ガイド
圧縮前に画像をリサイズすべきタイミング
圧縮だけでなく先にリサイズした方が良いケースをわかりやすく解説します。
容量の原因は圧縮不足より、サイズ過剰であることが少なくありません。表示幅に合わせてから圧縮する方が品質を守りやすいです。
Why dimensions matter more than many teams expect
A 3200px image shown at 900px carries unnecessary pixel data.
That extra data increases transfer size and often forces harsher compression settings later.
Clear signs you should resize first
Use resizing first when source dimensions are much larger than layout width or when quality drops quickly under compression.
- Hero image rendered far smaller than source.
- Blog inline image looks tiny in layout but file is large.
- Text in screenshots becomes blurry at lower quality settings.
Simple resize-then-compress workflow
Set width close to maximum display width, then run compression with moderate settings.
This sequence usually preserves detail better than aggressive compression on oversized files.
How to decide target dimensions
Check your page layout and pick practical widths for each image slot.
Keep a few standard sizes for thumbnails, inline visuals, and hero images to reduce guesswork.
Final quality check before upload
Preview the resized and compressed image in the actual page draft.
If details still look clear on mobile and desktop, your workflow is ready to reuse.
When this guide helps
- You upload high-resolution originals to relatively small layouts.
- Compressed files still feel too heavy.
- Images look soft after strong compression.
- You need a repeatable pre-upload workflow.
Resize first in most web workflows
If display size is much smaller than source size, resize first. Then apply moderate compression and validate the result in real page context.