PDF to Book

Why am I getting low resolution warning?

I’ve done a million of changes on my cover book and I’m still getting the low resolution on my book cover. 

I’ve checked the only two images I have for the book cover (back and cover) and they’re 300DPI, unless is something to do with the texts I’ve made in Adobe InDesign?

Thanks…

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Posted by
sapata
Jan 30, 2012 7:53pm PDT
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sapata
 

I occasionally get spurious low resolution warnings. Sometimes when I’ve uploaded the same book more than once I get the same warning about the same page, but InDesign tells me that I have at least 300 dpi, often a good deal more, so I ignore the warnings and never have any problems. I assume you’re ckecking the dpi in the links panel in InDesign? If it saysthat every image is at least 300 dpi (or even more than 200 dpi) you should be right.

Posted by
Maharg
Jan 30, 2012 8:40pm PDT
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Maharg
 

I was checking the resolution on Photoshop,  It’s the first time I’m using the InDesign and I didn’t know this option…

Just had a look now and it says "Actual PPI : 300  Effective PPI: 72 " and for the other image "Actual PPI:300 Effective PPI 125" 

Is that what it may causing ?  One of the files is  8.5 mega!

Thanks…

Posted by
sapata
Jan 31, 2012 3:48am PDT
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sapata
 

The "effective PPI" is the one you need to look at. You can set up the links panel so that there’s a column in the main panel for effective PPI, then order the list of links from low to high.

The actual PPI will change as you resize images. Try it and you’ll see. If you make an image smaller, the effective PPI will increase.

If you print a book with images of 72 PPI (or dpi … in this situation the same thing), then there is a risk you’ll be able to see the dots, and the image will appear grainy. You really need to get the figure over 200, or, to take full advantage of the printing process, 300. You can make the images smaller in the book, or upsize images in Photoshop if you’re desperate. (Image>Image Size)

Posted by
Maharg
Jan 31, 2012 1:31pm PDT
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Maharg
 

I ran into this problem recently while using InDesign for a Blurb book.  I got a low res warning on many images even though when I checked them inside InDesign they were all 300 dpi.  Turns out there is a bug in the Blurb preflight check. Here is the email from Blurb describing the issue. Based in their response I went ahead and orderd the book and the images were fine.

Robert Katz

Response Via Email(David) – 12/11/2011 08:58 PM
Hi Robert,

If you are receiving a low-resolution warning on your PDF to Book preflight page and you have confirmed your images are at least 150ppi, you may have encountered a small bug in our preflight software.

You can verify this by seeing if any images on the affected page(s) have a rotation applied to them. If they do, you may get this warning. Not to worry, as we do not modify your content and your images should print at the resolution you originally sent us. So go ahead and ignore that warning and order away!

Posted by
rkatzphoto
Feb 11, 2012 11:48am PDT
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rkatzphoto