Here is the entirety of my code:
#include "CImg.h"
#include <iostream>
using namespace cimg_library;
int main() {
CImg<float> image(100,100,1,3,0);
const float color[] = {1.0,1.0,0.0};
image.draw_point(50,50,color);
image.save("file.bmp");
CImgDisplay local(image, "Hah");
while (true) {
local.wait();
}
}
This successfully displays what I expect in a window, namely, a completely black square with a white pixel at 50,50. However, file.bmp is simply a black square, without that pixel (and saving a cimg Image that has been modified with repeated calls to draw_point in a larger program that does something useful also fails). What's going on here?
The problem is that you create CImgDisplay
with normalization enabled. Thus, your pixel of {1,1,0}
is normalized to {255,255,0}
and is visible on your screen.
CImg.save
does not perform normalization, so the the pixel is saved to disk as a very dark pixel.
You can fix the problem by changing your white pixel color:
const float color[] = {255.,255.,255.};
And, optionally, by disabling normalization:
CImgDisplay local(image, "Hah", 0);
In the alternative, you could normalize the original image before saving or displaying it:
image.draw_point(50,50,color);
image.normalize(0, 255);
image.save("file.bmp");
References: