Archive for the ‘Computing’ Category

Be A Mind Blower

Imagine this: you’re blowing imaginary soap bubbles, smoothly … Now there’s a twist: it’s not your yoga class, and instead of bubbles, you’re moving virtual digital objects. In other words, you’re scrolling, zooming, panning, moving, setting volume levels, skipping tracks… and so on.From anywhere you happen to be in the world, judge others’ ideas and win a Motorola Droid™ Smartphone or a Samsung Go™ Netbook. You will select the most mind blowing ideas in the fields of gaming, PCs, phones, assistive (tech for a better access to computers), music, etc.
This is today made possible thanks to a beautifully intuitive and intelligent sensor developed by Zyxio be embedded in a million things, from the boom of your gaming headset to the collar of your snowboard jacket, as well as Bluetooth® accessories and more.

Now what do I need from you? well this:

STEP 1: Sign up there please.

STEP 2: Now and enter your sign up details (if you aint logged in already)

STEP 3: search by: ‘MB Field of Interest’ and selectMultimodal, Virtual Reality’ in the box.

STEP 4: Find the username ‘philmetz’ in that column and click on philmetz, The click RATE THIS CONCEPT and give me 5 stars.

STEP 5: Vote for me again as you got 2 votes each day, now repeat this every day for 37 days, dont be lazy

NOTE: When you vote you enter the chance to win a Samsung Go Netbook or Motorola Droid Smartphone. Keep it up!


Data Compression

Todays world is an on line world. Those on line seek to share their experiences with others via images and videos. But this would all not be possible if it wasn’t for the data compression techniques. The reasons for this compression arise from the fact that there are transmission bandwidth limitations in place in order to give everyone fair access to the World Wide Web. Web administrators also look to cut as many costs as possible such as storage capacity in order to hold more for less.

So how do we compress data then? Well the aim is to obtain a more efficient representation of the image while preserving the essential information  contained in the data. This is done by using clever information about how we perceive our environment. In images, not all the information is needed to represent it on a computer screen. This is due to the fact that the human eye is less sensitive to fine color detail than it is to fine brightness details due to the densities of receptors in the eye. The human eye is also good at seeing small differences in brightness over large areas but not exact strengths of high frequency brightness variations. This all simply means that the eye does not see all the colors in the environment and is also more sensitive to different brightness variations. Therefore by removing duplicate and redundant information, we can compress an image or video. However audio is a little more difficult due to the fact that our ears have a far more dynamic range of sounds than the eye has to pictures.

There are two main types of compression being Lossless and Lossy. Lossless compression retains more data at the expensive to lower compression. It also offers the advantage that the image can be encoded/decoded without loss of information. Lossy on the other hand provides higher compression ratios though poorer image quality. Despite the loss of information, the lossy algorithms can encode and decode images without any “visual” difference (for the human eye) from the original image.

To compress data, there are 5 main algorithms that exist. These being Run Length Encoding, Chain Coding, Vector Quantization, Arithmetic Coding, Predictive Coding. I shall not go into how each of these work, but if any of you need an explanation, leave a comment and ill be happy to explain it to you.
In terms of compression, the choice of algorithm depends on 3 factors: compression efficiency, compression complexity and the distortion.

Image Compression
A picture is worth a thousand words. But without compression techniques, how would we display the trillions of images on the WWW today.
JPEG (Joint Photographic Expert Group) is the most popular image compression technique designed for gray scale and full color images of natural world scenes due to the fact more data can be removed and can be either simple or progressive for web pages. JPEG uses a lossy compression technique to exploit the known limitations of the human eye as mentioned above. It allows a trade-off between quality and size. The main disadvantage of this algorithm is the fact that repeated compression and decompression results in increased degradation. Gray scale images compress less than that of color images as the human is more sensitive to the brightness variations than to hue variations. Compression ratios of up to 20 to 1 are possible. The algorithm proceeds as follows:

  1. Translate the image into a suitable color
  2. Group the pixel values into 8×8 blocks (experiment prove thats the best section size)
  3. Apply a Discrete Cosine Transformation (DCT) – I assume you know what that is, if not drop me a comment
  4. Divide each block by a separate quantization coefficient based on luminance and round the result to the nearest integer
  5. Next to more encoding using either Huffman or arithmetic coding.
  6. Output the image

Video Compression
MPEG (Moving Pictures Expert Group) is one of the best compression techniques for videos and draws its inspiration from JPEG. It is used to represent video and audio signals exploiting more perceptual redundancies and allows for up to 30 to 1 compression ratios however audio is less due to the fact explained above. The algorithm basically predicts the  motion from frame to frame in the temporal direction, and then uses discrete cosine transforms to organize the redundancy in the spatial directions.

  1. Convert the image to YUV space
  2. Apply the discrete cosine transforms (DCTs) to 8×8 blocks and use the luminance channel to predict the motion
  3. Quantize the DCT coefficients
  4. Encode the DCT coefficients + parameters using Huffman/arithmetic coding

There are many other compression techniques out there but I prefer to narrow it down to the mainstream techniques. For any other questions or more information related to this topic, please do not hesitate to drop us a comment.

    The World of Biometrics



    For more than 4000 years, man has devised the means for securing important objects. Way back in the 1400 BC, the Egyptians devised a simple yet effective lock and key mechanism to protect the Pharaohs from grave robbers. Not only were the tombs secure, but traps were devised which would fill a room with sand if incorrectly unlocked. Now in the 21 century we still search for the strongest protection means possible – with biometrics being the key (pardon the pun) for the 21st century.

    So what is biometrics? Well it is the automated use of physiological or behavioral characteristics to determine or verify identities (from Biometrics, 1999). It can be used for many applications from simple door locks to access control to a computer.
    The traditional authentication methods were the use of passwords and lock-key mechanics. Yet these methods without luck can be easily cracked using simple brute force. However biometric data cannot be guessed or stolen in the same fashion that passwords and locks can. They can be broken under certain conditions though BUT today’s technology is highly unlikely to be fooled by a picture of a face, an impression of a fingerprint or a recording of a voice. Though biometrics seems like the solution to all our problems, it may not be for all applications based on factors such as cost, risk and privacy. What biometrics does is bring the greatly simplified authentication process  and in most cases, increased accountability, and the fact that they are next to impossible to be forgotten or fooled.

    So let us know move on to describing the main types of system that have been developed. These systems are based on behavior and physiological characteristics and are almost always done automatically by computers due to the increased processing speed. In this article I shall separated biometrics into 7 types those being:

    finger-scan                retina-scan
    facial-scan                voice-scan
    hand-scan                 signature scan

    There are 2 main goals in biometrics, that being to identify (The computer finds the identity of a person without that person first claiming an identity) and to verify (The computer verifies a given identity that the person claims to be) and are used to restrict access to either physical or logical access.

    So how does biometrics work? Well to put it simply, the user first creates a template which is stored in a database. The next time the user tries to access the system, the new template is compared to the stored one and accessed granted if the score is within a confidence method as the data will never completely match again. When the user submits some biometric information such as a finger print, it is not usually stored as an image due to the size, think about it – over 10 million finger prints would require a tremendous amount of space, but as a template with features such as curves extracted out. This storage of data has some people worried however what they have to understand is that it would cost enormously to save all the raw data in its current form. Templates are small files that have distinct characteristics for each user.

    Finger Scan
    Finger scans are probably the most common form of biometric authentication. Police stations all over the word use it to identify criminals, a reason why some people refuse to use it under normal circumstances – they see themselves like criminals. The basic process is as follows:
    > Image Acquisition – The finger print is acquired by some sort of device such as chip based cameras or ultra sonic imaging. Hight resolutions are needed in order to see the detail clearly.
    > Image Processing – The captured finger print is then converted to black and white to simplify the process and are thinned as much as possible to bring out the features clearly. Image processing such as erosion can be used. After this a template is extracted with swirls, loops and ridge endings all being stored.
    > Template Processing – The template(s) are processed to store the correct information.
    Many finger print technology now checks for blood flow so that an intruder cannot just cut off someones finger. The popular discovery channel show, Mythbusters, have shown that these systems can be fooled with simple cut outs of photocopied fingers and molds by simply licking the mold which inhibits an electric charge.

    The advantages of finger scans are the facts that it can be used in a wide range of environments with already existing proven technology that is easy to use and cost effective. However there are a small percentage of users that would have trouble using the system (EG: The Polynesians are known to have feint finger prints). Accuracy may also decrease over time.

    Facial Scan
    Facial scanning technology extracts features from a users face such as distance between eye sockets and the placement of these features. Nose shape and cheekbone structure can also be used. But using the mouth as a feature is not usually done due to the fact that growing a beard can affect the accuracy. There are several different approaches to face recognition which I will not all go into. One example is the Eigen Faces in which information is broken into principal components that are used to derive the template used for matching. The general algorithm used is to first train the system using a variety of poses of a person. Eigen vectors are then determined. The recognition stage involves calculating the distance between features for example and storing them in a template.

    The advantages of facial recognition is that existing image capture technology can be used and no physical contact is needed. However there are numerous problems with this system in the fact that the environment can deeply affect the accuracy due to changes in lighting among others.  Also as one ages these features can become less distinguished.

    Iris Scan
    The iris scan is one of the most accurate and secure systems around. The processing done involves finding the iris’ outer edge and then finding the inner edge of the iris. It performs by dividing the iris into a number segments and a      count is kept of the frequency of the features as well as their position. The process though can be difficult if one has very dark eyes which makes feature extraction difficult. With the outer and inner parts determined, the system them extracts features such as color tones.

    The advantages of this system is that it provides a high level of accuracy and is generally stable over long periods. However due to hardware costs this option may not be viable to everyone. This is due to the complex image capturing devices and algorithms.

    Retina Scan
    Retina scans are even more secure than iris scans as it involves features within the user’s eye such as blood vessels. But due to the complex task of mapping the blood vessels, specialized equipment is needed making this option again complicated.

    The advantages are the high accuracy and stable physiological trait. However as the equipment is specialized it is expensive and the user may be discomforted due to the eye technology.

    So what method is right for you? well that all depends on what you are protecting. If you a protecting a computer lab of US$200,000 worth of equipment then a US$1 million dollar retina scan system may not be what you are looking for. Selecting the right system depends on your needs. There are many examples of these system in operation today from banks in Puerto Rico using finger prints for authorization, to cameras in casinos protecting their interests by recognizing frequent gamblers. One thing is for sure, biometrics is here now and is here to stay.


    Googles search for a beautiful mind

    Googel-job-codeBack in September, Google had started putting up banners around the MIT campus, and for some reason in the gym also, with the phrase “If you figure this out, you may have a future with Google”, following by a seemly rather random sequence of numbers and letters: 8MLDQ6 T UI 6TFML RH AA NRA6Q 8EFL DMQ86II2 O3 2S5J 13JXOJ (see diagram to the right). If they crack the code, which is a fairly simple substitution cipher (or not), it reveals a phone number where they can leave their contact information.

    The solution, which now I will reveal, is as follows:
    In a nutshell, the sequence is a substitution cipher that you get by writing out 0-9 then A-Z, then using the keyword “JOBS” to shift the letters.
    What you have to note about the sequence is that the last 13 characters were not present in the beginning set and that spaces do not matter. Another thing you may notice is the two I’s just before the number 2. This could possible be LL as in LL in caLL.

    This said could then mean that 8 is C and 6 is A. Using this knowledge and substituting into the sequence you get the following:


    An avid eye could see the word ‘congratulations’ (note the atula). Further substituting this would solve it as follows:

    So what have we got so far?
    I=L, 8=C, 6=A, M=O, L=N, D=G, Q=R, T=T, U=U, F=I, R=S

    Further substitutions would produce the following (with spaces included):

    Again you can see a possible word in ‘searching’ and so substitution gives:

    I=L, 8=C, 6=A, M=O, L=N, D=G, Q=R, T=T, U=U, F=I, R=S, A=E, E=H, H=K, N=P

    we’re almost there just for what is almost certainly the number. Let us first list out the alphabet and numbers and see what we have determined:

    ______A_C_E__GHI_KL__NOP___RS_TU______ (Notice a pattern anyone?)

    So fill in the gaps, but be aware it does not follow the exact alphabet as you will notice:

    (This is more of a guess which leaves the letters B, J, O, S, can anyone spell JOBS :P, and the number’s 0-5)

    Seeing JOBS was the key because that changed the order of 0123 to 2013 (based on the positions of BJOS) producing:


    Finally the shift (of 4) is performed with the final substitution cipher being :


    From there on the solution to Googles puzzle is (drum roll....):
    “Congratulations Keep Searching or Call 617-639-0570 x10” with the X probably meaning extension.