straighten a image

hello people am working on a ocr of braille! i have finished the entire project! the one drawback of my project seems to be that, my code doesn't work on images which are slightly curved during scanning! the input to my code is a scanned braille script! so if the image is tilted, then my code gives me an error! so i wanna know if there's any algorithm or method by which i can straighten that image!! any help would be greatly appreciated. thank you

[Geoff]

Sorry, first you say "curved", then you say "tilted". Which is it? Or is it both?

"Curved" implies you need to de-warp the image. "Tilted" implies you just need to rotate it. If it's the latter, do you have any reference lines in your image to indicate what true vertical or horizontal is?

[goutam]

sorry, my bad!! the image is tilted. no theres no reference lines!

Answer 1

[Image Analyst]

Can you detect the dots? If so, you might be able to use radon() or RANSAC ( http://en.wikipedia.org/wiki/Ransac) or possibly hough() to find the angle, then use imrotate.

Answer 2

[goutam]

yes i can detect the dots! i know where the dot starts and where it ends! i also knw the centroid of the dot! using this data can i straighten the image? the image consists of many dots! so i presume i have to find the rotation angle for the dots which are adjacent and then rotate the whole image for tat required value???

[Image Analyst]

There are a few different ways to do it. Did you look up any of the ways I suggested?

Answer 3

[goutam]

actually yes! i devised a simple method using imrotate. taking a subset of the image i calculated the angle between the centroid of the dots! then i rotated the whole image the required number of degrees! this soln worked! but now i get a new error when i run the whole code. it says "Undefined function or method 'reading' for input arguments of type 'logical'." here reading is a function i had written for identifying the dots. am stuck here! the input to this READING function is my image itself!

[Image Analyst]

Well what can I say without seeing your code? All I can say is that you did something wrong. It's case sensitive - did you call Reading and define reading? Is the function not on the search path or the folder of the calling routine?

[Image Analyst]

By the way, you should put your comments as "Comment on this Answer" (my Answer) rather than adding your comment as a new "Answer" all by itself.

[goutam]

sorry about that! am a newbee to this, hence the problem.

and about my code, i have defined it properly! and the function is in the search path itself! yet it doesnt work!

[Image Analyst]

Well what can I say without seeing your code? All I can say is that you did something wrong.

Answer 4

[ali dulla]

Dewarping by means of flow lines