Image Quality

All images published in digital media will render at the standard screen resolution of 72dpi. As such, images do not require a higher resolution than this to be published. Larger dpi will only result in unnecessarily large image file sizes.
Though your Web browser is capable of scaling photos to make them bigger or smaller, it's not very good at it. A graphics editor like Photoshop or Paint Shop will do a much better job. Resizing the image before uploading ensures the browser will load the smaller file, the area it occupies will be smaller and the whole page will load faster for visitors.