Need a shadow for an image that doesn't require using any graphics library calls, you can simply use this tool to generate the HTML for any image you might have. This tool does use some graphics library calls to get the size. Simply copy and paste the HTML that this tool generates for your image with whatever shadow options that you might set. Completely free to use or download.

For the web form or the function call, you need to supply the image URL, background color (to blend away to), shadow color (if blank, uses the image's average color - neat effect), shadow distance (1 to 20px), blend strength, as well as "alt" tag for image. Accepts HEX codes or colors by name. Override width and height are optional parameters. Gets size info for GIF, PNG, JPG, but other img src types should pass override values. The source code only handles images, but could easily be changed to apply shadows to tables, paragraphs, blockquotes, etc. as long as they have a set width and height.