IGCSE ICT: Images — Revision Notes

Topic 12 of Cambridge IGCSE ICT 0417 is about placing and editing images in documents, presentations and web pages: positioning precisely, resizing with or without keeping the aspect ratio, cropping, rotating, reflecting, adjusting brightness and contrast, and grouping or layering. You also need to know that an image’s file size can be reduced by lowering its resolution or colour depth. These skills are assessed through the practical tasks in Papers 2 and 3.

Condensed for revision. For the full explanation, use the images study guide, then try the images practice questions.

Syllabus coverage

Topic 12 has no numbered subtopics; the syllabus gives two content rows.

Syllabus content row	You should be able to / know
Place and edit an image	Place an image with precision; resize as specified to maintain or adjust the aspect ratio; crop; rotate; reflect (flip) horizontally or vertically; adjust brightness; adjust contrast; group and layer images including grouping and ungrouping, moving to the front or back
File size reduction	Recognise that reducing the file size can be achieved by reducing the image resolution or colour depth

Key definitions

Term	Meaning
Aspect ratio	The ratio of an image’s width to its height
Maintain aspect ratio	Resize so width and height change in proportion; the image is not distorted
Adjust aspect ratio	Change width and height independently; the image is stretched or squashed
Crop	Remove unwanted outer parts of an image; the remaining part keeps its scale
Rotate	Turn the image through an angle, for example 90° clockwise
Reflect (flip)	Mirror the image horizontally (left–right) or vertically (top–bottom)
Brightness	How light or dark the whole image is
Contrast	The difference between the light and dark areas
Group	Join several objects so they move and resize as one
Layer	The order in which overlapping objects are stacked (bring to front, send to back)
Resolution	The number of pixels in an image
Colour depth	The number of bits used to store the colour of each pixel

How do you place an image with precision?

• Use the position or layout settings to set the exact distance from the margin or page edge, or align it (left, centre, right) as the task says.
• Line the image up with a stated element, for example “top of the image aligned with the first line of the paragraph” or “to the right of the text”.
• Combine with text wrapping (Topic 13) — square or tight — so text flows around the image as instructed.

How do you resize an image correctly?

1. Open the size settings rather than dragging by eye when a measurement is given.
2. Lock aspect ratio when you are told to keep the proportions, then type one measurement (for example width 6 cm); the height changes automatically.
3. Unlock aspect ratio only when the task gives both a width and a height that do not match the original proportions.
4. Check the final size matches the instruction to the stated unit.

Dragging a corner handle usually keeps proportions; dragging a side handle distorts the image.

Crop, rotate and reflect

• Crop with the crop tool: drag the crop handles inwards to remove the part you do not need (for example, remove the sky to leave only the building). Cropping is not the same as resizing.
• Rotate by a stated angle using the rotate options or by typing the angle.
• Reflect: flip horizontal mirrors left–right (a person facing right will face left); flip vertical turns the image upside down as a mirror image. A vertical flip is not the same as a 180° rotation: the flip mirrors the picture, while the rotation does not.

Brightness and contrast

Use the picture correction tools to increase or decrease brightness or contrast by the amount specified, for example “increase brightness by 20%”. Brightness lightens or darkens every pixel; contrast makes light parts lighter and dark parts darker.

Grouping and layering

• Group several shapes or images (select them all, then group) so that they move, resize or copy together. Ungroup to edit one part.
• Bring to front / send to back (and forward/backward) controls which overlapping object is on top — for example a logo in front of a coloured rectangle.

How can an image’s file size be reduced?

Change	Effect on file size	Side effect
Reduce resolution (fewer pixels)	Fewer pixels to store, so the file is smaller	Image can look blocky (pixelated) when enlarged
Reduce colour depth (fewer bits per pixel)	Each pixel needs fewer bits, so the file is smaller	Fewer colours available, so colour changes look less smooth

Worked example (illustration)

An image is 1000 × 800 pixels with a colour depth of 24 bits. Size = 1000 × 800 × 24 = 19 200 000 bits = 2 400 000 bytes (about 2.4 MB) before compression. Halving the colour depth to 12 bits halves the size to about 1.2 MB. Halving the width and height to 500 × 400 cuts the number of pixels to a quarter, so the size falls to about 0.6 MB at 24 bits.

Common mistakes and exam traps

• Resizing without keeping the aspect ratio, so a photograph is stretched — a common reason for losing an image mark in the practical papers.
• Cropping when the task asks you to resize, or resizing when it asks you to crop.
• Confusing flip vertical with rotate 180°.
• Placing the image roughly instead of where the instruction says (alignment with text or margins).
• Saying a smaller display size on the page reduces file size. Only lowering the resolution or colour depth reduces the stored data.

Frequently asked questions

What does “maintain the aspect ratio” mean? It means changing the width and height in the same proportion, so the picture keeps its shape and is not distorted. Lock the aspect ratio and change only one dimension.

What is the difference between cropping and resizing? Cropping removes part of the image. Resizing keeps the whole image but makes it larger or smaller.

How do you reduce the file size of an image for a web page? Reduce its resolution (number of pixels) or its colour depth (bits per pixel). Both mean less data is stored, so the page loads faster.

Why group objects? Grouped objects behave as one, so a logo built from several shapes can be moved or resized without the parts moving out of place.

Self-test

1. Define aspect ratio.
2. Which handle should you drag to resize an image without distorting it?
3. Give the difference between flip horizontal and flip vertical.
4. Name the two ways listed in the syllabus of reducing an image’s file size.
5. A logo should appear on top of a coloured box. Which layering command is used?

Answers: 1 ratio of width to height; 2 a corner handle (or lock aspect ratio); 3 horizontal mirrors left–right, vertical mirrors top–bottom; 4 reduce resolution, reduce colour depth; 5 bring to front (or send the box to back).

Official syllabus

Cambridge International, Cambridge IGCSE Information and Communication Technology (0417) syllabus for 2026, 2027 and 2028, Version 3, Topic 12 “Images” (content rows: Place and edit an image; File size reduction).