Book Design and Imaging

What is the photo is 600dpi?

Most of my photos are 600 dpi (I scan them from slides and negatives) and now I’ve read in one of the answers that they should be 300dpi. What happens if I use them to make a book? Will the quality suffer for any reason? So should I cahnge the resolution to 300dpi before I make the book or can I leave them as they are?
Thanks, Viktor

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Posted by
teveve
Jan 12, 2009 3:02pm PDT
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teveve
 

Hello Viktor;

300dpi is the industry standard for printing… there is no benefit in printing at a greater resolution, so, BookSmart will downsize your imported images to 300dpi for anything which exceeds that maximum.

HOWEVER, if I were you, I would re-work my images first in PhotoShop (or similar) for maximum control of how they will appear… if you leave it up to BookSmart, although it does a decent job in general terms, there are exceptions… and… if you allow BS to do the work you wil have no comeback if you have printing artifacts as a result…

Good luck;

Lee

Posted by
lkb-28
Jan 13, 2009 1:51am PDT
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lkb-28
 

Thank you for the advice. By the way, do you think I should scan the images in 300dpi in the first place or is there any advantage of a higher resolution at all (if printing uses 300dpi anyway)?

Posted by
teveve
Jan 13, 2009 2:10am PDT
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teveve
 

Hi Viktor;

There are definate advantages in scanning initially at GREATER than 300dpi…

See part 4 of this post for some scanning tips – that may help… [click on link]...

Cheers;

Lee

Posted by
lkb-28
Jan 13, 2009 2:35am PDT
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lkb-28
 

Thank you again, I’ve read the posts and now I understand a lot more. One final question, though. The size of my images is generally around 7000×4700 pixels, scanned at 600dpi. If I downsize them to 300dpi for BS, the size also halves, which means that they may be too small for some containers or covers. Is it a good solution in this case to increase the size back to e.g. 4000 pixels on the long side (staying in 300ppi), or will this affect quality?
(I cannot initially scan them at any larger size as the maximum resolution of my scanner is 5400dpi.)

Viktor

Posted by
teveve
Jan 13, 2009 4:02am PDT
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teveve
 

Hi Viktor;

This is indeed a two-part process; but you need to do it in the reverse order to your post above…

Starting with your c. 7000×4700 (3:2) image, in PhotoShop;

 - Image, Resize, Image Size… CHECK "Constrain Proportions" and UNCHECK "Resample Image"...

 - In the "Document Size" window enter the finished width of the image you want… this should be sized (at 300dpi) to the width of the BookSmart container you want to use… Assuming you are using a full-bleed page of 3888×3263 pixels you would enter 12.96" ( 3888 / 300 )... the height takes care of itself… You will see that your dpi has reduced to c. 540…

 - Click OK to save this change…

 - Reopen Image, Resize, Image Size, and now CHECK "Resample Image"...  In "Resolution" enter 300, click OK and SAVE AS the change… as a NEW file so you preserve the original…

You now have a correctly sized image ready for import to BookSmart at 300dpi…

If you did it your way, your image would either wind up less than 300dpi, or result in interpolated pixels being added…...

Hope that helps;

Cheers;

Lee

 

Posted by
lkb-28
Jan 13, 2009 5:50am PDT
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lkb-28
 

Absolutely. I can’t thank you enough. Have a nice day.

 

Viktor

Posted by
teveve
Jan 13, 2009 6:23am PDT
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teveve
 

I don’t think any of the above is necessary.

Booksmart does not care what "dpi" your photos are. DPI is meaningless unless you are actually printing directly from a file. All that matters is the size in pixels.

An image that is 10in x 5 in at "600dpi" is EXACTLY the same as an image that is 20in x 10in at "300dpi". Both are simply 6000×3000 pixels.

The size in inches is utterly meaningless for a digital file. All that matters is pixels. In fact I think Booksmart should remove the "size in inches" from its containers, as it only leads to this sort of confusion.

Posted by
robkingston
Jan 17, 2009 5:49am PDT
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robkingston
 

Rob,

I agree that it is not necessary but I suspect that only photographers think in Pixels. "Normal" people think in terms of inches (or cm), and if they are sizing their photos in (say) Photoshop or Picassa they may be more comfortable defining that in inches/cm, in which case the dpi is important. I suspect they may be the largest part of the Blurb customer base.

..........Tony 

 

Posted by
tfrankland
Jan 17, 2009 6:47am PDT
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tfrankland
 

Hi Rob;

With respect – BookSmart DOES care what dpi a users image is – and it DOES matter – but I do agree that it frequently leads to confusion and does need to be used alongside other factors to be fully meaningful!

In the case in point here – the net dpi for a full-bleed image brought into a 13×11 landscape would have been 540! (A smaller book size would have resulted in an even greater net dpi.) That’s way too big for BookSmart – so BookSmart would have downsized the image to 300dpi – without the user having any control over the effects generated by that downsizing routine!

Conversely, a smaller image (pixel dimension wise – say from an older 3 or 4 Mp camera) brought into a larger container may well return just 151dpi, but will not raise any warning flags in BookSmart (that doesn’t happen until you breach 150 dpi) but it would NOT return a decent print!

So, although you can’t use dpi as a stand-alone tool – it does matter in the greater scheme of things… Shame is, a large number of users don’t understand the whole relationship of these measurements – that’s why I wrote my briefing note; in an endeavour to explain things in simple lay-man’s terms…

Cheers;

Lee

Posted by
lkb-28
Jan 19, 2009 4:00am PDT
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lkb-28
 

I have just read the latest comments on the topic. I think, to be on the safe side, I will go through the procedure recommended above. There is one more think, though.

A friend of mine is now constructing his book (wedding photos) and the images were taken using a Canon Rebel. These images are all approx. 4200 pixels (long side) and 72 dpi. I do not know whether this will be OK (he’d like standard landscape format). The photos look good on the monitor but I’m not sure they’ll be OK in print.

Any suggestion?

Posted by
teveve
Feb 22, 2009 11:47am PDT
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teveve
 

Arg, this seems like such an easy concept but people have such tough problems with it.

Victor,  scanning a slide at 600 dpi is not high enough resolution.  The dpi is only valid for the size you scanned the slide at, in this case 35mm or about 1.4 inches.  So you have approximately 826 pixels across.  If you print this picture 4 inches wide, (826/4) you have a resolution of ~206 dpi.

When Rob, says that Booksmart doesn’t care what the dpi of the photo is, I think what he means is that it doesn’t care what the setting is in the photos metadata.  The only thing that matters is how many pixels there are spread across the container to create the dpi when printing.  Your friend with 4200 pixels @ 72dpi has a much higher resolution than your 600 dpi scans.  If anything, he might want to use photoshop to reduce the resolution before putting his photos into very small containers in blurb. 

One last comment.  When I say "the size of the container", I don’t necessarily mean the size of the opening in the blurb template.  If you enlarge your photo so only a portion of it shows, then you must take the new size of the enlargement, divided into the number of pixels to get the dpi.

It’s really very simple.  The total number of pixels divided by the number of inches in the print size = pixels per inch (dots/inch, pixels/inch same thing).  The dpi in the photo metadata is meaningless.

Mike

Posted by
Charybdis
Feb 22, 2009 5:32pm PDT
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Charybdis
 

Mike, thank you for your advice but there is something you might have misunderstood (or I wasn’t clear enough). When I scan my slides the scanner’s application has two resolution values that I can set: input and output. The input resolution is maximum 5400 dpi and in most cases I scan at around this value, while I set the output resolution to 600 dpi (it’s because this way the size of the print is 20×30 cm or around 7000×4700 pixels). Now, I’d really like to know if you think this is too low resolution or did you think I was referring to the input resolution in the first place?

Posted by
teveve
Feb 23, 2009 1:38pm PDT
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teveve
 

 You were clear enough, I simply missed your third post. 

You have more than enough resolution.  Probably too much.  I don’t know your skill level with photoshop, but Lee’s advice is the path I’d follow. 

Mike

Posted by
Charybdis
Feb 23, 2009 5:46pm PDT
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Charybdis
 

I think it’s high time for Blurb to stop confusing the matter by inferring that ppi and dpi are synonyms. Images are created with a ppi value; printers print with a dpi setting. There is no way Blurb is “printing at 300 dpi”—the results would be terrible. Check out your desktop printer. If you print at 300 dpi the output would be draft quality at best. Most desktop printers go to at least 1440 dpi; my Epson Stylus Pro 7600 goes to 2880 dpi. Images are created with a ppi value, but they are printed at a dpi setting—and they are virtually never the same. For quality output the printer dpi needs to be significantly greater than the image ppi, typically by a factor of 5. What Blurb really wants is images that are 300 ppi for the container size they specify. Understanding the difference between ppi and dpi and the relationship between image pixel dimensions and image size at 300 ppi is basic to quality. Blurb needs to put forth a simple clear explanation and/or provide online calculators to assist users. People are not stupid; I think they can handle both ppi and dpi if Blurb would put forth the effort to address the topic clearly.

 David 

Posted by
rdavidd
Feb 25, 2009 4:02pm PDT
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rdavidd