Cropping removes the parts of an image you do not need, so it can fill a differently shaped space without being distorted. It appears in practical tasks that ask for a picture to fit a frame, column or banner.
All file names, sizes and documents in this lesson are invented for practice. Menu names differ between programs and versions, so the steps below describe the feature, not one brand’s buttons.
What is the difference between cropping and resizing?
Resizing scales the whole image, keeping everything but changing its size. Cropping cuts away edges, keeping the original pixel scale but losing content. Stretching, which means changing width and height by different factors, is neither: it damages the shape.
When the picture and the space have different ratios, crop first to the ratio of the space, then resize to the exact size (resizing is covered here).
How do you crop to a required shape?
- Note the target ratio, such as 1 : 1 for a square or 4 : 3.
- Keep the full length of the shorter side.
- Calculate the length of the other side: shorter side × target ratio.
- Remove the extra equally from both sides unless the subject sits off-centre.
- Resize to the final size with the ratio locked.
Worked example
An invented photo sports_day.jpg is 1800 × 1200 pixels. The notice needs a square 400 × 400.
Step 1: a square ratio means width equals height. The shorter side is 1200, so keep a 1200 × 1200 area.
Step 2: remove 1800 − 1200 = 600 pixels of width, which is 300 from each side. Check where the main subject is first. If it is off-centre, move the crop box instead of centring it.
Step 3: resize 1200 × 1200 to 400 × 400, scale factor 400 ÷ 1200 = 1/3.
The mistake to watch for
The student types 400 for both width and height without cropping.
Mistaken result: the width shrinks by a factor of 0.222 and the height by 0.333, so people look tall and narrow.
The correction is to crop to the target ratio first. Cropping loses some content, so choose the crop box deliberately and keep the important subject inside it. Keep a copy of the original file, because cropping is easier to undo before you save over it.
Check yourself
1. A 1600 × 900 image must be cropped to a 4 : 3 shape using the full height. What width remains, and how much is removed in total?
Show answer
Height 900, so width = 900 × 4/3 = 1200. Removed = 1600 − 1200 = 400 pixels in total. Result: 1200 × 900.
2. A portrait photo is 1200 × 1600. It must become a square. Which dimension is cropped and to what length?
Show answer
The shorter side is the width, 1200. Crop the height from 1600 to 1200, removing 400 in total.
3. Give one sign that a picture has been stretched rather than cropped.
Show answer
Circles look like ovals, or people look unnaturally wide or narrow. A cropped picture keeps true proportions.
Where this leads next
Move on to Apply a reusable text style to keep text as tidy as your images. The module guide shows the full order, and the practical task and evidence checker helps you confirm requirements.
Students often follow each step in a lesson but lose marks when the same skill sits inside a longer practical task. Our teachers look for exactly that pattern in online one-to-one ICT tuition.