Many image processing operations involve the modification of the spatial frequency content of images. Here we demonstrate object-plane spatial frequency filtering utilizing the angular sensitivity of a commercial spectral bandstop filter. This approach to all-optical image processing is shown to generate real-time pseudo-3D images of transparent biological and other samples, such as human cervical cancer cells. This work demonstrates the potential of non-local, non-interferometric approaches to image processing for uses in label-free biological cell imaging and dynamical monitoring.

Notch filters are band-stop filters used to remove unwanted frequencies. Here we demonstrate their capacity for phase contrast imaging of transparent objects enabled by their angle-sensitive transmission. Applications in unstained biological cell imaging are anticipated.

We demonstrate a high resolution (1024 × 768 px), low noise, full color, and computationally simple single pixel imaging system using cyclic patterns that scroll down the digital micromirror device.