PureViewOptimization & Evaluation

Techniques in Image Processing

Puru AgrawalCSE – 4TH Sem

SSIPMT - Raipur

What is a Pixel…??

It is the smallest controllable element of a picture represented

on the screen.

Pixels

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How a pixel saves information…??

Single Pixel Combination of Pixels

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Image Sensors

• An image sensor is a device that converts an optical image into an electronic signal.• Measured in number of

pixels.• Size determines the

amount of light falling on it.

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Megapixel

• A megapixel (MP or Mpix) is one million pixels.• Number of image sensor elements

of digital cameras.• Example, a camera that makes a 2048 ×

1536 pixel image is commonly said to have "3.2 megapixels“.

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Myth

• More Megapixels results in better imagesReality- Megapixel increases image size

and not quality.

• More Megapixels better focus.Reality- Focus depends on optical parts of

camera and not on sensors.

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Problems with existing digital cameras

• Poor low light performance.• Loss in quality at

digital zooming.• Low image quality.

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PureView Technology

• Developed by NOKIA inspired by the imagery system used in satellites.

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PureView

Super High Resolution

Image Sensor (41 Mpix)

Techniques like Pixel

Oversampling and

Interpolation

Good Optics and Image Processor

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High resolution image sensors

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High resolution image sensors

Mobile Phones

Digital Cameras

PureView Sensors

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Pixel Oversampling

Sampling means how many pixels are used to produce a details. Thus oversampling means combining several pixels to form one super pixel.

• Possible only when using a large image sensor.• It eliminates noise from images.• Better zooming.• Better low light pictures and videos.• Combines 7 pixels to 1 super pixel.

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Pixel Oversampling

Without Oversampling With Oversampling13

Zoom to Oversampling output graph

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Interpolation

Interpolation works by using known data to estimate values at unknown points.

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Image interpolation works in two directions, and tries to achieve a best approximation of a pixel's color and intensity based on the values at surrounding pixels. The following example illustrates how resizing / enlargement works:

Interpolation

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Zooming

Digital zoom is a method of decreasing (narrowing) the apparent angle of view of a digital photographic or video image.

Zooming in PureView

Due to large image sensors zooming results in use of only a part of the image sensor. Thus providing lossless zoom.

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Examples of PureView

Nokia 808 PureView

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Nokia Lumia 92020

Future

• PureView uses big image processors. With advancement in processors this technology will also develop.• Better Optics smaller in size will add to its utility.• Even larger image sensors will add to better

working of techniques like Pixel Oversampling and interpolation.

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Thank you…