An algorithm for analyzing noisy, in situ images of high-aspect-ratio crystals to monitor particle size distribution

Larsen, Paul A.; Rawlings, James B.; Ferrier, Nicola

doi:10.1016/j.ces.2006.03.035

Cited by 101 publications

(74 citation statements)

References 16 publications

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“…Effort was also made to extract particle shape information from FBRM CLD measurements such as the imaginative work of (Ma et al, 2001;Yamamoto et al, 2002), but concern remains on the magnitude of error that is introduced in the conversion from CLD to crystal shape. Microscopy imaging is considered as probably the most promising technique for measuring particle shape since one can see the shape of the particles, as a result has attracted much attention in recent years De Anda et al (Calderon De Anda et al, 2005a;Calderon De Anda et al, 2005b;De Anda et al, 2005), Wang et al (Wang et al, 2007) and Larsen et al (Larsen and Rawlings, 2009;Larsen et al, 2006Larsen et al, , 2007 used a GSK imaging system with non-invasive high-speed camera to record images and monitor the particle shape and size in a stirred batch crystalliser. Zhou et al (Zhou et al, 2011;Zhou et al, 2009) used image analysis to automatically extract the maximum possible information from in situ digital particle vision and measurement (PVM) images, which was employed to monitor particle shape and size distribution on-line.…”

Section: Introductionmentioning

confidence: 99%

On-line measurement of the real size and shape of crystals in stirred tank crystalliser using non-invasive stereo vision imaging

Zhang

Cai

Liu

et al. 2015

Chemical Engineering Science

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Non-invasive stereo vision imaging technique was applied to monitoring a cooling crystallisation process in a stirred tank for real-time characterisation of the size and shape of needle-like Lglutamic acid (LGA)  polymorphic crystals grown from solution. The instrument consists of two cameras arranged in an optimum angle that take 2D images simultaneously and are synchronised with the lighting system. Each 2D image pair is processed and analysed and then used to reconstruct the 3D shape of the crystal. The needle shaped LGA  form crystal length thus obtained is found to be in good agreement with the result obtained from off-line analysis of crystal samples, and is about three times larger than that estimated using 2D imaging technique. The result demonstrates the advantage of 3D imaging over 2D in measurement of crystal real size and shape.

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Section: Introductionmentioning

confidence: 99%

On-line measurement of the real size and shape of crystals in stirred tank crystalliser using non-invasive stereo vision imaging

Zhang

Cai

Liu

et al. 2015

Chemical Engineering Science

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“…On measurement, on-line microscopic imaging and image analysis for real-time characterisation of the shape and CShD of crystals in a crystalliser has attracted much attention in recent years (Barrett and Glennon, 2002;Calderon de Anda et al, 2005a;Calderon De Anda et al, 2005b;Huo et al, 2016;Larsen and Rawlings, 2009;Larsen et al, 2006;Patience and Rawlings, 2001;Wang et al, 2007;Zhang et al, 2015;Zhao et al, 2013;Zhou et al, 2011;Zhou et al, 2009). There are also readily available products on the market such as Mettler Toledo's PVM MessTechnik's PIA , PharmaVision (Qingdao) Ltd's 2D…”

Section: Introductionmentioning

confidence: 99%

Stereo imaging camera model for 3D shape reconstruction of complex crystals and estimation of facet growth kinetics

Zhang

Cai

Liu

et al. 2017

Chemical Engineering Science

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The principle that the 3D shape of crystals that grow from a solution can be characterised in real-time using stereo imaging has been demonstrated previously. It uses the 2D images of a crystal that are obtained from two or more cameras arranged in defined angles as well as a mathematical reconstruction algorithm. Here attention is given to the development of a new and more robust 3D shape reconstruction method for complicated crystal structures. The proposed stereo imaging camera model for 3D crystal shape reconstruction firstly rotates a digitised crystal in the three-dimensional space and varies the size dimensions in all face directions. At each size and orientation, 2D projections of the crystal, according to the angles between the 2D cameras, are recorded. The contour information of the 2D images is processed to calculate Fourier descriptors and radius-based signature that are stored in a database. When the stereo imaging instrument mounted on a crystalliser captures 2D images, the images are segmented to obtain the contour information and processed to obtain Fourier descriptors and radius-based information. The calculated Fourier descriptors and radius-based signature are used to find the best matching in the database. The corresponding 3D crystal shape is thus found. Potash alum crystals that each has 26 habit faces were used as a case study. The result shows that the new approach for 3D shape reconstruction is more accurate and significantly robust than previous methods. In addition, the growth rates of {111}, {110} and {100} faces were correlated with relative supersaturation to derive models of facet growth kinetics.

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“…One of the properties for particulate products is shape, not only because it is now recognized that size alone as often defined as volume equivalent diameter is over simplified and sometimes misleading, but also because shape can affect product performance properties such as bioavailability of drug particles. Optical microscopy has been proved to be one of the most effective techniques to determine particle shape and size off-line or on-line (Brittain, 2001; Calderon De Anda, Larsen, Rawlings, & Ferrier, 2006;Larsen, Rawlings, & Ferrier, 2007;Wang, Calderon De Anda, & Roberts, 2007;Wang, Roberts, & Ma, 2007). The images can be analyzed using image analysis algorithms (Zhang & Lu, 2004) to obtain particle shape information, which is often defined by some descriptors that have physical meanings such as aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

Particle shape characterisation and classification using automated microscopy and shape descriptors in batch manufacture of particulate solids

et al. 2016

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It is known that size alone, as often defined as the volume equivalent diameter, is not sufficient for characterizing many particulate products. The shape of crystalline products can be as important as size in many applications. Traditionally particulate shape is often defined by some simple descriptors such as the maximum length and aspect ratio. Although these descriptors are intuitive, they result in loss of some information of the original shape. This paper presents a method to use principal component analysis (PCA) to derive simple latent shape descriptors from microscope images of particulate products made in batch processes, and the use of the descriptors for identification of batch to batch variations. Data from batch runs of both a laboratory crystalliser and an industrial crystallisation reactor are analysed using the approach. Qualitative and quantitative comparison with the use of traditional shape descriptors that have physical meanings and Fourier shape descriptors is also made.

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An algorithm for analyzing noisy, in situ images of high-aspect-ratio crystals to monitor particle size distribution

Cited by 101 publications

References 16 publications

On-line measurement of the real size and shape of crystals in stirred tank crystalliser using non-invasive stereo vision imaging

On-line measurement of the real size and shape of crystals in stirred tank crystalliser using non-invasive stereo vision imaging

Stereo imaging camera model for 3D shape reconstruction of complex crystals and estimation of facet growth kinetics

Particle shape characterisation and classification using automated microscopy and shape descriptors in batch manufacture of particulate solids

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