Inverse ImagePartition with offset

Question

when I call the function ImagePartition I get an image list from which I can reconstruct the image by calling ImageAssemble onto the list.

I would like to be able to reconstruct the image after I call ImagePartition with a given offset. For example:

ImagePartition[image,{50,50},{1,1}]

Is there a quick solution to this or do I have to revert the images back into normal lists?

Best, Max

Answer 1

Assuming the offsets are less or equal to to the subimage sizes:

FromImagePartition[part_, {_, _}, {dw_, dh_}] := ImageAssemble[ArrayFlatten[{
      {Map[ImageTake[#, dh, dw] &, Drop[part, -1, -1], {2}],
       Map[ImageTake[#, dh, {1, -1}] &, part[[;; -2, {-1}]], {2}]},
      {Map[ImageTake[#, {1, -1}, dw] &, part[[{-1}, ;; -2]], {2}],
       part[[{-1}, {-1}]]}}]]

though I'm not sure if it's quick. Example:

im = Import["ExampleData/spikey.tiff"]
part = ImagePartition[im, {50, 25}, {7, 4}];
inv = FromImagePartition[part, {50, 25},{7, 4}]

ImageData[inv, "Byte"] ===
  ImageData[ImageTake[im, Sequence @@ ImageDimensions[inv][[{-1, 1}]]], "Byte"]
(* True *)