jpg quality: 28
cwebp quality: 40
jxl quality: 37
avifenc quality: 38

Saving file 'out.webp'
File:      in.png
Dimension: 960 x 769
Output:    25516 bytes Y-U-V-All-PSNR 37.56 41.66 42.14   38.58 dB
           (0.28 bpp)

JPG CVVDP= 9.00 Fsize= 44.5 KB [ cjpeg -baseline -sample 1x1,1x1,1x1 -quality 28 ]

Webp CVVDP= 9.00 Fsize= 24.9 KB [ cwebp -m 6 -af -q 40 ]

JXL CVVDP= 9.01 Fsize= 21.1 KB [ cjxl -e 10 -q 37 ]

AVIF CVVDP= 8.99 Fsize= 14.3 KB [ avifenc -y 420 -d 10 -s 0 -q 38]


WebP compression efficiency relative to [ JXL:  83.8 % ] & [ AVIF: 64.9 % ]