Houghlines in java.
Houghlines does detect white lines. Use binary_inv to show with houghlineTest.png

OTSU threshold gives best black and white response

Would it be useful to process what lines have been detected?
As in, filter out every line detected except for horizontal lines?

BINARYINV seems to be result in a better looking image than canny for sheet music

In houghlines parameters, having resoluation of 1 degree and 1 pixel makes sense. Would allow for sheet music image to be at any orientation.
Threshold would ideally need to vary dependant on how much sheet music there is.
Which brings to the table filtering. Having a good filter that eliminates noise leaves the sheet music free would be good. The binary inv would be suitable, since houghlines detect white lines.
Need filter to denoize image. OTSU seems to do a good job.

The threshold would need to be adjusted dependant on how many white pixels there are.
houghlinesP has start and end points. where houghlines does not. Which is why houghlinesP performs better on a set of images becuz of the end points rather than just "a line must meet a certain threshold at that coordinate for it to be registered"
Houghlines in order to be effetive must be scaled to suit the image.

HoughlinesP contains this:
minLinLength: The minimum number of points that can form a line. Lines with less than this number of points are disregarded.
maxLineGap: The maximum gap between two points to be considered in the same line.

____ _____     ______ 	______

HoughlinesP can calculate on a local scale, comaparing the distance between just the gap in the line.
Houghlines  only calculates on the lines scale, checking the whole lines point count(attenuator?) reaching over the threshold.

This means houghlinesP can scale better and allow for more accurate results


The mathRound does not make difference

Drawing forloop with cols, seems to be less effective
Even though it does employ same calculations? 
https://stackoverflow.com/questions/29493267/how-to-detect-lines-using-houghlines-in-opencv-java



not enough MP records with more than 10 pages