title: Error to create a global Features dataframe from frame-splitted features dataframe
body: <p>I'm using R and EBImage packages for image processing.
  I want a dataframe of cell basic features for each frame, and after, join these dataframes to have only a global one. I'm having issues with the cell number column, I have repeated numbers, or when I'm using another source image, says the number of columns not match. This is an example:</p>
  
  <pre><code>library("EBImage")
  
  # Load Image
    nuc &lt;- readImage(system.file("images", "nuclei.tif", package="EBImage"))
  # Segmented Image
    nucbw &lt;- bwlabel(nuc &gt; 0.5)
  # Create empty dataframe
    data &lt;- data.frame()
  # Compute for each frame
    for (i in 1:numberOfFrames(nuc)){
      # Create cell column to identify each cell
        if (i == 1){
          cell &lt;- 1:max(nucbw[,,i])
          } else {
            cell &lt;- (max(nucbw[,,(i-1)]) + 1) : (max(nucbw[,,i]) + max(nucbw[,,(i-1)]))
            }
      # Create frame column to know the frame where each cell belongs
        frame &lt;- rep(paste("Frame", i, sep = ""), max(nucbw[,,i]))
      # Create de features dataframe  
        x &lt;- computeFeatures.basic(nucbw[,,i], nuc[,,i])
      # Binding dataframe for each frame
        comb &lt;- cbind(cell, frame, x)
      # Binding dataframe different frame  
        data &lt;- rbind(data, comb)
       }
  data
  </code></pre>