R magick 抛出负或零图像大小错误

如何解决R magick 抛出负或零图像大小错误

我正在尝试编写一个迭代的用户指导函数来浏览图像 (PDF) 列表并在对它们运行 OCR/文本识别之前进行调整。其中一个块涉及通过去除噪声、去斑、增强和调整对比度来改善图像。重要的是，相应的 image_xxx 函数中的任何一个都倾向于在每次运行 rsession.exe: NegativeOrZeroImageSize `' @ error/image.c/CloneImage/794 时随机抛出此错误。我正在运行带有最新版本的 R、magick 及其依赖项的 Windows 10 64 位。谷歌搜索无法提供有关此问题的任何见解。

注意：此处的 while 循环对于让用户返回并更改参数至关重要。我尝试通过使用 tryCatch() 将其封装在 break/next 中来避免破坏流程的错误。我删除了函数的所有工作块，并提供了出现问题的部分的可重现示例：

PDF of the scanned page

library(tesseract)
library(magick)
library(dplyr)

img.list <- list(Alabama.pdf)  ### <<< this is a list with many PDFs (in this case just one,linked above)

ocr.manual <- function(img,denoise = T,denoise.rad = 1,despeckle.times = 2,enhance = T,sharpen.factor = 2) {

  img.out <- img[[1]]
  
  if(denoise) {
    # Initial parameters
    proceed.user.input <- 0
    denoise.rad.new.input  <- denoise.rad
    despeckle.times.new.input  <- despeckle.times
    enhance.new.input  <- enhance
    sharpen.new.input  <- sharpen.factor
    
    while(proceed.user.input != 1) {
      img.denoise <- img.out
      skip <- FALSE
      
      repeat {
        tryCatch({
          if(!is.null(denoise.rad.new.input) | denoise.rad.new.input != 0) img.denoise <- image_reducenoise(img.denoise,radius = denoise.rad.new.input)},error = function(e){cat("Error in 'image_reducenouse()':",conditionMessage(e),"\n")},finally = {skip <<- TRUE; break})
      }
      
      if(skip) {next}
      skip <- FALSE
      
      repeat {
        tryCatch({
          if(!is.null(despeckle.times.new.input) | despeckle.times.new.input != 0) img.denoise <- image_despeckle(img.denoise,times = despeckle.times.new.input)},error = function(e){cat("Error in 'image_despeckle()':",finally = {skip <<- TRUE; break})
      }
      
      if(skip) {next}
      skip <- FALSE
      
      repeat {
        tryCatch({
          if(enhance.new.input) img.denoise <- image_enhance(img.denoise)},error = function(e) {cat("Error in 'image_enhance()':",finally = {skip <<- TRUE; break})
      }
      
      if(skip) {next}
      skip <- FALSE
      
      repeat {
        tryCatch({
          if(!is.null(sharpen.new.input) | sharpen.new.input != 0) img.denoise <- image_contrast(img.denoise,sharpen = sharpen.new.input)},error = function(e) {cat("Error in 'image_contrast()':",finally = {skip <<- TRUE; break})
      }
      
      if(skip) {next}

      print(image_ggplot(img.denoise))
      
      ### FOR CONTEXT: THIS PART IS JUST FOR USERS TO CHECK AND ADJUST ParaMETERS,IF NECESSARY
      proceed.user.input <- as.numeric(readline("Please look at the image. Continue? (next step = 1 / try different settings = 2): "))
      
      if(proceed.user.input == 2) {
        denoise.rad.new.input  <- as.numeric(readline("Input denoise smoother radius value in pixels (e.g. 3): "))
        despeckle.times.new.input  <- as.numeric(readline("How many times to run a speckle remover?: "))
        enhance.new.input  <- as.logical(readline("Change whether to enhance the image (T/F,TRUE/FALSE): "))
        sharpen.new.input  <- as.numeric(readline("Sharpness factor (e.g. 1): "))
      }
    }
    # If all cleared,reassign to img.out object to proceed to next step
    img.out <- img.denoise
  }
  
  # OCR
  img.out %>% image_ocr(language = "eng") %>% {. ->> out.text}
  
  return(out.text)
}

# Example of a run
ocr.manual(img = img.list[1])

Error in 'image_despeckle()': rsession.exe: NegativeOrZeroImageSize `' @ error/image.c/CloneImage/794 
Error in 'image_contrast()': rsession.exe: NegativeOrZeroImageSize `' @ error/image.c/CloneImage/794 
Error in magick_image_write_frame(image,format = format,i = i) : 
  rsession.exe: NegativeOrZeroImageSize `' @ error/image.c/CloneImage/794
Called from: magick_image_write_frame(image,i = i)

如果您能帮助我处理（或忽略）错误，我将不胜感激。换句话说，如果其中一个图像增强功能失败，我也可以，只要代码不中断即可。