Scaling a JPEG with ZoomFactor Property

[Doug M]

Hi everyone,

I would like to know how big of a problem this scaling issue is in LabVIEW 8.2.  There was previously a bug with colors when using a zoom factor of less than 1, but that should be fixed in LabVIEW 8.2.

If the community feels the scaling is a problem, I'd like to create a report for R&D on the issue -- the attached VI is my interpretation of what is involved.  Could someone post some high rez images of before and after scaling in LabVIEW 8.2 versus some other utility?

[zou]

tst,

It seems your zoom.llb doesn't support zoom factor < 1

George

[tst]

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@zou wrote:

tst,

It seems your zoom.llb doesn't support zoom factor < 1

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That's because it was only a very quick proof of concept which was only meant to zoom in. The actual resizing VI supports this, so the slide and the input in the Get Rect VI just needs to be changed to a DBL representation for this to work.

Doug, your VI was not attached.

[Doug M]

Sorry about that!

[tpascaru]

If the community feels the scaling is a problem, I'd like to create a report for R&D on the issue -- the attached VI is my interpretation of what is involved.  Could someone post some high rez images of before and after scaling in LabVIEW 8.2 versus some other utility?

Hello -- I'll repost how Labview mucked the image up, as well as the original. Unfortunately, I have not installed LV 8.20, and am still using LV 8.0.1, so I cannot check out your example.

It would be great if this could get fixed.

Cheers

-Ted

[altenbach]

Hey, I recognice that place! Even found it on Google Earth 🙂

(See hermosa.png)

Anyway, looks pretty good in 8.20. Agreed? (nothing fancy, just the property node):

Message Edited by altenbach on 02-27-2007 02:29 PM

[tpascaru]

OK, I guess it's time to upgrade. Thanks for the info! -- Enjoy browsing Hermosa: you'll find more volleyball courts on the beach than anywhere else.

[zou]

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@tst wrote:

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@zou wrote:

tst,

It seems your zoom.llb doesn't support zoom factor < 1

---

That's because it was only a very quick proof of concept which was only meant to zoom in. The actual resizing VI supports this, so the slide and the input in the Get Rect VI just needs to be changed to a DBL representation for this to work.

Doug, your VI was not attached.

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The quality isn't impressive through.

I guess you get what you pay for. 😉

Doug's VI seems working.

George

Message Edited by zou on 02-27-2007 04:53 PM

[tst]

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zou wrote:

The quality isn't impressive through.

I guess you get what you pay for. ;)

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Can't argue on that. The VI doesn't do any interpolation - it just takes some of the rows and columns (if zooming in) or duplicates some of them (if zooming out).

It usually looks relatively reasonable on images, but in a case like you showed, with straight, thin lines, you sometimes lose some of the information.

I'm not sure about this, but I've seen similar behaviour when Internet Explorer, so it might use a similar algorithm.

[Doug M]

Hi everyone,


Are we on the same page that scaling seems to be decent in 8.2?  I went ahead and did a couple simple tests (disclaimer I know very little about image manipulation).  I took the following test image from a website and scaled it in LabVIEW, MS Paint, and The GIMP to 50% to see if there was noticeable image degradation.

Message Edited by Doug M on 02-28-2007 08:17 AM

Message Edited by Doug M on 02-28-2007 08:18 AM