Digital images have thousands of tiny, tile-like picture elements. When choosing a digital camera (digicam), the first thing that you should consider is the resolution. Image resolution is the amount of detail the image holds.
Line pairs are used to measure resolution. A line pair is a pair of adjacent dark and light lines. A resolution of 10 lines per millimeter is equivalent to 5 dark lines alternating with 5 light lines (or 5 line pairs per millimeter). For example, a 640 x 480 image would have 307,200 pixels, or approximately 3.1 megapixels; a 3872 x 2592 image would have a10,036,224 pixels, or approximately 10 megapixels. The more pixels an image has, the higher the resolution.
Below is an illustration of how the same image might appear at different pixel resolutions.
Image at different pixel resolutions
The number of megapixels is not an absolute measure, but only indicates the potential image resolution. Important factors that affect resolution include sensor design, the lens quality, focus (distance and length), aperture, position in the image field, orientation (horizontal, vertical, and diagonal), scene contrast, and vibration.
There is a wide misconception about the resolving power of digicams. For instance, my 12-megapixel digital camera does not have twice the resolving power of a 6-megapixel camera. It only has twice that of a 3-megapixel camera. Why? Because images are two-dimensional objects. When we double the resolving power, there is a fourfold increase in pixels (of equal quality) and not just a twofold increase!
The world’s first Wi-Fi digital camera with a web browser, it allows you to upload photos and videos to popular photo and video sharing sites like Shutterfly and Picasa, and YouTube, for which it has direct links. The Sony Cyber-shot DSC-G3 Wi-Fi camera comes with complimentary AT&T Wi-Fi access to Sony’s Easy Upload Home Page,till the end of 2012 and gives you Wi-Fi access at a number of AT&T hotspots,including hotels, airports, and coffee shops, across the United States. You can even send email notifications from the sharing websites so that your loved ones know your latest postings. You can view the uploaded images on its high-resolution 3.5″ LCD screen. The Sony Cyber-shot DSC-G3 Camera supports DLNA (Digital Living Network Alliance) guidelines, so that you can connect to other DLNA-compatible devices like Sony BRAVIA televisions and Sony VAIO PCs to view the photos in high-definition quality.
The camera got its name from camera obscura, the predecessor of the modern day camera. It is a Latin term which means “dark chamber,” and it refers to the early mechanism of projecting images and using an entire room as a real-time imaging system. Camera obscura consisted of a darkened chamber or a box that allowed light into the box through a convex lens. The image of the object was then formed on a surface of paper or glass, which was placed at the focus of the lens. The credit of inventing this gadget goes to an Iraqi scientist, Ibn al-Haytham. He described it as early as the 11th century in his Book of Optics (1015-1021). 
The Canon EOS 5D Mark II camera features an advanced DIGIC 4 image processor that helps in faster processing of fine details, color reproduction, and reduced image noise. It also lets the camera handle large 14-bit RAW images at a speed of 3.9 frames per second. It also boasts of a new 21.1-megapixel CMOS sensor. This feature will definitely be a boon for professional photographers. It has a vast ISO sensitivity setting range of 100-6400, which is expandable, enabling you to take pictures in near-dark conditions. The large 3.0-inch LCD display is covered with anti-reflective and scratch-resistant coatings. This provides better clarity and also prevents smudging. The Canon EOS 5D Mark II camera is the first EOS camera with full high definition video capability. It can record video clips at 1920 x 1080 resolution for nearly 30 minutes.
Framed Up: Many digital cameras come with face detection technology. This feature of detects faces while composing an image and then adjusts the focus and exposure accordingly. This is very useful when taking a picture of large groups or when the subject is at a distance.