使用Cimg C ++进行图像处理

Question

I'm using c++ and I have a project Im working on that requires us to remove the take in a command of encode or decode along with an "image.jpg" a "new image name" and an "ASCII_file.txt" that contains ascii characters. What we need to do is remove the least significant bit of a pixel and replace that with the ASCII value until there is no more ASCII characters. What I need to know is how to access the least significant bit using the cimg library, I have looked around but I haven't found any way of doing this. There is of course this http://cimg.eu/reference/group__cimg__storage.html but it does not tell me a good way of finding the end just a "...". My proffessor told me to either use cimg or imagemagick for C++ and cimg looked the most straightforward. I really need to know how to get this done, any help is appreciated. If you have any further questions, feel free to ask.

PS Im using visual studio 2015 to program this in.

Answer 1

CImg store image as R-red, G-green, B-blue, A-alpha. Let's start, so you have your image loaded to memory:

#define cimg_use_jpeg 1

CImg<unsigned char> *image = new CImg<unsigned char>("image.jpg");

//Now we will get pointers to each channel
unsigned char * ptr_r = image.data(0, 0, 0, 0);//red pixels array 1'st row
unsigned char * ptr_g = image.data(0, 0, 0, 1);//green pixels array 1'st row
unsigned char * ptr_b = image.data(0, 0, 0, 2);//blue pixels array 1'st row
unsigned char * ptr_a = image.data(0, 0, 0, 3);//alpha array 1'st row

//Iterating over image buffer

//image rows
for(int row = 0; row < image->height(); row++) {
  unsigned char * ptr_r = image.data(0, row, 0, 0);//red pixels array 1'st row
  unsigned char * ptr_g = image.data(0, row, 0, 1);//green pixels array 1'st row
  unsigned char * ptr_b = image.data(0, row, 0, 2);//blue pixels array 1'st row
  unsigned char * ptr_a = image.data(0, row, 0, 3);//alpha array 1'st row

  for(int col = 0; col < image->width(); col++) {
      //rewriting all r chanel values with 255
      *(ptr_r) = 255;
       ptr_r++;
      //this is equal
      ptr_r[col] = 255;
  }
}

What we need to do is remove the least significant bit of a pixel

I'm not sure what you mean, but my example should help you.