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Buying Guides

Digital Camera

Points you should note while buying a digital camera are:

  • Resolution:
    Although a decent resolution is necessary, investing just on resolution does not necessarily make sense. When 2-3 MPixel camera is sufficient for most of us, I have seen people put hundreds of dollars into getting a 6.3 MPixel one.
    There are two places where higher resolution comes in handy:
    • Printing : When you are going to develop your photos to huge prints, higher resolutions come in handy. But ask yourself, how many times are you going to print larger than 5x10? To help you make a decision, here is a table of Resolution to printable size table:
      Digital Camera Resolution Chart
      Capture Resolution
      Video Display*
      Print Size***
      2x3"
      4x5"/4x6"
      5x7"
      8x10"
      11x14"
      16x20"
      320x240
      Acceptable
      Good
      Acceptable
      Poor
      Poor
      Poor
      Poor
      640x480 -
      0.3 Megapixel
      Good
      Excellent
      Good
      Poor
      Poor
      Poor
      Poor
      800x600
      Excellent
      Photo Quality
      Very Good
      Acceptable
      Poor
      Poor
      Poor
      1024x768
      Excellent
      Photo Quality
      Excellent
      Good
      Acceptable
      Poor
      Poor
      1280x960 -
      1 Megapixel
      Excellent
      Photo Quality
      Photo Quality
      Very Good
      Good
      Poor
      Poor
      1536x1180
      Excellent**
      Photo Quality
      Photo Quality
      Excellent
      Very Good
      Acceptable
      poor
      1600x1200 -
      2 Megapixel
      Excellent**
      Photo Quality
      Photo Quality
      Photo Quality
      Very Good
      Acceptable
      Acceptable
      2048x1536 -
      3 Megapixel
      Excellent**
      Photo Quality
      Photo Quality
      Photo Quality
      Excellent
      Good
      Acceptable
      2240x1680 -
      4 Megapixel
      Excellent**
      Photo Quality
      Photo Quality
      Photo Quality
      Photo Quality
      Very Good
      Good
      2560x1920 -
      5 Megapixel
      Excellent**
      Photo Quality
      Photo Quality
      Photo Quality
      Photo Quality
      Excellent
      Very Good
      3032x2008 -
      6 Megapixel
      Excellent**
      Photo Quality
      Photo Quality
      Photo Quality
      Photo Quality
      Photo Quality
      Excellent
    • Cropping: When you have not enough optical zoom to zero into the subject, or you want to take a photo which is not of regular size (like panoramic ones), you might want to take the photo and later crop (delete portions of it from borders) the photo on a computer. From my experience, after the first few months of buying the DigiCam, you won't have time to do cropping most of the time. For long distance photography, it's better to invest on a camera with good optical zoom. For Panoramic photographs, there are digital cameras (at least Canon has this feature) which allows you to take wide panoramas in stitch-assist modes (each shot is aligned to the next shot on the screen).
  • Optical Zoom:
    A lot of lower end digital cameras claim significant digital zoom. Some of them increment the zoom factor by multiplying Digital and Optical zooms (i.e. a camera with 3x optical and 4x digital zooms claims to have 4X2=8x total zoom!!). It is better to discount the digital zoom part totally, as, it is effectively extrapolating your pixels (and losing details in the process). To do digital zoom, your photo editing computer will be much more effective than your camera. It's better to invest in a camera with good optical zoom that other bells and whistles.
  • Shutter Delay:
    A regular film camera operates in the following mode: when you press the shutter, the barrier between the outside world and the film gets removed for a brief period of time, allowing the chemicals on the film to react to the external light, thus capturing a 'photo' of it. On the other hand, a digital camera has a sensor plate (CCD or CMOS) in place of the film. As soon as the shutter is pressed, the barrier gets removed in the same manner as the film camera for a minute amount of time. But, instead of chemicals reacting to light (which can happen all over the film simultaneously), a processor starts reading the info from the sensor plate. This, depending on the capabilities of the camera, can take a significant time, causing a shutter lag (delay between pressing the shutter and capturing the photo). Research the shutter lag of the camera you are planning to buy before committing on it.
  • Night Shot:
    You'll have one of the major set-backs while shooting at lowlight with a digital camera. In case of a film camera, the shots taken at lowlight can be dim, but they will always be smooth. Whereas for digital cameras, the image taken at lowlight will not be smooth but significantly grainy, giving it that ghostly look. Do a little research on the nightshot capabilities of the camera you are going to buy. Another major disadvantage of digital cameras is significant red-eye. This phenomenon is present in the film cameras too. But digital cameras, being smaller and smaller, the distance between the lense and the flash has reduced, enhancing the red-eye problem.
  • Battery Type:
    This is of not much concern if you are buying and using the camera in the same geographical region. But if you are buying the camera, say in USA, and sending it to, say India for your kid brother, you might take the battery type used by the camera into consideration. A replacement of the proprietary rechargeable batteries used in the compact digital cameras may not be available everywhere.
    Also, you might want to consider buying a spare battery for you. Going on a long camping trip, you don't want to run out of bettery. If you go for long trips to back-country, away from civilization (meaning BestBuy, CircuitCity or Frys!!), you might want to consider cameras that take standard (AA/AAA) batteries.

Linux/Unix

System calls and Libraries

General Topics

Caching

In general terms, caching is a way of storing important/immediately needed information on a specific location so that it can be accessed faster than if it is stored in a regular location. To give a real life example, you generally store most of your books in the bookcase, but keep the few which you use very regularly on your desk so that you can access them fast. This is exactly the same process of caching.
This concept of caching is used in different aspects of computer science and engineering. Some of the cases are Web Caching, File System Caching, Caching of computer memory etc. These three are described in brief in the following paragraphs.

Web Caching  -   Web caching is primarily used for caching WebPages/ Web contents. Primarily, there are two sides of web caching, Server Side & Client Side. The Server side caching, which is always referred to as "Web Caching" is the technology by which regularly accessed web content is served from a faster storage space/memory and less frequently accessed content is served from slower storage space. There are other smart ways to do Server Side caching for dynamic contents too, but I would not delve into such details. In turn, client side web caching is used by most of us. In this, our web browser or some other agent keeps the webpages we access for the first time in our local storage for sometime, and serve those contents from the local storage when we try to access them later. On the client side, caching is done primarily by either our web browser, or the proxy server (if one is used) or both.

File System Caching  -   FACT: Disks are slow. FACT: Computer files reside on disks (mostly). These two together made accessing files a tremendously slow process, until filesystem caching came about. The basic premise of filesystem caching is, not all files that are there on the disk are accessed simultaneously. Only few of them, and for that matter, only few areas in each individual file, are accessed at the same time. So, instead of getting and storing these files to the disk directly, we can temporarily store the currently accessed file contents in main memory, which is much much faster than the disks. Modern filesystems do exactly the same thing, using main memory as a "cache" for the files on disks. Nifty tricks of mapping files to memory and using paging hardware to make the decision of getting the data from disk only when necessary is very common.

Main Memory Caching  -   All the computer programs, and the data they operate on, has to sit on the main memory for it to be accessed. Memories have gone faster and faster over time, but the ability of CPUs to execute instructions fast have gone up at a rate higher than memory speed. These instructions, and the data they operate on, comes from the main memory, making it the bottleneck in performance. To work around this issue, faster (and more expensive) memories are used to cache part of the less expensive main memory. Different levels of faster memories are used at different locations. For example, Pentiums have two levels of memory caches on-chip on the processor, known as L1 and L2 caches. In Celerons, however, only L1 cache resides on the chip, and L2 cache is supported externally, making it slower (but cheaper).

Web

PHP and cookies

Cookies can be used very easily in PHP. To set a cookie for a page, you need to use the
setcookie function to set the cookie for a domain name/webpage. To retrieve the cookies sent by the browser/client, the variable $_COOKIE should be accessed.

Google Search Inclusion

Okay, so you have registered your domain, designed your webpage, hosted it. But now you want to go public and get included in Google Search. The best way to get listed by google is to get yourself a link on a page that is already listed on Google. The easiest way to do that, in case you don't have access to any webpage that is listed by Google, is to sign a couple of guestbooks which are listed on Google. How do you know which are looked at by google? Just do a google search on Guestbook. Signing a huge number of guestbook, or signing the same guestbook multiple times is considered Spamming, and is looked down upon, and can get you blacklisted.
Some rules of thumb:
  • Don't put junk stuff in your keywords. That can give you a negative rating. Google probably does not use the keywords section but looks at the main body to decide what is important.
  • Put the MAIN keywords in the page title.
  • If the main keyword is in the URL, your site has a much brighter chance of being above other sites for search results for that keyword.

NewsGrabbers

If you are interested in knowing how the Geek News page grabs the news items from pages like SlashDot or LWN, read on.
Most of the news sites, especially tech-news ones, have something called "RSS Feed", which essentially means, they export their news in a certain predefined XML format. XML, in general, is a generic format which allows for defining name-value pairs. RSS, is a specific type of XML, where these names are pre-defined, and is used mostly for news feeds. Because the names are predefined, RSS readers, on the web or on the desktop, can grab these items and make sense out of it, and show it.
What generates the Geek News page is a perl script I wrote that can grab these RSS/XML feeds from different websites, and show it in the format I like. If you want this functionality on your site, you can download one of the RSS grabbers from the public domain script sites. In near future, I'll make all my scripts public so that other people can use them.

DMOZ Open Directory Editing. GreenBusting [From DMOZ Documentation]

What is Greenbusting?
I was baffled by the term Green Busting, and had to search a little to know the meaning. For the people equally baffled, here is the description. A type of editor permission granted on a per-category basis. It allows the 'greenbuster' access to the category's Unreviewed queue (and those of sub-categories thereof) but not usual editor functions such as creation/deletion of sub-categories and modifying/deleting existing listings. In fact, all the editor is able to do is move newly submitted sites to other Unreviewed queues and 'greenbust' new submissions.
'Greenbusting' a new submission involves the greenbuster adding a title and description to a new submission and entering it into the "Greenbust queue". Listings in this queue are visible from the edit side but not from the public side. They appear in a cluster below the other sites that are listed in the category and are not included in the RDF.
GreenBuster

Having your own website

  Quite a few times I have been asked by friends and acquaintances about how they can have their own website. Most of the time, they think that "Having a web site" is just a one shot process. So, for the beginners who want a piece in the World Wide Web, here is the information on how to have your own site.
  Step 1: Free vs. Paid
    Free is always good, but not always convenient. The Pro of the Free variant is... it's FREE. The Cons are:
  • Banner/Pop-up advertisements. These are very annoying for the people visiting your site.
  • Bandwidth is highly restricted. If you are expecting hundreds of people visiting your site every month, you can easily run out of bandwidth. Under such condition, you site becomes unavailable.
  • Restricted control. You cannot pick and choose what you want to host and what kind of server side tools (Database, scripting etc) are supported. You cannot have sub-domains or email ids.
  • Limited storage space.
  • Weired Address. Your website address shows up a little weired. For example, this website would have been http://home.tripod.com/~indiangeek instead of www.indiangeek.com.
  • Website Management. Most of the "Free" services will give you online uploading or at the most FTP access to upload your files. No Shell access is provided for you to "log-in" to the server and test out your scripts/update files etc.
  • Statistics support. Most of the "Free" services have a very limited statistics support.
In spite of all these cons, it is a good idea to start off with a Free website, develop your initial pages, and test out your idea on the web. Once you start getting some hits AND you have the money to spend, you can always move on to the paid service. Some of the common "Free" services are: You can register at these sites, create your HTML files and upload them through their web tools or over FTP. Read on to Step 2 if you want to go for the paid option.
Step 2 [Paid] Registering Domain Name.
     In this phase, you choose the domain name you want. Domain Name is thename of your site. For example, yahoo.com is the domain name for Yahoo!, indiangeek.com is the domain name of my site. A few things to notice here:
  • When you are buying your domain name, you also automatically own all the subdomains. For example, if you buy mydomain.com , you automatically own www.mydomain.com, mail.mydomain.com, goblewoble.mydomain.com and here.is.my.domain.called.mydomain.com . Essentially your domain is made up of two things, [Name of Domain].[domain extension, which can be com/net/us/biz/tk/tv etc].
  • Domain names are case insensitive. GoberDonkeR.coM is same is goberdonker.com .
  • www.indiangeek.com may not be pointing to the same location as indiangeek.com. Putting www before a domain name is not necessary and you can make it point to somewhere else too.
    You can easily buy your domain name from commercial domain name sellers like Register.com or Godaddy.com. New domain names are resonably cheap (anywhere from 5-20 $s). However, if you want a specific domain name which is already owned by someone else (i.e. twistedmind.com), there is no way you can get hold of that domain name unless you cut a deal with the current owner. Based on how populer that domain name is, you might have to pay a significant sum. However, if you are planning to use a paid hosting service and go for a brand new name, then you might consider buying the domain name through them, as most of the hosting services give you the domain name for free as promotional offer.
    Step 3 [Paid] Choosing a Hosting Service.
    [Will write later]

    Windoze !!

    Command Prompt Arrow Key History

    In your command prompt if you want the up arrow key to take you to previous command (something doskey.exe used to do in the DOS days), follow the following steps.
    • Run "regedit" at command prompt. This should open up the Windows Registry Editor in another window.
    • Go to the key HKEY_CURRENT_USER->Software->Microsoft->Command Processor.
    • On the right window pane, you should have a variable CompletionChar. Double click on that.
    • In the pop-up that shows up, set the value data to 9. Click OK.
    • Close regedit.
    • Restart the command prompt. Your up-down keys should take you through the command history now.

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    This page was last modified on: 09/19/04