Research on climate change based on carbonate porosity analysis in Jinping, China

Fig 3a shows the climate change (porosity change) curve obtained using saddle line 1 in Table 1 (Column D); and Fig 3b shows the climate change (porosity) curve fitted using the car- dioids curvy function. 2.4 Optimal selection of image processing algorithms The saddle line has been used for a long time as an image processing algorithm in the Jinping area. However, there are many curves in the saddle line curve family. Which curve is suitable for climate change research? Through repeated screening, it was found that the arithmetic mean of the carbonate porosity obtained from the following four curves was closest to the mea- sured porosity value. ½En� ¼ Z¼ : ðx2 y2Þ=T1 � T2 � sinððx þ yÞ=256Þ Z¼ : ðx2 y2Þ � T � sinððx þ yÞ=256Þ Z¼ : ð x2 y2Þ � T � sinððx þ yÞ=256Þ Z¼ : ðx2 y2Þ � T � cosððx þ yÞ=256Þ 8 > > > > > > > < > > > > > > > : ð2Þ All of the curves in Eq (2) were used as candidate curves in Fig 5, and further screening was performed (Fig 4). Fig 4a presents a flowchart of how the pixel point of a slide image is processed using an image processing algorithm; Fig 4b shows a schematic diagram of the implementation of the algorithm; and Fig 4c shows a binary image used to obtain a pore distribution map for Fig 3. Fitting of climate change (porosity) curves. https://doi.org/10.1371/journal.pone.0281630.g003 PLOS ONE Research on climate change based on carbonate porosity analysis in Jinping PLOS ONE | https://doi.org/10.1371/journal.pone.0281630 March 30, 2023 7 / 21