Memory & StorageKey Facts
Image Representation - Bitmap Graphics
Part of Images & Sound — GCSE Computer Science
This key facts covers Image Representation - Bitmap Graphics within Images & Sound for GCSE Computer Science. Revise Images & Sound in Memory & Storage for GCSE Computer Science with 18 exam-style questions and 16 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 4 of 11 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 11
Practice
18 questions
Recall
16 flashcards
Image Representation - Bitmap Graphics
How Bitmap Images Work:
- Pixel: Smallest unit of an image (picture element)
- Grid: Image is a 2D grid of pixels (e.g., 1920×1080 = 2,073,600 pixels)
- Color: Each pixel stores RGB values (Red, Green, Blue)
- Storage: Store every pixel's color = large files!
Key Image Properties:
1. Resolution (Width × Height):
- 1920×1080: Full HD (2.1 megapixels)
- 3840×2160: 4K UHD (8.3 megapixels)
- 4000×3000: 12 megapixels (typical phone camera)
- Higher resolution: More detail but larger file
2. Color Depth (Bits per Pixel):
- 1-bit: Black or white (2 colors)
- 8-bit: 256 colors or grayscale
- 16-bit: 65,536 colors (old games)
- 24-bit (True Color): 16.7 million colors (8 bits per RGB channel)
- 32-bit: 24-bit + 8-bit alpha (transparency)
RGB Color Mixing (24-bit):
Each pixel: Red (8 bits) + Green (8 bits) + Blue (8 bits) = 24 bits total Red (255, 0, 0) = pure red Green (0, 255, 0) = pure green Blue (0, 0, 255) = pure blue Yellow (255, 255, 0) = red + green White (255, 255, 255) = all colors max Black (0, 0, 0) = no color Total possible colors: 256 × 256 × 256 = 16,777,216 colors