Sep 26 2013

Wild monitor lizard on the way Kuantan in Malasiya

Published by under general

We saw a huge monitor lizard while We were on our way to Kuantan in Malaysia . It was heavily raining and the monitor lizard was trying to cross the road.

Wild Monitor Lizard

Wild Monitor Lizard

 

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Sep 23 2013

SQL designer to design and normalize relational database table

Published by under general

I happen to bounce on a web based SQL Designer. The tool is hosted at GAE SQL Designer. Using this tool I was able to create relational database tables and normalize it. As this is
Visual design, I was able to visualize the table relationship and normalize it much more easily. The other benefit of this tool is that it allows you to create SQL statements for various databases. It also allows to export in XML.

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Aug 25 2013

Installing ubuntu from USB stick on a Via EPIA M System

Published by under general

I recently purchased a VIA EPIA M 10000 motherboard and a micro-ATX case to build my home server. There was not a CD drive and hence the installation of OS was not straight forward.

I wanted to install Ubuntu 8.10 ( Interpid Ibex) on this system and I had to install from a USB stick. Instalation from USB stick is not straight forward either. Hence, I thought of sharing how I installed the OS. Please follow the steps below:

My System Configuration

Via EPIA M 1000 motherboard ,1 GHz Fan cooled x386 Processor

160 GB harddisk and 512 MB PC3200 RAM

  1. Get a USB thumdrive with atleast 1 GB freespace.
  2. Format the drive using Windos Format tool
  3. Download syslinux . Syslinux utility is avilable for both Linux and WIndows. I downloaded Windows version. Follow this link to learn more about SysLinux. Syslinux is used to install the bootloader on the USB Drive
  4. Insert the thumbdrive into your Windows machine and open a command window
  5. Execute  syslinux.exe -m -a -d e: ( Here e: is assumed to be the Drive letter for the USB thumbdrive. ). After this command, you should see syslinux.cfg in the root dir of the thumdrive.
  6. Download Ubuntu 8.04 ISO image to your local drive. ( Please note, the kernel is  i386 compatible for these set of processors. I know for sure Ubuntu 8.04 and below are i383 compatible. VIA EPIA M 10000 instruction sets are not fully i686 compatible. So any OS kernel that is compiled for i686 instruction set will not boot on these systems. I learnt it the hardway. Ubuntu 8.10 did not work for me. Whenever I try to boot, the bootloader threw a warning ” ……”)
  7. Using “Winrar” extract the ISO image on to your harddisk. This is needed to copy some files into the USB thumbdrive.
  8. Download initrd.gz and vmlinuz files  for Ubuntu 8.04 ( Hardy ) from this link. These files are required for installing from USB Thumbdrive.
  9. Copy the following into USB thumdrive root folder
    1. copy the contents of isolinux into the root dir of USB thumbdrive. (To be unambigious:  isolinux is a folder you get when you extract the 8.04 iso image  )
    2. create a directory named “install” and copy “initrd.gz” and “vmlinuz”  into this folder.
    3. copy the whole 8.04 iso image into the USB thumdrive. ( To be unambiguous: You need to copy the whole ISO image and NOT the extracted files )
  10. Rename isolinux.cfg to syslinux.cfg
  11. Power your EPIA M based system  and hold the DEL key to enter the bootloader menu.
  12. In the “Advanced” option select the boot drive to be USB Drive
  13. Then plug in your USB thumbdrive and restart the system
  14. Ubuntu install screen will be presented and follow the instructions to complete Ubuntu 8.04 Instalation

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Dec 23 2010

RF Power Conversion Table from dBm to mWatts

Published by under general

dBm = log10 (mW)*10
mW =10^(dBm/10)

40 dBm 10.00 watts
36 dBm 4.00 watts { Maximum ERP allowed by FCC in U.S.
30 dBm 1.00 watts
27 dBm 500 milliwatts
26 dBm 400 milliwatts
25 dBm 320 milliwatts
24 dBm 250 milliwatts
23 dBm 200 milliwatts { Typical output from WLAN devices at 915MHz
22 dBm 160 milliwatts
21 dBm 130 milliwatts
20 dBm 100 milliwatts { Maximum ERP allowed by E.T.S.I. In Europe
15 dBm 32 milliwatts
10 dBm 10 milliwatts
5 dBm 3.2 milliwatts
4 dBm 2.5 milliwatts
3 dBm 2.0 milliwatts
2 dBm 1.6 milliwatts
1 dBm 1.3 milliwatts
0 dBm 1.0 milliwatts
1- dBm 0.79 milliwatts
5- dBm 0.32 milliwatts
10- dBm 0.1 milliwatts
20- dBm 0.01 milliwatts
30- dBm 0.001 milliwatts
40- dBm 0.0001 milliwatts
50- dBm 0.00001 milliwatts
60- dBm 0.000001 milliwatts
70- dBm 0.0000001 milliwatts
80- dBm 0.00000001 milliwatts {Receive threshold for most WLAN devices

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Jun 09 2010

GLOSSARY OF BOTANICAL, ENGLISH AND TAMIL NAMES OF CERTAIN CROPS

Published by under general

Government of Tamil Nadu

Department of Economics and Statistics

Season and Crop Report 2005-06

GLOSSARY OF BOTANICAL, ENGLISH AND TAMIL NAMES OF CERTAIN CROPS

BOTANICAL ENGLISH TAMIL jäœ
1. Oryza Sativa Paddy Nel beš
2. Sorghum Vulgare Cholam Cholam nrhs«
3. Pennisetm typhoideum Bulrush / Spiked Millet Cumbu f«ò
4. Eleusine cora cana Ragi Kelvaragu / Ragi Keppai nfœtuF
5. Satariaitalica Italian Millet Thinai Âid
6. Paspalum Scrobiculatum Kodo Millet Varagu tuF
7. Panicum Milliare Samai Samai rhik
8. Panicum Miliaceum Common Millet Panivaragu / Kaadaikanni gåtuF
9. Panicum crasgalliver-Frumenta-cum Sanwa Millet Kudiraivaali FÂiuthè
10.Zeamays Maize Makka Cholam / Thullukka Cholam k¡fh¢nrhs«
11.Triticum spp Wheat Godumai nfhJik
12.Hordeum Vulgare Barley Barley gh®è
13.Phaseolus Mungo Greengram Pacchapayaru g¢ir¥gaW
14.Gajanus indicus Redgram Tuvarai Jtiu
15.Phascolus radiatus Blackgram Ulundu cSªJ
16.Cicer arietinum Bengalgram Kadalai fliy
17.Dolichos lab lab Field bean Mochai bkh¢ir
18.Phaseolusa conitifolius Dewgram Naripayaru / Kallupayaru / Tullikkapayaru eç¥gaW
19.Vigna Cating Cowpea Karamani / Tattapayaru fhuhkâ
20.Capsicum annum Chillies Milagai äsfhŒ
21.Coriandrurm sativum Coriander Kothamalli bfh¤jkšè
22.Peper nigrum Pepper Milagu äsF
23.Curcuma longa Turmeric Manjal kŠrŸ
24.Allium sativum Garlic Vellaippoondu ó©L
25.Zingileer Offenale Ginger Inji ÏŠÁ
26.Carum copticum Omum / Bnishoop’s weed Omum Xk«
27.Saccharum officinarum Sugarcane Karumbu fU«ò
28.Mangifera Indica Mango Maa kh
29.Musa sapientum Plantain Vazhai thiH
30.Allium cepa Onion Vengaayam bt§fha«
31.Solanumtuberosum Potato Urulaikkizhangu cUis¡»H§F
BOTANICAL ENGLISH TAMIL jäœ
32.Arachis hypogea Groundnut Verkkadalai / Nilakkadalai ãy¡fliy
33.Seasamum indicum Gingelly Ell
34.Ricinus Communis Castor Amanakku / Kottaimuthu Mkz¡F
35.Cocos nucifera Coconut Thengaai nj§fhŒ
36.Linum usitatissimum Linseed Alivira Më éij
37.Braesicea spp Rapeseed and Mustard Kadugu fLF
38.Guizotia abyssinica Nigerseed Peyell / uchchel ngbaŸ
39.Carthmaus tincorius Safflower Kusumbavrai FR«gtiu
40.Gyossium spp Cotton Paruthi gU¤Â
41.Crotolaria juncca Sunhemp Sanappu rz¥ò
42.Hibiscus Cannabins Bombay hemp / Himlipatam Jute Pulichhai / Pulimanji òë¢ir
43.Crochorus spp Jute Sanal rzš
44.Indigo fera Sumatran Indigo Avuri / neeli mÎç
45.Nicotiena tabacum Tobacco Pugaiyilai òifæiy
46.Areca cattcehu Arecanut Paakku fKF
47.Coffee arabic Coffee Coffee fh~Ã
48.Camellia thea Tea Theyilai njæiy
49.Piper betel Betelvine Vethilai bt‰¿iy
50.Cannabis Sativa Indian hemp Ganja fŠrh
51.Heva Brasilienis Rubber Rubber Ïu¥g®
52.Bitrus aurantifolia Acid lime Elumichai vYä¢ir
53.Bitrus limon Lemon Kodi Elumichai bfho vYä¢ir
54.Brassica clavacca Varbullata Cabbage Muttaikose K£il¡nfhR
55.Aoacardpum Occiemtable Cashew Munthiri KªÂç
56.Vitis Vinifeia Grape Dratshai / Kodimunthiri Âuh£ir
57.Psidrium guajarvs Guava Koyya bfhŒah
58.Aropcarpus Integrifolia Jack Pala gyh
59.Hibiscus esculantus Lady’s Finger Vendai bt©il
60.Citrus cincsin Orange Orange MuŠR
61.Amanas Sutivus Pine Apple Annasi m‹dhÁ
62.Apomaca Batalas Sweet Potato Sarkaraivalli r®¡fiu tŸë
63.Mainhot utilissima Tapioca Maravalli kutŸë
64.Carice papaya Papaya Pappali g¥ghë
65.Daucus Carot Carrot Carrot nfu£
66.Helianthus annus Sunflower Suriyakanthi NçafhªÂ

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Mar 21 2009

Converting Optical Density of a Neutral Target into its RGB code value

Published by under color science

Converting Optical Density of a Neutral Target into its RGB code value

Update

Recently a Color Science  expert who I worked with reviewed this post and here is his comment:

Everything you have is correct.  However, in talking about scanners I think you should make it very clear that you are speaking about the linear response of the scanner.  The work you did on scanners was very much at the core of the true engineering that goes into making a good scanner and dealt with the data before subsequent image processing and color management.

Most people, however are used to seeing the scan data after it goes through gamma correction and image processing (trivial image processing stuff).  Gamma correction is applied “approximately” as such:

CV = 255*T^(1/2.4)

So, your 0.5 transmittance sample will have an 8 bit code value of 191 .  This is further complicated by the fact that my equation above is a simplification of the true 2.2 gamma function (the fact that I use 2.4 instead of 2.2 approximates the effect of an offset term) .  Also, not everyone uses sRGB and there are some 1.8 gamma scanners out there.  Finally, the scanner manufacturer may apply some color management which would further confuse the issue.

Long story short:  Just make it clear that your discussion is on the Linear Response.

====== Original Post Below=======

Well, the headline seems nerdy. Not really if you are into scanner world. This post it very much a knowledge sharing as I could not find anywhere in the net which says how to do the conversion. Not that it is difficult, but takes some understanding and head twitching to do the conversion.

To know what is Optical Density, refer to this wikipedia article . In layman terms, OD is a unit less measurement of  how much light passes through a sample.

Formula to know
OD_lambda = log_{10} O = - log_{10} T = - log_{10} left ({I over I_0} right )

O = the per-unit opacity
T = the per-unit transmittance
I0 = the intensity of the incident light beam
I = the intensity of the transmitted light beam

if you want a sample to have 50% transmittance, then OD of that sample is

OD (50%) =  -log(.50) = 0.3

A neutral target is one that has equal amount of RGB color coded in it. A OD 0.3 neutral target is one whose transmittance is 50%. Now you ask what is the RGB value of the OD 0.3 neutral target. If we consider 8 bit RGB value, then 0 stands for black and 255 stands for white. For 50% transmittance, then the value should be exactly half and it is 128 for R,G & B.

Now let us say you want to prepare a sample that has OD of 0.6. RGB value for OD 0.6 can be obtained as below

-log10(x) = 0.6
x = 10−0.6  ( Should be read as 10 to the power of -0.6 )
X = .25  ( This is 25% transmittance. )
Hence the RGB code will be ( .25 X 256 ) =  64 each ( i.e R=64, G=64,B=64)

Another example, OD of .08

-log10(x) = .08
x = 10−0.08  ( Should be read as 10 to the power of -0.08)
X = .83  ( This is 83% transmittance. )
Hence the RGB code will be ( .83X 256 ) =  212 each ( i.e R=212, G=212,B=212)

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