Image size % shown in Publisher info bar.

[Mike_B]

I’m transitioning to Affinity Publisher from Adobe InDesign, and for the most part, am making the change fairly smoothly. I have a question regarding images placed in a document. In InDesign I always placed all my images into the document and then resized as needed in the picture boxes and used that percentage to then resize them in Photoshop so that they could all be re-placed at 100% in the document. The DPI of those images varied as I like to keep the resolution as high as possible and that a press can use, so some may be 300 dpi and some may be higher. In Publisher, I notice that the % (shown in the picture frame information at the top left of the document window) varies by the dpi assigned to the document at set up. So, if I bring an image that has a resolution of 400 dpi (and already final sized to what I want in the document) into a document set to 400 dpi, it correctly shows it as 100%. But if the document dpi doesn’t match that of the image, it shows the image is placed at a different % even though the document dimensions haven’t changed. I hope this makes sense. I’m also curious as to why the document even needs a dpi assigned.

[MikeTO]

Hi @Mike_B and welcome to the forums.

Publisher uses the document's DPI setting only to determine the default size of the images you place. It has no other purpose and you can set a different resolution when exporting to PDF. You can test this out by creating two documents, one with a DPI of 100 and the other with a DPI of 300, and placing the same image into them.

Tip: Select an image and click that resolution information in the Context Toolbar - a popup window will appear with text fields to edit the image DPI and scale as well as a button to reset to the original size. Many users miss this feature.

[Mike_B]

Thanks for your response. I had stumbled on to that drop down but hadn't played around with it. What I'm finding is the the % at which the image is in the picture box behaves as expected if the document dpi matches that of the placed imaged, but if the document dpi is set differently, the percentage is incorrect. Place a 4"x8" @ 400 dpi into a 4x8 picture box and it shows as 100%. Place it to fit in a 2x4 picture box and it shows as 50%. That's if the document dpi is set to 400. But change the document dpi setting and those %s change even though the physical size of the picture box and the crop remain the same. Perhaps I'm missing something simple.

[thomaso]

3 hours ago, Mike_B said:

I’m also curious as to why the document even needs a dpi assigned.

2 hours ago, MikeTO said:

Publisher uses the document's DPI setting only to determine the default size of the images you place. It has no other purpose

Apart from the absolute, physical size of a placed resource (inch, mm), the document resolution also defines the resolution for rasterization procedures in Affinity documents during the layout process.

1 hour ago, Mike_B said:

But change the document dpi setting and those %s change even though the physical size of the picture box and the crop remain the same.

Changing the document DPI is kind of changing the equivalent of the document size in pixels. For your placed image resources only their total number of pixels matter (megapixel) while their resolution is flexible. Your 4"x8" image file has a certain number of pixels, they do not change if you alter the resolution of the layout document where you placed the image.

To ensure a certain quality and avoid large, increased pixels for instance, Affinity offers a default placing size of an image which respects the document resolution. This size is called "100%" and the size of a pixel of the placed image corresponds with the current pixel size of the document (e.g. 300 per inch). If you change the document resolution later then the placed, physical dimension don't change but the resolution of the placed resource does and the pixels of the placed document get their size and density changed – otherwise a change of the document resolution would also change the physical (inch, mm) page size or the size of the layout objects. The latter case may happen if you copy/paste an element between Affinity documents that are set to different resolutions.

[Mike_B]

Thanks for your response. I know that pixel is a more widely considered unit these days, but I've only ever thought in pixels when working with images. As long as my placed images were of sufficient resolution when placed in a page layout document, I let the printer worry about everything when imposing and ripping to plates. My reasons for having all images in a document at 100% goes back to the days of prepress houses charging by the hour for processing time. Back when they had much less horsepower, the tighter your files, the less you paid.