Has anyone used the IMAQ Vision for Image Quality Testing?

[SunshineDesign]

Has anyone used IMAQ Vision for any Image Quality Testing? If so what tests did you use?

[GuenterMueller]

Not really. A couple of years ago I was involved in a test system that acquired a sequence of about 3000 frames from a DVD player that was playing a special test DVD. Analogue signals were acquired and for each frame a color histogram was calculated and compared to a "master record". The test system was able to identify frame drops and problems in the cabling (and other issues which I do not remember ...)

[invancea]

NI Vision offers Structural Similarity (SSIM) index for image quality testing. SSIM evaluates characteristics that are perceptible to the human eye.

Please follow the link for more information.

http://zone.ni.com/reference/en-XX/help/370281P-01/imaqvision/imaq_ssim/

[SunshineDesign]

Thanks Invancea, I looked it over, but it is not adiquite to the Image Qualtiy testing I need. If you Wikipedia for Image Quality, they actually have a nice write up of some of the considerations for Image Quality factors, when they are not blacked out like today. Some of the tests listed are Sharpness, Noise, Dynamic Range, Tone reproduction, Contrast, Color Accuracy, Distortion, Vignetting, Exposure accuracy, Lateral Chromatic Aberration, Lens Flare, Color Moire, Artifacts. I am not seeing any Image Quality tests available in the library. I think NI missed the mark with IMAQ Vision and it needs some upgrade and improvements in the offereing of functions. I find the examples are fairly weak as well and need some updating to more and better examples. Thanks for the input though.

[Andrey_Dmitriev]

When you talking about Quality Tests described in Wiki, then in most cases you talking about "subjective" tests. But for measuring Image Quality you need "Objective" criterias, which can be measured. Only then you can decide - is you qualiy good or not.

In most cases for measurement you have to use special Targets, something like that, for example:

In additional you need described algorithms - how to measure it. The rest is fair simply - in most cases analysis of the gray values, line profiles, etc.

The processing will depend from the used Target (and there different Targets available for such test)- as result here no "universal" solution.

[SunshineDesign]

Andrey,

You are correct on the tests beingmostly subjective. But like Voice Quality testing with a MOS (Mean Opinion Score) you can rate the voice or image quality and provide some degree of objectivity to the process.

Thru image analysis some "measure" of image quality can be derived. I am aware and familar with image test patterns and I am presently using the NI-IMAQ to create some functions to test the image quality. My question was has anyone else done the Image Quality test development, so I can gleen some basis and advice to work from or collaberate with. I have already created a function to select a region of interest and get the pixels from the area and their color quanta and average them for the region for an average white balance for that region. I also used edge detection on the image to llok for an analysis of focus. I also did a SNR and a hole detection functions to look at the image S/N ratio and the hgole detection of a white field and a dark field to look for bits stuck on or off. I also found an Imatest Master program to help with some of the other tests. These tests took a bit to figure out the tools in IMAQ, but once I figured things out, now it's not too bad to create new functions for image analysis.

So does anyone have functuions they created for Image Quality Testing they are willing to discuss and or share?

[Wee-Bey]

In addition to IMAQ (which is primarily designed for acquisition), the Vision Development Module gives you a lot of power to analyze images. This link shows many of the image processing VIs it provides. It sounds like you might already be using this though to build your algorithms.

[SunshineDesign]

Thanks Ravi, but these are not truely Image Quality analysis modules. There are few modules in the list that can be considered real Image Quality analysis modules. Do a Wikipedia search on "Image Quality" or google Imatest for their Imatest Master product to see what some real Image Quality tests are. What NI has in the Vision Library do not constitute Image Quality analysis. I hope NI consideres adding some Image Quality testing modules, as the IMAQ and NI-Visoin development module are not sufficient for this task.

[Wee-Bey]

Yes, this is true SunshineDesign; image processing techniques provide only a step towards image quality analysis. To clarify, I meant that with the image processing tools that are provided, you can build your own image quality metrics, aside from SSIM, which is now included. Since one's metrics for the quality of an image depend highly on context, the functions provided including histograms, frequency content, and wavelet information can help someone assess the quality of an image based on their specific needs. It sounds like you're already doing this, and want more. If you would like to see a more blackboxed / higher level of processing and analysis provided, you can certainly submit this to our Idea Exchange.

🙂

[SunshineDesign]

Thanks Ravi, yes I would like to see more functions directed for Image Quality testing. I'll submit to the Idea Exchange.