SinglePixelCamera

class deepinv.physics.SinglePixelCamera(m, img_shape, fast=True, device='cpu', dtype=torch.float32, rng: Generator | None = None, **kwargs)

Bases: DecomposablePhysics

Single pixel imaging camera.

Linear imaging operator with binary entries.

If fast=False, the operator uses a 2D subsampled hadamard transform, which keeps the first \(m\) modes according to the sequency ordering. In this case, the images should have a size which is a power of 2.

If fast=False, the operator is a random iid binary matrix with equal probability of \(1/\sqrt{m}\) or \(-1/\sqrt{m}\).

Both options allow for an efficient singular value decomposition (see deepinv.physics.DecomposablePhysics()) The operator is always applied independently across channels.

It is recommended to use fast=True for image sizes bigger than 32 x 32, since the forward computation with fast=False has an \(O(mn)\) complexity, whereas with fast=True it has an \(O(n \log n)\) complexity.

An existing operator can be loaded from a saved .pth file via self.load_state_dict(save_path), in a similar fashion to torch.nn.Module().

Parameters:

• m (int) – number of single pixel measurements per acquisition (m).

• img_shape (tuple) – shape (C, H, W) of images.

• fast (bool) – The operator is iid binary if false, otherwise A is a 2D subsampled hadamard transform.

• device (str) – Device to store the forward matrix.

• rng (torch.Generator (Optional)) – a pseudorandom random number generator for the parameter generation. If None, the default Generator of PyTorch will be used.

---

Examples:

SinglePixelCamera operators with 16 binary patterns for 32x32 image:

>>> from deepinv.physics import SinglePixelCamera
>>> seed = torch.manual_seed(0) # Random seed for reproducibility
>>> x = torch.randn((1, 1, 32, 32)) # Define random 32x32 image
>>> physics = SinglePixelCamera(m=16, img_shape=(1, 32, 32), fast=True)
>>> torch.sum(physics.mask).item() # Number of measurements
48.0
>>> torch.round(physics(x)[:, :, :3, :3]).abs() # Compute measurements
tensor([[[[1., 0., 0.],
          [0., 0., 0.],
          [0., 0., 0.]]]])

Examples using SinglePixelCamera:

A tour of forward sensing operators

A tour of forward sensing operators

PnP with custom optimization algorithm (Condat-Vu Primal-Dual)

PnP with custom optimization algorithm (Condat-Vu Primal-Dual)