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. 2020 Oct 29;3(5):1791–1810. doi: 10.1016/j.matt.2020.10.012

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© 2020 Elsevier Inc.

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Quantitative Analysis of Colorimetric Microscopy Images

(A) Since both unmodified and modified droplets are visible in the reflection mode of image, it was used to create marks to identify the positions of all droplets in (D) the corresponding transmission mode of image, in which only modified droplets are visible.

(B) The reflection image underwent a few steps of processing to yield a noise-reduced, binarized image to prepare for recognition using Hough circle transformation.

(C) Eventually the droplets were approximated as circular marks, which were used to identify the locations and sizes of the droplets in the transmission image.

(D and E) (E) The green channel of (D) was extracted to calculate pixel intensity values.

(F–H) (F) By overlapping the marking patterns (C) and (E), the pixel intensity inside each droplet, as illustrated by the yellow circles in (H), can be measured, together with the pixel intensity of local background around each droplet (red circle). Pixel intensities inside and outside a droplet were used to calculate its degree of modification based on Equation 1 (see also Supplemental Information). Such analysis produced the calculated degree of modification of all droplets and their corresponding radii based on optical microscopy images from (A) and (D), which are plotted in (G). Each dot represents one droplet.