Document resolution vs. Placed DPI

[thomaso]

When I increase in "Document Setup..." the document resolution, then in "Resource Manager..." the Placed DPI appears increased, too – instead of reduced.

For example: increasing the document resolution from 300 to 400 dpi increases the placed dpi from a 300 dpi jpg to 400 dpi.
Or vice versa: a documents DPI reduction from 300 to 72 dpi does also reduce the Placed images DPI from 300 to 72 dpi.

That can't be correct.*

* or would be a wonderful magic method to change lowres images to highres simply by setting the document dpi.
( this bug might be related to this different topic: https://forum.affinity.serif.com/index.php?/topic/66358-affinity’s-running-gag-not-honouring-resolution/ )

[Chris_K]

Hi Thomaso

This will depend if you have pixels or physical measurements set for the document. If pixels are selected changing the DPI will alter the documents physical dimensions, if a physical dimension is selected changing the DPI will affect the pixel density, but the image stay the same size relative to the page

[thomaso]

Hi @Chris_K, nope, I can not see a difference if a document is set to pixels or millimeters (except ruler units). In both settings, the "Placed DPI" becomes changed according to the set document resolution: Increasing the document resolution increases the placed dpi. So to speak, is a false information, both in pixels and in millimeters, as this information does not inform about the effective DPI value as it pretends or would be expected.

Also, in both, pixels or millimeters, a change of the documents DPI does not alter the documents dimensions nor the dimensions of placed images. And even for new documents in pixels: e.g. an A4 document becomes by APub the dimensions of about 3500 x 2500 px, totally regardless of its selected DPI. But this, I guess, might be a different, additional bug.