say cursor idx2) using code?
Better yet - why when I read the Val and write to Val(sngl) does the event not fire??? I have been searching for a basic XY table with sensor -type project but havent found one yet. Everyting works great - draginng the cursor moves the XY stage. Now I need to do the auto-scan part Use code to place the cursor - trigger the even that moves the stage.
Thanks
Steve
Attachments:
XY_Stage_Rev8.vi ‏53 KB

Change colors of individual pixels on intensity graph?

I would like to be able to change the color of a set of individual pixels within an intensity graph, to blue for example, while leaving the color table otherwise as is, for example, gray scale. The change to blue would be based on location, not on current gray value. I think I can accomplish this using the mask fx with picture controls, and then convert to intensity graph. Is there a more direct way? A good example to demonstrate this capability would be just using a 'mouse down' event on an intensity graph to change the color at the mouse location. Any thoughts are appreciated.
Sincerely,
Don

Yes, seems to work fine .
If you have LabVIEW 8.0, there is another possibility. There is a new property that allows drawing any pictures or picture elements on your graph area. Of course you could draw individual pixels, but nothing prevents you from e.g. drawing circles, squares, odd shaped areas, arrows or event text. ... Anything you could do with a plain picture indicator. One example that ships with LabVIEW 8.0 is Envelope.vi, see image.
Message Edited by altenbach on 06-12-2006 07:31 PM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
envelope.png ‏32 KB

Axes scaling and Intensity Graph

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