[dplavery92]

From the parent article:

>Importantly, this diffractive camera is not based on a standard point-spread function-based pixel-to-pixel mapping between the input and output FOVs, and therefore, it does not automatically result in signals within the output FOV for the transmitting input pixels that statistically overlap with the objects from the target data class. For example, the handwritten digits ‘3’ and ‘8’ in Fig. 2c were completely erased at the output FOV, regardless of the considerable amount of common (transmitting) pixels that they statistically share with the handwritten digit ‘2’. Instead of developing a spatially-invariant point-spread function, our designed diffractive camera statistically learned the characteristic optical modes possessed by different training examples, to converge as an optical mode filter, where the main modes that represent the target class of objects can pass through with minimum distortion of their relative phase and amplitude profiles, whereas the spatial information carried by the characteristic optical modes of the other data classes were scattered out.

It seems like that may not be so possible.

Later on in the article:

>It is important to emphasize that the presented diffractive camera system does not possess a traditional, spatially-invariant point-spread function. A trained diffractive camera system performs a learned, complex-valued linear transformation between the input and output fields that statistically represents the coherent imaging of the input objects from the target data class.

Note here that the learned transformations are linear, and the Fourier Transform is linear, but you cannot invert from output to input because the sensor measures real-valued intensities of complex-valued fields. All the phase information is lost.

[nomel]

Does this fall under holography?

As a layperson, do I understand this correctly?

There are point spread functions, but they vary, in an extreme way, across the "image plane". The diffraction patterns scatter the coherent light. Since the light is coherent, the output image brightness is the result of the number of photons, and the interference from all their waves coming from the patterns. This can't be reversed because the phase is a degree of freedom that means, even though we know how any ray of light will pass through, the image that made it is undetermined?

I assume these diffraction patterns, and the "film" have to be placed with sub-wavelength accuracy?

If you exposed this with holographic film, what would you see? Maybe a bright "2" protruding from a rough, bumpy, background? Surely it's 3d, that falls into chaos right behind, right?

[ggm]

This is almost exactly how I mentally framed the question.

[SiempreViernes]

Thinking of the underlying physics, I think all this means that their filters do funky things to the polarisation of the light to get cancellations, and since the detector isn't made to measure polarisation the process isn't invertible.