How to do Simple image processing with arduino Due?

Hi dears

What's a simple way to process the images using Arduino Due and a camera( for example ov7670 or open mv2) ?

I want to do a simple image processing for a moving robot with Arduino Due. But I don't know what to do.
My image processing is very simple. I want to recognize 3 letters (H,S,U) Whose fonts and sizes and the background (white) and color (black) are specific. This should only be done by the microcontroller (Without Pc or matlab).

Below is a screenshot of the sample:

What is your personal background in (simple) image processing ?

ard_newbie:
What is your personal background in (simple) image processing ?

I'm familiar with some ordinary building blocks in Matlab as edge detection, histogram, etc.
But as you know, I can't use PC and Matlab environment in my robot.

You may start from this book.

The Due has enough memory to read in a small image, especially if binary, so look around for camera options that work with it.

All the image processing operations you are familiar with in MATLAB are available in open source C/C++ libraries, like OpenCV, so you can put together a small image processing package yourself, with just the functions you need.

I suggest to start by learning how to use MATLAB on a PC to collect and recognize those letters, keeping minimal processing steps in mind, and apply that successful technique to the Due program.

On the other hand, OpenCV is already implemented on the Raspberry Pi, for the same board price as the Due, and there is a dedicated camera for it, so why bother?