move image up and down when is larger

[leon700]

When I have an image larger, i can move it left and right but not up and down, why?

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linux mint 17.2 cinnamon
mozilla firefox 39
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[artofwalls]

I also have a similar issue. When I have an image displayed in the page (not in HTML, but directly loaded the jpg URL), I can zoom in, but then I can't scroll vertically to the top of the image.