4.3. 针对打印更改图像的大小

As discussed before, pixels don’t have a set size in the real world. When you set out to print an image on paper, GIMP needs to know how big each pixel is. We use a parameter called resolution to set the ratio between pixels and real-world units such as inches.

By default, most images open with the resolution set to 72. This number was chosen for historical reasons as it was the resolution of screens in the past, and means that when printed, every pixel is 1/72 of an inch wide. When printing images that are taken with modern digital cameras, this produces very large but chunky images with visible pixels. What we want to do is tell GIMP to print it with the size we have in mind, but not alter the pixel data so as not to lose quality.

要更改打印尺寸，请使用图像 → 打印大小打开“打印大小”对话框。选择您喜欢的尺寸单位，例如“英寸”。设置一维，让GIMP按比例改变另一个。现在检查分辨率的变化。如果分辨率为每英寸 300 像素或以上，则打印图像的质量会非常高，像素不会很明显。分辨率在 200 到 150 ppi 之间时，像素会有些明显，但只要不仔细检查图像，图像就会很好。低于100的值明显粗糙，仅应用于从远处看到的材料，例如标志或大型海报。

图 3.20. 设置打印大小的对话框