Images for your book
Images should be provided in either TIF or JPG format
Image resolution is measured in ppi (pixels per
inch) or dpi (dots per inch). For our purposes, we can assume them to
be the same.
The resolution of images created for display on computer screens is usually 72 ppi and seldom more than 96 ppi.
The resolution of photographic images for print (book covers and pages) should be at least 300 ppi. Therefore, a photographic image to be used on a 6 in. wide book cover should be at least 1800 pixels wide (6 in. X 300 ppi).
The resolution of line art* images for print (book covers and pages) should be at least 600 ppi. Therefore, a line art image to be used on a 6 in. wide book cover should be at least 3600 pixels wide (6 in. X 600 ppi).
*(Line art is any image other than a photograph
that consists of distinct straight and curved lines placed against a
(usually plain) background, without gradations in shade. Line art
illustrations are drawn by programs such as Corel Draw and Adobe
Read further for more information.
Taking photos for your book
Take photos with your digital camera at very hi-res (high resolution),
preferably in TIF format.
Photos for a 6 inch (15.25 cm) wide book cover should be at least 1800
pixels wide (300 PPI (pixels per inch)).
Photos that are to be 5" wide in your book should be 1250 to 1500
pixels wide (250 to 300 PPI).
not compress your photo files. Compression options in some programs
such as Microsoft Office Picture Manager reduce both file size and
picture dimensions based on how you intend to use the picture, such as
in web pages, e-mails or printed material (books).
Digital photo files
If you already have all your photos taken, send the photo files you have
(uncompressed) without making any changes to them.
them as email attachments or or using a large file sending service such
as found on my Contact page, not as insertions in an email or
insertions in a Word document.
I'll review them and determine their suitability for use in your book.
resolution of hi-res files can be decreased, but the
resolution of low-res files can not be increased. The only way to
properly increase the resolution is to re-scan the original photos at a
If we have to work with what we
have (lower resolution than normally considered acceptable) I'll do what I can to
improve their appearance in the book. However, don't expect them to look as good as a proper hi-res image.
screen shots and images dragged from web sites are usually about 96 PPI
-- lower than normally considered acceptable, but as above, I'll do
what I can to improve their appearance in the book.
and resolution information about a picture file can be obtained by
opening the file folder, right clicking on the file name and selecting
Print photos and scanning
If your photos are in print form taken by a film camera, they will need
to be scanned and converted into digital form.
Scanners usually represent resolution in DPI (dots per inch). For our
purposes, consider them the same as PPI (pixels per inch).
scan the photo at 300 DPI if you want it to remain the same size in the
book as the original.
scan the photo at 600 DPI if, in the book, you want it to be
scaled to twice the size of original
scan line art at twice the photo resolution (Line art is any image that
consists of distinct straight and curved lines placed against a
(usually plain) background, without gradations in shade.)
scan all the photos and line art to a TIF format
Below is more detailed information about photos
Using Photos in Your Book:
Understanding Print Resolution
by Joel Friedlander
I was talking to an author the other day about photos he wanted to put
in his book. I looked at the image files he had sent over with his
“They look great,” the author told me, “I’ve put them into the book in
Microsoft Word, I have it on the screen in front of me, it looks
“Uhm, I don’t think these are going to work in your book,” I said.
“What do you mean, they seem fine to me? What’s wrong with them?”
What the author couldn’t see was that I hadn’t even opened the image
files. I didn’t need to, all I had to do was look at the size of the
files in the email attachment panel. One was 4k, the others were 8k or
10K or even 24k in size.
“Look, I explained, “there’s a big difference in what we use online,
when you’re only going to be looking at them on a screen, and what we
need when we go to print these same photos. I know it doesn’t seem to
make sense, but the images you’re looking at on your screen are 72
dots-per-inch (dpi). We need files that are 300 dpi. And if they aren’t
300 dpi, there’s a good chance the printer will reject your job.”
Using File Size to Quickly Gauge Reproduction Size
I want to show you how to
calculate this for yourself, even if you just want to be able to tell
from the files you’re looking at if they are likely to work.
Okay, we’re going to do a little math now, but I promise it won’t hurt (too much).
Let’s look at the typical sizes of photographs or other grayscale
images you might use in a typical book. I’ve taken a page from a 6″ x
9″ book and divided the space within the margins:
A full page illustration can be as large as 4.25″ x 7.6″ without going into the margins or bleeding off the page.
A half page is 4.25″ x 3.8″
A quarter page is 2.2″ x 3.8″
Now, taking what we know—that graphics have to be 300 dots per inch at their reproduction size let’s do some calculating:
Our full-page illustration will need to have:
4.25″ wide x 300 dots per inch = 1275 dots, or pixels
7.6″ tall x 300 dots per inch = 2280 pixels
The photo that’s 1275 x 2280 will have a total of 2,907,000 pixels. That’s about 3 MB of data.
Our half-page illustration:
4.25″ wide x 300 dpi = 1275 pixels
3.8″ tall x 300 dpi = 1140 pixels
So the photo will be 1275 x 1140 or a total of 1,453,500 pixels, or about 1.5 MB.
Our quarter-page illustration:
2.2″ wide x 300 dpi = 660 pixels
3.8″ tall x 300 dpi = 1140 pixels
The photo will be 660 x 1140 or a total of 753,060, or about 800 KB.
Image Compression Makes a Difference
But wait. Most photos are
saved as JPG files. Leaving aside for a moment whether this is a good
idea (it’s not a good idea if you plan to keep editing the images). One
of the reasons we use JPG online is for its ability to compress the
files into much smaller sizes.
But it’s good to know what’s actually in the files. Let’s say we’ve
saved each of our illustrations in both TIFF format with no
compression, and JPG format with the compression set for maximum image
quality. Here’s what our final file sizes look like, as reported by the
Mac operating system:
Full page, TIFF: 2,989,336 bytes or 2,989 KB
or 842 KB
Half page, TIFF: 1,560,237 bytes or 1,560 KB
Half page, JPG: 537,242 bytes or 537 KB
Quarter page, TIFF: 844,607 bytes or 845 KB
Quarter page, JPG: 351,015 bytes or 351 KB
And now you know why I knew
many of this author’s photos were too small (and probably screen grabs
at 72 dpi, way smaller than what’s needed for offset printing).
Even for a quarter page photo, saved with compression, the file size
ought to be around 350 KB. Obviously, photo files showing a file size of
50 KB or 100 KB will not be usable for a printed book.
By the way, this is another reason it makes sense to create the layouts
and artwork needed for print production for your book before addressing
ebook versions. You need the high resolution images for print. While
it’s easy to reduce the size and resolution of your images, it’s not
possible to add detail and data (or resolution) back into the image
once it’s gone.
When planning to add photos to your book, make sure you have files with
enough resolution to print at the size you want in the finished product
Scanning Images for your Book
Photos in a quality printed book should be at a
resolution of 300 dots per inch (dpi). There is no point in having a
higher resolution than 300 dpi since the human eye will not notice any
improvement. If, however, you look at a photo with a resolution of 200
dpi beside the same photo with a resolution of 300 dpi, you may notice
that the lower resolution photo appears to be a bit patchy by
comparison. The flow of one shade into another is not as smooth as in
the higher resolution photo.
Photos should therefore ideally be scanned at a
will result in
an image file that is 300 dpi.
Let’s say you have a picture that is 2” wide.
If you scan it at 300 dpi, it will be 2” wide in the finished book.
If you scan it at 150 dpi, it will be 1” wide in the book.
If you scan it at 600 dpi, it will be 4” wide in the book.
If you scan it at 1200 dpi, it will be 8” wide in the book.
How to calculate the required scanner dpi setting:
If you have a photo that is 3” wide and you want it to be 6” wide in
the book, it should be scanned at 600 dpi
(300 dpi x 6”/3” = 600dpi)
If you have a photo that is 10” wide and you want it to be 6” wide in
the book, it should be scanned at 180 dpi
(300 dpi x 6”/10” = 180dpi).
You don’t have to be precise in the scanner dpi
setting, as long as it’s a little bigger than required. In the example
above, 200 dpi would be fine. Erring on the high side is better than
erring on the low side.
Line art is any image that consists of distinct
straight and curved lines placed against a (usually plain) background,
without gradations in shade. This type of image needs to be scanned at
600 dpi because our eyes can distinguish deviation from perfectly
smooth edges much more acutely than shade gradations. A 45 degree
angled line on a chart might appear to have a bit of a saw-tooth
appearance if the resolution is below 600 dpi. The same scaling rules
apply to line art as to photos.
File type: TIF or JPG.
TIF is THE leading commercial and professional image
standard. TIF is
the most universal and most widely supported format. TIF files for
photo images are generally pretty large. Uncompressed TIF files are
about the same size in bytes as the image size in memory. Regardless of
the novice view, this size is a plus, not a disadvantage. Large means
lots of detail, and it's a good thing. TIF stores it with recoverable
full quality in a lossless format (and again, that's a good thing).
JPG file format compresses the image into smaller file
sizes. It does
so by removing information about the image. The higher the compression
ratio, the more is lost from the image, and it is a loss that is not
recoverable. JPG format may be okay for scanned images, as long as you
know that the setting is for very little compression taking place,
otherwise, scan your images to a TIF format.
For a more detailed look at scanning, have a look at
site by Wayne Fulton: Scanning tips