Image search is a traffic channel many sites ignore. The crawling logic of Baidu Images and Google Images is not mysterious: can it be crawled, does the engine know what it is, and does it load quickly? Get those three right and you rank.
1. Stop naming files IMG_0001
Rename IMG_20261012_093311.jpg to one-inch-id-photo-white-background.jpg, and the search engine can read the content straight from the URL. For Chinese sites, use pinyin or English so the URL does not turn into a string of percent signs.
2. Alt is required, not optional
- Say what it is, without keyword stuffing:
alt="One-inch ID photo on a white background (295x413)"; - Purely decorative images get
alt=""so screen readers skip them; - On a page with several images, never repeat the same alt -- describe the difference.
3. Dimensions and file size
If an image is displayed 800 px wide, do not upload the 4000 px original. Resize to 1.5-2x the display size before uploading: sharp on high-DPI screens without wasting bandwidth. Keep each file under 200 KB, and above-the-fold images under 100 KB.
4. Switch to WebP with a fallback
WebP is about 30% smaller than JPG at the same quality. Give older browsers a way out:
<picture>
<source srcset="a.webp" type="image/webp">
<img src="a.jpg" alt="Description" width="800" height="600" loading="lazy">
</picture>Always set width and height, which stops the layout jumping before the image loads (the CLS metric).
5. Only lazy-load below the fold
loading="lazy" defers images outside the viewport, but adding it to the hero image makes it slower and can hurt your LCP score. Use loading="eager" for above-the-fold images, or leave the attribute off.
6. Add structured data
Product and tutorial images can carry ImageObject structured data declaring the content, author and copyright, which helps richer presentation in image search results.
7. Do not forget the sitemap
If a site has many images, add the image:image extension to the sitemap and submit image URLs with titles -- crawling efficiency improves noticeably.