Why is "Enlarging a bitmap and expecting no quality loss." a common mistake in Graphics?

Why it happens: Assuming all images scale freely. How to avoid it: Bitmaps pixelate when enlarged beyond their resolution. Use VECTORS for things that must scale (logos). Source: Edexcel 4IT1 examiner reports.

Why is "Distorting images by resizing non-proportionally." a common mistake in Graphics?

Why it happens: Dragging one side handle. How to avoid it: Lock the aspect ratio; apply the same scale factor to width and height. Source: Edexcel 4IT1 examiner reports.

Why is "Using the wrong format (e.g., PNG for large photos)." a common mistake in Graphics?

Why it happens: Not knowing format strengths. How to avoid it: JPG/WebP for photos (small), PNG for transparency/lossless, SVG for scalable logos.

Why is "Over-compressing and ruining quality." a common mistake in Graphics?

Why it happens: Chasing the smallest file. How to avoid it: Balance quality vs size — tune the compression/quality setting; aim for the smallest file that still looks good.

Why is "Editing destructively with no editable master." a common mistake in Graphics?

Why it happens: Editing the only copy directly. How to avoid it: Use layers and keep an editable master file so changes are reversible.

Software SkillsPearson Edexcel IGCSE ICT 4IT1

Graphics

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Graphics Software — Edexcel IGCSE ICT (4IT1) Detailed Notes

Working with images: bitmap vs vector, resolution and colour depth, file size, formats and compression, editing tools, and producing fit-for-purpose graphics.

What you’ll learn

Mapped to the Pearson Edexcel IGCSE 4IT1 syllabus (2026 onwards).

Distinguish bitmap and vector graphics.
Explain resolution and colour depth.
Calculate bitmap file size and colours.
Choose appropriate file formats and compression.
Use editing tools (crop, resize, layers, adjustments).
Produce graphics fit for print and web.

Bitmap vs vector

Pixels vs mathematical shapes.

Bitmap (raster) image — made of a grid of PIXELS.

Great for PHOTOS and detailed/complex images.
Fixed resolution → enlarging beyond it causes PIXELATION (blur).
Examples: JPG, PNG, GIF, BMP. Editors: Photoshop, GIMP.

Vector image — defined by MATHEMATICAL shapes (lines, curves, fills).

Scales to ANY size with NO quality loss.
Ideal for LOGOS, icons, diagrams, maps.
Usually small files; cleanly editable.
Examples: SVG, AI, EPS. Editors: Illustrator, Inkscape.

Choosing: photographs → bitmap; anything that must scale to many sizes (logo on a card AND a billboard) → vector.

Tip: design a logo as a vector master, then EXPORT bitmap versions (PNG/JPG) at the exact sizes needed.

Resolution and colour depth

What determines detail and file size.

Resolution — the number of pixels (e.g., 1,920 × 1,080) or pixel density (DPI/PPI). Higher resolution = more detail but larger files.

~300 DPI for print; ~72 DPI for screens.

Colour depth — the number of bits used per pixel. It sets how many colours are possible:

Number of colours = 2^(colour depth).
1-bit = 2 colours; 8-bit = 256; 24-bit ≈ 16.7 million ('true colour').

Effect on file size:

More pixels (resolution) AND more bits per pixel (colour depth) → BIGGER files.
Reducing either shrinks the file but lowers quality.

Bitmap file size (bits) = width × height × colour depth. Divide by 8 for bytes, by 1,024 for KB. (Vectors don't follow this — their size depends on the number of shapes.)

Formats and compression

Pick the right format; balance quality vs size.

Compression reduces file size:

Lossy (JPG) — discards data the eye barely notices; small files; quality drops with heavy compression.
Lossless (PNG, GIF) — preserves all data; larger than lossy for photos.

Common formats:

JPG — compressed PHOTOS; small; lossy.
PNG — lossless + TRANSPARENCY; good for logos/graphics on the web.
GIF — simple animation; limited colours (256).
SVG — VECTOR; scales infinitely; small for simple graphics.
WebP — modern, efficient (lossy or lossless).
BMP / TIFF — uncompressed/lossless masters (large).

Trade-off: more compression = smaller/faster but more artefacts; less = better quality but larger. Aim for the SMALLEST file that still looks good.

For web: JPG/WebP photos at display size and 72 DPI; thumbnails + lazy loading for galleries.

Editing tools

Edit precisely and non-destructively.

Core tools:

Crop — remove unwanted edges.
Resize / scale — change dimensions (PROPORTIONALLY to avoid distortion).
Rotate / flip — orientation.
Selection tools (marquee, lasso, magic wand) — select an area to edit (e.g., remove a background).
Layers — stacked, independently editable parts; allow NON-DESTRUCTIVE editing.
Adjustments — brightness, contrast, saturation, colour balance.
Fill / gradient, clone / heal (remove blemishes), filters/effects, text.

Non-destructive workflow:

Work on LAYERS, keep the original intact.
Save an EDITABLE master (e.g., PSD) so future edits are easy.
Export flattened versions (JPG/PNG) for use.

This lets you make precise, reversible edits and produce different outputs from one master.

Producing fit-for-purpose graphics

Right format and quality for each medium.

Match the image to its USE:

Print:

High resolution (~300 DPI).
Lossless/master formats (TIFF/PNG) or PDF.
Larger files acceptable.

Web/screen:

~72 DPI; resized to display dimensions.
Compressed JPG/WebP (or PNG for transparency) for fast loading.
Small files matter for speed and mobile users.

Logos/branding:

VECTOR master (scales to any size); export bitmaps as needed.

The goal: the best-looking image at an appropriate file size for the medium — high quality for print, small and fast for web. Choosing the wrong format or resolution (e.g., a huge uncompressed photo on a web page) is a common fitness-for-purpose failure.

How it’s examined

Paper 1: Distinguish bitmap vs vector (4–6 marks); define resolution/colour depth (4 marks); calculate file size or colours (5–6 marks); choose a format (4–6 marks); explain compression trade-offs (6 marks).

Paper 2 (practical): Edit images — crop, resize, use layers, adjust colours, remove backgrounds, and export in the correct format for the purpose.

Frequent stems: 'State the difference between bitmap and vector…', 'Calculate the file size of…', 'Name the most suitable file format for…', 'Explain one advantage of vector graphics…'

Sources: Pearson Edexcel International GCSE in Information and Communication Technology (4IT1) Specification — Issue 3; Edexcel 4IT1 Examiner Reports (2022–2024). Last reviewed 2026-05-20.

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Worked examples, formulae, definitions and the mistakes examiners flag — everything you need to push from a pass to an A*.

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Step-by-step worked examples — Graphics

Step-by-step solutions to past-paper-style questions on graphics, written exactly the way a tutor would explain them at the board.

1Classify each image as bitmap or vector
Getting started• Edexcel 4IT1 style — short-answer (6 marks)• bitmap-vector, AO1
Question
Classify as best suited to bitmap or vector: (a) A detailed photograph. (b) A company logo that must scale to a billboard. (c) A scanned painting. (d) A simple line diagram/icon. (e) A map with smooth scalable shapes. (f) An edited selfie.
Step-by-step solution
1. Step 1
  Photos/detail = bitmap; scalable shapes/logos = vector.
Answer
(a) Bitmap (photo detail).

(b) Vector (logo — scales without quality loss).

(c) Bitmap (scanned image).

(d) Vector (line diagram/icon).

(e) Vector (scalable shapes).

(f) Bitmap (photo).
Examiner tip
Bitmap = grid of pixels (great for photos, loses quality when enlarged). Vector = maths-defined shapes (scales perfectly, great for logos/diagrams).
2Choose the best image format
Building confidence• Edexcel 4IT1 style — short-answer (6 marks)• formats, AO1
Question
Name the best format: (a) A photo for a website (small file). (b) A logo needing transparency, lossless. (c) A scalable vector logo. (d) A short looping animation. (e) An uncompressed high-quality master. (f) An icon that must scale to any size.
Step-by-step solution
1. Step 1
  Match purpose to format strengths.
Answer
(a) JPG (compressed photos).

(b) PNG (lossless, transparency).

(c) SVG (vector).

(d) GIF (simple animation).

(e) BMP / TIFF (uncompressed/lossless master).

(f) SVG (vector, scales infinitely).
Examiner tip
JPG = lossy photos; PNG = lossless + transparency; GIF = animation/limited colours; SVG = vector. Know which fits which job.
3Identify the editing tool/feature
Building confidence• Edexcel 4IT1 style — short-answer (5 marks)• tools, AO1
Question
Name the tool/feature: (a) Remove unwanted edges of an image. (b) Stack editable parts independently. (c) Select an area to edit. (d) Make an image smaller in dimensions. (e) Adjust how light/dark an image is.
Step-by-step solution
1. Step 1
  Recall standard editing tools.
Answer
(a) Crop.

(b) Layers.

(c) Selection tool (marquee/lasso).

(d) Resize / scale.

(e) Brightness adjustment.
Examiner tip
Key tools: crop, resize, layers, selection, brightness/contrast, fill, rotate/flip, filters, clone/heal.
4Calculate proportional resizing
Building confidence• Edexcel 4IT1 style — calculation (5 marks)• resize, AO2
Question
An image is 2,000 × 1,500 pixels. It must be resized to 800 pixels wide, keeping proportion. Calculate: (a) The scale factor. (b) The new height. (c) State what happens to quality if a small bitmap is instead ENLARGED.
Step-by-step solution
1. Step 1
  Scale factor = new ÷ old; apply to height.
Answer
(a) Scale factor = 800 ÷ 2,000 = 0.4 (40%).

(b) New height = 1,500 × 0.4 = 600 pixels (so 800 × 600).

(c) Enlarging a bitmap beyond its resolution makes it pixelated/blurry — pixels are stretched, so quality drops. (Vectors don't suffer this.)
Examiner tip
Resize proportionally with one scale factor. Enlarging bitmaps loses quality (pixelation); vectors scale losslessly.
5Calculate bitmap file size from resolution and colour depth
Higher• Edexcel 4IT1 style — calculation (6 marks)• file-size, AO2, AO3
Question
A bitmap is 1,000 × 800 pixels with 24-bit colour depth. Calculate: (a) Total pixels. (b) File size in bits. (c) File size in bytes, then in KB (1 KB = 1,024 bytes), to 1 d.p. (ignore headers/compression).
Step-by-step solution
1. Step 1
  Pixels × bits-per-pixel = bits; ÷8 = bytes; ÷1,024 = KB.
Answer
(a) Pixels = 1,000 × 800 = 800,000 pixels.

(b) Bits = 800,000 × 24 = 19,200,000 bits.

(c) Bytes = 19,200,000 ÷ 8 = 2,400,000 bytes; KB = 2,400,000 ÷ 1,024 = 2,343.8 KB (≈ 2.29 MB).

Higher resolution and colour depth → larger files. This is the standard 4IT1 file-size formula.
Examiner tip
File size (bits) = width × height × colour depth. ÷8 for bytes, ÷1,024 for KB. A classic Higher-tier calculation.
6Calculate colours from colour depth
Higher• Edexcel 4IT1 style — calculation (5 marks)• colour-depth, AO2
Question
Calculate the number of colours represented by: (a) 1-bit colour depth. (b) 8-bit colour depth. (c) 24-bit colour depth. (d) State the effect of reducing colour depth on file size and image quality.
Step-by-step solution
1. Step 1
  Number of colours = 2^(colour depth).
Answer
(a) 2^1 = 2 colours (black/white).

(b) 2^8 = 256 colours.

(c) 2^24 = 16,777,216 colours (~16.7 million, 'true colour').

(d) Reducing colour depth → smaller file size but lower quality (fewer colours, possible banding).
Examiner tip
Colours = 2^(bits). 1-bit=2, 8-bit=256, 24-bit≈16.7 million. Lower depth = smaller file, lower quality.
7Plan an image edit for a poster
Higher• Edexcel 4IT1 style — extended (8 marks)• photo-edit, AO1, AO2
Question
A designer must turn a raw photo into a poster image: remove the background, add the company logo, adjust colours, and prepare versions for print and web. Describe the tools and steps.
Step-by-step solution
1. Step 1
  Crop/select → layers → adjust → export appropriately.
Answer
1. Work non-destructively.

Open the photo; duplicate it / use LAYERS so the original is preserved and parts edit independently.

2. Remove the background.

Use a SELECTION tool (magic wand/lasso/quick-select) to select the subject; delete or mask the background.

3. Crop and resize.

CROP to the poster composition; resize proportionally to the required dimensions.

4. Add the logo.

Insert the logo on its own layer (a VECTOR/PNG with transparency); position and scale it.

5. Adjust colours.

Adjust brightness/contrast, saturation and colour balance for impact and consistency with brand colours.

6. Export the right versions.

Print: high resolution (e.g., 300 DPI), lossless/master format (TIFF/PNG) or PDF.

Web: lower resolution (72 DPI), compressed JPG/PNG/WebP for a small, fast-loading file.

7. Keep an editable master.

Save the layered project file (e.g., PSD) so future edits are easy.

Why this works: layers + selections allow precise, reversible editing; exporting different versions makes the image FIT FOR PURPOSE for each medium (high quality for print, small size for web).
Examiner tip
A* answers (1) use LAYERS (non-destructive), (2) name selection/crop/resize tools, (3) export DIFFERENT versions for print (high-res) vs web (compressed), (4) keep an editable master.
8Explain bitmap vs vector for a branding project
Higher• Edexcel 4IT1 style — explain (6 marks)• bitmap-vector, AO1, AO2
Question
A company needs ONE logo that will appear on business cards, a website, and a large building sign. Explain whether the logo should be bitmap or vector and why.
Step-by-step solution
1. Step 1
  Compare scalability, file size, editability for the use cases.
Answer
The logo should be a VECTOR.

Why vector wins here:

Scalability: vectors are defined by mathematical shapes, so they scale to ANY size — from a tiny business card to a huge building sign — with NO loss of quality. A bitmap would become pixelated/blurry when enlarged to sign size.

File size: simple vector logos are usually small.

Editability: colours and shapes can be edited cleanly.

Crispness: sharp edges at every size.

Why NOT bitmap:

A bitmap has a fixed pixel resolution; enlarging it for the building sign would pixelate it.

Multiple bitmap sizes would be needed for each use.

Practical approach:

Design the logo as a VECTOR (SVG/AI).

Export bitmap versions (PNG/JPG) at the exact sizes needed for the website and print where required.

Conclusion: vector is fit for purpose because the SAME logo must work at many sizes without quality loss.
Examiner tip
Vector = scalable maths-defined shapes (logos/diagrams). The killer reason here is SCALABILITY across sizes. Note you can export bitmaps from a vector master.
9Choose formats and compression for a website gallery
Stretch• Edexcel 4IT1 style — extended (8 marks)• formats-compression, AO2, AO3
Question
A photographer is building a website gallery of 100 photos. They want good quality but fast loading. Describe the formats, compression and settings you would use and the trade-offs.
Step-by-step solution
1. Step 1
  Balance quality vs size; choose formats, compression, resolution.
Answer
1. Choose the format.

JPG (or WebP) for the photos — lossy compression gives small files at good quality; ideal for photographs.

Use PNG only where transparency/lossless is needed (e.g., a logo overlay), as PNG photos are larger.

2. Apply compression.

Lossy compression removes data the eye barely notices. Tune the QUALITY setting (e.g., 70–80%) to balance size vs quality.

Trade-off: more compression = smaller/faster but more artefacts; less compression = better quality but larger/slower.

3. Resize to display size.

Don't upload full-resolution camera files; resize to the dimensions actually shown (plus thumbnails).

Use small THUMBNAILS in the gallery grid; load full images only when clicked (lazy loading).

4. Resolution.

72 DPI is fine for screens; high print DPI is unnecessary online and wastes size.

5. Result.

100 optimised photos load quickly while still looking good.

Trade-off summary: the goal is the smallest file that still looks good — quality vs file size vs load speed. JPG/WebP + sensible compression + correct sizing achieves all three.
Examiner tip
A* answers (1) pick JPG/WebP for photos (lossy), PNG for transparency, (2) explain the quality-vs-size TRADE-OFF, (3) resize/thumbnail and use correct resolution, (4) tie it to load speed.

Key Formulae — Graphics

The formulae you need to memorise for graphics on the Pearson Edexcel IGCSE 4IT1 paper, with every variable defined in plain English and a note on when to use it.

Proportional resize
$New dimension = old dimension × scale factor (scale factor = new width ÷ old width)$
When to use
Resizing without distortion.
Example
1,500 × (800 ÷ 2,000) = 600 px.
Bitmap file size
$File size (bits) = width × height × colour depth$
When to use
Estimating uncompressed bitmap size.
Example
1,000 × 800 × 24 = 19,200,000 bits = 2,343.8 KB.
Colours from colour depth
$Number of colours = 2^(colour depth in bits)$
When to use
Finding how many colours a depth represents.
Example
2^24 = 16,777,216 colours.

Key Definitions and Keywords — Graphics

Definitions to memorise and the exact keywords mark schemes credit for graphics answers — sharpened from recent examiner reports for the 2026 Pearson Edexcel IGCSE 4IT1 sitting.

Bitmap (raster) image
Examiner keyword
An image made of a grid of pixels; great for photos but loses quality when enlarged.
Vector image
Examiner keyword
An image defined by mathematical shapes; scales to any size with no quality loss. Ideal for logos/diagrams.
Pixel
Examiner keyword
The smallest element of a bitmap image — a single coloured dot.
Resolution
Examiner keyword
The number of pixels in an image (e.g., 1,920 × 1,080) or pixel density (DPI/PPI). Higher = more detail and larger files.
Colour depth
Examiner keyword
The number of bits used per pixel; determines how many colours are possible (colours = 2^bits).
Compression
Examiner keyword
Reducing file size. Lossy (JPG) discards data; lossless (PNG) preserves all data.
Layers
Examiner keyword
Stacked, independently editable parts of an image, allowing non-destructive editing.
Crop
Removing unwanted outer areas of an image.
DPI / PPI
Dots/pixels per inch — pixel density; ~300 DPI for print, ~72 DPI for screens.
Transparency
Areas of an image with no colour, letting the background show through (supported by PNG/GIF/SVG).

Common Mistakes and Misconceptions — Graphics

The traps other students keep falling into on graphics questions — taken from recent Pearson Edexcel IGCSE 4IT1 examiner reports and mark schemes — and how to avoid them.

✕Enlarging a bitmap and expecting no quality loss.
Edexcel 4IT1 examiner reports.
Why it happens
Assuming all images scale freely.
How to avoid it
Bitmaps pixelate when enlarged beyond their resolution. Use VECTORS for things that must scale (logos).
✕Distorting images by resizing non-proportionally.
Edexcel 4IT1 examiner reports.
Why it happens
Dragging one side handle.
How to avoid it
Lock the aspect ratio; apply the same scale factor to width and height.
✕Using the wrong format (e.g., PNG for large photos).
Why it happens
Not knowing format strengths.
How to avoid it
JPG/WebP for photos (small), PNG for transparency/lossless, SVG for scalable logos.
✕Over-compressing and ruining quality.
Why it happens
Chasing the smallest file.
How to avoid it
Balance quality vs size — tune the compression/quality setting; aim for the smallest file that still looks good.
✕Editing destructively with no editable master.
Why it happens
Editing the only copy directly.
How to avoid it
Use layers and keep an editable master file so changes are reversible.

Practice questions

Exam-style questions with step-by-step worked solutions. Try one before checking the method.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Graphics

Short Study Notes in the form of Slides

Short Study Notes — Graphics

Detailed Notes

What you’ll learn

How it’s examined

1Classify each image as bitmap or vector

2Choose the best image format

3Identify the editing tool/feature

4Calculate proportional resizing

5Calculate bitmap file size from resolution and colour depth

6Calculate colours from colour depth

7Plan an image edit for a poster

8Explain bitmap vs vector for a branding project

9Choose formats and compression for a website gallery

Proportional resize

Bitmap file size

Colours from colour depth

Bitmap (raster) image

Vector image

Pixel

Resolution

Colour depth

Compression

Layers

Crop

DPI / PPI

Transparency

✕Enlarging a bitmap and expecting no quality loss.

✕Distorting images by resizing non-proportionally.

✕Using the wrong format (e.g., PNG for large photos).

✕Over-compressing and ruining quality.

✕Editing destructively with no editable master.

Practice questions

Past paper style quiz

Assess your understanding