Description

Since Hugo v0.153.0, the per-image quality and hint parameters are ignored when encoding WebP images. The WASM-based WebP encoder always uses the global site configuration values instead of the per-image settings.

For example, $img.Resize "300x webp q10" produces the same output as $img.Resize "300x webp q90".

Reproduction

Minimal reproduction repository: https://github.com/simonheimlicher/hugo-webp-quality-bug

git clone https://github.com/simonheimlicher/hugo-webp-quality-bug
cd hugo-webp-quality-bug
hugo
ls -la public/images/*.webp

Actual behavior (v0.153.x)

All WebP files are identical (~49KB) regardless of requested quality:

-rw-r--r-- 49432 test_hu_..._q1.webp
-rw-r--r-- 49432 test_hu_..._q10.webp
-rw-r--r-- 49432 test_hu_..._q25.webp
-rw-r--r-- 49432 test_hu_..._q50.webp
-rw-r--r-- 49432 test_hu_..._q75.webp

Expected behavior

File sizes should vary with quality (verified with standalone cwebp):

• q1: ~6 KB
• q75: ~49 KB

Root cause

The WASM WebP encoder is initialized once with global config values. The codec.go EncodeTo method receives the correct per-image ImageConfig but doesn't pass quality/hint to the encoder.

Affected versions

• v0.153.0 through v0.153.4 (current)

Fix

PR #14315 addresses this issue.