Thursday, October 30, 2014

Understanding the process of Image Segmentation

Image segmentation is the process in which we do portioning of digital image into multiple segments. We convert the image information into more meaningful and easy to analyze data.  Segmentation is not so easy in image processing and it is still in research.

In image segmentation we extract the information from the image. We use segmentation in object detection and feature extraction, in this we firstly do the edge segmentation. 

Edge segmentation is the process in which when the intensity changes abruptly it can create edges in an image. Second we use segmentation by Thresholding, in thresholding process we use grey scale image and composed dark intensity image on light background.

Image segmentation

Thresholding is the way to separate out your information from image and it easy to analyze. We use histogram, histogram is the technique improving the contrast of an image for thresholding. 

It is the common step of image processing when we are going to do recognition, object detection, region estimation, feature extraction.

Whenever we do segmentation our goal is to extract the information clearly because we want the information easy to analyse and understand.

Author - Rahul Bhardwaj
(Research Associate at Silicon Mentor)

Friday, October 24, 2014

Data Compression : What Makes Data Compression Possible

Data compression is referred as the process to reduce the size of data required to represent certain amount of information. Data and information are not the similar. Data refers to the way by which the information is conveyed. Various amounts of data can symbolize the same amount of information. Every so often the given data contains some data which has no relevant information, or repeats the identified information. It means there is data redundancy in image.

Data redundancy is the essential concept in image compression and can be mathematically defined.
The relative data redundancy R is: R= 1-1/C
Where C= compression ratio and C= N1/N2
Where N1 is original image size and N is compressed image size.
Ø    In general, three basic redundancies exist in digital images as follows:

Psycho-visual Redundancy: It is a redundancy corresponding to different sensitivities to all image signals by human eyes. Therefore, removing few less vital information in our visual processing might be reasonable. Removing this kind of redundancy is very lossy process and the gone information can't be recovered. To remove such kind of redundancy generally used a method that is called quantization which means the mapping of a range of input values to a limited number of output values..
Inter-pixel Redundancy: This type of redundancy is associated with the inter pixel correlations within an image. Much of the visual contribution of a single pixel is redundant and can be guessed from the values of its neighbors. This type of redundancy can be removed by run-length coding.

Coding Redundancy: The uncompressed image usually is coded with each pixel by a fixed length. For example, an image with 256 gray scales is represented by an array of 8-bit integers. Using variable length code schemes such as Huffman coding and arithmetic coding may produce compression in which shortest code words assign to the most frequent grey levels and longest code words assign to the least frequent grey levels.

Temporal Redundancy: Temporal Redundancy is the redundancy of information which survives among set of frames. Thus it can be referred as inter frame redundancy. In video sequence, the numerical values of the luminance/brightness and chrominance/color of all the pixels in a given frame is either exactly similar or at least near similar to those values in the preceding frames. In simpler words, this redundancy is the ‘repetition of information between frames’. Motion estimation techniques are used to eliminate temporal redundancy.

                                                                         Author - Hemika Yadav
(Research Associate at Silicon Mentor)

Tuesday, October 14, 2014

The Future of Very Large-Scale Integration (Conti…) - Stretchable electronics

Mechanically stretchable electronics are virtually non-existing today. In order to reach the “summum” of comfort, for electronic textiles and biomedical applications, the electronics should be flexible and stretchable to a certain extent, in order to follow all movements and deformations of the body parts onto/into which they are integrated. A stretchable electronic circuit is considered as a number of rigid or flexible component islands which are connected by elastic interconnections (Fig.1). Stretchable interconnections are achieved by embedding meander shaped metal wires in an elastic base material (Fig 2). Stretchabilities of 50% and more using our technologies have been obtained and also the possibility to embed components has been demonstrated (Fig 3). For implants, the stretchable electronics have to be biocompatible. The metal wires and electronic components must be shielded from the biological environment of the body. The BioFlex project focuses on this aspect. Certain applications for monitoring body functions are under development. 

The electronics are embedded in stretchable materials. To create dedicated shapes of these stretchable materials, for each electronic design dedicated moulds are created. Special attention goes out to make the moulded stretchable material bubble free. In places where rigid components are placed, the areas are deliberately made a lot thicker to make it locally less stretchable. (Fig 4). When stretchable electronics have to be worn the whole time, it is important to make them more or less breathable. These electronics will be more comfortable to wear. We try to integrate different kinds of synthetic materials, especially non-wovens, in our designs in combination with our standard stretchable materials. As our technologies are embedded in a layer of stretchable polymers, it is possible to make the circuits watertight. (Fig 5, 6) The idea rose to make the stretchable electronics washable. And so, the sweet-project was born. Washability is important when we want to use our technologies in health care. The electronics have to be sterilized or washed before they can be reused. Also for the textile industry, it is very important to be able to wash the clothes with integrated electronics easily.

   Fig.2 - Meanders in non-stretched state and stretched up to 40%                     

Fig.1- Elastic interconnections connecting flexible component islands             

Fig.3 - Stretchable thermometer demonstrating possibility of embedded components

Fig. 4 - Dedicated mould to obtain dedicated shapes in stretchable materials                 

 Fig. 5 - Stretchable LED-circuit embedded in PDMS