Tag Archive: Photography


Beyond MegaPixels – Its Femto-Photography!!!

Femto-photography is a term describing ultra high speed imaging. Femto-photography of macroscopic objects was first done by a team at the MIT Media Lab lead by Ramesh Raskar. Before that the term has at least been used for certain proposed experimental procedures in experimental nuclear physics.

In their publications Raskar’s team claims to be able to capture exposures so short that light only traverses 0.6 mm (Equal to only a few picoseconds, or thousands of femtoseconds) during one exposure by combining available high end research equipment and sophisticated sampling algorithms. Raskar presented his team’s feat during TEDGlobal 2012, reaching a wider audience through viral video.

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Gigapixel Camera

Researchers are developing cameras that can take digital snapshots made up of more than a billion pixels….

LAYERED LENS: To take a gigapixel image, which contains more than 1,000 times the amount of information as a megapixel image, in one snapshot requires a special setup. Here, Columbia University researchers propose a ball-shaped lens, half of which is covered by secondary relay lenses, to capture the entire image with minimal distortion.

 

Advances in technology tend to spoil us. PCs just a few years old have nothing on today’s smart phones, and, whereas megapixel images were once the state of the art in digital photography, gigapixel images (composed of at least one billion pixels, or picture elements) are beginning to show up on the Web in vivid detail.

Gigapixel images also hold tremendous potential for providing law enforcement and the military with detailed reconnaissance and surveillance information. Long-distance images taken today by satellites or unmanned aerial vehicles (UAVs) can capture detail down to a license plate number while flying at altitudes too high for these drones to be spotted from the ground. But these images provide only a narrow view, says Ravi Athale, a consultant to the Defense Advanced Research Projects Agency (DARPA) and a senior principal scientist at MITRE Corp. in McLean, Va. He likens UAV images to seeing a battlefield or city through a “soda straw” and satellite images to an injection needle.

 

Through its Advanced Wide Field of View Architectures for Image Reconstruction and Exploitation program, DARPA has for the past year been working on ways to develop a camera that can take a gigapixel-quality image in a single snapshot. This approach is novel, given that today’s gigapixel images actually consist of several megapixel-sized images pieced together digitally to provide a high level of detail over a large area. This is often done using a long-lens digital single-lens reflex (SLR) camera placed atop a motorized mount. Software controls the movement of the camera, which captures a mosaic of hundreds or even thousands of images that, when placed together, create a single, high-resolution scene that maintains its clarity even when the viewer zooms in on a specific area. DARPA plans to invest $25 million over a three-and-a-half-year period in its  program, which includes a component called Maximally scalable Optical Sensor Array Imaging with Computation (MOSAIC).

The single-snapshot approach to gigapixel digital photography has its drawbacks. The equipment is bulky, expensive and complicated. In addition, because it may take several minutes or even hours for the automated camera to shoot all of the individual images required to create the larger mosaic, lighting conditions may change and objects (cars, people, aircraft, etc.) can move into and out of the frames. And stitching together the individual images requires software that must match overlapping points—any errors must be corrected manually.

How it works?

These systems (and those like them) work quite simply in concept, but are actually quite complex. What happens is you need to mount the compact (point and shoot) camera inside the camera system. Then, simply put the camera in the position you want (mounted or sitting on the ground, etc) and you set up your shot. Remember that when you do this it is going to be a huge image, so make sure you place the camera to capture a great surrounding that adds to your image and doesn’t detract.
Once you have the camera set up you let the machine go to work, It will take photos as it rotates through a system and course and actually moves the camera into different positions and takes the photographs. Finally after the image is saved and captured you move to the computer to start editing the huge file together. Make sure you have some processing power, as this will produce 200+ images, and my MacBook Pro with 512mb video/4gb RAM gets killed with a 10 image photoshop file.

Gigapixel images allow you to capture amazing details inside an image. This allows you to zoom in and out using software online to view the picture as a whole, or the intimate details of the work. This creates a level of interaction with your images, something that is often lost online. The user can manipulate the image and create a larger or smaller image cropped to their liking to enjoy.

 

Why not use a digital camera?

Modern frame-exposure professional digital cameras have spatial resolutions ranging of 4-16 megapixels in “35mm D-SLR” formats and up to 22 megapixels for medium format backs. Using such cameras to create gigapixel images requires mosaicing hundreds of individual exposures. Alternatively, strip-sensors can be used to scan the image plane over a few seconds time. Even so, however, large format scanning backs have final image resolutions 1-2 decades below our gigapixel regime and require relatively static scenes, as does the mosaic approach, and are thus generally inappropriate for photos of traffic, people, water, and events. The single-exposure advantage is pronounced in images with crowds of people. The facial expressions of an half a stadium of fans can be captured at passport resolution in a single instant as they react to events on the field.
Using proven techniques allows artists to recreate this effect in many amazing places, from President Obama’s inauguration to the Rocky Mountains, allows for some amazing work to wow you and captivate your imagination.

 

Posted by

Hari Hara Sravan ( MGIT ECE 2ndYear)

Taking a Picture using Gestures

TAKING a photo using a camera timer is fraught with problems – not least making sure you are all in shot before the timer runs out. Gesture recognition algorithms could solve this, by allowing people to control a camera remotely, using only a wave of a hand.

Shaowe Chu at the University of Tsukuba in Japan has developed a digital camera whose software lets the photographer pan or tilt the frame before taking the shot.

The system only works with cameras equipped with viewfinders that can be flipped round to face the front, or those that have a viewfinder on the front and the back. This lets the user see the frame and control virtual buttons that appear on screen by moving their hand over where they appear in the frame.

One, which Chu calls the “hover button”, operates the shutter. When a hand within the viewfinder’s frame points a finger at this floating icon and stays on it for 1 second, the camera initiates a short countdown sequence before the shot is taken.

Panning and tilting is achieved by sliding a finger up and down, left and right, over a cross-hair icon displayed on the viewfinder’s screen, which is picked up and acted on by an algorithm that detects movement.

 

The system, due to be presented in July at the Human-Computer Interaction conference in Orlando, Florida, is still just a prototype and so uses a motorised digital camera to pan and tilt, but this would be easy to achieve digitally on a simpler camera, Chu says. The camera spots hands using an algorithm that detects skin tone, with fingers identified by a separate algorithm that analyses shape.

It’s a novel application for hand gesture recognition, says Chris Melhuish of the computer vision group at the University of Bristol, UK. But, he adds, “things like changing light levels can make it extremely difficult for a single camera system to be reliable”. Chu admits that lighting conditions have an effect, and says the system works best indoors.

The other problem is that Chu only tested the camera from a distance of 2 metres. Any further away and it might become difficult to see what’s going on in the viewfinder. To get round this, he is working on a feature that would activate the shutter with a head nod from any distance, allowing those all-important group shots.

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Hari Hara Sravan ( MGIT ECE 2nd year)

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About Cameras….

In olden days, whenever people used to go to hillside, they used to carry a camera with me and used to take extra film rolls.

As they are not very professional photographer’s, whenever they had to take photos, they used to take 2 photos so that they could get the photo positively.

Now with new digital camera technology, they don’t have to take 2 photographs. He can just check the photo on LCD and decide whether to keep it or delete it. If he delete’s it, he can take new photo. This saves a lot of time and anxiety, With new cool digital camera technology.

Digital camera is a camera without film. The basic principle is the same. It has lens, flash and shutter. However there are no mechanical moving parts. The advanced model has LCD screen which displays the photo. If you don’t like the photo, simply delete it and click it again. That’s the beauty of digital camera technology. There is no film hence no processing and development.

How Camera Focus Works

We’ve seen that a real image is formed by light moving through a convex lens. The nature of this real image varies depending on how the light travels through the lens. This light path depends on two major factors:

  • The angle of the light beam’s entry into the lens
  • The structure of the lens

The angle of light entry changes when you move the object closer or farther away from the lens. You can see this in the diagram below. The light beams from the pencil point enter the lens at a sharper angle when the pencil is closer to the lens and a more obtuse angle when the pencil is farther away. But overall, the lens only bends the light b­eam to a certain total degree, no matter how it enters. Consequently, light beams that enter at a sharper angle will exit at a more obtuse angle, and vice versa. The total “bending angle” at any particular point on the lens remains constant.

As you can see, light beams from a closer point converge farther away from the lens than light beams from a point that’s farther away. In other words, the real image of a closer object forms farther away from the lens than the real image from a more distant object.

You can observe this phenomenon with a simple experiment. Light a candle in the dark, and hold a magnifying glass between it and the wall. You will see an upside down image of the candle on the wall. If the real image of the candle does not fall directly on the wall, it will appear somewhat blurry. The light beams from a particular point don’t quite converge at this point. To focus the image, move the magnifying glass closer or farther away from the candle.

This is what you’re doing when you turn the lens of a camera to focus it — you’re moving it closer or farther away from the film surface. As you move the lens, you can line up the focused real image of an object so it falls directly on the film surface.

You now know that at any one point, a lens bends light beams to a certain total degree, no matter the light beam’s angle of entry. This total “bending angle” is determined by the structure of the lens.

Digital Technology in Cameras

The film in analog camera is replaced by CCD (Charge Coupled Device) or CMOS chip. Whenever you take a photo, based on the light, color and intensity, charge is developed on CCD. This charge is converted into digital information with the help of analog to digital converter. This digital data is ultimately converted into image format by onboard computer chip.

Understand what happens when you take a photograph. When you take a photograph, light enters through aperture through a series of lenses and falls on CCD. The charge generated in CCD is proportional to light falling on it.

As the light intensity increases, the CCD charge also increases. This signal is converted from analog to digital data. The digital data is stored in an on-board memory buffer and then converted into jpeg format by on board computer chip. Then it is transferred to flash memory. You can later watch the photograph as it is stored in flash memory.

Difference between CCD and CMOS:

There are 2 types of sensors inside the digital camera, CCD & CMOS.

  • The CCD sensors are more accurate and generate high-quality, low-noise images. However CMOS sensors are generally more prone to noise.
  • Due to large number of transistors present in CMOS, the light sensitivity of CMOS chip is lower than CCD sensor. Each pixel is divided into transistors and photo-diodes.
  • The CCD sensor system is more mature and is proven over the period.
  • CMOS sensors require very less power compared to CCD. The CCD sensor system requires 100 times more power than CMOS sensor system.Resolution:Resolution is the amount of detail a digital camera can display in a photograph. It is generally measured in pixels. That means the digital camera with more number of pixels is capable of showing more details in an image. If price is no constraint, go for the highest resolution.

    Some typical resolutions include:

    • 256×256 – If you want cheapest digital camera, then you should select this low resolution. But you will not get very high quality due to low number of pixels.
    • 640×480 – If you want to send the pictures thro’ Internet this is the ideal resolution as the image size is low with this resolution.
    • 1216×912 – With this starts the mega pixel series. Here you get more than 1 million pixels. The printed pictures will also look sharp.
    • 1600×1200 – If you want more than 2 million pixels, you should go for 1600×1200 resolution.
    • 2240×1680 – For more than 4 million pixels, you should select this resolution. This is high end digital camera. You can print large size photo directly with this resolution.

    Higher resolutions in the range of 10 million and more pixels are available in the market. But as resolution increases, price also increases.

Latest Cameras in town

KODAK EASYSHARE SPORT Camera

KODAK EASYSHARE TOUCH Camera

COOL PIX.P500COOL PIX.P300Source :howstuffworks , http://www.build-your-own-cheap-computer.com

Posted by

Mahesh ( MGIT ECE 3rd year)

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