small resolution image to pdf can't convert to A4 size

[liugt34]

Magick.NET version

Magick.NET-Q8-AnyCPU 13.6.0

Environment (Operating system, version and so on)

Windows 11

Description

when i convert the image to pdf, it genrate the pdf page with a small size,not A4 size

pageNumber 2 is normal A4 size

so how can i get the A4 size pdf with small image?

Steps to Reproduce

using var images = new MagickImageCollection();

var settings = new MagickReadSettings();
settings.Page = new MagickGeometryFactory().CreateFromPageSize("a4");
settings.Density = new Density(72);
settings.Width = settings.Page.Width;
settings.Height = settings.Page.Height;

var names = new string[] { "d20220118150203.png", "map.png" };

foreach (var name in names)
{
    var image = new MagickImage(SRC + name, settings);

    if(image.Width > settings.Page.Width || image.Height > settings.Page.Height)
    {
        // 计算图片应该被缩放到多大才能适应页面宽度并居中
        double scaleX = settings.Page.Width / (double)image.Width;
        double scaleY = settings.Page.Height / (double) image.Height;
        double scale = scaleX < scaleY ? scaleX : scaleY;
        int newX = (int)(image.Width * scale); 
        int newY = (int)(image.Height * scale);

        // 设置图片的缩放和定位
        image.Resize(newX, newY);
    }

    //图片居中显示
    image.Extent(settings.Page, Gravity.Center);

    images.Add(image);
}

// Create pdf file with two pages
images.Write(DEST + "Merge.pdf");

the test image used in code