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Jaguar and Land Rover Just Created Transparent Pillars For Cars

Arkh89 Not transparent... (191 comments)

Not transparent... but "augmented".
(misleading title, sloppy journalistic work... as always)

5 days ago

Ask Slashdot: Best Software For Image Organization?

Arkh89 Re:By Kids Ages (259 comments)

On a side note : IMO, You should have started indexing your kids at 0...

about a week ago

An Algorithm To Prevent Twitter Hashtag Degeneration

Arkh89 An Algorithm To Prevent Slashdot... (162 comments)

An Algorithm To Prevent Slashdot's Bennett-Haselton-Degeneration...

Yeah, we need one...

about two weeks ago

The Fastest Camera Ever Made Captures 100 Billion Frames Per Second

Arkh89 Re:Yeah, but black and white (122 comments)

They acquire only for a very very short lapse of time (in the order of a ps) and perform compression before the acquisition (compressed-sensing).
They cannot record longer than this because of how slow the sensor in the back of the streak camera is.

about two weeks ago

Single Pixel Camera Takes Images Through Breast Tissue

Arkh89 Re:Single-pixel what? (81 comments)

Ok, let's say that you want to build a 1 "mega-pixel" camera (1000x1000 pixels, for instance). You have the optics but not the sensor array. Instead, you only have a single photo-diode... which is basically a single pixel.

First approach : you decide to scan the image plane with this photo-diode, trading spatial resolution for time. You move the photo-diode to where the first pixel in the top-left corner of the sensor should be, integrate (collect the photons) for some time, then move to the second pixel position. After making 1 million of such movements/integrations, you have fully sampled the image plane and have a complete 1 "mega-pixel" image.
Problem : this is slow as hell, you need to move the photo-diode up to some accuracy, etc.

Second approach : instead of moving the photo-diode you will modulate the incoming signal (photons) and integrate everything to this detector. You take a small video projector and open it to find a component called a DMD which is an array of controllable bistable micro-mirrors. Basically, displaying an image on the video projector is turning this surface as a transmissive gray-scale pattern (note that it is not actually transmitting light, just reflecting). You put it in the image plane (at the position of the sensor array) and you use a lens to focus all of the light coming out of the DMD surface onto the photo-diode.
Now, instead of scanning, you just have to display a pattern consisting of a "black" frame (fully "blocking") except only one "white" pixel ("transparent") and integrate as usual. As you know which patterns was used for each integration and can, as previously, rebuild the image.

Second approach, first improvement : instead of lighting pixel per pixel you can use specific patterns. The basic idea is to integrate photons coming from multiple pixels at the same time and reconstruct with a specific algorithm. The idea is to express the problem as a linear equation A x = y where x is the input image, A is the measurement operator = a matrix representing the system and y is the measured vector. In the previous case, you were measuring pixel per pixel which is equivalent as modelling A as the identity matrix (ones on the main diagonal, zeros everywhere else and so y = x). Imagine now that you use another matrix / another way to combine multiple pixels, such that each row of A is pattern you have to display on the DMD and the matrix row is still square and full-rank (a well defined system). In the end you can still reconstruct x from y with A' y = x (where A' is the inverse of A) and get back your image.
Why would you do this? Well, instead of getting a bunch of photon from a tiny opening you will be measuring many more photons which is a good thing as our real-world detector is noisy. You will thus increase the signal to noise ratio.

Second approach, third improvement : the main problem of the previous system is that, to obtain a 1 mega-pixel image, you still need to do 1 million projections/measurements which is a lot, and makes the whole process slow. But, you know for a fact that images are compressible signals (JPEG is a proof of that) which means that you can represent any 1 mega-pixel image signal into a much smaller vector size. This is because natural images are not random structures and possess some level of coherency = redundancy between pixels. So instead of making as many projection as they are pixels (a square matrix), you will do less, say by a factor between 4 and 10. The matrix A becomes rectangular and you have to use a more complex reconstruction algorithm (non linear, or based on a convex optimization system) which takes into account prior knowledge you would have of natural images (think of it as external constraints that will help you make the system sufficiently well behaved).

This is basically how single-pixel cameras work (with compressive sensing)...

I'll pass for the bonus point.

about three weeks ago

Microsoft Rolls Out Robot Security Guards

Arkh89 Re:Outdoor Roomba + Kinect (140 comments)

When they are released on an intervention, they start flashing their Blue Screen of Death and Red Ring of Death...

about a month ago

Google Announces Image Recognition Advance

Arkh89 "A picture may be worth a thousand words..." (29 comments)

Especially considering a 1 mega-pixels image in 8 bits gray-scale. That's 1 MB worth of information. Considering 8 letters in average per word (including the various punctuation characters) and 250 words per page in whatever-16-bits character encoding, the image weighs the same as a book of 200 pages.

about a month ago

First Demonstration of Artificial Intelligence On a Quantum Computer

Arkh89 Re:Read the Paper, article is exagerating "Quantum (98 comments)

(I can't believe I didn't notice I misspelt Quantum in that subject field.)

If you want to, we have this neat quantum computer which is capable of making the difference between 'n' and 'h'...It might be pricey but it is totally worth it...

about 2 months ago

Microsoft Develops Analog Keyboard For Wearables, Solves Small Display Dilemma

Arkh89 Re:Great "invention" (100 comments)

His smart-watch didn't recognize the characters I presume...

about 2 months ago

Study Weighs In On the Reliability of Eyewitness Testimony

Arkh89 Re:Reader's Digest Version (102 comments)

Do they mean that eyewitnesses should wear glasses?

about 2 months ago

Japan's Shinkansen Bullet Trains Celebrate 50th Anniversary

Arkh89 Re:Possible numberwang (111 comments)

Divide by the number of trains to be operated...

about 3 months ago

Flurry of Scans Hint That Bash Vulnerability Could Already Be In the Wild

Arkh89 Re:"could be worse than Heartbleed" (318 comments)

The system function has thus nothing to do with that, right? The main point here being : start bash with a badly formatted environment variable.
The vulnerability :
env -i VAR='() { echo "Here is a legitimate function content"; }; echo "This is the vulnerability";' bash -c 'echo "Some code which is irrelevant";';

Some C code (gcc -o testCode main.c) :
int main(void)
        printf("This is a Shelllock test\n");
        system("echo \"Hello World\"");
        return 0;

And start it with :
env -i VAR='() { echo "Here is a legitimate function content"; }; echo "This is the vulnerability";' ./testCode

I don't have any vulnerability message appearing here.

about 3 months ago

Flurry of Scans Hint That Bash Vulnerability Could Already Be In the Wild

Arkh89 Re:"could be worse than Heartbleed" (318 comments)

Thanks for the explanation. I also finally got it a few hours ago (I am not a sysadmin or web developer) and I am more concerned about the rogue DHCP requests.

about 3 months ago

Euclideon Teases Photorealistic Voxel-Based Game Engine

Arkh89 So... (134 comments)

They essentially haven't made any progress since when they turned to laser scanning a few years ago.
Oh and no, not really impressive graphics. They're just showing a cloud of points with some color. No dynamic lights and shading, no dynamic geometries/skeletal deformation here...

about 3 months ago

Users Report Warping of Apple's iPhone 6 Plus

Arkh89 Re:front pocket? (421 comments)

As a physicist would tell you : assuming the average person can be replaced by a sphere of 1m radius, the phone, being in the front pocket of the hemispherical pants will bend to their surface, a flex of about 12mm on the side (parabolic approximation of the cap of spherical people, considering a 151.8mm long IPhone 6 Plus).

about 3 months ago

When Scientists Give Up

Arkh89 Re:Stop using tax dollars (348 comments)

for every stupid project they come up with

Do you have any examples for this?
Oh yeah you don't, because there is no such thing...

about 3 months ago

In France, a Second Patient Receives Permanent Artificial Heart

Arkh89 Pardon me but... (183 comments)

If I receive wi-fi enabled organs, will I be required to also get the horrible wi-fi logo tattooed on my forehead?

about 3 months ago

Changing the Rules of a 15-Year-Old Game: Quake Live Update Causes Controversy

Arkh89 Wait... (170 comments)

[OA player here]
They allowed bunny hopping to do the same as strafe-jumping? seriously?
Bye bye defrag...

about 4 months ago

This 'SimCity 4' Region With 107 Million People Took Eight Months of Planning

Arkh89 Did it... (103 comments)

Did it also crashed 107 million times while simulating this city?

about 4 months ago


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