Chpater 3Resolution, File Formats and Storage

Introduction

There are two factors that determine the quality of the picture you take; The resolution of your camera The type of file you save it in

Both of these factors determine the number of images you can store on the memory card in your camrea.

Pixels

The digital image you take is made up of pixels.

The word pixel is a contraction of the term picture element

The digital image you capture is made up of millions of individual small squares (pixels)

To the human eye they may look smooth but close up you can see the individual squares.

Pixels Each pixel in the image has a

numerical value of between 0 and 255 and is made up of three color channels

For example a pixel could be 37-red, 76-green and 125-blue and it would then look like this .

If it were 162 red, 27 green, 12 blue it would look like this.

This system will produce 16 million different colors

Resolution

The term "Resolution", when used to describe a digital camera refers to the size of the digital image the camera produces.

The resolution of a camera is expressed in megapixels.

The image on the following pages show a representation of the image size verses megapixels.

Image Size Megapixels Native Print Size (in inches)

4064 x 2704 11.1 13.5 x 9

3088 x 2056 6.3 10.25 x 6.8

3008 x 1960 5.3 10 x 6.5

2048 x 1536 3.0 6.8 x 5.1

1600 x 1200 2.0 5.3 x 4Standard 4X 5 Print

Advantage of Higher Resolutions  More resolution means better

print quality. It gives you an advantage if you

need to crop the image. Cropping is when you only use part

of the image for the final print You have an advantage when

creating larger prints The more you have to start with the

less likely it is for defects to appear.

Digital File Formats

There are three file formats used for storing digital images JPEG TIFF RAW

Except in high end digital cameras the file format used for storage is JPEG.

TIFF

TIFF (Tagged Image File Format) is a high-resolution file format .

TIFF files don’t lose image file information when they are saved during the compression process.

A tiff file also takes longer time to write to a memory card.

Most new Cameras do not support the TIFF format.

RAW RAW file format is the uncompressed,

unprocessed data file captured by the camera's image sensor, before any in-camera processing has been applied.

In this sense, an image saved in the RAW file format is the digital equivalent to the (exposed but as yet unprocessed) film negative.

The fascination with RAW is that it seems to magically give you the ability to "correct your mistakes.“

Only certain image editing software will open and work with the RAW format.

JPEG The name comes from Joint

Photographic Experts Group, the organization that created the format.

JPEG images can contain 16.7 million colors (24-bit color information)

JPED compression uses lossy compression algorithm this means that JPEG cast off some image information.

However, this compression if set right is not perceptible to the human eye

JPEG

JPEG compression is set by a scale from 0 to 100.

100 is the least amount of compression and 0 is the most.

Digital cameras can change the amount of compression by using the quality setting.

Setting the Image Quality It is always best to set the

camera for the largest image size and the highest picture quality.

That way you will have more to work with when you use your image editing software.

The only exception to this rule is if you are running out of space on your storage card.

Storage Cards

There are a number of types of storage cards Compact Flash XD Picture Card Memory Stick Smart Media Secure Data