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画像フォーマット、圧縮、ウェブパフォーマンスに関するガイド。

How-To Guides

Learn how to convert HEIC photos from your iPhone to JPG format on any device — no app downloads required.

Exact pixel dimensions for Instagram, Facebook, YouTube, LinkedIn, Twitter/X, TikTok, and Pinterest in 2026.

The exact crop ratios for every Instagram format — feed posts, Stories, Reels, carousels — and how to crop without losing the subject.

PNG or JPG? We break down the differences, pros and cons, and when to use each format for web, print, and social media.

WebP explained: what it is, how it compares to JPG and PNG, browser support, and when you should use it.

A complete guide to image formats — what each one is for, when to use it, and how they compare for web, mobile, and print.

A practical guide to compressing images for faster websites — the right tools, settings, and formats to use in 2026.

Exact recommendations for image dimensions, file sizes, and formats to maximize website speed and Core Web Vitals scores.

A practical guide to JPEG quality levels — what 50%, 75%, 85%, and 95% actually look like and when to use each.

The best free online tools for converting, compressing, resizing, and editing images — all without creating an account.