feature: Add background estimator

Added a new background preprocessor to estimate the background/ambient noise. This block can be simply added in front of the existing pre-inv-post pipeline

configs/train_background_estimator.yaml

@@ -0,0 +1,31 @@
+# python scripts/recon/background_estimator.py -cn configs/train_background_estimator
+
+defaults:
+  - train_mirflickr_multilens_ambient
+  - _self_
+
+wandb_project: null
+device_ids: [1]
+torch_device: cuda:1
+
+# Dataset
+files:
+  dataset: Lensless/TapeCam-Mirflickr-Ambient-100   # 100 examples
+  image_res: [600, 600]
+  per_pixel_color_shift: True
+  per_pixel_color_shift_range: [ 0.8, 1.2 ]
+
+alignment:
+  # when there is no downsampling
+  top_left: [85, 185]  # height, width
+  height: 178
+
+optimizer:
+  type: AdamW
+  cosine_decay_warmup: True
+  final_lr: 2e-5
+
+training:
+  lr: 7e-5
+  batch_size: 4
+  num_epochs: 4

lensless/utils/dataset.py

@@ -1422,6 +1422,8 @@ def __init__(
         cache_dir=None,
         single_channel_psf=False,
         random_flip=False,
+        per_pixel_color_shift=False,
+        per_pixel_color_shift_range=None,
         bg_snr_range=None,
         bg_fp=None,
         **kwargs,
@@ -1461,6 +1463,10 @@ def __init__(
             If multimask dataset, save the simulated PSFs.
         random_flip : bool, optional
             If True, randomly flip the lensless images vertically and horizonally with equal probability. By default, no flipping.
+        per_pixel_color_shift: bool, optional
+            If True: randomly shift the color of each pixel in the lensless image. By default, no color shift.
+        per_pixel_color_shift_range: list, optional
+            Range of possible color shifts for each pixel in the lensless image. Used in conjunction with 'per_pixel_color_shift'.
         simulation_config : dict, optional
             Simulation parameters for PSF if using a mask pattern.
         bg_snr_range : list, optional
@@ -1488,6 +1494,8 @@ def __init__(
 
         # augmentation
         self.random_flip = random_flip
+        self.per_pixel_color_shift = per_pixel_color_shift
+        self.per_pixel_color_shift_range = per_pixel_color_shift_range
 
         # deduce downsampling factor from the first image
         data_0 = self.dataset[0]
@@ -1826,6 +1834,16 @@ def __getitem__(self, idx):
                 psf_aug = torch.flip(psf_aug, dims=(-3,))
                 background = torch.flip(background, dims=(-3,))
 
+        if self.per_pixel_color_shift:
+            color_filter = torch.empty(1, 1, 1, lensless.shape[-1], device=lensless.device).uniform_(*self.per_pixel_color_shift_range)
+            lensless = lensless * color_filter
+            lensed = lensed * color_filter
+
+            # Uncomment to visualize the effect of color shift
+            #save_image(background.squeeze().cpu().numpy(), f"background_pre{idx}.png")
+            background = background * color_filter
+            #save_image(background.squeeze().cpu().numpy(), f"background_post{idx}.png")
+
         return_items = [lensless, lensed]
         if self.multimask:
             if self.return_mask_label: