Correction of Dropped Frames in High-Resolution Push-Broom Hyperspectral Images for Cultural Heritage

Charlie Willard¹, Nancy Wade², Matija Strlič¹, John R. Gilchrist³, Tim Weyrich¹, Adam Gibson¹

¹ University College London
² Guildhall Art Gallery, City of London
³ Clyde Hyperspectral Imaging and Technology

Abstract

When conducting high-resolution push-broom hyperspectral imaging, it is necessary to combine multiple push-broom images into one composite image mosaic. Dropped frames can occur in push-broom images which, if uncorrected, result in misalignments in the composite image. Much previous work to identify dropped frames in video prioritises fast computation over high accuracy, whereas in heritage imaging, high accuracy is often preferred over short computation time. Two approaches to identify the position of dropped frames are presented, both using the A* search algorithm to correct dropped frames. One method aligns overlapping sections of push-broom images and the other aligns the push-broom image to a lower resolution reference image. The methods are compared across a range of test images and the method using the overlapping sections is shown to perform better than the method using a reference image under most circumstances. The method was applied to hyperspectral images acquired of La Ghirlandata, an 1863 oil on canvas painting by Rossetti, enabling a high-resolution hyperspectral image mosaic to be produced. The resulting composite image is 10,875 x 14,697 pixels each with 500 spectral bands from 400–2500 nm. This corresponds to a spatial resolution of 80 𝜇m/pixel and a spectral resolution of 3–6 nm.

Citation Style: Display Alpha ACM SIGGRAPH IEEEtran Publication

Correction of Dropped Frames in High-Resolution Push-Broom Hyperspectral Images for Cultural Heritage.
Charlie Willard, Nancy Wade, Matija Strlič, John R. Gilchrist, Tim Weyrich, Adam Gibson.
ACM Journal on Computing and Cultural Heritage (JOCCH), 15(2), pp. 1–19, April 2022.Charlie Willard, Nancy Wade, Matija Strlič, John R. Gilchrist, Tim Weyrich, and Adam Gibson. Correction of dropped frames in high-resolution push-broom hyperspectral images for cultural heritage. ACM Journal on Computing and Cultural Heritage (JOCCH), 15(2):29:1–29:19, April 2021.Willard, C., Wade, N., Strlič, M., Gilchrist, J. R., Weyrich, T., and Gibson, A. 2021. Correction of dropped frames in high-resolution push-broom hyperspectral images for cultural heritage. ACM Journal on Computing and Cultural Heritage (JOCCH) 15, 2 (Apr.), 29:1–29:19.C. Willard, N. Wade, M. Strlič, J. R. Gilchrist, T. Weyrich, and A. Gibson, “Correction of dropped frames in high-resolution push-broom hyperspectral images for cultural heritage,” ACM Journal on Computing and Cultural Heritage (JOCCH), vol. 15, no. 2, pp. 29:1–29:19, Apr. 2021. [Online]. Available: https://doi.org/10.1145/3479011