Depth Map Estimation from Digital Holograms via Thumbnail Metrics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating depth from digital holograms face challenges in precision and accuracy due to depth redundancies and noise, such as speckle noise and blurring, which can result in incorrect depth assignments to pixels.
Innovation Solution
A method that reconstructs multiple images from a digital hologram, forms thumbnails from contiguous pixels, applies an operator to each thumbnail to generate metrics, and determines pixel depth by selecting the depth with maximum repetition across two-dimensional regions, thereby reducing noise sensitivity and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If depth information is recovered from two-dimensional images using blur measurements, then depth estimation can be obtained, but precision and accuracy deteriorate due to depth redundancies where multiple depths are associated with the same pixel
Solution Approach 1:
The image is divided into multiple focal planes, with each plane capturing depth information for a specific depth range. By segmenting the depth space into discrete planes and assigning pixels to the plane where they are sharpest, the patent eliminates depth redundancies and ensures each pixel has a unique, accurate depth assignment.
Solution Approach 2:
Each pixel is evaluated locally to determine which focal plane produces the sharpest image at that specific location. This local quality assessment ensures that depth assignment is optimized for each pixel individually based on its own focus characteristics rather than using a global depth map approach.
2Measurement precision
If multiple focal planes are reconstructed to resolve depth redundancies, then depth accuracy improves, but computational complexity and processing time increase
Solution Approach 1:
Instead of processing the entire image at all possible focal planes simultaneously, the patent applies a stopping criterion that halts the focal plane search once a sufficient number of planes have been identified. This partial action approach maintains depth accuracy while significantly reducing computational complexity by avoiding unnecessary processing of excessive focal planes.
Solution Approach 2:
The patent performs preliminary processing by identifying and selecting only the relevant focal planes before generating the final depth map. This preliminary selection of focal planes based on image sharpness criteria prepares the data in advance, making the subsequent depth map generation more efficient and less computationally intensive.
Data Source
AI summary
Disclosed is a method, implemented by a calculation unit, for estimating a depth map from a digital hologram representing a scene, the method including: reconstructing, using the digital hologram, of n images of the scene, each associated with a depth of the scene and including multiple pixels, each image being defined by a same window; for each image, forming thumbnails composed of contiguous pixels and associated with two-dimensional regions of the window; applying an operator to each thumbnail of each image associated with a depth to provide a metric per thumbnail and by depth; determining a depth associated with each region two-dimensional based at least on the metrics relating to the thumbnails associated with the two-dimensional region concerned; determining the depth of a pixel of the depth map by selecting the depth having a maximum repetition number in the two-dimensional regions including the pixel concerned.