There are a three common of images that are presented by your browers.  They are the *.GIF images generated by graphic packages.  The *.JPEG and *.JPG images that are commonly generated via digital cameras.  There is a third image format that most of you would not know its name.
    The commonly seen graphics *.BMP and *.PDF are not able to be presented via the browsers, but are presented by such programs like MS-PAINT and Adobe Reader.  There are other graphic files, like movies, that require a package other than your browsers.
    There is a third common graphic presented directly via your broswers.  They are graphic files created in real time by the servers that hold the tabular data that is used to generate them.
    They are created on a demand request and sent to your browsers.  The most common graphics of this type are "graphs" that you see within the Yahoo! Finance pages.  They are called *.PRN files.  These image files are virtually created in a instant from tabular data files that varies with time.
    The following links are to *.PRN file graphics.  They are "dynamic" when the stock market is open (10:00 EST - 4:00 EST), and they appear "static" when market is closed.

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You will likely need to "refresh/reload" the graphic to achieve the latest image as your local computer may find a previous image in your computer memory.  Check the date/time stamp on the image.