Photoshop

After so much of theory, you must have been little bit vexed. So in this and the following chapters you will deal with something which will enlighten you to a way of being more creative. In upcoming six chapters we will be dealing with an Adobe product named Photoshop 5.5. This software is used for manipulating images. If you are already familiar with earlier version of Photoshop then you must be happy to know that now you can create animation in Photoshop 5.5. The appellation Adobe has given to Photoshop 5.5 is "the camera for your mind". If you are creative and can conceive ideas then Photoshop is there to execute your ideas. This package enables graphic artists, designers, Webmasters and photographers to create original artwork, retouch and correct images, manipulate scanned images also. Before you actually start working with Photoshop, you should be familiar with few terminologies discussed below.

Photoshop 5.5 is having many added features compared to the previous version. It has the option for saving an image and previewing of images in different Web graphics file formats and with different file attributes. There are features to optimize images for the Web in GIF, JPEG, and PNG file format, create background transparency and background matting, and preview and control dithering. In fact new capabilities are added with few tools for example now there is a type tool, which helps in writing any text on the image vertically. Now along with Photoshop 5.5 another software called Adobe ImageReady 2.0 comes which helps in creating animation.

Vector Data

Vector data in the world of computer graphics refers to a means of representing lines, polygons or curves by numerically specifying key points or by using mathematical formulae. Essentially a program renders the actual image by regenerating the lines, curves etc using the key points and mathematical formulae. For example, a straight-line segment can be defined by the two end points of the line and these two end points are the key points. Some more attributes are also ascribed with vector data such as color and line thickness information.

Bitmap Data

This kind of data is formed from a set of color of individual pixel. Pixels are dots of color arranged on a regular grid in a pattern representing the image to be displayed. In lay man's term bitmap is an array of pixels juxtaposed, but technically it consists of an array of numerical values used to set colors when the image is rendered. It may sound abstruse at this moment but will be much clearer when we will talk about pixels. Bitmap data are also called Raster data.

Video Card

Video cards are specialized hardware, which enables managing a monitor's display. The video card usually has its own processing circuitry and memory. It ensures that the monitor displays the screen created by the CPU.

Screen

Inside the monitor's screen there is a coating of a specialized material. This material glow when electron beams strike it. Monitor and video hardware controls the various levels of brightness of glow.

Pixels

The elementary component of an image rendered on a monitor screen is pixel. Pixel size depends on the video card, the hardware configuration and the size of the monitor. Pixels are so small and close together that they are not visible and distinguishable and hence give the impact of a single piece. The number of pixels that a monitor screen displays is called the screen's resolution. There are two types of pixels. They are Physical pixel and Logical pixel.

Physical Pixel

They are the physical dots displayed on an output device. Each pixel takes some space on the surface of output device. It is the job of display hardware to manipulate the physical pixels. Display hardware juxtapose or overlays several dots to form an individual pixel.

Logical Pixel

They are very different from physical pixel. They are like mathematical points and hence specify a location, but are assumed to occupy no area. There is a mapping between logical and physical pixel. They both together, account for the actual size and arrangement of the physical pixels.

Physical Depth

The color exhibited by a pixel depends upon the number of bits required to represent that pixel. If there are more bits used, the number of possible colors it can exhibit is more. Number of bits per pixel of an image is known as pixel depth. As we know that a bit can have two values only. So, if 1-bit pixel value information is used to represent each pixel then it can have two color states only. Generally 1-bit displays are monochromatic monitors. So if 24-bit pixel is used then it can have 16 million color states. So obviously the storage space needed to store a pixel with 24 bits is more as compared with 1-bit pixel.

Color Map

It's a one-dimensional array of color values. It is also referred as index map, color table, Look Up Table (LUT) or a palette. Thus the colors can be referred by specifying their corresponding positions in the array of color values. Data regarding the colors in a file can be stored as a series of index values resulting in drastic reduction of size.

Let us take an example to get it more clarified. A 4-bit pixel data can represent an image containing 16 colors. These 16 colors are defined in a palette, which is included with the file. Now a rendering application will read and assay a pixel value from the file. It will use it as an index into the palette and retrieve the value of the color from the palette. This retrieved value further specifies the color of the pixel.

Color Spaces

As you must have read in your science courses, when you were in school, that using primary colors you could define all other colors. There are three fundamentals colors. By specifying the amount of each of a set of fundamental colors called color channels, you can generate another color. Thus a composite color is specified as an ordered set of values. In a graphical plot of gamut of color, a particular color is said to represent a point. This gamut of colors is called a color space.

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