Bitmap and Vector graphics
A bitmap graphic is composed of a grid containing a large number of dots. A binary number is used to store the color of each dot. A grid is used to divide a picture into pixels. Every pixel is assigned a color which is stored in as a binary number. Bitmap image can be created by Adobe Photoshop, Microsoft Paint or Corel Painter.
How to create a bitmap image:
A bitmap graphic can be created by using the graphic software such as Microsoft paint, corel Painter, Adobe Photoshop etc. these graphic software provides tools for creating shapes, filling the shapes with color, shading the shapes and also used for freehand sketching. Cameras and scanners are also used to create bitmap graphics.
How to store bitmap images:
Bitmap graphics are stored in the form of binary number. Ever binary number pixel of the grid is stored as a series of bits. Bitmap graphics can have anyone of the file format to store a bitmap graphic i.e. TIFF, JPEG, GIF, RAW, BMP, PNG.
Use of bitmap graphics: Bitmap graphics are used for desktop publishing, web graphics and used by photographers.
Vector graphics contains a set of instructions which are used for recreating the image. Vector graphics does not store the color value. It stores the instructions which the computer use for creating the shapes and size and color and position of the objects of images. Each part of vector graphics is created as a separate object.
How to create and store the vector graphics:
Clip art are the best example of the vector graphics. Vector graphics can be created by drawing software. Corel Designer, Adobe illustrator, inkScape, and open office draw software are used to create vector graphics.
The vector graphic files can be stored with file extension.wmf,.ai,.cps,.dxf,.suf
Use of Vector graphics:
Vector graphics is used to draw logo, line arts and simple diagram which user wants to show in different sizes. It is because stretching a vector graphic will not affects its quality.
Concept of layering for modification of vector graphics:
In vector graphics, each object is layered on another object. These objects can be edited or moved separately. Any object in the vector graphics can be distorted, stretched, moved, shrink or color separately.
Bitmap images have a single layer of pixels. Erasing or deleting a shape will create a hole of white pixel in the bitmap files while this does not happens in the case of vector graphics
Effect on file size by adjusting following terms
• Resolution: Resolution is defined as the dimensions of the grid which forms a bitmap graphics; it is usually represented by number of horizontal and vertical pixels contained by a graphics. For example if a picture contains
pixels, then it will have 250 pixels horizontally and 150 pixels vertically.
Resolution is directly proportional to file size. A Higher resolution image has larger file size then lower resolution image file.
• Image size : In a bitmap graphic, each pixel is stored as bit. One or more bits can be used to store the bitmap graphics. So, larger is the number of pixel larger number of bits will be required to store the image. Cropping is used to reduce the image size. Cropping is the process used to remove the unwanted parts from image.
Image size is also directly proportional to file size. A larger image has larger file size then lower smaller image file.
• Color depth : Color depth is defined as the number of color used in the image. Larger is the number of colors into the graphics, better will be the quality. But within increase in the number of colors, image size is also keeps on increasing. Color palettes are used to reduce the image size.
• Color palettes : A color palettes is used to decrease the color depth. A color palette holds the colors which a user uses in his paining. Color palettes contain only 256 colors. The color for every pixel is stored in 80bit binary number instead of using 24-bits, this will helps in reducing the image size.
Color pallet is inversely proportional to file size. Larger the color pallets in image, smaller will be the file size.
Preparation of graphics for various purposes:
• Prepare graphic for e-mail:
When user wants to create the bitmap graphic for the email, he must use photo shop or firework. The image dimensions for an email should not be more than 400 widths and 300 heights. Use of cropping feature also helps in keeping the graphic size less. Now user must save the graphics in jpeg format. File size must not be more than 1 Mb as it makes it difficult to upload and view.
The graphics that are used for the e-mails should be compressed before sending them.
• Preparing graphics for the web pages:
Firework is used for preparing graphics for the web pages. It will helps in creating elements and controls of the web pages. A file which is of 10 megapixels will be unsuitable for the web pages as it will take a long time for downloading.
Web graphics size must not increase more than 100kb so that they can be easily handled and can be downloaded.
• Prepare graphics for desktop publishing:
Desktop publishing is used for creating documents by using page layout. Desktop publishing is used for producing both image and text having an attractive layout. By desktop publishing software like coral draw individual organization or business can publish their printed matter. This printed matter can be books, newspaper; magazine etc. for desktop publishing resolution should be high. The file size of these images is generally greater than email attachments and web pages.
• Prepare graphics for printed photos:
There are many graphics software available which are used to print the photo without change in the resolution. An acceptable image can be get if the size is 400dpi.
Analog sound wave
Analog sound wave is a continuous curve of wave. Vibration of matter like drum head or violin string produce sound and the sound is always in the form of the waves. The continuous curve of the sound wave is smooth and it is recorded with the help of the analog device.
For converting an analog audio sound to the digital format, sampling is done. Sampling is the process of converting the sound waves in the form which a computer can store or understand.
For recording the sound digitally, samples of the sound audio are collected at regular interval and they are stored as the numeric data.
For digitalizing a sound wave, it must be divided into vertical segments which are called samples. The height of every sample is converted to the binary form and then stored to computer as the computer only understands the binary data.