ITPEC IP October 2019 Question 25

The type and brightness of a colour can be adjusted for each pixel — a raster image is a grid of pixels, each storing its own colour value.

Painting software keeps the image as rows and columns of pixels, and every pixel holds its own colour and brightness. Editing therefore works pixel by pixel: retouching, blurring or brightening an area changes the values of those pixels. This suits photographs and freehand painting. The other method, vector graphics, stores shapes as coordinates and formulas (lines, curves, fills) and redraws them at any size.

Answer (b)

Why not others:

• •(a) — CAD handles exact shapes and dimensions that must scale and be edited as objects, so it uses vector graphics
• •(c) — a raster file holds one value per pixel, so a higher resolution means more pixels and a larger file; its capacity is not constant
• •(d) — enlarging a raster image enlarges its pixels, so slanted edges show jaggies (stair steps); smooth edges at any size belong to vector graphics

Key rule: Raster means pixels: editable per pixel, resolution-dependent, jagged when enlarged; vector means shapes as formulas: scalable without jaggies, used in CAD and fonts.

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