Compress original image

WordPress media editor, by WP design, preserves original image compression & quality as source for all theme sizes/thumbnails and for image editor (crop/flip/resize).
Compression applies only on images derived from original, not on original.
Else each “regenerate thumbnails” from compressed original image would further degenerate quality of derived thumbnails (would not be repeatable with same result as first time after upload).

In example, regenerating thumbnails from 50% reduced original would generate 50% of 50%, which is 25% quality.

In addition, original would loose quality each time is re-compressed again.

Solution: Do not use original on the www, use one of generated sizes/thumbnails or WebP image created from original.

• This reply was modified 4 years, 11 months ago by ddur.

@kovacserik

Actually, when you apply server rewrite rules (see plugin help on settings page), browsers that do send “image/webp” in the HTTP: “Accept:” header, will be automatically served with “WebP” image, which is created both for “original image” and for “thumbnails” (other image sizes).