I found that setting the canvas size in CSS caused my images to be displayed in a blurry manner.
Try this:
<canvas id="preview" width="640" height="260"></canvas>
as per my post: HTML Blurry Canvas Images
I found that setting the canvas size in CSS caused my images to be displayed in a blurry manner.
Try this:
<canvas id="preview" width="640" height="260"></canvas>
as per my post: HTML Blurry Canvas Images