Cambridge Syllabus Notes

Graphics Creation – Layers, Transform, and Alignment (Cambridge IGCSE/A‑Level IT)

1. Syllabus Mapping – What Is Covered?

Cambridge IT Syllabus Requirement	Status in These Notes	Additional Content Required
20.1 Overall concepts of graphics creation	Covered (layers, transforms, alignment, export)	None
20.2 File formats, raster vs. vector, colour models, resolution/DPI, colour depth, compression, ethical/legal issues	Partially – layers & export only	Conceptual overview, format comparison, copyright & security notes
21 Programming for the web – embedding graphics, responsive design	Not covered	Web‑ready graphics subsection
13 New and emerging technologies – AI‑assisted design, AR/VR, 3‑D printing	Not covered	Future‑tech box
5 e‑Security – copyright, watermarking, secure distribution	Not covered	e‑Security note
8 Spreadsheets – data‑driven graphics	Not covered	Spreadsheet graphics tip

2. Conceptual Overview

2.1 Raster vs. Vector

Raster (bitmap) – stores colour information for each pixel. Ideal for photographs, complex shading, but quality degrades when scaled. Common formats: PNG, JPEG, TIFF.
Vector – stores mathematical descriptions of shapes (lines, curves, fills). Scales indefinitely without loss of quality. Common formats: SVG, EPS, PDF (when vector‑based).

2.2 Colour Models

Model	Primary Uses	Key Characteristics
RGB (Red‑Green‑Blue)	Screen‑based media	Additive; values 0‑255 per channel.
CMYK (Cyan‑Magenta‑Yellow‑Key/Black)	Print production	Subtractive; percentages per channel.
HSL / HSV (Hue‑Saturation‑Lightness/Value)	Colour‑selection tools, UI design	Separates hue from intensity for easier adjustments.

2.3 Resolution, DPI, and Colour Depth

Resolution – number of pixels in width × height (e.g., 1200 × 300 px). Determines the level of detail.
DPI (dots per inch) – physical print density. 300 dpi is standard for high‑quality print; 72 dpi is typical for web.
Colour depth – bits per pixel (8‑bit = 256 colours, 24‑bit = ~16 million colours). Higher depth yields smoother gradients but larger file sizes.

2.4 File‑Format Comparison

Format	Type	Best Use	Pros	Cons
PNG	Raster	Web graphics with transparency	Lossless compression, alpha channel	Large files for photographs
JPEG	Raster	Photographs on the web	Adjustable compression, small size	Lossy – artefacts appear when re‑saving
TIFF	Raster	High‑resolution print	Lossless, supports layers (Photoshop)	Very large files, not web‑friendly
SVG	Vector	Icons, logos, responsive web graphics	Scalable, editable in text editor, small size	Limited support for complex raster effects
PDF	Hybrid	Print‑ready documents, vector artwork	Preserves fonts, vectors, and raster images	Requires PDF viewer for editing

3. Layers

3.1 Why Layers Matter

Think of layers as transparent sheets stacked in a specific order. Each sheet can contain one or more objects, allowing you to edit any part of a composition without affecting the others. This non‑destructive workflow is essential for complex designs and for meeting the Cambridge requirement to “create, edit and organise layers”.

3.2 Core Layer Operations

Action	Menu / Shortcut	Purpose
Create New Layer	Layer → New Layer (Ctrl + Shift + N)	Start a fresh sheet for a new element.
Rename Layer	Double‑click the layer name	Identify the layer’s content quickly.
Show / Hide	Eye icon next to layer (click)	Temporarily remove a layer from view.
Lock Layer	Layer → Lock (Ctrl + L)	Prevent accidental changes.
Re‑order (Bring Forward / Send Backward)	Layer → Arrange → Bring Forward / Send Backward (Ctrl + ])	Change stacking order.
Group Layers	Layer → Group (Ctrl + G)	Treat several layers as a single unit while keeping them editable.
Merge Layers	Layer → Merge Down (Ctrl + E)	Combine two adjacent layers permanently.
Adjust Opacity	Opacity slider in Layers panel (0‑100 %)	Make a layer semi‑transparent.
Apply Blending Mode	Blend Mode dropdown (Normal, Multiply, Screen, Overlay, Difference, …)	Control how a layer interacts colour‑wise with layers beneath it.
Smart Object	Layer → Smart Object (Ctrl + Shift + Alt + S)	Encapsulate raster or vector data for non‑destructive scaling, filtering and warping.
Adjustment Layer	Layer → New Adjustment Layer → [Brightness/Contrast, Hue/Saturation, …]	Apply colour or tonal changes to all layers beneath without altering the original pixels.

3.3 Smart Objects vs. Adjustment Layers

Smart Object – preserves the original pixel data. Ideal when you need to resize, rotate or apply filters repeatedly. The content can be edited later by double‑clicking the thumbnail.
Adjustment Layer – does not contain pixel data; it stores parameters (e.g., “+20 % contrast”). It affects every visible layer underneath, making it perfect for global colour correction.

3.4 Blending‑Mode Quick Reference

Mode	Result
Normal	Displays the top layer unchanged.
Multiply	Darkens – multiplies colour values; useful for shadows.
Screen	Lightens – opposite of Multiply; good for highlights.
Overlay	Combines Multiply and Screen; boosts contrast.
Difference	Subtracts colour values, creating a high‑contrast “inverted” effect.

3.5 Typical Layer Workflow (A‑Level Example)

Create a new layer for each logical element: Background, Header Image, Title Text, Call‑to‑Action Button.
Rename layers descriptively (e.g., “Header‑Image”).
Set the Background layer’s blending mode to Multiply and opacity to 80 % for a subtle texture.
Lock the background layer (Ctrl + L) before editing foreground objects.
Group Title Text and Button (Ctrl + G) so they move together.
Convert the button to a Smart Object – now you can resize it later without pixel loss.
If you need a global colour shift, add a Hue/Saturation Adjustment Layer above all layers.

3.6 Diagram Suggestion

Illustrate a stack of transparent sheets labelled “Background (80 % opacity, Multiply)”, “Header‑Image”, “Title‑Text”, “CTA‑Button (grouped)”.

4. Transform Tools

4.1 Understanding the Transformation Matrix

Every 2‑D transformation can be expressed by a $3\times3$ matrix:

$$\begin{bmatrix} a & b & c\\ d & e & f\\ 0 & 0 & 1 \end{bmatrix}$$

a, e – scaling factors (horizontal & vertical). Values > 1 enlarge; 0 < value < 1 shrink.
b, d – skew (shear) components. Positive b slants the shape rightward; negative b leftward. Positive d slants upward; negative d downward.
c, f – translation (movement) along X‑ and Y‑axes.

Negative scaling values flip the object (mirror) about the corresponding axis.

4.2 Transformation Tools Overview

Transformation	Tool / Shortcut	How to Use
Scale Uniformly	Shift + Drag corner (Ctrl + Shift + S)	Hold `Shift` to keep the aspect ratio.
Scale Non‑Uniformly	Drag side handle (Ctrl + S)	Stretch width or height independently.
Rotate	Hover near a corner until rotate cursor appears (Ctrl + R)	Drag to the desired angle; hold `Alt` to rotate about the centre.
Rotate by Exact Angle	Options bar → Angle field (or Ctrl + Alt + R)	Enter a numeric value such as “45°”.
Skew / Shear	Right‑click → Transform → Skew (Ctrl + K)	Enter horizontal and vertical shear values.
Flip Horizontal / Vertical	Object → Flip Horizontal (Ctrl + H) / Flip Vertical (Ctrl + V)	Mirror the object across the chosen axis.
Perspective / Distort	Object → Perspective (Ctrl + P) / Distort (Ctrl + D)	Drag each corner independently for a 3‑D effect.
Free‑Transform	Ctrl + T (or Object → Free‑Transform)	Combine scale, rotate, skew and perspective in one step; numeric entry available in the options bar.
Set Transform Origin (Pivot)	Click the centre‑point icon that appears when a transform box is active.	Move the pivot to any corner, edge or custom point before rotating or scaling.

4.3 Practical Transform Exercise

Resize a company logo to 150 % of its original size, rotate it exactly 30°, then apply a slight perspective so the left side appears closer.

Select the logo layer.
Press Ctrl + T. In the options bar set Scale X = 150 % and Scale Y = 150 %.
Enter Angle = 30° and press Enter.
Switch to Perspective mode (Ctrl + P) and drag the left‑hand corner inward until the desired depth is achieved.
Confirm the transformation. The Info panel will now show the updated matrix values (e.g., a = 1.5, e = 1.5, c ≈ ‑30, f ≈ ‑15).

4.4 Diagram Suggestion

Show a square undergoing (a) uniform scaling, (b) 30° rotation, (c) perspective distortion, each accompanied by its $3\times3$ matrix.

5. Alignment, Distribution & Grid Tools

5.1 Alignment Options

Horizontal: Align Left, Align Centre, Align Right.
Vertical: Align Top, Align Middle, Align Bottom.
Reference: Align to Selection, Page/Canvas, Margins or Grid.

5.2 Distribution Options

Horizontal Space Evenly – equal gaps between left/right edges.
Vertical Space Evenly – equal gaps between top/bottom edges.
Distribute Centres – centre points are spaced equally.
Distribute with Fixed Gap – specify an exact pixel distance.

5.3 Alignment & Distribution Shortcut Table

Command	Shortcut	Effect
Align Left	Ctrl + Alt + L	All selected objects share the leftmost X‑coordinate.
Align Centre (Horizontal)	Ctrl + Alt + C	Objects are centred horizontally within the reference.
Align Right	Ctrl + Alt + R	All share the rightmost X‑coordinate.
Align Top	Ctrl + Alt + T	All share the topmost Y‑coordinate.
Align Middle (Vertical)	Ctrl + Alt + M	Vertical centre alignment.
Align Bottom	Ctrl + Alt + B	All share the bottommost Y‑coordinate.
Distribute Horizontally	Ctrl + Alt + H	Equal horizontal gaps between adjacent objects.
Distribute Vertically	Ctrl + Alt + V	Equal vertical gaps between adjacent objects.
Distribute with Fixed Gap	Shift + Ctrl + Alt + H / V	Prompt for a specific pixel gap (e.g., 15 px).

5.4 Using the Grid and Snap

Show Grid: View → Show → Grid (Ctrl + ’).
Snap to Grid: View → Snap to Grid (Ctrl + Shift + ’).
Set Grid Spacing: Edit → Preferences → Guides & Grid – define major/minor divisions for precise layout work.
Snap to Guides: View → Snap to Guides – useful when you need a single alignment line rather than a full grid.

5.5 Practical Alignment Example – Banner Design

Create a 1200 × 300 px banner with three icons equally spaced along a baseline.

Create a new layer called “Banner‑Icons”.
Place the three icons roughly where you want them.
Select all three icons → Align Bottom (Ctrl + Alt + B) to line them on the same baseline.
Choose Distribute Horizontally (Ctrl + Alt + H) for equal gaps.
Turn on Snap to Grid and set the grid spacing to 20 px; verify that the leftmost and rightmost icons are exactly 20 px from the banner edges.
Group the icons (Ctrl + G) and rename the group “Header‑Icons”.

Diagram Suggestion

Show three icons before and after distribution, highlighting the baseline alignment and equal spacing.

6. Web‑Ready Graphics

Optimising for the web: use PNG‑8 for simple graphics with transparency, PNG‑24 for richer colours, and JPEG for photographs. Aim for ≤ 150 KB for fast loading.
Exporting SVG (vector): File → Export → Export As → SVG. Keep the code clean – remove unnecessary metadata if the file will be edited later.
HTML embedding:
```
<img src="logo.svg" alt="Company Logo" width="200">
```
Use the alt attribute for accessibility and SEO.
CSS background‑image example:
```
.hero { background: url('hero.jpg') no‑repeat center/cover; }
```
The cover keyword ensures the image fills the container while preserving aspect ratio.
Responsive design tip: export an SVG for icons (scales with viewport) and a set of raster images at different breakpoints (e.g., 1×, 2× for high‑DPI screens) using the srcset attribute.

7. Emerging Technologies (New & Emerging)

AI‑assisted up‑scaling – tools such as Adobe Super‑Resolution or open‑source ESRGAN can increase raster resolution without noticeable artefacts. Useful when a client supplies a low‑resolution logo.
Generative design – algorithms that create multiple layout variations based on constraints (colour palette, grid, hierarchy). Students can explore Adobe’s “Explore” feature or free tools like Canva Magic Resize.
AR/VR assets – export 2‑D graphics as PNG with transparent backgrounds or as GLTF textures for 3‑D models. Remember to keep texture sizes powers of two (256, 512, 1024 px) for optimal performance.
3‑D printing preparation – convert vector logos to STL or OBJ files via Illustrator’s “Export → 3D Model”. Ensure the design is watertight (no gaps) and set an appropriate wall thickness.

8. e‑Security & Copyright

Copyright awareness: only use images you have created, purchased, or that are clearly licensed for reuse (e.g., Creative Commons‑BY). Always give attribution where required.
Embedding metadata: File → File Info → Metadata tab – add author name, copyright notice, and usage rights. This travels with the file and helps prove ownership.
Watermarking: create a low‑opacity text or logo layer set to Overlay or Screen. Keep the watermark on a separate layer so it can be toggled off before final export.
Secure distribution: export the final composition as a password‑protected PDF (File → Save As → PDF → Security) or zip the file with AES‑256 encryption before sending to clients.

9. Spreadsheet‑Generated Graphics

Many A‑Level exams require you to incorporate charts created in a spreadsheet.

In Excel/Google Sheets, select the chart and choose Copy as Picture (or “Download as PNG”).
Paste the image into your graphics editor on a new layer.
Apply any required layer effects (e.g., a subtle drop‑shadow using Multiply at 30 % opacity) to match the surrounding design.
Export the final composition in the format specified by the exam (usually PNG at 300 dpi).

10. Summary Checklist for the Lesson

Layers: created, renamed, ordered, opacity/blending set, grouped or converted to Smart Objects/Adjustment Layers where appropriate.
Transformations: applied using mouse and/or numeric entry; pivot point correctly set; matrix values verified for complex transforms.
Alignment & Distribution: objects aligned to the chosen reference (selection, page, grid); gaps are equal or set to a specific value.
Export: final composition saved in the required format (PNG, JPEG, SVG, TIFF) with appropriate resolution (e.g., 300 dpi for print, 72 dpi for web).
Web & Security: file size optimised, metadata added, watermark applied if needed, and export settings match the intended delivery platform.

11. Assessment Questions

Explain why locking a background layer is useful when editing foreground objects, and give an example of a situation where you would unlock it again.
Given the transformation matrix $\displaystyle\begin{bmatrix}2 & 0 & 0\\ 0 & 3 & 0\\ 0 & 0 & 1\end{bmatrix}$, describe the visual effect on an object.
List the exact steps (including menu choices or shortcuts) required to centre a text box both horizontally and vertically within an A4‑size page.
Which shortcut would you use to distribute a set of shapes evenly along the vertical axis, and how would you modify the command to specify a fixed 15 px gap?
Describe how you would use blending modes and opacity to create a subtle drop‑shadow effect without adding a separate shape.
When would you choose to use a Smart Object instead of merging layers, and what advantage does it give for future edits?
Identify two raster file formats and two vector file formats, and state one advantage and one disadvantage of each.
Outline the steps to embed a graphic in an HTML page so that it scales responsively on mobile devices.
Briefly discuss one ethical or legal consideration when re‑using images found on the internet for a school project.
Explain how AI‑based up‑scaling could be used to improve a low‑resolution logo before it is placed on a printed poster.

Use graphics tools (layers, transform, alignment)