Formats & Compression

AVIF Encoder Effort: Speed vs File Size on 20 Photos

AVIF effort 9 took 13.8 times as long as the default effort 4 for files only 0.4 % smaller. Effort 0 encoded a photo in 34 ms at a 10 % size cost.

Formats & Compression ▸ 4 min read

Chroma Subsampling 4:2:0 vs 4:4:4: When It Matters and What It Costs

Full colour (4:4:4) made JPEG photos 28 % larger for under 2 points of quality, while WebP's sharp YUV gave screenshots 7–9 points for about 10 % more bytes.

Formats & Compression ▸ 4 min read

PNG, oxipng or Lossless WebP for Screenshots? 8 Captures Measured

Lossless WebP made our screenshots 59 % smaller than Chrome's PNGs with identical pixels. oxipng saved 45 %; its slow zopfli mode added only 1.4 %.

Formats & Compression ▸ 4 min read

Which WebP Quality to Use for Photos, Screenshots and Graphics

Across 28 images, the lowest WebP quality reaching SSIMULACRA2 70 ranged from 30 for flat graphics to 95 for a screenshot. One setting does not fit all.

Formats & Compression ▸ 4 min read

WebP alphaQuality: How Low Can Transparency Go?

Lowering alphaQuality from 100 to 80 saved 5 to 15 % with near-exact transparency. At 50 soft shadows degraded, and for logos lossless WebP was smaller and perfect.

Formats & Compression ▸ 4 min read

Animated GIF vs WebP vs AVIF: Three Animations Measured

A two-second photo pan was 2,176 KB as GIF and 64 KB as AVIF. For a flat animated chart, lossless WebP was smallest at 3.7 KB. Lossy animated WebP scored worst.

Formats & Compression ▸ 4 min read

Progressive vs Baseline JPEG: File Size and What Visitors See

Progressive JPEGs were 2.8 to 4.3 % smaller at equal quality. On a slow connection they showed the whole image at 1.6 s, while baseline had drawn half its height at 4.6 s.

Formats & Compression ▸ 4 min read

SVG Icons: Separate Files, a Sprite or Inline?

Twenty icons took 20 requests and arrived at 883 ms as separate files, one request and 362 ms as a sprite, and no request as inline SVG, which added 2.2 KB to the HTML.

Formats & Compression ▸ 4 min read

Retina Screenshots: What a 2× File Really Costs

Four times the pixels cost 1.8 to 3.9 times the bytes. A 2× AVIF screenshot was about the size of a 1× JPEG, and its text was visibly sharper on 2× screens.

Formats & Compression ▸ 4 min read

CMYK JPEGs on the Web: File Size and Colour in Chrome

CMYK JPEGs were three to four times larger than sRGB versions without a profile, and up to 21 times larger with sharp's 939 KB print profile embedded. Their colours shifted visibly in Chrome.

Formats & Compression ▸ 3 min read

Display P3 Photos and ICC Profiles: What Stripping the Profile Does

An ICC profile cost about 480 bytes. Removing it from Display P3 photos shifted colours by a median ΔE of 1.1, up to 2.3, and cut colourfulness by 12 % in Chrome.

Formats & Compression ▸ 3 min read

Base64 Data URIs: Does the 33 % Overhead Survive Compression?

After Brotli, Base64 added under 1 % to PNG and JPEG images, but about 70 % to SVG icons. Embedding SVG as text instead kept the penalty to 15 to 26 %.

Formats & Compression ▸ 3 min read

Charts as SVG, PNG, WebP or AVIF: What Each Format Costs

Our bar and line charts were 0.8 KB as Brotli-compressed SVG and 21 to 45 KB as raster images at 1×, doubling at 2×. SVG was 26 to 140 times smaller than any raster format.

Formats & Compression ▸ 3 min read

SVG and HTTP Compression: gzip vs Brotli on 28 Files

Our 28 SVG files shrank from 1,622 KB to 418 KB with gzip and 339 KB with Brotli, far more than SVGO alone saved. Our host compressed SVG automatically; here is how to check yours.

Formats & Compression ▸ 3 min read

SVGO on Real SVG Files: Savings and Visual Safety

SVGO cut public-domain SVGs from drawing programs by a median 21 to 38 % and by 15 to 18 % after Brotli, with no visible change in our renders. Files written by code saved only 2 to 4 %.

Formats & Compression ▸ 4 min read

WebP and AVIF for Thumbnails: Do the Savings Hold at Small Sizes?

At equal quality, AVIF stayed about 30 % smaller than MozJPEG from 160 to 1600 pixels wide, while WebP went from no saving at 1600 pixels to 12.5 % at 160.

Formats & Compression ▸ 3 min read

oxipng Optimisation Levels: Bytes Saved vs Time

oxipng's default level 2 saved 12.6 % on screenshots in under a second per image. Higher levels added at most half a percent, and Zopfli one more percent for about a minute per file.

Formats & Compression ▸ 3 min read

PNG for Photos: How Much Bigger Than JPEG?

Saved as PNG, our 20 photos were a median 14.5 times the size of a MozJPEG at quality 85. Maximum PNG compression and lossless WebP still left them 8 to 10 times larger.

Formats & Compression ▸ 3 min read

Palette PNG (Quantisation) vs Full-Colour PNG vs WebP

A 256-colour palette PNG made our screenshots 65 % smaller with a quality score above 90, smaller than lossless WebP. For transparent graphics, lossless WebP was smaller and exact.

Formats & Compression ▸ 4 min read

Sharpening After Resizing: What It Costs in File Size

Light sharpening at sigma 0.5 made resized photos 14 to 22 % larger, and sigma 1.0 added 29 to 47 %, with WebP and AVIF hit harder than JPEG.

Formats & Compression ▸ 3 min read

10-bit vs 8-bit AVIF for Ordinary Images: Size, Quality and Speed

10-bit AVIF made a smooth gradient 10 to 21 % smaller and 4 to 5 points better, and photos about 3 % smaller at equal quality, for roughly a third more encoding time.

Formats & Compression ▸ 3 min read

Greyscale JPEG vs Colour JPEG for Black-and-White Photos

Saving black-and-white photos as one-channel greyscale JPEGs made them only 1.2 to 2.3 % smaller than colour JPEGs at identical quality. WebP ranged from 47 % smaller to 28 % larger.

Formats & Compression ▸ 3 min read

cwebp Presets Compared: Do photo, picture and text Make a Difference?

At equal quality on 20 photos, cwebp's picture preset saved 2.0 % and photo 0.9 %, while icon and text needed 5.8 % more bytes. The default preset produced exactly the same files as no preset.

Formats & Compression ▸ 3 min read

WebP Near-Lossless: Smaller Than Lossless, Cleaner Than Lossy?

Near-lossless WebP at level 60 made screenshots 13.2 % smaller than lossless WebP with a SSIMULACRA2 score of 94. For photographs it stayed almost four times larger than lossy quality 90.

Formats & Compression ▸ 3 min read

Matching Quality Settings Across JPEG, WebP and AVIF

For the same visual quality on 20 photos, MozJPEG and WebP needed nearly the same quality number, about 73 to 74, while AVIF needed a setting 15 to 20 points lower, about 54.

Formats & Compression ▸ 3 min read

MozJPEG vs Default JPEG Settings: 20 Photos at Equal Quality

At the same SSIMULACRA2 score, MozJPEG settings saved a median 15.1 % over sharp's default JPEG settings, with every photo at least 10.7 % smaller, for about four times the encoding time.

Formats & Compression ▸ 3 min read

WebP vs AVIF vs JPEG at Equal Quality: 20 Photos Measured

At the same SSIMULACRA2 score, AVIF was smaller than MozJPEG for all 20 CC0 photos (median −29.4 %), while WebP was not smaller at the median. Screenshots told a different story.

Formats & Compression ▸ 6 min read

JPEG Quality in the Browser: Chrome’s Canvas Encoder vs MozJPEG

At the same visual quality, Chrome's canvas JPEG encoder produced files a median 18.4 % larger than MozJPEG across 20 CC0 photos, and its quality 0.8 is not MozJPEG's 80.

Formats & Compression ▸ 4 min read

PNG vs WebP for Transparency: Edges Tested on Three Backgrounds

Lossless WebP halved transparent PNGs with identical pixels. Lowering WebP alpha quality to 50 dropped one asset's score on a dark background from 83 to 9.

Formats & Compression ▸ 4 min read

SVG vs PNG for Interface Icons: Bytes and Sharpness Measured

Twelve line icons as one Brotli-compressed SVG sprite weighed 456 bytes, less than a single 48-pixel PNG of the clock icon, and stayed sharp at every screen density.

Formats & Compression ▸ 4 min read

Removing EXIF Metadata: What 20 Real Photos Contained and What It Saves

Five of 20 public photos still carried GPS data. Stripping metadata saved 0.25 % of the originals but a median 6.9 % (up to 27.5 %) of 1600-pixel web copies.

Formats & Compression ▸ 5 min read