Question

I want to feed my extracted character bitmaps (.bmp files) into some kind of matrices that can be processed in C++ and then fed into the artificial neural network e.g. the network will take 72 inputs – each one as a pixel of the binarized picture of dimensions 6 x 12.

For instance: I have a binarized bitmap of size let’s say 40 x 80. I want to make out of it a structure that will have dimensions 6 x 12 and it would consist of my scaled bitmap. So I need a bitmap library that would allow me to scale the bmps and then fed them into the ANN. (As some of you stated already, they will be stored already as a matrix of so kind so no transformations will be necessary)

What can I use in here ?

Answer 1

It seems that any image processing library could suit your needs. So, my advice would be to use a library that is as simple as possible to integrate in your build process.
In this context, the CImg library is extremely easy to us, as it is composed of a simple .h file.

Concerning your need, a possible implementation would be

#include "CImg.h"
using namespace cimg_library;

int main(int argc,char **argv) 
{
  CImg<unsigned char> image("img/logo.bmp");

  //Simple resize with nearest neighbour interpolation
  //image = image.resize(64, 64); 

  //If you want to specify the interpolation type
  image = image.resize(64, 64, -100, -100, 4);//The last param specifies the interpolation type 
  //\param interpolation_type Method of interpolation :
  //   -1 = no interpolation : raw memory resizing.
  //  - 0 = no interpolation : additional space is filled according to \p border_condition.
  //  - 1 = nearest-neighbor interpolation.
  //  - 2 = moving average interpolation.
  //  - 3 = linear interpolation.
  //  - 4 = grid interpolation.
  //  - 5 = bicubic interpolation.
  //  - 6 = lanczos interpolation.

  CImgDisplay main_disp(image,"Image resized");

  //This last part of code is not usfeul for you, it is only used to display the resized image
  while (!main_disp.is_closed() ) 
    main_disp.wait();
  return 0;
}