如何将TIFF文件转换为R中的二进制图像？

Question

我有一个TIFF文件，我需要把它变成二进制图像。这可能在R？我应该如何编写设置阈值的参数？

Answer 1

您可以使用imager库的threshold函数。从文档：

library(imager)
im <- load.image("cameraman.tif") # provide the correct image path 
im.g <- grayscale(im)
im.g %>% plot

threshold(im.g,"15%") %>% plot # the threshold will be set at 15th percentile 

threshold(im.g,"auto") %>% plot # a threshold will be computed automatically using kmeans

#If auto-threshold is too high, adjust downwards or upwards using "adjust"
threshold(im,adjust=1.3) %>% plot

Answer 2

另一个选择是使用基于ImageMagick库的magick R包：

library(magick)
#> Linking to ImageMagick 6.9.7.4
#> Enabled features: fontconfig, freetype, fftw, lcms, pango, x11
#> Disabled features: cairo, ghostscript, rsvg, webp

logo <- image_read("logo:")

plot(logo)

logo_gray <- image_convert(logo, colorspace = "Gray")

plot(logo_gray)

logo_bw <- logo_gray %>%
  image_threshold(type = "white", threshold = "50%") %>%
  image_threshold(type = "black", threshold = "50%")

plot(logo_bw)

由reprex package创建于2019-03-20（v0.2.1）

或者，如果您想要局部自适应阈值处理，您应该查看image_lat()函数。