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Research · field test · not indexed

Hero images a real business ships.

A storefront, the team, food, a landscape, a headshot, two product screenshots — at 1920 px, the way a founder exports them. Each was converted with the product defaults into AVIF + WebP + fallback at 640 / 1024 / 1600 / full width. The "after" pictures below are served with the generated <picture> + srcset markup, so your browser is downloading the variant that fits this column. See the measured hero demo page for the LCP case. Table and notes: docs/research/hero-images.md.

  • Hairdresser's shop front on a UK high street

    Hairdresser's shop front on a UK high street — original
    original JPG · 942 KB
    Hairdresser's shop front on a UK high street
    AVIF · 271 KB full · 28 KB at 640 px

    photo · 1920×1280 3.5× smaller

    AVIF 271 KB (PSNR 28.5, SSIM 0.930) · WebP 580 KB · JPG 529 KB · variants 640px 28 KB, 1024px 75 KB, 1600px 183 KB, 1920px 271 KB

    On a phone (640-px AVIF via srcset): ≈ 5.0 s → 293 ms on Slow 4G · 199 % → 12 % of the 2.5 s LCP budget · desktop (full AVIF): 794 ms → 257 ms

    source · CC BY-SA 4.0 · Claireneon

  • Craft shop front with window display

    Craft shop front with window display — original
    original JPG · 743 KB
    Craft shop front with window display
    AVIF · 181 KB full · 19 KB at 640 px

    photo · 1920×1280 4.1× smaller

    AVIF 181 KB (PSNR 31.2, SSIM 0.919) · WebP 390 KB · JPG 395 KB · variants 640px 19 KB, 1024px 51 KB, 1600px 126 KB, 1920px 181 KB

    On a phone (640-px AVIF via srcset): ≈ 4.0 s → 250 ms on Slow 4G · 158 % → 10 % of the 2.5 s LCP budget · desktop (full AVIF): 634 ms → 185 ms

    source · CC BY-SA 4.0 · Claireneon

  • Field team in hi-vis vests reviewing plans outdoors

    Field team in hi-vis vests reviewing plans outdoors — original
    original JPG · 440 KB
    Field team in hi-vis vests reviewing plans outdoors
    AVIF · 89 KB full · 17 KB at 640 px

    photo · 1920×1276 4.9× smaller

    AVIF 89 KB (PSNR 36.7, SSIM 0.959) · WebP 163 KB · JPG 222 KB · variants 640px 17 KB, 1024px 35 KB, 1600px 68 KB, 1920px 89 KB

    On a phone (640-px AVIF via srcset): ≈ 2.4 s → 239 ms on Slow 4G · 96 % → 10 % of the 2.5 s LCP budget · desktop (full AVIF): 392 ms → 112 ms

    source · Public domain · Win Henderson

  • Dishes at a vegetarian restaurant

    Dishes at a vegetarian restaurant — original
    original JPG · 456 KB
    Dishes at a vegetarian restaurant
    AVIF · 90 KB full · 15 KB at 640 px

    photo · 1920×1440 5.1× smaller

    AVIF 90 KB (PSNR 36.7, SSIM 0.950) · WebP 149 KB · JPG 203 KB · variants 640px 15 KB, 1024px 32 KB, 1600px 67 KB, 1920px 90 KB

    On a phone (640-px AVIF via srcset): ≈ 2.5 s → 226 ms on Slow 4G · 99 % → 9 % of the 2.5 s LCP budget · desktop (full AVIF): 405 ms → 112 ms

    source · CC0 · Mx. Granger

  • Plumbing students fitting pipes in a workshop

    Plumbing students fitting pipes in a workshop — original
    original JPG · 643 KB
    Plumbing students fitting pipes in a workshop
    AVIF · 145 KB full · 20 KB at 640 px

    photo · 1920×1440 4.4× smaller

    AVIF 145 KB (PSNR 33.7, SSIM 0.914) · WebP 301 KB · JPG 314 KB · variants 640px 20 KB, 1024px 45 KB, 1600px 102 KB, 1920px 145 KB

    On a phone (640-px AVIF via srcset): ≈ 3.4 s → 252 ms on Slow 4G · 138 % → 10 % of the 2.5 s LCP budget · desktop (full AVIF): 555 ms → 156 ms

    source · CC0 · State Government Photographer

  • Mountain lake at Mammoth, California

    Mountain lake at Mammoth, California — original
    original JPG · 694 KB
    Mountain lake at Mammoth, California
    AVIF · 192 KB full · 21 KB at 640 px

    photo · 1920×1280 3.6× smaller

    AVIF 192 KB (PSNR 30.1, SSIM 0.921) · WebP 395 KB · JPG 363 KB · variants 640px 21 KB, 1024px 53 KB, 1600px 130 KB, 1920px 192 KB

    On a phone (640-px AVIF via srcset): ≈ 3.7 s → 257 ms on Slow 4G · 148 % → 10 % of the 2.5 s LCP budget · desktop (full AVIF): 595 ms → 194 ms

    source · CC BY-SA 4.0 · King of Hearts

  • Portrait of an astronaut in a flight suit

    Portrait of an astronaut in a flight suit — original
    original JPG · 335 KB
    Portrait of an astronaut in a flight suit
    AVIF · 95 KB full · 25 KB at 640 px

    photo · 1535×1920 3.5× smaller

    AVIF 95 KB (PSNR 37.8, SSIM 0.974) · WebP 156 KB · JPG 237 KB · variants 640px 25 KB, 1024px 51 KB, 1535px 95 KB

    On a phone (640-px AVIF via srcset): ≈ 1.9 s → 279 ms on Slow 4G · 75 % → 11 % of the 2.5 s LCP budget · desktop (full AVIF): 308 ms → 116 ms

    source · NASA public domain · NASA

  • Product screenshot: this project's landing page (1600×900)

    Product screenshot: this project's landing page (1600×900) — original
    original PNG · 174 KB
    Product screenshot: this project's landing page (1600×900)
    AVIF · 27 KB full · 9.5 KB at 640 px

    screenshot · 1600×900 6.5× smaller

    AVIF 27 KB (PSNR 41.3, SSIM 0.999) · WebP 49 KB · JPG 69 KB · variants 640px 9.5 KB, 1024px 18 KB, 1600px 27 KB · trace tried: 10.0 KB at PSNR 25.8 → rejected

    On a phone (640-px AVIF via srcset): ≈ 1.0 s → 199 ms on Slow 4G · 42 % → 8 % of the 2.5 s LCP budget · desktop (full AVIF): 179 ms → 62 ms

    own work

  • Product screenshot: the converter page (1600×900)

    Product screenshot: the converter page (1600×900) — original
    original PNG · 118 KB
    Product screenshot: the converter page (1600×900)
    AVIF · 19 KB full · 6.3 KB at 640 px

    screenshot · 1600×900 6.4× smaller

    AVIF 19 KB (PSNR 43.4, SSIM 0.999) · WebP 35 KB · JPG 46 KB · variants 640px 6.3 KB, 1024px 12 KB, 1600px 19 KB · trace tried: 7.4 KB at PSNR 27.9 → rejected

    On a phone (640-px AVIF via srcset): ≈ 756 ms → 182 ms on Slow 4G · 30 % → 7 % of the 2.5 s LCP budget · desktop (full AVIF): 135 ms → 55 ms

    own work

Photos: Wikimedia Commons (licences on each card) and NASA; screenshots are of this site. Bytes are as encoded; fidelity is PSNR / SSIM against the 1920-px source.