[1] Yang J Y, Lin J M, Yu J et al. Research on focal length measurement based on digital image processing[J]. Optical Technique, 33, 796-798(2007).

[2] Li Q, Feng H J, Xu Z H et al. Digital image sharpness evaluation function[J]. Acta Photonica Sinica, 31, 736-738(2002).

[3] Wang Y R, Feng H J, Xu Z H et al. Autofocus evaluation function based on saturate pixels removing[J]. Acta Optica Sinica, 36, 1210001(2016).

[4] Qin B Y, Shang R, Li S Y et al. Reliable clarity automatic-evaluation method for optical remote sensing images[J]. Proceedings of SPIE, 9675, 967533(2015).

[5] Lüthi B S, Thomas N, Hviid S F et al. An efficient autofocus algorithm for a visible microscope on a Mars lander[J]. Planetary and Space Science, 58, 1258-1264(2010).

[6] Yang X L, Lu Y X, Sun D et al. An improved clarity evaluation algorithm based on HVS theory[C], 852-855(2018).

[7] He C M, Li X R, Hu Y Y et al. Microscope images automatic focus algorithm based on eight-neighborhood operator and least square planar fitting[J]. Optik, 206, 164232(2020).

[8] Wang X F, Sun X W, Wang J K et al. Focus measure operator combining cosine transform and Laplacian operator[J]. Laser & Optoelectronics Progress, 58, 2410005(2021).

[9] Bahy R M. Autofocus microscope system based on blur measurement approach[J]. Journal of Physics: Conference Series, 1721, 012058(2021).

[10] Zeng H F, Han C P, Li K et al. Improved gradient threshold image sharpness evaluation algorithm[J]. Laser & Optoelectronics Progress, 58, 2211001(2021).

[11] Xiong R, Gu N T, Xu H Y. An auto-focusing evaluation function adapted to multi-directional gray gradient change[J]. Laser & Optoelectronics Progress, 59, 0418001(2022).

[12] Osibote O A, Dendere R, Krishnan S et al. Automated focusing in bright-field microscopy for tuberculosis detection[J]. Journal of Microscopy, 240, 155-163(2010).

[13] Rudnaya M E, Mattheij R M M, Maubach J M L. Evaluating sharpness functions for automated scanning electron microscopy[J]. Journal of Microscopy, 240, 38-49(2010).

[14] Redondo R, Cristóbal G, Garcia G B et al. Autofocus evaluation for brightfield microscopy pathology[J]. Journal of Biomedical Optics, 17, 036008(2012).

[15] Xu C Y, Wei G Z, Ding C et al. Study on algorithm for line scale identification and eigenvalue extraction[J]. Journal of Electronic Measurement and Instrumentation, 31, 1937-1942(2017).

[16] Fernandes L A F, Oliveira M M. Real-time line detection through an improved Hough transform voting scheme[J]. Pattern Recognition, 41, 299-314(2008).

[17] Herout A, Dubská M, Havel J. Review of Hough transform for line detection[M]. Real-time detection of lines and grids, 3-16(2012).

[18] Lan T C, Lan R H, Chen X X et al. Research on liquid crystal lens hill climbing autofocus algorithm[J]. Acta Optica Sinica, 40, 1411003(2020).

[19] Yu C S, Lu R S. Performance evaluation method for focusing evaluation operator in superposed large depth imaging[J]. Laser & Optoelectronics Progress, 59, 1415027(2022).

[20] Zhang C P, Cao W Z, Xu M G et al. Automatic focusing of micro-vision detection system of mycobacterium tuberculosis smear[J]. Optics and Precision Engineering, 26, 1480-1488(2018).