QOI

Egami reads and writes the whole Quite OK Image format, with 3 or 4 channels and both colorspaces. Files it writes are byte for byte what the reference encoder writes.

A QOI loads as Rgb8 or Rgba8.

// 3 channels when every pixel is opaque, 4 otherwise. The bytes match the reference encoder's.
image.Save("duck.qoi");
image.Save("duck-rgba.qoi", new QoiWriterOptions { IncludeAlpha = true });

QOI's colorspace byte maps to RasterMetadata.ColorSpace (sRGB or linear) and back.