PDF export rasters placed afphoto images in low resolution

[mark us]

On exporting a press ready PDF from publisher, my placed afphoto image is showing at a very low resolution when I open the generated PDF file.

If I use png exported from the same afphoto it's okay and sharp.

What is strange: If I make in the afphoto the upper lying group (that is set to invisible)  - that covers only part of the image - in the afphoto image visible, then the whole pdf is  sharp, too, if I make it invisible,  every part of the placed afphoto in pdf is blurry.

I found out: This occurs only if the placed afphoto image is set to 72 DPI - no matter that the pixel size is sufficient, as it shows - in Resource Manager - a "placed DPI" of 560dpi.

I reproduced the same with Photoshop and Indesign (CS4) and it worked well as I am used to, even if the psd-file is set to 72 dpi. Only the pixel-size matters. That's what I expect.

[John Rostron]

I have been having a similar problem. I created an A4 threefold flyer in Serif Page Plus, but needed to revise it. I exported from PP to pdf and then opened this pdf in Affinity Publisher 1.9.1.  I made my amendments and exported as pdf and sent it off to the printer. To my horror, all the images (a map and several photos) were all blurry. I discovered that the default resolution for rasterising images when exporting from publisher is 72ppi. Changing this to 300 on export generated sufficiently sharp images. I now have to get these printed again.

The document setup gives the document resolution as 300ppi. Why does Publisher export with a default rasterisation of 72ppi? Can I  change this?

The olriginal PP document exported a pdf with adequately sharp images. I note that it did not give me any ppi option for rasterising.

John