Comments on: Basic OCR in OpenCV

By: damiles

damiles — Tue, 31 Aug 2010 09:45:30 +0000

Hello Seongman, this line is correctly, the findY function, line 55, must be imgSrc->height, but it’s no problem in my example because images has same with and height.

Regards. David

By: Seongman

Seongman — Tue, 31 Aug 2010 06:13:23 +0000

Hello.
Thanks for this example.

I think you want maxVal with cvRealScalar(imgSrc->height) in findX() func. (about 34 lines)
Isn’t it?

By: damiles

damiles — Thu, 26 Aug 2010 13:24:53 +0000

In the last download demo, you can generate it with cmake util.

cmake -g xcode

By: pbharrin

pbharrin — Thu, 26 Aug 2010 01:13:44 +0000

This is a great example!
Did you do this on Mac in Xcode?

By: Utkarsh

Utkarsh — Sun, 22 Aug 2010 13:40:00 +0000

Awesome! Exactly what I was looking for!! Thank you!

By: damiles

damiles — Mon, 02 Aug 2010 08:47:10 +0000

Hi mithun, i don’t understand what is your problem, sorry, my english is so bad.

for you get the bounding rect you should first search the contours, and use this contours to get the bounding rect.

By: damiles

damiles — Mon, 02 Aug 2010 08:43:59 +0000

Hi Yanlin

1.- Yes it should be height instead width, but my OCR images are same width and height, then you can use to max value the with width or height.

2.- for convert 8bit to 32bit, 8bit are in range 0 to 255 but 32bit should be 0 to 1, then you no only convert the internal format, you rescale the values, then you when convert 0 – 255 to 0 – 1, you get this formula: pixel_src/255, this si pixel_src* 1/255, and 1/255=0.0039125.

By: mithun

mithun — Mon, 02 Aug 2010 07:53:34 +0000

hi,thanks for your suggession,now my problem is how to select the starting point for the boundingbox using boundingRect function .So that in cam boundingbox appears across my hand only

By: yanlin

yanlin — Sun, 01 Aug 2010 08:02:03 +0000

First of all .Thanks a lot for you BasicOCR, it helps me a lot in my study. Well done.
But I have several question about your code:
(1)In function both “findX” and “findY” you calculate the maxVal use
“CvScalar maxVal=cvRealScalar(imgSrc->width * 255)”.
but i think maxVal for X and Y should be different,
int “findX” it should be CvScalar maxVal=cvRealScalar(imgSrc->height * 255)
(2)In function “getData” and “classify” ,in order to use opencv’s knn, you convert the image depth from 8bit to 32bit use param 0.0039125 , why?

Thank you very much

By: damiles

damiles — Mon, 26 Jul 2010 07:19:47 +0000

Hi Mhd, opencv require cmake to build and install opencv but your projects can be compiled with makefiles, cmake, sh, vc++ and all you want, cmake is a makefile generator then you can use makefile.

In this tutorial i use a shellscript for compile OCRbuild.sh, you can execute this script to compile.

But in few days i create the cmake compiler for you Regards David.