Elementary Statistics and Computer Application

 

 

Multimedia Building Block II –Images

Making Still Images

• Still images are drawn in one of two ways:
• Bitmapped images
• Clip art
• Bitmap software
• Capture
• ScanningVector-drawn images
Images are usually compressed to save space

• Formats like GIF, JPEG and PNG incorporate compression
Bitmapped Image

• A simple matrix or grid of dots with color information.
• i.e. an array of color dots that when looked at from distance forms an image.
• The smallest element of a bitmap is a pixel (Picture element)
Vector Image

• Image data are stored in the form of
• Data points that describe the collection of lines, curves, circle, ellipses, text, polygon and other shape
• The characteristic of each shape such as line type and fill/shading specification
• The information of the images can be stored as coordinates
• The computer recreates the image based on the information describing the image.
Bitmapped vs Vector Images

• Vector images are easily scaled without quality loss.
• Bitmapped images get grainy and pixilated when zoomed in
• Bitmapped vs Vector Images:
• Vector image require plug-ins
• Vector image can easily be edited
• Vector image files are usually smaller compared to bitmap
• Contain only information how to recreate the image
• Vector graphics are web friendly
• However, to display complex vector images might require more system resources
• Bitmaps are more suitable for large images with many different colors (photograph)
• Special effect can easily be applied on bitmapped image (distortion, blurring).
• To apply the same effect, vector image need to be transformed to bitmapped first.
Image File Formats

• There are many file formats used to store bitmaps and drawings :
• Windows device-independent bitmap (DIB)
• .bmp, .dib, .rle
• CompuServe GIF (.gif)
• JPEG (.jpg)
• Apple Macintosh PICT (.pic or .pct)
• Portable Network Graphic (.png)
• Windows Metafile (.wmf)