Resolution of the text drops when I use an image with text on a homepage

I created an image file (jpeg) with text and graph. I am trying to display this image on my homepage. For some reason, the text becomes blurry when I import and display this file. When I click on the displayed image, it opens a new window with the image, and the resolution is great there. But when it’s displayed on the homepage, the text is blurry. I am using Canvas by WooThemes in case that affects anything.
Please advise,
Thank you