Whilst browsing, you might find a few Web page images that are a little small. In which case you should check out the Image Zoom add-on for Firefox. With that you can resize and rotate page images to make them clearer.
Open this page  and click on the + Add to Firefox > Install Now options to add it to the browser. Then open a website page with images on it. When you right-click on one of the images, you will find the context menu now includes Zoom Image and Rotate Image options as below.
Move the cursor over Zoom Image to open the submenu below. That includes Zoom In, Zoom Reset and Zoom Out options. Click on the Zoom In and Zoom Out options to expand and reduce the image dimensions.
Alternatively, you can enter specific dimensions for an image. Select the Custom Dimensions option from the context menu to open the window below. There you can enter alternative numbers for the image width and height values.
With this add-on you can also rotate images. Right-click on an image and select Rotate Image to open the submenu in the shot below. Then select Rotate Right to rotate the image by a 90 degree angle as below. Click on Rotate Reset to restore the default angle of the picture.
So when a website image is not entirely clear this add-on might be handy. With it you can adjust the image dimensions and angles to enhance clarity. Check out the Image Zoom homepage  for further details.