I have a project that requires detecting and processing letters in a given input image. I am also new to subject of image processing. There are lots of subsubjects in image processing. I believe I don't have to learn all the concepts of image processing to achive my purpose.

Question above; how can I detect letters in a given input image? Note: I already know matlab. I need to do this by implementing algorithm, not by a built-in function.

I am gonna tell my thoughts. I want to write an application which takes an input image as an argument. If there is are English letters on that image (photo), it will detect them by circling each of the letters. I don't know which subject in digital image processing I must look at.

  • 1
    $\begingroup$ Welcome to SciComp.SE! As stated, your question is much too broad to have a sensible answer -- there is a vast literature on character recognition in image processing. Didn't whoever gave you that project also give you some pointers? $\endgroup$
    – Christian Clason
    Feb 23, 2015 at 16:33
  • $\begingroup$ Welcome to SciComp! OCR and image processing questions are generally better suited to DSP Stack Exchange. $\endgroup$ Feb 23, 2015 at 20:40
  • $\begingroup$ my research topic is handwritten document recognition in image processing .which algorithm is best for recognizing English characters in matlab for performing project also $\endgroup$ Jan 19, 2018 at 6:43

2 Answers 2


The field is knows as Optical Character Recognition (OCR) and it's a broad field.

Since it's clearly an academic exercise, you can keep it simple. Start by image segmentation : find shapes where a shape is just a set of connected pixels. [1] Then compare the shapes to known shapes. Don't expect an exact match, do an approximate match. What overall properties can you reliably determine for the shape? Aspect ratio? Holes in the middle?

[1] At this point, you can already draw circles around each shape that's not too big nor too small.


There is a text detection example in the Computer Vision System Toolbox in MATLAB. It is not a built-in function, but it uses many built-in functions.

  • $\begingroup$ If MATLAB were open-source, it would be great. The problem is that they don't share the image processing toolbox of theirs. $\endgroup$
    – Bora Semiz
    Feb 24, 2015 at 17:45

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