How do digital images work? | Year 6 Computing PDF Download

What are pixels?

• A digital image is a picture stored on a computer, created by assembling numerous tiny squares known as pixels (short for picture element).
• When an image is digitized to be stored on a computer, it's transformed into a set of pixels.

How do pixels make up an image?

• Imagine an avatar with a square grid overlaid on it. Each square in the grid represents a pixel.
• The computer assigns a number to represent the color of each pixel to store the image, akin to a digital color-by-numbers activity.

How Pixels Make Up a Display?

• When you observe a computer screen closely, you'll notice it comprises millions of small squares, known as pixels.
• Each of these squares represents a pixel.
• To showcase an image, the computer instructs the screen to display a specific color for each pixel.

How Pixel Images are Stored?

• Images composed of pixels can be saved as files utilizing various formats.
• Different file types employ pixels in different ways to store the image.
  Some common formats include:
  • JPEG
  • TIFF
  • PNG
  • GIF
  • BMP (short for bitmap)

What are bitmap images?

• A bitmap image is a type of image format that stores graphics using a grid of individual pixels. The term "bitmap" comes from the fact that it is essentially a map of where each bit of information is located. Each pixel's color information is represented as a sequence of numbers.
• In a simple black and white bitmap image, only two colors are used - black and white. Each pixel is represented by a single bit, where '1' typically signifies black and '0' signifies white. This binary representation simplifies the storage of such images.
• For color images, more complex bit patterns are used to represent a wider range of colors. Typically, 24 bits are used to represent the color of each pixel. With 24 bits, it is possible to represent up to 16.8 million different colors in an image, providing a rich and detailed color palette.

What are vector images?

• Definition of Vector Images: Vector images differ from traditional images as they are constructed using lines, curves, and shapes instead of pixels.
• Components of Vector Graphics:
  • Lines, Curves, and Shapes: Instead of being composed of pixels, vector graphics are built using these elements.
  • Objects: Each element within a vector graphic is referred to as an object, which is easily editable and modifiable.
• Advantages of Vector Graphics:
  • Editable Nature: Objects in vector graphics can be easily modified without compromising image quality.
  • Smooth Lines: Algorithms used to store objects ensure smooth lines, making vector graphics ideal for diagrams and graphics.
• Comparison with Raster Graphics:
  • Raster Images vs. Vector Images: Raster graphics, composed of pixels, can lose quality when resized, unlike vector graphics.
  • Photographs as Raster Images: Photographs are typically raster images due to their pixel-based composition.

Working with Objects

Vector graphic applications offer numerous methods for manipulating objects.

• Resizing Objects
  • Vector graphic applications offer various methods to resize objects, allowing you to make them larger or smaller as needed.
  • For instance, in design software like Adobe Illustrator, you can easily adjust the size of shapes, text, or images by dragging the corners of the object.
    

• Duplicating Objects

  • You can quickly create copies of objects within vector graphics applications.
  • For example, in programs like CorelDRAW, duplicating an object is as simple as selecting it and then using a keyboard shortcut to create a copy.
    

• Alignment

  • Objects can be aligned next to each other in a straight line to create a visually appealing composition.
  • Tools like Adobe InDesign allow users to align objects precisely using grids and guides for professional layouts.

• Layers

  • Objects in vector graphic design can be organized in layers, allowing you to place them in front of or behind other elements.
  • Software like Sketch enables designers to work with layers, making it easier to manage complex designs by separating elements into different levels.