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Domain: iatia.com.au

Stories and comments across the archive that link to iatia.com.au.

Comments · 6

  1. Quantitative Phase Imaging by JudgeSlash · · Score: 0 · on Airport Screeners could see X-rated X-rays

    I can't wait until it's combined with this tech from Iatia http://www.iatia.com.au/investors/press/2004-09-23 .asp

    The last one viewing reality in the visible spectrum is a loser!

  2. Re:Unused links on how it works - some detail by mikael · · Score: 1 · on Camera that Sees through Smoke and Fog Underway

    Is anybody able to dumb-it-down by about 7 notches so I can understand it :p

    I'll have a go :)

    A 1D FFT is used to convert a set of data values into a series of sine waves, which when added together, form the original set of data. The input is an 1D array of values. The output is a 1D array of complex numbers (real and imaginary planes), which represent wavelengths from The phase is the starting angle of the sine wave, and can be calculated from taking the inverse-tangent (atan2) of the real and imaginary amplitudes. If there are N samples, then the frequencies range from 0 to N/2 (Nyquist information theory). DC=0 is used to represent a signal with no known wavelength ie. a constant value.

    The 2D FFT is used to convert an image into its component sine waves. Similar to the 1D FFT, the input is a 2D grid of values, and the output is a 2D grid of complex numbers. Each grid cell represents the amplitude and phase of a sine-wave travelling in the direction of that point to the centre of the grid. For visualisation purposes, the output of the 2D FFT is rearranged so that the low frequencies are at the centre of the grid (width/2,height/2). The Inverse-FFT is the reverse of this process. Using the FFT in this way, various image process techniques can be applied. By removing (masking out) various circular rings of the image, high, low and medium pass filters can be applied; a high pass filter removes low frequency noise, allowing fine detail to be viewed. A low pass filter removes high frequency noise (useful for removing banding caused during scanning newspaper photographs).

    While ordinary cameras only take an image at the focal point of the lens, this camera takes two additional images slightly in front of, and behind the focal point (+/- 5 microns). Applying the FFT/Inverse FFT allows for the phase information to be calculated for any image. The image processing flow-chart gives an idea of what is going on.

    There are three input images I-5, I0 and I+5, whic are the distances from the focal point. For maximum accuracy, the difference between image I-5 and I+5 are calculated, and scaled. This is converted into frequency space by a Forward-FFT, masked by precalculated filters (high pass filter to remove low-frequencies and make fine detail visible) and Inverse FFT. The resulting image is divided by the normal image, and the low-frequencies are removed again.

  3. Re:Dense Camera Arrays for seeing through bushes by ajna · · Score: 3, Interesting · on Camera that Sees through Smoke and Fog Underway

    You've basically said what I wrote elsewhere in this article's comments. We both agree that it would have limited utility for real life applications (as in not in fields where confocal microscopy gets people hot and bothered) in as many words.

    Incidentally the IATIA link itself held the answer to my above musings, about what the transport equation actually is. I still don't understand it, but it can be viewed by one and all at the bottom of this page: http://www.iatia.com.au/technology/insideQpi.asp

  4. Blatantly stealing my parent post's material... by Anonymous Coward · · Score: 2, Informative · on Camera that Sees through Smoke and Fog Underway

    ...to make it clickable.

    http://www.iatia.com.au/technology/insideQpi.asp


    http://www.iatia.com.au/technology/applicationNote s.asp

  5. Blatantly stealing my parent post's material... by Anonymous Coward · · Score: 2, Informative · on Camera that Sees through Smoke and Fog Underway

    ...to make it clickable.

    http://www.iatia.com.au/technology/insideQpi.asp


    http://www.iatia.com.au/technology/applicationNote s.asp

  6. Keith Nugent by metlin · · Score: 4, Interesting · on Camera that Sees through Smoke and Fog Underway

    Hmm, Keith Nugent is fairly well known in some niche areas of optics. If I remember right, his initial work on the use of x-rays and the like to compensate for normal visible hindrances were met with some opposition, but he is quite famous otherwise.

    That was because, ironically, this was developed as a method to visualize biological stuff, and some felt that his methods would not quite be suitable for such a task. His ideas were to use various parameters such as phase, intensity and angle of vision to extract information which could be correlated and converge to recreate images with minimal amount of information, which later gained acceptance.

    I guess he developed on that technique, and later on evolved to have the military to take notice. Interesting neverthless.