Lossless Compression
Compression that reduces file size while allowing the original data to be reconstructed exactly.
Measured in
ratio
In depth
Lossless schemes exploit statistical redundancy — repeated values, predictable gradients — rather than perceptual limits, so they typically achieve only two- or three-to-one on photographs against ten-to-one or better for lossy methods. Most camera raw formats use it, which is why raw file sizes vary with scene complexity.
Examples in practice
A raw frame of a plain grey sky compresses far smaller than one of a detailed forest, despite identical pixel counts.