问题描述
我想删除形成大簇的像素，只保留小簇进行分析（即获取像素数和位置）。首先，我将所有值小于0.66的像素应用滤镜以白色着色。然后，我在R中使用了函数clump（）。该模型可以工作，但不能仅删除大型群集。我不明白丛集函数的工作原理。
初始图片：
结果图像：plot_r是将值
library(magick)
library(pixmap)
library(raster)
library(igraph)
f <- "https://i.stack.imgur.com/2CjCh.jpg"
x <- image_read(f)
x <- image_convert(x,format = "pgm",depth = 8)
# Save the pgm file
f <- tempfile(fileext = ".pgm")
image_write(x,path = f,format = "pgm")
# Read in the pgm file
picture <- read.pnm(file = f,cellres = 1)
str(picture)
picture@size
mat <- picture@grey
mat[mat<0.66] <- 0; x
##############################################################
##Remove clumps of pixels in R using package Raster and igraph
#Detect clumps (patches) of connected cells
r <-raster(mat)
rc <- clump(r)
#extract IDs of clumps according to some criteria
clump9 = data.frame(freq(rc))
#remove clump observations with frequency smaller/larger than N
clump9 = clump9[ ! clump9$count > 700,]
# record IDs from clumps which met the criteria in prevIoUs step
clump9 = as.vector(clump9$value)
#replace cells with IDs which do not belong to the group of interest
rc[rc != clump9[1] & rc != clump9[2]] = NA
# converting rasterlayer to matrix
n <- as.matrix(r)
m <- as.matrix(rc)
解决方法
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