Benchmarking Webp format (draft)

Introduction

Webp is a modern image format created by Google, in this article, we will benchmark it against others lossless formats like avif, png, jpegxl.

The benchmark is done using the PNG format as input, and the output formats are Webp, Avif, and JpegXL.

Setup

Lossless compression

The dataset for the lossless benchmark is:

• ~9900 screenshots (32'253 Mo) from Minecraft (720p to 1440p, some 2160p).
• ~9600 screenshots (41'738 Mo) from Fortnite, Battlefield, 7 Days to Die, and GTA V etc... (1080p to 1440p, some 2160p).
• ~2150 screenshots (901 Mo) from desktop applications (240p to 1440p).

The PNG to Webp lossless compression command is:

cwebp -quiet -metadata all -lossless -exact -z <Compression> <Input> -o <Output>

The options are:

• -quiet: Quiet mode.
• -metadata all: Copy all metadata.
• -lossless: Lossless compression.
• -exact: Use exact mode, keep invisible pixels.
• -z <Compression>: Compression level, from 0 to 9, 9 best compression.
• -mt: Use multi-threading (we don't use it for the benchmark, gnu parallel is used).
• <Input>: Input PNG file.
• <Output>: Output Webp file.

For PNG to Avif lossless compression:

avifenc --jobs 1 --lossless --speed <Compression> --codec <codec> <Input> --output <Output>

The options are:

• --lossless: Lossless compression.
• --speed <Compression>: Compression level, from 0 to 9, 9 best compression.
• --jobs 1: Number of jobs.
• --codec: Use the aom codec, only codec available for lossless compression (11-2024).
• <Input>: Input PNG file.
• <Output>: Output Avif file.

For PNG to JPGXL lossless compression:

cjxl --num_threads 1 --quiet --effort <Compression> --distance 0.0 --brotli_effort 11 <Input> <Output>

The options are:

• --quiet: Quiet mode.
• --num_threads 1: Number of threads.
• --effort <Compression>: Compression level, from 0 to 9, 9 best compression.
• --distance 0.0: The quality, 0.0 is "mathematically lossless".
• --brotli_effort 11: Brotli compression level, 11 best compression.
• <Input>: Input PNG file.
• <Output>: Output JPGXL file.

Results

Desktop applications (901 Mo):

Cleanup

find . -type f -name "*.webp" -delete

Sources

• cWebp
• Avif
• JpegXL