Introduction to Photoshop
Photoshop is a raster program, also known as a paint or image
manipulation program. It is the industry standard software of raster
programs. There are many other image manipulation programs include
Macromedia's Xres, Paint Shop Pro and Corel's Photo Paint, all similar
in content to Photoshop.
and image-editing software, such as Adobe Photoshop, generate bitmap
images, Also called raster or pixel based imagery. The images use a grid
of small squares, known as pixels, to represent graphics. Each pixel in
a bitmap image has a specific location and colour value assigned to it.
For example, a bicycle tyre in a bitmap image is made up of a
collection of pixels in that location, with each pixel part of a mosaic
that gives the appearance of a tyre.
working with bitmap images, you edit pixels rather than objects or
shapes. Because they can represent subtle gradations of shades and
colour, bitmap images are the most common electronic medium for
continuous-tone images, such as photographs or images created in
painting programs. Bitmap images are resolution dependent; they
represent a fixed number of pixels. As a result, they can appear jagged
and lose detail if they are scaled on-screen or if they are printed at a
higher resolution than they were created for. Bitmap images are good at
reproducing the subtle shading found in continuous-tone images, such as
photographs. However, bitmap images do not enlarge well and can show
jagged edges when magnified or output to higher-resolution devices.