Smartphone cameras demystified

Many people still believe that increasing the megapixels results in better photos. This may be true in some cases while in others you may find that even a 8 MP camera can take photos as good as, if not better, a 13 MP one.

These discrepancies are observed because the level of detail captured in an image largely depends on the amount of light in the surroundings. A 13 MP camera may capture minute details in broad daylight but while clicking photos in your college or office parties you will need a camera optimized for taking images in low light.

Firstly, let me clarify a thing behind the megapixels. As you all may  know, more the megapixels, greater the image resolution. In day-to-day use this reflects on the quality of photos captured using digital zoom. This means that a 13 MP camera can capture the same amount of details as the 8 MP one even if one is standing further away. This is because you can zoom in on the target without losing much on quality with a 13 MP camera. That's it!!! Nothing great about a 13 MP shooter. This is not even an advantage in cases where you are taking your Facebook party photos because obviously you would be shooting from as close as possible.

But the main issue is that photos are darker than normal. This can be solved by increasing the camera sensor size while keeping the megapixels constant. The camera sensor size is usually 1/4" for common smartphones, 1/3.2" for iPhone 5 and 1/3" for Lumia 925. Usually, larger the sensor size greater is low light image clarity.
This is because a larger sensor can take in more light using a larger pixel size. The pixel sizes are 1.1 µm for common smartphones and 1.4 µm for iPhone 5 and Lumia 925. Higher pixel sizes (ultra pixel) can process more light given megapixels are kept constant. The HTC one has got a high pixel size of 2 µm but it lags because the resolution is limited to just 4 MP.

However, one can increase the light input by keeping the same sensor. This is done by increasing the aperture size to F2.0 from the conventional F2.2 or F2.4. The iphone 5 has an aperture of F2.4 while iPhone 5s has increased it to F2.2. The Nokia Lumia 925 and Xiaomi Mi-2S have the largest aperture of F2.0.

For a detailed pictorial representation you can checkout below link to HTC's website.
http://www.htc.com/www/zoe/ultrapixel-sensor-size

If you want better auto focus and anti-shake features (image stabilization) then it's always better to go for optical image stabilizer. This idea is also best explained on HTC's webpage at http://www.htc.com/www/zoe/stabilization

Facebook privacy settings explained

We all post photos on Facebook but we seldom realize that we may be sharing them with a lot more persons than we would like. This is because of the default post privacy setting which is set to either "Public" or "Friends of Friends".

When the privacy is set to "Public" everyone can see your content which may not be desirable.

By default, the privacy is set to "Friends of Friends" which means that your post will be visible not only to your direct friends but also to their other friends. This may be risky in some cases as you may not know many of these "third-party" friends yet they can view, like and even comment on your content.

For this reason you should always set your privacy settings to "Friends" and nothing more broader.

But there is still one small issue hidden in the "Friends" setting. Even now, the friends of all the people tagged in the photo can view the post in their news feed even if they are not directly your friends. This is because they may be direct friends with the people that you tagged in your photo. This may not be an issue for many, but in some special cases even this may be a point of concern.
Consider the case when you want your office pics to be visible only to your direct friends and not to any other third party friends even if they are "friends" with your colleagues that you tagged in your photo.

For this, I use the "Custom" privacy setting where it allows you to uncheck the "Friends of people tagged in" option.

After doing these settings for future posts, you may want to change the privacy of all the past posts to "Friends"

Also, you can review how your timeline looks like to different audience categories like "Public" or any specific friend. For more details, please refer the below screenshots.

Who can see my stuff?

Custom Privacy:

Limit old posts:

Review timeline as another user:

Unraveling the mystery behind mobile processors (SoC)

Ever been confused by many top brands behind processors used in mobile phones and android tablets?

Don't worry, I will share a lesser known fact about them that will clear all your doubts.
Firstly note that,
SoC means "System-on-a-chip" architecture. This means that, along with main processor, GPU and other peripherals also are embedded in the same single chip for compactness.

There are mostly only TWO mobile processor architectures in the market !!!!

They are, Intel Atom and, the one and only, ARM processor family.

Out of these two, Intel Atom is not popular at all as it consumes much more power and yet delivers poorer performance as compared to ARM processors.
Thus, finally we are left with only one brand in mobile market ---- ARM.

ARMv7 instruction set is currently in use and will be for the next 5-7 years for mobile devices.

So, what about the other brands, namely,

• Snapdragon by Qualcomm
• OMAP by Texas Instruments
• Exynos by Samsung
• Ax by Apple
• RK3xxx by Rockchip
• A31 by AllWinner
• MTxxxx by MediaTek

Well, the most surprising fact is that all these are basically different implementations of the same ARM processor family.

For example,

• Apple A5/A5X
 

• Nvidia Tegra 2/3/4i
 

• Rockchip RK30xx
 

• S
• T-Ericsson NovaThor

• Texas Instruments OMAP 4
 

• Samsung Exynos 4
 

are all based on the SAME ARM cortex A9 technology and thus may be considered more or less equivalent.

So, instead of going after brands like Qualcomm and Nvidia, we can just check their cortex version number to check

their performance index easily. Even Apple A6 processor used in the iPhone 5 is based on ARMv7 instruction set. 

But they have not directly implemented any application processor model like cortex A9 or A15, etc.

Thus, the latest and fastest processor can be easily known by checking it's ARM Cortex generation.

Nvidia Tegra 4,

 

Samsung Exynos 5 and

 

Texas Instruments OMAP 5 

are some implementations of ARM Cortex A15 model.

For further credibility,

Samsung Chromebook and Google Nexus 10 utilize ARM Cortex A15 super processor.

The upcoming Samsung Galaxy S4 will be using it too!!!

Qualcomm S4 SoC(System-on-chip) has some similarities with ARM Cortex A15 model.

Main advantage of Qualcomm S4 chipsets over others is that Qualcomm SoC has additional hardware like cellular radio, Wi-Fi, GPS/GLONASS and Bluetooth on the same die. This reduces cost and complexity for equipment manufacturers like Samsung, Nokia, LG, Apple, etc.

From laptops to ultrabooks

1. Why to buy an ultrabook in the first place?
Ultrabook is basically characterized by it's longer battery life (7 hrs.), medium to high performance (based on cost), lighter weight (<1.5 kg) and thinner frame (<22 mm). In my opinion a laptop should weigh less so that we can carry it conveniently and maximize it's usage. After all, this itself mostly differentiates it from a desktop. But for using a device on the go implies a better battery life.

But now there is a catch. If the manufacturer provides a larger battery, then the laptop's weight increases which in turn again hampers it's mobile usage. Breaking this vicious circle is what makes ultrabooks costlier than normal laptops.

2. Factors to consider for selecting your suitable ultrabook:
Remember a state flow diagram as given below---
'->' means 'depends on'


device weight -> screen size + battery
Generally, 11 inch screens have lesser weight as compared to 13 inch screens for obvious reasons.
Similarly, 8 cell battery will weigh more than a 6 cell battery.

device battery -> processor + standby time
More powerful the processor, more heat it dissipates, more the cooling required and thus results in faster battery drain.
Thus, for greater standby time we need to compromise either on processor or get a bulkier battery.

Speaking of processors, there are mostly two brands as of now --- Intel and AMD.
Intel is better, costlier and more famous of the two. This is because Intel provides more overall performance and is manufactured using the latest die technology (22 nm) unlike AMD. AMD processors are known to provide better integrated graphics support. But AMD is relatively cheaper.

Basically, Intel is much ahead than AMD in the race for balancing processor performance with it's heat dissipation.
The heat given out by a processor is known by a parameter called TDP (Thermal desigh power).
Lesser the value, more the standby time. (Performance may be hampered if cost remains constant).

You may check the latest Intel Core i5 processors at
http://ark.intel.com/products/family/65504

Note:
1. Core i3 processors have lower TDP values as compared to Core i5 ones.
2. "mobile processor series" are used in ultrabooks (from drop down list).
3. Letter "U" suffixed to processor name implies "Ultra low power".

device performance -> processor + SSD (solid state drive)
Device performance is largely dependent on it's processor more than any other thing.
A SSD helps to boost up performance further by enabling faster boot times and faster response.
This is because SSD does not have any moving parts (no RPM!!!). This also helps to cut down weight,
consume lesser power and to have longer device life. But they are quite costly.

Different ways to check on latest ultrabook brands:

Way 1
Instead of manually searching in each vendor's site or goggling for "top 10 ultrabooks", you may browse
to Intel's site and select a vendor from a common list provided by Intel itself.

Browse to below link:
http://www.intel.in/content/www/in/en/ultrabook/ultrabook-showcase.html

Way 2
Or you can browse to
http://www.notebookcheck.net/Laptop-Search.8223.0.html

Enter the exact processor model from the Intel link given earlier in the search form above and hit
search to get an exhaustive list of notebooks along with their costs, ratings and reviews.

Ex: Select "Intel Core i5-3317U" from processor field and see the results!!!

Further tips
In Intel -> select (lower TDP + higher generation and series within generation)

Extras -> wifi adapter, usb 3.0, bt 4.0, ethernet port, card reader, optical disk drive.

Java OCJP quick review points

These are the quick review points that I assembled into a text file while studying OCJP for my campus placement. It also contains the important topics to be covered in Java for cracking technical interviews.
I hope others could get some quick review of Java language via reading it.

It is just 300 lines of text which includes the most peculiar and interesting features that I was able to found in the 1000 page OCJP book.

I have also included a smaller file of java data structures which can also serve as an important tool for last minute revision.

A small preview of the file:

---------------------------------------PREVIEW---------------------------------------------------------

assert keyword
java has printf("sas %d hbgvhnd",arg1);
enum constant declarations, constructors, values(), valueOf("a") inbuilt methods
each enum constant is a final, static reference that stores the reference value of an object of the enum type.
finalize()
daysInMonth = new int[] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int[] mXnArray[]; // 2-dimensional array
unboxing
even references are passed by value in java
final keyword means constant
public static void publish(int n, String... data) ---- varargs, always last parameter
public static void main(String... args) // Method header
javac -s "D:\study files\p1" -d . Heron.java   ---- package file structure compilation
javac -cp /top/bin -d ../bin A.java --- cp is class path used for searching class files
-cp /pgjc/work:/top/bin/pkg:.  ---- search in work, then bin, then curr dir by order
>java -jar bundledApp.jar
>javac -cp /top/lib/gui.jar:/top/lib -d /top/bin MyApp.java
>java -DFontSize=18 SysProp os.name java.version appName FontSize   ---- -D means define system property

------------------------------------------------------------------------------------------------------------

Links:

1. http://www.mediafire.com/?zp49ge2ns5fvdj8 --- scjp.txt

2. http://www.mediafire.com/?xy6842he5w7d9r3 --- datastruct.txt

Draw engineering block diagrams online

Use this site:

https://www.draw.io/

Features:

1. Draw directly without any ads or delay.

2. Export to PNG.

3. It is free to use.

4. Works well even on slow internet connections.

I drew my software's prescriptive architecture here in 5 minutes.

Please recommend this to all your friends.