Upsample Image on export? (Publisher)

[user_0815]

Is it possible to upsample images to a certain dpi on export as PDF? I've set the re-calculate option to the dpi that I need, but that doesn't upsample images. I'd like to avoid replacing the images manually.

[lacerto]

You can upsample to document DPI if your low-res image is masked (and you actually cannot avoid it). IMO this is a bad idea especially as upsampling will always be done using the bilinear method (this e.g. results in blurred versions of initially low-res but "sharp", jagged images like low-res screenshots that would look better when simply just resized mechanically). Upsampling should ideally be done selectively and controlled, and as there is dedicated software easily available that can do upsampling very well (including generating "missing" data), automatic upsampling is (IMO) kind of a last resort.

Exported to PDF to document DPI:

upsampled.pdf

[user_0815]

Thanks for the tip. Yes I agree, for best quality it should be done before adding the image to the Publisher document. Usually I do that. However, my assignment was to place the images as they were givent to me and send them to the print shop. For me it's just about meeting the technical requirements of the print shop. I thought that images in the document could be resampled on export.

The quikest work-around that I found is to "Rasterise" the image (Image Layer in a picture frame) via the context menu. The Preflight list shows me a list of those images which have lower dpi than required. A double-click on that list item brings me right to that particular image in the layers panel. Right-click -> Rasterise wil raster the image in the document dpi (300 in my case). 

[lacerto]

8 hours ago, user_0815 said:

The quikest work-around that I found is to "Rasterise" the image

Yes, that is the quickest destructive method. The mask method is pretty much just a trick and a quirky attempt to mere export time (non-destructive) and ad hoc upsampling (DPI being definable also at export time), and does not work trustworthily. But being aware or the behavioral connection to cropped/masked images is useful, at least to avoid inadvertent upsamplings.