ALL ABOUT RESOLUTION


The size of a photograph is specified in one of two ways—by its dimensions in pixels or by the total number of pixels it contains. For example, the same image can be said to have a resolution of 3648 by 2736 pixels or to contain 10.0 million pixels (3748 multiplied by 2736).

Camera Resolutions
Digital photographs are made up of millions of tiny squares called picture elements, or just pixels. Each of these pixels is captured by a single photosite on the camera’s image sensor when you take the photo.

In short, the resolution of a digital camera refers to the sharpness of its pictures. CCD image sensors contain a grid of photosites—each representing one pixel in the final image. The sensor's resolution is determined by how many photosites there are on its surface. This resolution is usually specified in one of two ways—by the sensor's dimension in pixels or by its total number of pixels. For example, the same camera may specify its resolution as 3648 by 2736 pixels or 10.0 million pixels.

Resolution can affect the image in three ways:

Pixel dimensions - indicate image size 3748 x 2736 pixels or 10 megapixels
File size – the larger the image dimensions, the larger the file size
Print size – the larger the stated print size (4x6 in.), the larger the file size

and is referred to as dots per inch  or dpi―the more dots per inch (300dpi), the larger the file size

The size of the individual photosites on the sensor’s surface determines how high a camera’s ISO numbers go. Larger photosites allow a camera’s ISO to reach 1600 to 6400.

Like the Impressionists who painted wonderful scenes with small dabs of paint, your computer uses tiny pixels to display or print photographs. To do so, the computer divides the screen or printed page into a grid of pixels, much like the image sensor is divided. Each pixel is a small square made up of a single color. The more pixels add detail and sharpen edges. But if you enlarge a digital image, the pixels separate into what’s called pixelation.

Size Isn't Everything
The size of a photograph is specified in one of two ways—by its dimensions in pixels and by the total number of pixels it contains. The larger an image's size in pixels, the larger the image file needed to store it. For this reason, some cameras allow you to specify more than one size when you take a picture. This is usually indicated by stars–one, two, three, or four. Although you are likely to get better results with a higher number of stars or larger image, it isn't always needed—especially when the image is going to be displayed on the Web or printed very small. In these cases smaller images will suffice and because they have smaller file sizes, you'll be able to squeeze more into the camera's memory. In addition, most digital cameras allow you to switch from one size image to another during the same photo session.

Although more photosites often means better images, adding more isn't easy and creates other problems. It adds significantly more photosites to the chip so the chip must be larger and each photosite smaller. Larger chips with more photosites increase difficulties and costs of manufacturing. Smaller photosites must be more sensitive to capture the same amount of light. More photosites create larger image files, creating storage problems.

Today, there are three sizes of sensors—small, medium, and large (full frame). The largest sensor contains the largest photosites.