However, it is up to the user to determine whether an image was produced by myself or someone else. In nearly all cases, if an image is not my own, I have clearly stated so either in the web page's text or in the "alternate text" given in the HTML code source for the page.
Most browsers are configured so you can place your cursor over a picture and see the alternate text. If yours isn't, then place your cursor over the image you want, right-click on your mouse, click on "PROPERTIES," and determine the image's file name, such as "hand.gif." Then at the top of your browser click on VIEW, then SOURCE, and do a search for the file name. In the code placing the image in text, there should be something like "alt="To email Jim..."" That's the ALT statement, and if the image is someone else's and the fact isn't mentioned in the page text, it should be here. If not, usually you can be sure that it's my own image and you can use it.
Of course it's always nice to know that others are benefiting from my work. You might consider dropping me a line to let me know what you've done.