Edit bitmap images (selection, correction, resizing)

Selection – Picking the Right Pixels

Think of a bitmap image as a giant grid of tiny coloured squares (pixels). Selection is like using a pair of scissors to cut out a shape from a paper collage.

• ✂️ Rectangular Marquee – Drag to create a straight‑lined box.
• 🖱️ Lasso Tool – Freehand draw a custom shape.
• 🟦 Magic Wand – Click a colour to select all similar pixels.

Tip: Ctrl + Shift + I (or Cmd + Shift + I on Mac) toggles the selection – handy for quick inversions.

Correction – Fixing Colours and Lighting

Imagine a photo taken on a rainy day. The colours look dull, like a washed‑out painting. Correction restores vibrancy.

1. 🔧 Brightness/Contrast – Adjust sliders to brighten or deepen the image.
2. 🌈 Hue/Saturation – Shift colours or make them more saturated.
3. 🧼 Spot Healing Brush – Click on blemishes to “clean” them.

Analogy: Think of it as adding a splash of paint to a canvas – a little goes a long way.

Resizing – Stretching the Canvas

Resizing changes the overall dimensions of the image. It’s like stretching a rubber band: too much stretch can make the picture look pixelated.

• 📏 Image Size – Enter new width/height in pixels.
• 🔄 Maintain Aspect Ratio – Keep the image from looking squashed.
• 🖼️ Resample – Choose Nearest‑Neighbour for pixel art, Bicubic for photographs.

Remember: Always keep a copy of the original before resizing.

Exam Tip Box

When answering questions about bitmap editing:

• Use clear, concise language – e.g., “Use the Lasso Tool to isolate the subject.”
• Include step‑by‑step actions – list the tools and shortcuts.
• Show before/after logic – explain why you chose a particular correction.
• Remember the rule of three – keep your answer within three main points.