  Unprocessed RAW data is a highly valuable image format for image editing and
computer vision. However, since the file size of RAW data is huge, most users
can only get access to processed and compressed sRGB images. To bridge this
gap, we design an Invertible Image Signal Processing (InvISP) pipeline, which
not only enables rendering visually appealing sRGB images but also allows
recovering nearly perfect RAW data. Due to our framework's inherent
reversibility, we can reconstruct realistic RAW data instead of synthesizing
RAW data from sRGB images without any memory overhead. We also integrate a
differentiable JPEG compression simulator that empowers our framework to
reconstruct RAW data from JPEG images. Extensive quantitative and qualitative
experiments on two DSLR demonstrate that our method obtains much higher quality
in both rendered sRGB images and reconstructed RAW data than alternative
methods.
