Libcaesium is a Rust library for lossy/lossless compression and conversion of JPEG, PNG, GIF, WebP, and TIFF images, with a C API for cross-language usage. It provides both file-based and in-memory compression, targeting specific output sizes, and preserving EXIF metadata or orientation. The architecture is modular, with format-specific compressors (jpeg.rs, png.rs, etc.) and shared utilities. The code is well-structured, tested across multiple platforms, and integrates advanced libraries like mozjpeg-sys, oxipng, gifski, and libwebp. It avoids framework boilerplate and demonstrates strong engineering practices, though some parts use unsafe Rust for direct JPEG manipulation.