java – 使用pdfBox从PDF中提取的图像的DPI

我知道pdf文件本身不包含DPI信息.

然而,文档中具有相同尺寸的图像在提取后具有不同的像素大小并且没有dpi元信息.

那么有可能以某种方式计算相对于pdf页面的图像大小或使用pdfBox提取其dpi信息(对于png或jpeg图像文件)的图像？

谢谢！

            float imageXScale = ctmNew.getXScale();
            float imageYScale = ctmNew.getYScale();
            System.out.println("position = " + ctmNew.getXPosition() + ", " + ctmNew.getYPosition());
            // size in pixel
            System.out.println("size = " + imageWidth + "px, " + imageHeight + "px");
            // size in page units
            System.out.println("size = " + imageXScale + "pu, " + imageYScale + "pu");
            // size in inches 
            imageXScale /= 72;
            imageYScale /= 72;
            System.out.println("size = " + imageXScale + "in, " + imageYScale + "in");
            // size in millimeter
            imageXScale *= 25.4;
            imageYScale *= 25.4;
            System.out.println("size = " + imageXScale + "mm, " + imageYScale + "mm");

            System.out.printf("dpi  = %.0f dpi (X), %.0f dpi (Y) %n", image.getWidth() * 72 / ctmNew.getXScale(), image.getHeight() * 72 / ctmNew.getYScale());

这是一个示例输出：

找到图像[X0]

position = 0.0,0.0

size = 2544px,3523px< ---- pixels size = 610.56pu,845.52pu< ----“page units”,1pu = 1/72英寸 size = 8.48in,11.743334in 尺寸= 215.39198mm,298.28067mm dpi = 300 dpi(X),300 dpi(Y)