Increase the resolution of a TH2D plot on a TCanvas

Dear all,

I am trying to plot TH2D histograms of different sizes:
100 x 100
200 x 200
500 x 500
1000 x 1000
2000 x 2000
5000 x 5000

But when I plot them on a canvas, the resolution does not seem to increase past 500 x 500 or so. I don’t see more pixels on the screen than roughly 500 x 500.
My computer screen does not have 5000 x 5000 resolution, but I would have expected it to make it so big that it can’t fit my screen and I have to scroll over it, which would be fine.
I am saving the histograms to a .pdf file (perhaps the problem is there?)

My code is as follows:

TH2D** histList = new TH2D*[nHists];
for(int i = 0; i < nHists; i++){
  histList[i] = new TH2D(Form(hist_%d, i), sizeX, x1, x2, sizeY, y1, y2);
  // Load contents of TH2D via reading in a .txt file 
  // And set via ->SetBinContent(x, y, <binContent>);
  TCanvas* c1 = new TCanvas("c1", "");
  c1->SetCanvasSize(6000, 6000);
  c1->SetWindowSize(5000, 5000);

Does anyone have an idea what I might be doing wrong?

auto  c = new TCanvas("c", "c",3000,2000)

should work.