# PDF转JPG
在下面的示例中，我们将该gographics/imagick包用作ImageMagick的C库的包装，以将我们的PDF转换为JPG。处理过程如下：我们使用软件包将测试文件加载到测试文件中，然后通过设置分辨率，压缩级别和alpha通道设置进行处理，然后保存最终的输出文件。由于该库基于C构建，因此重要的是我们必须适当调用Terminate和Destroy函数以检查内存使用情况。
**本文转自 http://www.topgoer.com/**
在Ubuntu 18.04下运行的前提条件：
```
sudo apt install libmagic-dev libmagickwand-dev
```
代码：
```go
package main
import (
"log"
"gopkg.in/gographics/imagick.v2/imagick"
)
func main() {
pdfName := "ref.pdf"
imageName := "test.jpg"
if err := ConvertPdfToJpg(pdfName, imageName); err != nil {
log.Fatal(err)
}
}
// ConvertPdfToJpg will take a filename of a pdf file and convert the file into an
// image which will be saved back to the same location. It will save the image as a
// high resolution jpg file with minimal compression.
func ConvertPdfToJpg(pdfName string, imageName string) error {
// Setup
imagick.Initialize()
defer imagick.Terminate()
mw := imagick.NewMagickWand()
defer mw.Destroy()
// Must be *before* ReadImageFile
// Make sure our image is high quality
if err := mw.SetResolution(300, 300); err != nil {
return err
}
// Load the image file into imagick
if err := mw.ReadImage(pdfName); err != nil {
return err
}
// Must be *after* ReadImageFile
// Flatten image and remove alpha channel, to prevent alpha turning black in jpg
if err := mw.SetImageAlphaChannel(imagick.ALPHA_CHANNEL_FLATTEN); err != nil {
return err
}
// Set any compression (100 = max quality)
if err := mw.SetCompressionQuality(95); err != nil {
return err
}
// Select only first page of pdf
mw.SetIteratorIndex(0)
// Convert into JPG
if err := mw.SetFormat("jpg"); err != nil {
return err
}
// Save File
return mw.WriteImage(imageName)
}
```
如果您看到类似以下的错误，请参阅[指南](https://alexvanderbist.com/posts/2018/fixing-imagick-error-unauthorized "指南")。
```
ERROR_POLICY: not authorized `TestPdf.pdf' @ error/constitute.c/ReadImage/412
```
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