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JPEG encoder presets at quality 90
Five encoding presets compared on identical source images at the same quality setting.
Quantisation tables across the quality range
The same two encoders at quality 40, 50, 60, 70 and 90, to find where the size curves cross.
Lossless PNG recompression on 261 files
Real PNG files recompressed with oxipng, with a pixel-by-pixel comparison against the original.
Image metadata across 1,086 JPEGs
How many real JPEG files carry EXIF, XMP, ICC profiles and usable GPS coordinates, and how large the metadata blocks are.
WebP round trip cost at quality 90
Each image encoded straight to JPEG versus through WebP and back, so the difference is the cost of the detour.
Re-encoding a damaged JPEG at high quality
Files first compressed at quality 45, then re-saved at 90, measured against both the clean path and the damaged one.
这些是真实测量，不是基准测试：一个图库、一个编码器版本、一台机器。它适用于什么、不适用于什么，文章里都写了。