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sd5e8a
Inspiring
September 22, 2022
Question

Jagged details on screen and in print

  • September 22, 2022
  • 2 replies
  • 393 views

I noticed that some details in some of my raster images appear jagged (ussually diagonal lines). This happens not only on screen, but also in print (and here I mean professional prints).

 

I see this in Indesign, but also in Acrobat after I export a PDF (with no downsampling), especially if I zoom out or if I scale down the image. The more I zoom in or scale up - the image looks better, the more I zoom out or scale down - it looks worse ("it shows teeth"). First I thought that this appears only on screen and that I can safely ignore it, but I was wrong.

 

People just repeat: "Use a hi-res image, use a hi-res image...", but that doesn't always help. These images have large dimensions, so I guess that's not the problem. In Indesign they're over 300 ppi. If I view them in an ordinary image viewer, they look perfect. Note that I'm not scaling up low-res images.

 

Some printeries (regardless if they are offset or digital) handle these problematic images better and some worse.

 

I tried a 3rd party anti-aliasing tool to iron this out, but I'm loosing sharpness and there're still some jaggies, and I'm still not sure how this will appear in print. Another problem is that I don't know many anti-aliasing tools, so I can't compare them. And I'm not even sure whether this has to do with aliasing.

 

I noticed that other forum participants have similar problems, but I couldn't find a solution for my case:


https://community.adobe.com/t5/indesign-discussions/jagged-edges-in-photographs-printed-from-indesign/m-p/10775658

 

https://community.adobe.com/t5/indesign-discussions/indesign-pdf-export-results-in-jagged-lines-when-zoomed-out/m-p/9619917

 

Thanks

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2 replies

rob day
Community Expert
rob dayCommunity Expert
Community Expert
October 4, 2022

Hi @sd5e8a , Can you share a problem PDF?

E
Community Expert
Eugene TysonCommunity Expert
Community Expert
October 4, 2022

Hey

 

Here's an article I wrote

https://creativepro.com/high-res-image-look-low-res/

 

Hope it helps.

    S
    sd5e8aAuthor
    Inspiring
    October 4, 2022

    Thanks, @Eugene Tyson, I know about the View > Display Performance settings and the related things mentioned in your article.

     

    Your article is very useful, but my problem is different. Not only that the images appear jagged on screen, but also in print (not all of them, but some of them).

     

    @rob day, I'm sorry that I can't share the images that I work with, but this is an example posted by another forum participant, so you can have an idea about the problem. Most problematic are the diagonal lines. For example, it can be a photo of birds on a wire or something like that.

     

     

    I didn't know how to solve the problem, so in some cases I tried to smooth the problematic images with some anti-aliasing tools. This way I loose sharpness, but that's it. In other cases I used moire-removal or descreening tools. Sometimes I enlarge the images a bit, then I print them (on a printer that gives me good results) and then I scan them with descreening turned on (note that I'm not confusing anti-aliasing and descreening, which are two different things, but I have no idea what else to do).

    rob day
    Community Expert
    rob dayCommunity Expert
    Community Expert
    October 5, 2022

    I'm sorry that I can't share the images that I work with,

     

    A screen capture doesn’t really help, I would need to see a PDF to determine whether the problem is not enough output resolution, or simply a limitation of display anti-aliasing at different zoom magnifications.

     

    Black and white line art needs considerably more resolution for print than a typical halftoned image. The rule of thumb for image resolution is 2x the halftone screen (300 ppi for 150 lpi), but if there is high contrast detail (black lines on a white background) you would need more.

     

    Also, you have to inspect the image in AcrobatPro to get the output resolution—placing a 300ppi image doesn’t mean the output resolution will be 300ppi in the PDF.

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