High-Resolution HTML5 Canvases

You can make your canvases as high-res as the user's computer can stand. I've recently used canvases of size 12000x6750 to create bitmaps that, when printed at 200dpi, which is sufficient for very high quality, would print a 60"x34" print.

It's very simple to do. The key is this. The CSS width and height values of a  <canvas> determine only the size the canvas appears on the screen. The width and height attributes of the <canvas>, on the other hand, determine the size of the canvas that you work with in your JavaScript code. 

In the below code, the canvas appears on the screen to be 80x300, but if you use toDataURL to capture a jpg or png image of the canvas, it will be 1000x500.

<canvas width="1000" height="500" style="width:80px;height:300px;border:1px solid black;">
</canvas>

Aleph Null 3.1 and later versions of Aleph Null support creating high-res work, as you can see in a tutorial video on the matter