Slice a mathematica image into sub images along black straight lines?

Question

I have a tic tac toe board I want to dynamically process in mathematica to have my robot play a user in tic tac toe. In order to determine the users move, I want to slice the board into 9 images, which are the 9 boxes of the board. How can I slice this image of the board into 9 boxes representing each space where there can be a move?

The image has white space and therefore using imagePartition produces something like:

This is because the boxes are not perfect squares, and the board is not perfectly in the center of the image.

Additionally, here is an example of the board that our delta robot draws:

Answer 1

Framed[i = Import["https://i.stack.imgur.com/tTeBU.png"]]

ib = ColorNegate@Binarize@i;
sc = SelectComponents[ib, "Count", -1];
bb = ComponentMeasurements[sc, "BoundingBox"];
bs = Reverse[Sort /@ {#[[1]], Last@ImageDimensions@sc - #[[2]]} &@ Transpose[bb[[1, 2]]]];
it = ImageTake[sc, Sequence @@ bs];
it1 = ImageTake[i, Sequence @@ bs];
eps = MorphologicalTransform[Thinning@it, "EndPoints"];
nw = NestWhile[ImageTake[#, {2, -2}, {2, -2}] & /@ # &, {it1, it, eps}, 
   ComponentMeasurements[#[[3]], "Mask", "BorderComponents" -> False] =!= {} &];

Partition[Framed /@ (ImageMultiply[nw[[1]], #] & /@ (Erosion[#, 1] & /@ Image /@
              (ComponentMeasurements[ColorNegate@nw[[2]], "Mask"][[All, 2]]))), 3] //
              Grid

Answer 2

One way to approach this is to use a Watershed algorithm to segment the image. Each of the watersheds contains one of the symbols.

i = Import["https://i.stack.imgur.com/tTeBU.png"];
waterI = WatershedComponents[i];
waterI // Colorize

You can then separate out the three symbols

{m1, m2, m3, m4} = ComponentMeasurements[waterI, "Mask"];
{ImageMultiply[Image[Normal[m1[[2]]]], i], 
 ImageMultiply[Image[Normal[m3[[2]]]], i], 
 ImageMultiply[Image[Normal[m4[[2]]]], i]}