can std::unique be used to determing if objects of a custom class have the same values?

I have a list of framerates and a list of associated screen resolutions. The problem is that I get loads of duplicates in my resoltuions list. Actually, I get loads of duplicates in the framerates list as well (thanks a lot, Windows!), but those are eliminated by a simple comparison when I sort through the raw list. I guess that I want to use std::algorithm to help me eliminate my duplicates, but I can't get it to work.

Code:

#include <algorithm>
#include <vector>
#include <iostream>

struct resolution {
    int w;
    int h;
};

int main(void) {

    std::vector<std::pair<int, std::vector<resolution>>> vec;
    for (int i = 0; i < 5; i++) {
        std::pair<int, std::vector<resolution>> p;
        p.first = i;
        for (int j = 0; j < 5; j++) {
            resolution res;
            res.w = j;
            res.h = j;
            p.second.push_back(res);
        }
        vec.push_back(p);
    }

    for (std::vector<std::pair<int, std::vector<resolution>>>::iterator it = vec.begin();
        it != vec.end();
        ++it) {
        it->second.erase(std::unique(it->second.begin(), it->second.end()), it->second.end());
    }

    for (std::vector<std::pair<int, std::vector<resolution>>>::iterator it1 = vec.begin();
        it1 != vec.end();
        ++it1) {
        for (std::vector<resolution>::iterator it2 = it1->second.begin();
            it2 != it1->second.end();
            ++it2) {
            std::cout << it1->first << ": " << it2->w << " x " << it2->h << std::endl;
        }
    }

    return 0;
}

I get the following compiler errors from algorithm:

Error   C2672   'operator __surrogate_func': no matching overloaded function found  dummy_erase c:\program files (x86)\microsoft visual studio 14.0\vc\include\algorithm    1503    
Error   C2893   Failed to specialize function template 'unknown-type std::equal_to<void>::operator ()(_Ty1 &&,_Ty2 &&) const'   dummy_erase c:\program files (x86)\microsoft visual studio 14.0\vc\include\algorithm    1503    
Error   C2672   'operator __surrogate_func': no matching overloaded function found  dummy_erase c:\program files (x86)\microsoft visual studio 14.0\vc\include\algorithm    1506    
Error   C2893   Failed to specialize function template 'unknown-type std::equal_to<void>::operator ()(_Ty1 &&,_Ty2 &&) const'   dummy_erase c:\program files (x86)\microsoft visual studio 14.0\vc\include\algorithm    1506    

I've not much experience with <algorithm> but I suspect the problem is that std::unique doesn't understand how to compare my resolution objects. If this is in fact the case, is there something I can add to my resolution class to make it nice for std::unique? Or, is there any other way to do this elegantly?

I could always just do it by hand with another pass on the list and some conditionals, but avoiding doing that kind of thing is exactly one reason to use C++ as opposed to C. If there is a trick to this, I'd love to know it.