将像素转换为pdf的点数 [英] Convert pixels to points for pdf

问题描述

我使用php和fpdf生成pdf。如何缩放400像素高的图像以适应300点高的空间？尺寸只是示例，图像和可用空间是动态的。

I am using php and fpdf to generate a pdf. How can I scale a 400 pixel high image to fit in a 300 point high space? The dimensions are just examples, the image and available space are dynamic.

推荐答案

如果你想在300点中调整400像素，然后你的调整大小因子只是 300/400 = 0.75。你需要将每个像素放在0.75点。

If you want to fit 400 pixels in 300 points, then your resizing factor would simply be 300 / 400 = 0.75. You need to put each pixel in 0.75 of a point.

但是你应该知道另一个故事：每个点都是1/72英寸。以及1英寸的像素是选择的问题。

But there is another story you should know: Each point is 1/72 of an inch. and how many pixels make 1 inch is a matter of choice.

所有图像都有一个名为DPI的属性：每英寸点数。它指定图片的每英寸有多少像素。因此，如果您想将400px * 400px图片转换为（例如）96 dpi图像，则调整大小因子将为 400 /（（72/96）* 400）。 72这里是将英寸转换为点数。

All images have a property called DPI: dots per inch. It specifies how many pixels are there for each inch of the picture. So if you want to convert a 400px * 400px picture to a (say) 96 dpi image, your resizing factor will be 400 / ((72 / 96) * 400). 72 here is for converting inches to points.

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