We present a method of hyperspectral snapshot imaging that is based on diffraction in an intermediate image plane. In this intermediate image, plane diffracting microstructures are used to deflect light toward an iris that performs spectral filtering. The method is related to imaging spectrometry with a reduced spectral resolution. However, the spectral shifts of the signal are detected very accurately at a potentially low cost. Our prototype system is capable of detecting a spectral shift of 0.5 nm, and the spectral operating range reaches from 510 to 700 nm. Application-specific arrays of microgratings are lithographically manufactured and lead to custom spatial and spectral sampling of an (intermediate) image. Compared with filter-based hyperspectral snapshot imaging, this approach avoids the difficult manufacturing of the mosaic filter array, but the spatial and spectral resolutions will become coupled. This leads to an uncertainty product for spatial and spectral resolutions. We explain the basic principle and show an experimental verification based on a first laboratory prototype.