LERC Limited Error Raster Compression

LERC is an open-source image or raster format which supports rapid encoding and decoding for any pixel type (not just RGB or Byte). Users set the maximum compression error per pixel while encoding, so the precision of the original input image is preserved (within user defined error bounds).

Core features

  • Core features

    • works on any common data type, not just 8 bit: char, byte, short, ushort, int, uint, float, double.
    • works with any given MaxZError or max coding error per pixel.
    • can work with a byte mask that specifies which pixels are valid and which ones are not.
    • is very fast: encoding time is about 20-30 ms per MegaPixel per band, decoding time is about 5 ms per MegaPixel per band.
    • compression is better than most other compression methods for larger bitdepth data (int types larger than 8 bit, float, double).
    • for 8 bit data lossless compression, PNG can be better, but is much slower.
    • in general for lossy compression with MaxZError > 0, the larger the error allowed, the stronger the compression. Compression factors larger than 100x have been reported.
    • this Lerc package can read all (legacy) versions of Lerc, such as Lerc1, Lerc2 v1, v2, and the current Lerc2 v3. It always writes the latest stable version.

Implemented Standards

  • Open Geospatial Consortium (OGC)