Resizing and compression are related but different. Resizing changes pixel dimensions, while compression changes how efficiently those pixels are stored. Understanding the difference helps you avoid huge files, blurry images and unnecessary repeated editing.
Resize when the dimensions are larger than needed
A 5000-pixel photograph displayed in a 900-pixel content column usually contains far more pixels than the page can show at once. Reducing dimensions can dramatically lower file size before compression is even considered.
Compress after the target size is known
Lossy formats such as JPEG and WebP can discard visual detail to save space. The right quality setting depends on the image. Smooth photographs tolerate compression differently from screenshots, diagrams and text-heavy graphics.
Crop before resize when composition needs to change
If you know the final aspect ratio, crop first so you are not resizing pixels that will later be discarded. Then resize to the intended dimensions and apply final compression. This also makes comparison easier because each export has the same composition.
Choose the format for the content
JPEG remains practical for many photographs. PNG is useful for crisp graphics and transparency but can be large for photos. WebP often provides efficient web delivery. Keep an original or high-quality master when future editing is likely.
Worked example
Example workflow
A 5000×3333 photo will display at 1200 pixels wide. Crop to the final composition, resize to roughly the required display width, export a WebP or JPEG copy, then compare quality at normal page size.
Practical checklist
Before you finish
- Crop → resize → compress is a useful default workflow.
- Compare exports at the actual display size.
- Do not repeatedly save a lossy JPEG through multiple editing cycles.
- Keep a master copy before web optimization.
Common mistakes
What to avoid
- Compressing a 5000-pixel photo without first asking whether the page only needs 1200 pixels.
- Repeatedly editing and resaving a lossy JPEG.
- Cropping after all optimization and forcing another export.
- Judging a web image only at extreme zoom.
Further reading from authoritative sources
Use these references when you need the underlying specification or platform guidance.