Detect implicit grid in image with monospaced characters

Question

I'm trying to detect the monospaced-grid in a possibly slightly deformed image of a receipt. Example input (full size here)

My idea is to obtain the centroids or bounding boxes of all components and do a kind of Hough transform on these points, but I wouldn't know how to do this in Mathematica.

The output could have different formats, but should look something like this.

In this particular example, equi-spaced lines horizontally and vertically are enough, but It would be a pro if the algorithm can also handle a little perspective distortion.

Answer 1

Simple enough, and fails only on one scarcely populated column. Easily fixed if you enforce the "monospaced" property

i = Binarize@Import@"https://i.sstatic.net/XWhHv.png";
(* delete noisy border*)
i1 = DeleteSmallComponents[ImageTake[i, {1, 1650}, {30, -1}], 10];

id = ImageDimensions@i1;
cm = ComponentMeasurements[i1, "Centroid"][[All, 2]];
bb = Abs@Mean[ Subtract @@@ ComponentMeasurements[i1, "BoundingBox"][[All, 2]]];

(* The following is basically a MeanShiftFilter[], but I couldn't make
   MeanShiftFilter[] to behave properly after a cursory try. Probably you should try it *)

yc = Mean /@ Split[Sort@cm[[All, 2]], Abs[#1 - #2] <= bb[[1]]/4 &];
xc = Mean /@ Split[Sort@cm[[All, 1]], Abs[#1 - #2] <= bb[[2]]/4 &];
a = 1.3;
Show[i1, Graphics[{{Red, {Line[{{1, # - a bb[[1]]}, {id[[1]], # - a bb[[1]]}}]} & /@ yc}, 
                  {Yellow, {Line[{{# - a bb[[2]], 1}, {# - a bb[[2]], id[[2]]}}]} & /@ xc}}]]