Can effective ppi be too high?

[bammelam]

I wonder if a high resoultion image placed and downscaled in InDesign can result in a blurred image via pdf and then print?

I sometimes find that images of very high resolution come out in print somewhat blurred.

Can this be a result of the many original pixels/effective ppi being sampled wrong via the pdf?

If so - can it be solved by settings in the pdf?
Or should the image size and resolution ideally be closer to the output - at least without heavy downscaling/a very high effective ppi?

To my knowledge anything the same or higher than the wanted output resolution (typically 300) is fine.
But I do suspect that rule a bit.
In this case the blurring comes from the general 'High Quality' pdf setting to a good laserprinter.

... ?
🙂

[oleh_melnyk · Accepted solution]

As far as I know (and I'm not an expert in this field) - too high resolution is as bad as a too small res... And any automated downsample/upsample can go wrong...

So, ideally, it's recommended to upscale/downscale, RGB-2-CMYK conversion, scaling/rotation, etc. image manipulations be made in image editing software, such as Photoshop, and then be placed as is in InDesign...

But it's pretty hard to scale/rotate/prepare image for layout without seeing layout, so personally, I prefer not to open Photoshop if it's not absolutely necessary (I'm a freelance magazine designer, dealing with hundreds of images weekly, so I can't edit each of them manually)

[bammelam]

Thank you for answering, it seems the answer is actually that if possible it is better to avoid the very high effective ppi and ideally stick to the output size from the beginning (Photoshop). But as you say this is usually not possible, and besides that would be something quite different than intended with working in InDesign.
I have also asked a printers office. They say that usually - very rarely - it is a problem, but it can be. She mentioned taht InDesign has algoritms to take care of this.
Alternatively one can make the pdf with 'no downsampling', but this may produce too large/complicated files for the printer, ripping (and whatever goes on in printing).

Bottomline so far for me is that it is better to avoid the very high effective ppi and/or besides that have som testprint done to check with the output machinery how it will manage the images.