A blog for things that fascinates Siva

Countries' self-image: National pride | The Economist

2009-10-04T13:17:00.000+08:00

Countries' self-image: National pride | The

Interesting ... I knew that Indians were proud about their country but I was surprised to see that their national pride is in top 10 of the 31 countries listed below.

Economisthttp://media.economist.com/images/ga/2009w40/Image.jpg

Photos of Perumal temple in Tirumayam, Pudukottai district, Tamilnadu

2009-09-20T18:03:00.000+08:00

Photos of Perumal temple in Tirumayam, Pudukottai district, Tamilnadu

2009-09-20T17:57:00.000+08:00

These photos are of rock-cut Perumal and Sivan temple in Tirumayam, Pudukottai district, Tamilnadu. This temple was built in 1600's by nayaka kings of the region. The beauty of this temple is that it has both Siva and Vishnu sannathis and it is believed that Sivan temple is older than the Vishnu temple.

Such an ancient treasure has been neglected for long by the government. Though this temple comes under Archaeological Survey of India (ASI), a Government of India body that maintains and protects ancient temples of India, for past 50 years, it has been completely left for ruins.

Recently, ASI has recognised the uniqueness of this temple architecture. This is partly due to pressure on ASI from few well wishers of the temple and part luck. ASI has been spending quite a bit of resources for up-keep of the temple. Tourists from various part of Taminadu are visiting the temple.

Even though we knew this temple, as it is on the way to another temple we regularly visit, we never visited this temple. However, this time while we were driving to visit our regular temple, we were surprised by the activities around the temple. Out of curiosity, we visited this temple. We were supposed to be there only for 30Min's, but we were in the temple for almost 3 hours. I was awe-stuck by the rock carvings and Vishnu statue. I did not have any good camera with me, however I used my mobile phone camera to take few snaps of the temple. I have shared those snaps here.

Photos of Perumal temple in Tirumayam, Pudukottai district, Tamilnadu

2009-09-20T17:47:00.000+08:00

Snaps taken at the private beach of nexus resort, karumbunai

2009-08-30T14:34:00.000+08:00

Limestone hills in Thailand

2009-08-22T08:37:00.000+08:00

These are the pics from Thailand.

SINGTEL ICC INTERNATIONAL ACCESS NUMBERS AND SINGAPORE DIRECT SERVICE (SDS)

2009-08-11T11:08:00.000+08:00

WHEN IN	DIAL ACCESS NO.	FOOTNOTE
Argentina	0800 555 6500	#1
Australia	1800 55 1165
	1800 881 650
	1800 24 87 65
Austria	0800 200 265	#2
Bahrain	8000 0065
Bahrain	10#	#4
Bangladesh	1570 650	#5
Belgium	0800 1 0065	#23
Brazil	0800 890 6512	#23
Brunei	80 0065	#23, #26
Cambodia	1800 88 1065	#7
Canada	1800 665 6002
China (North -e.g Beijing, Changchun, Shenyang, Tianjin)	10 8650	#8, #23
China (North -e.g Beijing, Changchun, Shenyang, Tianjin)	10800 650 0095	#8, #23
China (South-e.g Shanghai, Guangzhou, Hangzhou, Xiamen)	10 82650	#8, #23
China (South-e.g Shanghai, Guangzhou, Hangzhou, Xiamen)	10800 265 0095	#8, #23
Cyprus	8009 0065	#2
Denmark	800 1 0065	#23, #26
Egypt	365 6065	#9
Finland	0800 110650
France	0800 99 0065
France	0800 908 767
Germany	0800 180 2042	#23, #26
Germany	0800 080 0065	#23, #26
Greece	008 00 6511	#23
Guam	1 888 8650081	#3
Hawaii	1800 865 7464
Hong Kong	800 96 0065
	800 932 650
	800 944 065
	1500 650 6565
India	000 6517	#2, #5, #25
India	000 6588	#14
Indonesia	001 801 65	#5, #23, #26
Iran		#11
Ireland	1 800 55 0065	#23
Israel	180 9494 650
Israel	180 920 6565
Italy	800 172650	#23
Japan	00539 651	#22
	0066 35 651	#22
	0034 811 651	#22
	0066 33 65 5651	#22
Macau	0800 650
Malaysia	1800 800065	#26
Malaysia	1800 18 0065	#26
(Kuala Lumpur )	(03) 780 55 555	#10
Mauritius	01650
Monaco	800 9 00 65
Nepal	0800 77065
Netherlands	0800 022 8865	#23, #26
New Zealand	000 965
New Zealand	0800 600 065
Norway	800 19965	#2
Pakistan	00800 11065	#23
Philippines	10 10 55 6510	#6, #15, #26
	10 10 55 6511	#6, #15, #26
	128 0565	#15, #24, #26
Poland	00 800 651 1165	#2
Portugal	800 800 650	#23
Puerto Rico	1 877 336 6588
Russia	810 800 110 1065	#1, #5, #16, #23
Russia	(495) 747 33 65	#5, #10, #17, #23
San Marino	800 172650
Saudi Arabia	1800 65
South Africa	0800 99 0065
South Korea	00309 65	#18, #22
	0722 650
	00369 650	#26
Spain	900 990 065	#23
Sri Lanka	(011) 2430 800	#10, #19
Sweden	020 799 065	#23
Switzerland	0800 55 52 65	#23, #26
Taiwan	0809 096565	#26
Taiwan	00801 65 6565	#5
Thailand	001 999 65 0000	#5, #26
Thailand	1800 0065 99	#20
Turkey	00 800 65 117
Ukraine	81 0065	#5
United Arab Emirates	0800 1165	#27
UK	0800 89 0065	#1
UK	0500-890-065	#1
USA	1800 937 6588
	1800 800 6500
	1800 822 6588
Vietnam	120 65 0065	#21, #23
Virgin Islands (US)	1 877 336 6589

Ben10 protector of earth

2009-08-10T09:26:00.000+08:00

Snapshots of water bottles that I bought for Meenu and Sundar

2009-08-10T09:22:00.000+08:00

photos of the suite I am staying in

2009-08-10T09:05:00.000+08:00

Snaps taken at bayshore shopping district at glendale milwaukee

2009-08-10T04:47:00.000+08:00

I took few snaps while I was walking around the shopping district.

Snaps taken in milwaukee

2009-08-09T21:03:00.000+08:00

Some of the snaps are taken while landing. The one where you can see me is taken at shores of lake Michigan

blueprintcss - CSS Framework

2008-01-13T19:22:00.000+08:00

blueprintcss - Google Code

BlueprintCSS 101 CCS Layout generation Tutorial

2008-01-13T19:21:00.000+08:00

BlueprintCSS 101 | Blue Flavor

Blueprint Grid CSS Generator

2008-01-13T19:20:00.000+08:00

Blueprint Grid CSS Generator

Online Writing Lab (OWL) by Purdue University

2007-12-09T09:27:00.000+08:00

Welcome to the Purdue University Online Writing Lab (OWL)

Welcome to the Purdue OWL. We offer over 200 free resources including:

* Writing and Teaching Writing
* Research
* Grammar and Mechanics
* Style Guides
* ESL (English as a Second Language)
* Job Search and Professional Writing

Writing lab at Purdue Logo The Writing Lab at Purdue (in-person consultations)

Purdue University students, faculty, and staff at our West Lafayette, IN campus may access this area for information on the award-winning Purdue Writing Lab. This area includes Writing Lab hours, services, and contact information.

Imaging Science Links

2007-11-08T18:58:00.000+08:00

[object HTMLImageElement]

H.264 Codec: Video Compression for Consumer Applications

2007-08-27T17:27:00.000+08:00

Cut and Paste from Embedded.com for my reference

H.264 Codec: Video Compression for Consumer Applications

By Yasuhiro Yamada, Hitoshi Watanabe & Ming Ning Gu

Digital TV Designline

(01/10/07, 09:00:00 AM EST)

A New Video Compression Standard and its Paradigm
As the transition from analog to digital content continues in the AV (audio-visual) world, the number of new consumer devices supporting digital audio and video processing, including TV-sets, DVD players, Digital Still Image Cameras (DSCs), and Digital Video Camcorders (DVCs), continues its rapid climb. Every portable personal device these days seems to include audio-visual features, including mobile phone, portables media players and PDA. In addition, the PC, networking and the broadband technologies are also doing their part to fuel this transition by facilitating the creation, streaming and sharing of content.

The desire to create and share AV content in digital format was one of the key factors contributing to the creation of international compression standards. The MPEG (moving picture expert group) and JPEG (joint photographic expert group) committees created the original standards that allowed the transition from analog AV to digital AV formats, allowing the sharing and transfer of multimedia content via networks or portable storage media (e.g. DVD-disc, SD-card, etc.). However, with the major paradigm shift in the consumer space from content consumption to content creation, there is an increasing need for higher quality content creation, larger volume of content storage, and easier content transmission/sharing.

In typical AV products, the video content consumes most of the processing power, storage space and communication channel bandwidth. MPEG-2 video compression technology was instrumental in the transition from analog to digital video processing. As a result, it became one of the most widely adopted compression standard in the consumer space. H.264 is now poised to replace MPEG-2 as the new compression technology with better quality at lower transmission bitrate and storage requirements. These improvements are critical in cost-sensitive consumer products and especially in portable consumer devices.

The H.264 (also known as MPEG-4-AVC ) standard was completed at the end of 2005 by a joint effort of the ITU-T and the MPEG organizations. This standard greatly improves the MPEG-2 compression ratio in a wide range of applications from small size (mobile AV) to HD (high definition) video. Many applications of H.264 technology have already been launched, including Blu-Ray Disc, HD-DVD, AVCHD-Camcorders (HD-CAM), iTune-video, 1-seg DTV (mobile digital TV in Japan), DVB-H for European handheld DTV, among others. There are two key factors behind the wide adoption of H.264:

H.264 offers between 2-to-1 and 3-to-1 improvement over MPEG-2 in compression ratio, resulting in significant savings in video storage capacity and network bandwidth.

H.264 provides efficient implementation of Internet based application because of its well considered scheme to harmonize with network protocols. Networks are proliferating at home, office and anywhere in between! The bandwidth and quality of service of wired and wireless networks is increasing, and video streaming over these networks is already commonly seen in cable, satellite, IPTV and other applications. The combination of H.264 video compression technology and this ubiquitous broadband network connectivity is fueling an era of mobile digital life style.

All indications are that this era has already begun and is gaining momentum rapidly. The following table of AV products market in Japan supports this view:

Table-1 Consumer AV products market (Japan)

Notes:

Above figures (unit-sales) were derived from JEITA (Japan electronics and information technology industries association) and CIPA (Camera & Imaging Products Association).
Prediction of 2007 is anticipated from monthly figures of 2006.
In Japan, most mobile phones include DSC.
A percentage of 3G mobile phones contain video telephony and its services.
A percentage of the mobile phones are equipped with 1-seg DTV receiver.

The above table highlights the following key points:

Portable consumer device segment (mobile phone, DSC) is a big and growing market.

The evolution of personal portable devices is having a notable change in our life style, in particular the way we communicate.

Beside the changes in the portable market shown in table-1, video in the home is rapidly transitioning towards High Definition (HD) quality. Similarly video in portable devices is moving toward Standard Definition (SD) or VGA quality from QVGA or smaller. There is a very clear trend in consumer AV (audio-visual) world and market where many products are becoming personal mobile devices rather than desk-top and home centric devices.

H.264's advanced algorithms offer higher compression, lower communication channel bandwidth, smaller storage requirements and flexible scheme for AV networking; however, those algorithms also require more processing power to encode and decode the video content. Obviously the first requirement of any mobile device is low power consumption for longer battery life. In the following sections, we would summarize how Qpixel's H.264 compression ICs satisfy the video quality and low power requirements of portable consumer devices.

Technological Summary of H.264 with Comparison to MPEG-2
Background of H.264 standardization
H.264 development was started in 1998 as a long term project of ITU-T, and its target was to achieve half the bit-rate of the H.263 and MPEG-4 standards, for the same perceived video quality. Unlike past video compression standards (MPEG-1/-2/-4, H.261/262/263), the H.264 effort was to improve compression efficiency and not restrict the implementation complexity. This resulted in the current H.264 implementation that requires substantial amount of computational power. The resulting H.264 encoder offers improved features in which the encoder structure and compression profiles are quite different from MPEG-2.

H.264 Encoder Structure

This diagram indicates a generalized hybrid (motion-compensation and transform) H.264 encoder structure which is common to MPEG-2 and H.264 encoders; however the details in each box in the block diagram are different between Codecs. Table-2 shows the differences from MPEG-2 for those items which improve video quality significantly.

Table-2 H.264 Encoder Improvements Versus MPEG-2 Encoder

Table-3 lists the various profiles offered in the H.264 standard, along with a brief description, as well as target applications.

Table-3 H.264 Application Oriented Profiles

The first four profiles (Baseline, Main, Extended, High) are intended for consumer applications, while the following three profiles (High 10, High 4:2:2, High 4:4:4) are intended for non-consumer (professional) applications. There are also "Level" definitions that are similar to MPEG-2. Level-3 is for SD (standard definition: 720x480x30 or 720x576x25), and Level-4 is for HD (high definition: 1920x1080x30 or x25).

Qpixel's Approach and Solution to the AV Market Requirements
Considering the AV market needs and the H.264 technological characteristics, we directed our efforts as follows:

Lowest power Codec (Encoder/Decoder)suitable for use with portable applications.

High quality standard definition video processing (with an eye towards high definition resolutions in the future).

Specialized H.264 Codec algorithm and architecture to meet specific market requirements. More specifically, we selected "Main-profile at Level-3" as the most suitable profile for standard definition applications with very good video quality.

Meeting the Quality Requirement (Algorithmic Efforts)
Using the basic theory of video compression technology suggests the following:

(a) The human psycho-visual system ignores the detail of high-frequency textures.

(b) The resultant bitrate can be reduced by finding the best motion-estimation match among many possible options.

(c) Entropy coding results in the least number of bits without loss of information.

Items (a) and (b) required many algorithmic iterations to find out the best human-eye perception for a given bitrate. Item (c) required an innovative implementation.

In general, the Encoder is required to generate a standard compliant bit-stream, while the video quality and compression efficiency are not specified in the H.264 standard. However, our goal is to achieve high quality at low bit-rate under low-power conditions. These criteria are the focus of our efforts. The following summarize our algorithmic efforts and direction:

Break the highly sequential structure of H.264's syntax chain into a smaller number of syntax elements without sacrificing compression efficiency, thus allowing more parallelism where processing power becomes a bottleneck.

Intelligently pre-select more efficient compression algorithms without sacrificing video quality, thus reducing a required overall processing power.

Implement the bursty and content-dependent characteristics of CABAC in a highly scalable manner, thus rendering CABAC more tractable for hardware implementation.

Implement B pictures in a way which best balances its video quality with implementation costs.

Re-use data effectively to maximize the performance of our video algorithms.

Highly sequential syntax structure with syntax inter-dependency.

Long-term memory allowed among syntax elements.

Our technology comes from a thorough, careful analysis of how each coding tool in the H.264 encoder contributes to the video quality as well as the implementation cost in an ASIC environment. Starting from scratch without any bias from pre-existing coding standards such as MPEG-1/2/4, our technology group focused on the best cost-performance advantage for each block in the H.264 encoder. In addition to the video coding algorithm, a highly intelligent TDM-based scheme was adopted to reduce the amount of data traffic required to handle the large amount of video data, thus further reducing power consumption.

Meeting the Physical Requirements
The following is a summary of the architectural decisions that were made to meet our target the physical requirements:

The Qpixel H.264 video compression IC was designed to target the portable consumer devices market. It is well understood that the H.264 implementation complexity is almost 10 times as much as MPEG2. To achieve high video quality and simultaneously reduce the system power consumption, we produced a flexible architectures that is power conscious using state of the art design techniques to reduce die size and power consumption while efficiently handling data traffic to minimize the inefficient, power consuming interactions with external memory.

The major factor impacting power consumption is the IC clock tree. In order to fully utilize the potential of H.264 encoding tools to achieve high video quality, the clock frequency must be increased to provide more processing power. However running an IC at higher frequencies directly increases dynamic power consumption, so compromises needed to be made in choosing the performance target and power dissipation of the system.

To achieve the highest performance with a given power target, the IC was architected so that external memory stall-cycles were minimized and bus arbitration was optimized to yield high data transfer efficiency.

In light of the above considerations, two innovative schemes were implemented to reduce external memory data transfers. One is a frame mapping scheme and the other is TDM bus arbitration. TDM arbitration is highly optimized for our video processing pipeline and frame mapping is optimized for the highest DRAM bandwidth. The H.264 compression tools are carefully evaluated and selected for the trade off between video quality and the DRAM bandwidth requirements to meet the low power budget.

Conclusion and the Next Steps

Our unique patented and patent-pending video algorithm and architecture made it possible to implement the Qpixel H.264 Main profile codec in a way best suited for video products requiring both low-power and high video quality.

In next generation consumer AV products, there is a need for HD (high definition) resolution and quality. We will continue to apply our innovative algorithmic and architectural techniques to offer highly competitive solutions for HD applications.

References

JVT-N050d1.doc
H.264 / AVC TEXTBOOK, Authored by S. Okubo et al, Impress Limited
Development of Video Coding Technology and Future Prospects, T. Chujo, Toshiba Review Vol.60 No.7, 2005
A Study for Bit-rate Control of H.264/AVC Coding, Y. Akima, Graduate Paper of Waseda University, 2004

About the authors
Mingning Gu received his Masters Degree in Computer Science from University of Wisconsin, Madison. He has over 13 years of experience in designing ASICs for video processing and compression standards such as MPEG1, MPEG2, and H.264. Mr. Gu is currently the Director of Architecture at Qpixel Technology, where he's heading up all architecture design activities. Prior to Qpixel, Mr. Gu was the Manager of the ASIC team at VWeb, working on MPEG2 ICs.

Yasuhiro Yamada received his Masters Degree in Electrical Engineering from Doshisha University, Kyoto, Japan in 1971. He then joined JVC R&D Laboratory, where he spend most of his time managing the digital audio-visual technology research and development. He was an active member of MPEG Committee during MPEG-1 and MPEG-2 standardization. He retired JVC in 2005 and is currently working at Qpixel Technology Inc. for its technology strategy.

Hitoshi Watanabe received his Bachelor of Engineering degree from Department of Applied Physics, University of Tokyo, Tokyo, Japan in 1990. He then moved to Stanford University and received his Ph.D. degree from Department of Applied Physics in 1999. Following the completion of his research at Stanford, he joined the R&D team of Pulsent corp. His contributions include the development of a proprietary codec based on object-based video compression algorithm, aiming at 2x coding advantage over H.264, object-based coding algorithm, image segmentation/object extraction, and video pre/post processing. After Pulsent, Dr. Watanabe joined Qpixel as a founding member and has been leading a team to develop Qpixel's core H.264 encoder algorithm. Dr. Watanabe holds patents for H.264 as well as object-based video compression algorithm.

All of the authors can be reached at kamiri@qpixeltech.com.

Generating a tree view using XSL and XML

2007-08-26T16:58:00.000+08:00

Generating a tree view using XSL and XML

The CImg Library - C Template Image Processing Library

2007-06-22T10:10:00.000+08:00

The CImg Library - C Template Image Processing Library
Need to explore this for Image processing

SVN repository Creation and importing your first project

2007-06-17T21:09:00.000+08:00

How to create a SVN repository and import a project

Published by admin under Uncategorized

If you are new to SVN, it is a source code control(versioning) tool that is intended to replace CVS. CVS stands for Concurrent Versioning system that is very popular in software development world. SVN tries to address the deficiencies of CVS. SVN can be downloaded at this location.

This post assumes that you have already installed SVN in linux. I am showing here how to create a Source Code repository and import your first project.

Let’s do it

First, create the respository

svnadmin create /path/to/repository

for example, if you want to create the source repository in /home/username/source

then, you would issue the following command in Ubuntu.

svn create /home/username/source

The repository can be anywhere as long as you have right permissions to the directories.

Now, to create your project

Go to a tmp directory

cd /tmp

Then create the following

mkdir yourprojectname

cd yourprojectname

mkdir trunk

mkdir tags

mkdir branches

“trunk, tags and branches” are must for any SVN projects.

Then issue the following command

svn import /tmp/yourprojectname file:///home/username/source/yourprojectname -m “My first project “

Now you can delete the structure created at /tmp directory

rm -rf /tmp/yourprojectname

Hope this helps some newbies.

API Dashboard: ProgrammableWeb

2007-06-17T13:24:00.000+08:00

API Dashboard: ProgrammableWeb
This site shows all the webservice API avilable on the net

How to turn on automatic logon in Windows XP

2007-06-04T08:35:00.001+08:00

How to turn on automatic logon in Windows XP

View products that this article applies to.

Article ID	:	315231
Last Review	:	May 7, 2007
Revision	:	4.6

This article was previously published under Q315231

Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 ( http://support.microsoft.com/kb/256986/) Description of the Microsoft Windows Registry

INTRODUCTION

This article describes how to configure Microsoft Windows XP to automate the logon process by storing your password and other pertinent information in the registry database. This feature permits other users to start your computer and to use the account that you establish to automatically log on.

Important If you turn on autologon, using Windows XP becomes more convenient. However, using this feature can pose a security risk.

MORE INFORMATION

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.
If you set a computer for automatic logon, anyone who can physically gain access to the computer can also gain access to everything that is on the computer, including any network or networks that the computer is connected to. Additionally, if you turn on automatic logon, the password is stored in the registry in plain text. The specific registry key that stores this value is remotely readable by the Authenticated Users group. Therefore, only use this setting if the computer is physically secured and if you make sure that users who you do not trust cannot remotely see the registry.

You can use Registry Editor to add your log on information. To do this, follow these steps:

Click Start, click Run, type regedit, and then click OK.

Locate the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon

Using your account name and password, double-click the DefaultUserName entry, type your user name, and then click OK.

Double-click the DefaultPassword entry, type your password under the value data box, and then click OK.

If there is no DefaultPassword value, create the value. To do this, follow these steps:

a.	In Registry Editor, click Edit, click New, and then click String Value.
b.	Type DefaultPassword as the value name, and then press ENTER.
c.	Double-click the newly created key, and then type your password in the Value Data box.

If no DefaultPassword string is specified, Windows XP automatically changes the value of the AutoAdminLogon registry key from 1 (true) to 0 (false) to turn off the AutoAdminLogon feature.

Double-click the AutoAdminLogon entry, type 1 in the Value Data box, and then click OK.

If there is no AutoAdminLogon entry, create the entry. To do this, follow these steps:

a.	In Registry Editor, click Edit, click New, and then click String Value.
b.	Type AutoAdminLogon as the value name, and then press ENTER.
c.	Double-click the newly created key, and then type 1 in the Value Data box.

Quit Registry Editor.

Click Start, click Restart, and then click OK.

After your computer restarts and Windows XP starts, you can log on automatically.

If you want to bypass the automatic logon to log on as a different user, hold down the SHIFT key after you log off or after Windows XP restarts. Note that this procedure applies only to the first logon. To enforce this setting for future logoffs, the administrator must set the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Winlogon

Value:ForceAutoLogon
Type: REG_SZ
Data: 1

You can also use turn on automatic logon without editing the registry in Microsoft Windows XP Home Edition and in Microsoft Windows XP Professional on a computer that is not joined to a domain. To do this, follow these steps:

1.	Click Start, and then click Run.
2.	In the Open box, type control userpasswords2, and then click OK. Note When users try to display help information in the User Accounts window in Windows XP Home Edition, the help information is not displayed. Additionally, users receive the following error message: Cannot find the `Drive`:\Windows\System32\users.hlp Help file. Check to see that the file exists on your hard disk drive. If it does not exist, you must reinstall it.
3.	Clear the "Users must enter a user name and password to use this computer" check box, and then click Apply.
4.	In the Automatically Log On window, type the password in the Password box, and then retype the password in the Confirm Password box.
5.	Click OK to close the Automatically Log On window, and then click OK to close the User Accounts window

Effecient Sorting Algorithm For Applying Median Filter to a Image

2007-05-31T22:14:00.000+08:00

Effecient Sorting Algorithm For Applying Median Filter to a Image

Published by admin under Uncategorized

Normally median filters are applied to remove speckle noises in an Image. There are many variations of Median Filters but all these variations are for choosing the kernel dimensions and shape. What i mean by kernel is that it could be a 3X3 kernel or 5X4 kernel or a radius 3 kernel.

A 3×3 kernal will have 9 elements to sort

A 5X5 kernal will have 25 elements to sort

A radius 3 kernel will have 29 elements to be sorted before you can pick the median.

Bottom line is you choose any variations of kernals, it boils down to effeciency of sorting. I have come up a one such algorithm that i think is very effecient for Median Filtering

Assumptions:

RGB Planar data. The bit depth Per pixel is 8 bits.
Median Filter Kernel size is Odd Number. Like 5, 9, 25 etc
The following code is PseuodCode.

A pseudo Code implementation of the Algorithm is shown below:

Global First_Element

Global Median_Value

Global PointOfInterest

Global Array [ 256 ] /* This assumes a bitDepth of 8. That is a Red Pixel is 8 bits in length.

Int FirstTimeSort ( char * sourceAddr, int NumberOfElementsToBeSorted )

{

int i , j;

// Reset all elements to 0

ZERO( Array)

for ( i = 0; i <>

{

/* The value in the sourceAddr must be between 0 and 255 */

/* We use values in SourceAddr to index into the Bucket. Then we increment to keep track of the repitations of the same number. If any value in sourceAddr is unique, then the Bucket count for that unique will be 1. */

Bucket[ sourceAddr[i] ] = Bucket[ sourceAddr[i] ] + 1 ;

/* At this point the values are sorted */

}

/* Now find the median*/

median = NumberOfElementsToBeSorted/2 +1

for ( i = 0, j=0; i <>= median, i++ )

{

j += Bucket[i];

Median_Value = i;

}

First_Element = sourceAddr[0];

PointOfInterest = sourceAddr[median -1 ]; /* C arrays are 0 indexed. Hence if you want to access the third element, you have to index array[2] */

return Median_Value;

}

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Int SubsequentSort ( char * sourceAddr, int NumberOfElementsToBeSorted )

{

int i , j;

Bucket[First_Element] -= 1;

Bucket[Median_Value] += 1;

Bucket[PointOfInterest ] -= 1;

Bucket[sourceAddr[NumberOfElementsToBeSorted-1]] += 1;

/* At this we have sorted all our values */

/* Now find the median*/

median = NumberOfElementsToBeSorted/2 +1

for ( i = 0, j=0; i <>= median, i++ )

{

j += Bucket[i];

Median_Value = i;

}

First_Element = sourceAddr[0];

PointOfInterest = sourceAddr[median -1 ];

return Median_Value;

}

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

The following code snippet shows how to use the above routines.

int main ()

{

char * source = 0;

char * PointOfInterest = 0;

int KernelSize;

source = SourceOfBuffer /* Point to the source of Buffer that holds the image to which we need to apply median filter */

PointOfInttest = source+2; /* Applying 1 dimensional Median filter. There is no difference for 2 dimensional kernel as well. */

KernelSize = 5; /* So the median will always be he third element of the sorted array */

/* Do a first tme sort */

*PointOfIntrest = FirstTimeSort ( source, KernelSize );

/* Now do subsequent sorts */

PointOfIntrest += 1;

source += 1;

Until ( END OF ( source ) )

{

*PointOfIntrest = SubsequentSort(source, KernelSize );

PointOfIntrest += 1;

source += 1;

}

Simple PHP framework for Build your Websites

2007-05-29T07:44:00.001+08:00

Looks like an simple PHP framework that can be used to Build Frameworks
http://code.google.com/p/simple-php-framework/