PDF Table Text Extraction - pdf

Question

I know that Table Text Extraction not everyone's cup of tea. But while reading PDF Stream data about table, there are certain things that I don't understand.
The PDF Code Stream of Table is:
q % Graphic State Starting Point
0 292.5 595.3 442.8 re % Rectangle x y Width Height
W* % Clipping Even Odd Rule
n % End without Filling
0 0 0 rg % Color of Stroke
161 735 m % Move to New Path
160.8 734.7 l 89.3 734.7 l 89 735 l 88.8 735.3 l 161.3 735.3 l
161 735 l % straight line
h % Close the Current Path
f* % Fill Path with Even Odd Rule
Q
And Underline is:
q % Graphic State Starting Point
1 0 0 1 451.5 759.5 cm % Current matrix
0.5 w % Width of Stroke
0 0 0 RG % color
0 -0.8 m % Move to New Path
72 -0.8 l % Straight Line
S % Stroke Line
Q % End of Graphic State
In underline the m modifies the cm and sets that to 451.5 759.5 and straight line is drawn from current point i.e. 451.5 to 72 points i.e 493.5 which is less that 0.8 to cm, i.e 759.5
I don't understand now, how the table line would be drawn from which point to which point.

Answer 1

Consider the line drawing section, where m is the move to operator and l is line-to:
% command coordinates
% =====================
161 735 m % Move-to a(161, 735)
160.8 734.7 l % line-to b(161, 735 -.3)
89.3 734.7 l % line-to c(90, 735 -.3)
89 735 l % line-to d(90, 735)
88.8 735.3 l % line-to e(90, 735 +.3)
161.3 735.3 l % line to f(161, 735 +.3)
161 735 l % line to g(161, 735)
h % close-path
f % fill
(There's some strange minor variations in x around 160 and 89 which are too small to register visually - rendering quirks?).
[Under very high resolution line will have arrows at end
<============ ... =======>
]
Other than that it's drawing a very thin long box with corners (89, 734,7), (161, 734.7), (161, 735.3), and (89, 735.3). The affect of the +/- ).3 points on the y-axis is most likely to give the effect of a slightly thickened line rather than a rectangle.