画像圧縮とCore Web Vitalsの改善

このガイドの本文は英語です。

Google’s Core Web Vitals directly impact organic search rankings, and Largest Contentful Paint (LCP) is the hardest metric for image-heavy websites to pass. A hero banner or product photograph can be the LCP element.

1. The Real Cost of Uncompressed Hero Images

To achieve a "Good" LCP score, your main above-the-fold visual must render within 2.5 seconds even on a throttled 4G mobile connection. A single 2.5MB PNG banner takes over 3 seconds just to transfer over mobile networks, immediately triggering a poor PageSpeed Insights score.

2. The 3-Step LionPress SEO Workflow

• Cap Maximum Dimensions: Never serve a 4000px camera original in a 1200px container. Use the Max Width selector in LionPress to cap hero images at 1920px and blog visuals at 1280px.
• Target the 76% Perceptual Sweet Spot: Our default Balanced (76%) preset can reduce byte weight; review the actual file size and compare the output because savings and visual quality vary.
• Serve Next-Gen Formats: Switch the Output Format dropdown to Convert to WebP to compare the actual output size with JPEG and PNG files.