The browser does not typically understand or honor dots-per-inch (DPI) encoded in images and will always render images in the browser at a 96 dpi resolution.

浏览器通常不能理解或支持图像编码中”点每英寸”（DPI）的计量单位，而总是以96 dpi分辨率来显示图像。

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To do this, you first need to tell Photoshop the dpi (dots per inch) of your computer display. Mine, for example, is 113.21. You can figure out yours with this handy.

要做到这一点，首先需要知道你的电脑显示分辨率(每英寸的点数)。例如我的是113.21。你可以用这个公式计算出你的分辨率。

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For example, you may want to use dots per inch (DPI) scaling on a control displaying a chart or other graphic so that it always occupies a certain percentage of the screen.

例如，对于显示图表或其他图形的控件，可能希望使用每英寸点数(DPI)缩放，以便该控件始终占据一定百分比的屏幕。

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The biggest improvement is the screen it displays text at 265 dots per inch (dpi), compared with the Kindle Paperwhite's 212 dpi or the Nook SimpleTouch's 167 dpi.

WSJ: The Best E-Reader: Kobo's Aura HD