Restore spotted cornea image with inpainting

Optical coherence tomography (OCT) is a non-invasive imaging technique used by ophthalmologists to take pictures of the back of a patient’s eye [1]. When performing OCT, dust may stick to the reference mirror of the equipment, causing dark spots to appear on the images. The problem is that these dirt spots cover areas of in-vivo tissue, hence hiding data of interest. Our goal here is to restore (reconstruct) the hidden areas based on the pixels near their boundaries.

This tutorial is adapted from an application shared by Jules Scholler [2]. The images were acquired by Viacheslav Mazlin (see skimage.data.palisades_of_vogt()).

[1]

David Turbert, reviewed by Ninel Z Gregori, MD (2023) What Is Optical Coherence Tomography?, American Academy of Ophthalmology.

[2]

Jules Scholler (2019) “Image denoising using inpainting” https://www.jscholler.com/2019-02-28-remove-dots/

import matplotlib.pyplot as plt
import numpy as np
import plotly.io
import plotly.express as px

import skimage as ski

The dataset we are using here is an image sequence (a movie!) of human in-vivo tissue. Specifically, it shows the palisades of Vogt of a given cornea sample.

Load image data

image_seq = ski.data.palisades_of_vogt()

print(f'number of dimensions: {image_seq.ndim}')
print(f'shape: {image_seq.shape}')
print(f'dtype: {image_seq.dtype}')

number of dimensions: 3
shape: (60, 1440, 1440)
dtype: uint16

The dataset is an image stack with 60 frames (time points) and 2 spatial dimensions. Let us visualize 10 frames by sampling every six time points: We can see some changes in illumination. We take advantage of the animation_frame parameter in Plotly’s imshow function. As a side note, when the binary_string parameter is set to True, the image is represented as grayscale.

fig = px.imshow(
    image_seq[::6, :, :],
    animation_frame=0,
    binary_string=True,
    labels={'animation_frame': '6-step time point'},
    title='Sample of in-vivo human cornea',
)
fig.update_layout(autosize=False, minreducedwidth=250, minreducedheight=250)
plotly.io.show(fig)