Photoshop-Viz: Acquiring Digital Images

Acquiring Digital Images

While Photoshop is a great tool for many tasks,

most of them center on the sizing, manipulation,

and processing of digital images. Even though

their contents may vary, all digital images are es-

sentially the same: They are composed of pixels

that contain color and luminance information.

Photoshop’s powerful features allow you to adjust

those pixels to better match your needs.

And while the destination may be the same,

the path your digital images take to get inside

Photoshop will vary. Some may start out as digi-

tal images acquired with a still camera, whereas
others may be loaded via a scanner. You might

Pixels in detail: When you zoom into an image at 1600%
magniﬁcation, the pixels are very easy to see. You can open

also search online resources to ﬁnd specialized

the photo Ch03_Car_in_Mirror.tif from the Chapter 3 folder

images. Let’s take a look at the many ways to
acquire your digital images.

and use the Zoom tool (Z) to magnify the image. In fact, you
can zoom up to 3200%, which makes pixel viewing quite easy.

Digital Cameras

This book will not teach you how to use your digi-

tal camera. Many excellent books on that subject

as well as classes are offered. What this book will

address is how the pixels are converted, what ﬁle

format you should choose to shoot your images,

and how to transfer them to your computer.

Digital Camera Technology

Shooting a photo digitally produces a less ac-

curate image than scanning a photo shot on

Sensors in a digital camera acquire an image by converting

ﬁlm and scanned with a ﬂatbed scanner using a

light into pixel data.

26 Chapter 3 Acquiring Digital Images

high spi setting. This is because digital cameras
capture data using photosensitive electronic sen-
sors. These sensors record brightness levels on a
per-pixel basis. However, the sensors are usually
covered with a patterned color ﬁlter that has red,
green, and blue areas. While the ﬁlter attempts
to capture all detail that the lens sees, it is unable
to due to its design.
The ﬁlter used is typically the Bayer ﬁlter ar-
rangement, which contains two green pixels, one

The Bayer ﬁlter arrangement uses an
arrangement of red, green, and blue
pixels and is very common in digital
cameras. There are more green pixels
because the human eye is more sensi-
tive to green information.

red pixel, and one blue pixel. The Bayer ﬁlter
uses more green because the human eye has an
increased sensitivity to green. This ﬁlter allows
the image to record the brightness of a single pri-
mary color (red, green, or blue) because digital

cameras work in the RGB color space. The RGB
values combine using the additive color theory (which was brieﬂy
discussed in Chapter 1, “Digital Imaging Fundamentals”) and
form an image when viewed from a suitable distance.
Not all the properties of ﬁlm can be fully imitated by the computer
sensors in a digital camera, so the camera must interpolate the
color information of neighboring pixels. This averaging produces
an anti-aliased image, which can show visible softening. When
anti-aliasing is present, hard edges are blended into one another.
Sometimes this can be desirable (with low-resolution Internet
graphics where you reduce ﬁle size by limiting color). Other times,
anti-aliasing can produce an undesirable softness when you print
an image. Depending on the colors in the original image, a digital
camera might only capture as little as one-fourth of the color
detail. For example, if you had a desert scene with lots of red detail
and little green or blue, the sensor would rely on the red areas of
the ﬁlter (which only cover a fourth of the sensor face).
Does this mean you should shoot ﬁlm only? Of course not; I shoot
both. But it’s important to shoot for what you need. There are
strengths and weakness of both ﬁlm and digital capture (as well as
several stylistic decisions). Ultimately, ﬁlm captures a high-quality
image that can be optically enlarged using the negative. However,
digital capture can be more convenient and affordable because
you get instant feedback on the images you have just taken, and
you eliminate the time-consuming process and costs associated
with developing the ﬁlm.

Digital Cameras 27

It is important to shoot at a high pixel count (which can be accom-
plished by setting the camera to shoot in a high- or best-quality
mode). You can always crop or shrink the image for output or

7

VIDEO
TRAINING
Importing Images with
Adobe Bridge

display, but you should do your best to avoid enlarging the image.

When a digital image is enlarged, it can create unwanted image

softness or pixelization (a visible blockiness). Capture as much

pixel data as possible to minimize digital upsampling (increasing

the resolution of the image).

Shooting JPEG vs. RAW

When digital cameras became commercially available, the

memory cards used to store pictures were very expensive. Many

photographers could not afford multiple or high-capacity cards,

so they wanted more images to ﬁt on a single, smaller card. Many

users also emailed their pictures to friends and family. Small ﬁle

sizes enabled consumers who lacked an understanding of digital

imaging to attach photos to emails with minimum technical head-

aches. With these two scenarios in mind, manufacturers turned

to an Internet-friendly format, JPEG ( Joint Photographic Experts

Group). It was a proven technology and one that was familiar to

many users.

The JPEG format is extremely common because

most hardware and software manufacturers have

built support for it into their products. The JPEG

format is also extremely efﬁcient at compressing

images, and it is a good format for continuous

tone images, such as photos. A JPEG ﬁle looks

for areas where pixel detail is repeated, such as

the color white on every key of your computer

keyboard. The ﬁle then discards repeated infor-

mation and tells the computer to repeat certain

color values or data to re-create the image.

While JPEG is a good format for distributing

images (due to their compatibility and small ﬁle

size), it is not great for image acquisition or pro-
duction. A JPEG ﬁle is lossy, meaning that every

The JPEG Options box is available when you modify a JPEG
ﬁle with Photoshop. When saving, you can adjust the Qual-

time you modify it in Photoshop and resave, ad-

ity slider to reduce ﬁle size. It is best to leave Quality set to

ditional compression is applied to the image. Over
subsequent compressions, the image quality can

maximum if you will be making future edits to the image:
This applies the least compression that could damage the
image’s appearance.

noticeably deteriorate. This is similar to the act of

28 Chapter 3 Acquiring Digital Images

making a photocopy of another
photocopy: Additional image
deterioration occurs with each
processing step. The visible loss
in image detail or accuracy is re-
ferred to as compression artifacts.
So, if JPEG is so inferior,
why do so many people use
it? Money and resistance to
change are the simple answers.
It’s a lot cheaper to shoot JPEG
images because you don’t need
to buy as many memory cards.

This image was captured as both a raw and a JPEG ﬁle when it was shot. The

Additionally, even many pros

picture was taken with a Nikon D300, which can simultaneously write both ﬁles
to the memory card when shooting.

have been slow to abandon
JPEGs. Learning how to use

new technology requires time,
something that most people are short of these days.
Newer digital cameras, generally the pro models, offer newer
formats, typically called raw. These raw (or native) formats have
several beneﬁts over shooting to JPEG. The images are usually
captured at a higher bit rate, which means that the pixels contain
more information about the color values in the image. Most raw
ﬁles have a depth of 10, 12, or even 16 bits per channel instead of
the 8 used by JPEG. The raw format also has a greater tonal range;

TIP
Workaround for
Unsupported Cameras

hence, there is a better exposure for shadows and highlights. This
extra information makes your work in Photoshop easier because it
adds greater ﬂexibility and control in image adjustments and color
correction. You should have less work to do in Photoshop as well,

If Photoshop does not support a
particular raw format used by your
camera, use the software that

since the image captured has more color information than a JPEG
would have.

shipped with the camera. The im-

Raw ﬁles can be two to six times larger than JPEG ﬁles. This extra

age can be converted into a 16 bit

data is used to hold more image detail, which can reduce, or even

TIFF image (a high-quality ﬁle with

eliminate, compression artifacts found in JPEG ﬁles. However, that

no compression), which Photoshop

extra data can increase the time it takes for the ﬁles to write to the

can open.

memory card.

The raw ﬁle captures the unprocessed data from the camera’s
image sensor. While your camera may contain settings for sharp-
ness, exposure, or lighting conditions, the raw ﬁle stores that info

Digital Cameras 29

as modiﬁable information and captures the original (unmodiﬁed)
data that came through your camera’s sensors. This is very useful
because it lets you easily adjust white balance within Photoshop.
Each manufacturer treats the format differently, using a propri-

TIP
Camera Raw for TIFF
and JPEG?

etary format. Fortunately, Photoshop frequently updates its raw
technology to support the newest cameras on the market. To ﬁnd
out if you can access a particular camera format from within
Photoshop, visit Adobe’s Web site at www.adobe.com/products/
photoshop/cameraraw.html.

While the Camera Raw interface
can be used for JPEG and TIFF ﬁles,
those images have already had the
camera’s processing permanently
applied to the images. Shooting
raw has many beneﬁts and should

Because the raw data is unprocessed, you must essentially “de-

be fully explored by reading the

velop” the image data inside Photoshop. You’ll be presented with
several choices when opening a raw image. You can choose to

documentation that accompanies
your camera.

adjust several options related to the image, as well as the lens

and lighting conditions. All the adjustments made in the Camera

Raw dialog box are nondestructive, meaning the original image is

preserved in pristine condition. You can “tweak” the image after

shooting it, including being able to easily save those changes and

apply them to similar exposures.

The Adobe Camera Raw dialog box is a versatile environment for “developing”
your pictures. The image Ch03_Peppers.NEF is included on the CD. Choose File >
Open and navigate to the ﬁle in the Chapter 3 folder. In Photoshop CS4, you can
even make localized adjustments by painting an area and then using sliders to
modify it.

8

VIDEO
TRAINING
Camera Raw Interface

30 Chapter 3 Acquiring Digital Images

IS DNG THE NEW RAW?

In 2004 Adobe released the Digital Negative Speciﬁ-
cation (DNG) ﬁle format. The code and speciﬁcations
were made publicly available so manufacturers could
build in support for the format to their products.
The goal was to replace several proprietary raw ﬁle
formats with a universal format. Despite initial optimism, camera
manufacturers have been slow to adopt it (some even refusing). At this
point, DNG ﬁles are a useful way to archive raw ﬁles and attach addi-
tional metadata. You can ﬁnd out more about DNG by visiting Adobe’s
Web site at www.adobe.com/products/dng/main.html.

The Camera Raw dialog box
has continued to evolve since
it was ﬁrst introduced as a pur-
chased add-on to Photoshop 7.
Subsequent versions of Photo-
shop have updated the user in-
terface. To help you learn about
these options, your best bet is
to read the many entries in the
Adobe Help Center. Fortu-
nately, the Camera Raw dialog
box is fairly intuitive, especially

once you understand the con-
cepts of adjusting images. After
you have completed Chapter 10, “Color Correction and Enhance-
ment,” you should feel much more conﬁdent using the options in
the Camera Raw dialog box.

TIP

Acquiring Images from a Digital Camera

Make Backup Copies

There are two major ways of downloading images from a digital

You may want to work with a copy of

camera. Which connection type you choose will depend on your

your transferred image, especially if

work environment and budget for additional hardware.

you are just getting started in Pho-
toshop. Many users will duplicate
a folder of images and work with
those. Others will burn a copy of

The ﬁrst method involves plugging the camera directly into the
computer. Many cameras ship with a connecting cable (generally
USB). The advantage of this approach is that it doesn’t require

the original images to a CD or DVD

an extra hardware purchase. The primary disadvantages of this

for backup. Preserving an original

method are that it ties up the camera and it is hard on delicate

digital ﬁle is a good idea for future

ports built into the camera. If you break the USB port by constant-

use. If you are shooting raw, there

ly plugging and unplugging a camera, it can lead to an expensive

is no need to duplicate the raw ﬁle.

service bill. The data port is interconnected with several other

The modiﬁcations to the image are

systems on the camera; a break at one end can result in problems

stored in a separate sidecar ﬁle in
the folder with your images.

in other areas. Additionally, if the camera’s battery were to be
depleted during image transfer, it can corrupt the memory card.

A better option is to purchase a stand-alone memory card reader.
There are many options available, so consider these questions and
choose wisely:

•

•

Do you need only one card format, or do you need to read
multiple formats?
Is read-only enough, or do you want to be able to erase and
reformat cards while they are in the reader?

Scanners 31

•

How fast do you want your ﬁles to transfer? Many card readers
are USB 1, which can take a long time to transfer ﬁles. Look
for USB 2 or FireWire for faster data rates. Laptop users with

NOTE
Transferring Files

a card slot can purchase an effective card adapter for fast ﬁle

The actual transfer of photos is

transfers without tying up ports.

not handled by Photoshop. Rather,
you can use Adobe Bridge CS4,

which includes a Photo Downloader

Scanners

(File > Get Photos from Camera).
If you are not using Bridge, the

It may come as a surprise to some of you reading this book, but
not all cameras are digital. Shooting on ﬁlm is still a valid choice.
Film offers greater ﬂexibility for low-light situations, and it offers

ﬁles are handled natively by your
computer’s operating system. Just
manually copy them to a folder on
your computer.

some aesthetic options not afforded by digital capture. Many

purists swear that shooting ﬁlm adds richness in detail and color,

as well as introduces subtle nuances like ﬁlm grain, which cannot

be replicated with a digital camera. Additionally, many pictures

that you’ll need to work with might only exist on traditional media

(such as prints) or as a negative. You’ll need to use a scanner to

turn these optical formats into digital formats.

Choosing a Scanner

NOTE

If you work in a computer lab or other work environment, your

lpi versus ppi

choice in scanners may have already been made for you. However,

The general rule for printing is to

it is still important to understand the different types of scanners

take your lpi requirement and multi-

that are available to consumers.

ply by two. Round up to the nearest

large number and you have your ppi

Flatbed scanners

requirements.

The most common scanner type is a ﬂatbed

scanner on which photos are loaded face down

on a piece of glass. The scanner then moves a

charge-coupled device (CCD) across the im-

age to capture/digitize the image. High-quality

scans can greatly increase the amount of data

that is captured. So, be sure to look at high-speed

scanner-to-computer connection options. For a

modern computer, FireWire or USB 2 are the

best options.

Don’t get too bogged down with scanner attachments. Unless you

only occasionally need them, slide adapters and transparency

adapters don’t work as well as a dedicated specialized ﬁlm scan-

ner. These options often just add to the cost of the scanner.

32 Chapter 3 Acquiring Digital Images

COMMON PPI REQUIREMENTS FOR
FINAL FILES

Output Method Typical ppi
Onscreen (Web/slides) 72–96
Screen printing 100–150
Laser printing 150–250
Newsprint 120–170
Offset printing 250–300
High-quality offset printing 300–600

Be sure to pay close attention to the optical
resolution of the scanner: This is the maximum
size of the image before using software interpola-
tion to enlarge it. Most users doing intermediate-
level work or desktop publishing ﬁnd a scanner
capable of 600 to 1200 spi to be adequate.
Remember, samples per inch can translate fairly
well into pixels per inch. It is a good idea to have
more pixels to start with, and then reduce the
size of the image for delivery.

Film/Slide scanners
Specialized scanners load in slides or ﬁlm nega-
tives. These scanners use a tray to hold the mate-
rial, and then a motor pulls the tray slowly across
an optical sensor. This process is relatively slow
due to the resolution needed. The scanner must
capture a lot of data from a very small surface
area to produce a usable image. These scanners
are slightly more expensive than ﬂatbed scan-
ners but are essential if you frequently work with
slides or negatives.

Drum scanners
When top image quality is a must, pros turn to
drum scanners. These units are very expensive
(starting at $5,000 and going up—signiﬁcantly).
This scanning technology is the oldest. It calls
for the image to be mounted on a drum. This
drum is then rotated in front of a photomultiplier
tube. This tube is much more sensitive than the
CCDs used in ﬂatbed scanners. Drum scanners’
primary advantage is resolution, and they should
be used when you need to signiﬁcantly enlarge a
scanned image (such as museum archival pieces
or for magazine output). Because the machines

A drum scanner is a highly specialized piece of equipment.
These machines are very expensive and are usually found

are expensive and very complex (as well as
potentially destructive), users will often send im-

only in high-end service bureau facilities.

ages to a service bureau for drum scanning.

Scanners 33

What Size to Scan? Think in Pixels

TIP

People often get confused when determining what settings to scan

Capture More Than You Need

with. Too little information and the picture goes soft. Too much in-

There’s no need to overdo it, but I

formation and the scanner slows to a crawl. The answer is to know

always recommend capturing two

your intended output resolution as well as your device.

to three times more data then you

For example, if you need to create a 20-inch wide poster that will
be printed on a high-quality press requiring 300 ppi, use this

will need. For example, if you will
be outputting a Web graphic at
1024 × 768, you should capture at

calculation:

least 3000 × 2000 pixels to start.

20 (inches) × 300 (ppi) × 1.25 (pad for ﬂexibility) = 7500 pixels

Having the extra pixel data will give
you more details to work with when

Do not adjust your scanner’s dpi (or ppi) settings. Rather, crop the

zooming in for touch-up. It also

image after running a preview scan. You can then adjust the scan-

allows you to make decisions about

ner’s resolution by looking at the output size of the scanned ﬁle. As

cropping and reformatting.

you adjust the output ﬁle size, the scanning software will automati-

cally determine the appropriate settings for samples per inch. All

scanners tell you just how many samples you are about to capture.

Looking at these numbers gives you a truer sense of the end result.

Total pixel count is much more important than dpi, especially

when scanning images of various original sizes.

Scanner Operation

It is safe to say that every scanner model is a

little different. Hardware manufacturers must

write software that allows the scanner to in-

terface with your computer. When choosing a

scanner, be sure it works with your computer’s

operating system (always check the box or

manufacturer’s Web site carefully).

1. Before scanning an image, install the

software and drivers needed by your scan-

ner. These are usually included on a disc

provided by the manufacturer or are of-

fered for download from its Web site. This

software runs as an independent program,

but Photoshop can open the resulting scans.

2. Ensure that the scanner is lying ﬂat, or you

may get misregistered scans.

34 Chapter 3 Acquiring Digital Images

NOTE
Crooked Scan? Fix It Later
with Photoshop
If you get crooked photos, you
can use a Photoshop automation
command to automatically crop
and straighten your images. Simply
open the ﬁle, and then select File >
Automate > Crop and Straighten
Photos. You’ll ﬁnd two Crop and
Straighten demo ﬁles in the Chap-
ter 3 folder.

TIP
Scanning Previously
Printed Items?
If you are scanning an image that
has been previously printed in a
book or magazine, you may need to
descreen it (descreening prevents
moiré patterns). Look to see if your
scanner offers a hardware-based
descreening option.

3. Place your photos on the scanner and make
sure they are straight. Use the edges to help
you maintain parallel edges on your photos.
4. Run a preview scan ﬁrst to check image
placement and details.
5. If your scanner allows it, set the white and
black points before scanning. This is accom-
plished by making a preview scan, and then
using your scanner’s software to identify a
black and a white point in the image. You can
then use Photoshop’s color correction tools to
adjust the white and black points as well as
make additional color changes. Every scan-
ning software program is different, so be sure
to read the documentation included with the
scanner or on the manufacturer’s Web site.
6. Scan slightly higher than the quality you
need; for example, scan at 300 spi for news-
print, even though you may only deliver it at
170 ppi. The extra pixel information allows
you to zoom in for further corrections. It also
gives you extra pixels in case you need to
crop the image.

7. Save to formats such as TIFF (Tagged Image File Format, a
standard in the print industry). This ﬁle format is efﬁcient for
storage and supports lossless compression to reduce ﬁle size.
The Photoshop (PSD) format is great for layered ﬁles but is not
as efﬁcient for single-layer ﬁles. Always save the ﬁle using the
appropriate ﬁle extension for your ﬁle type.

Importing from CD/DVD
You will often ﬁnd image collections available for
sale (or those with educational books) on optical
discs. This is a great way to distribute images
(cheap to manufacture and large-capacity discs
that are cross-platform compatible). You’ll want
to copy the images to your hard drive before you
bring them into Photoshop. This will signiﬁ-
cantly increase the speed at which you can work

Stock Photo Services 35

on the images (hard drives transfer data faster than optical media
drives). Additionally, you will be able to save your work in prog-
ress to your hard drive; you can’t save to the CD or DVD.

NOTE
Royalty-free Does Not
Equal Free

Do not confuse royalty-free and

Stock Photo Services

free. A royalty-free image must
still be purchased. This is how the

Professionals ﬁnd it is often necessary to purchase images to com-
plete their projects. Whether it’s a shot of broccoli for a magazine
layout or the New York skyline for the cover of a DVD, stock
photo services can help. But ﬁnding the right stock photo service
is a balancing act. You must consider several factors when making

photographer and distributor make
money. Royalty-free images can be
a big savings because you can elimi-
nate model releases, talent charges,
location fees, travel, and many
other costs associated with a photo

a choice:

shoot. However, keep in mind that

•

Cost: There is a lot of competition out there, and photos are
priced accordingly. Some services offer annual subscriptions;
others charge per image. Be sure to keep your budget in mind
when searching for needed photos.

someone had to pay those charges
in the ﬁrst place, and selling their
pictures is their livelihood. Remem-
ber to pay for what you use. It’s the
professionally responsible way, as

•

Resolution: Sites often charge more for high-resolution images.
Be sure to know how you’ll use the image. Web site designers

well as the law.

will pay less for an image than someone designing an annual

report. A Web image is low resolution, whereas the report will

be professionally printed and require high-resolution images.

•

Exclusivity: Does the image need to be yours and yours
alone? Or is it OK if the photo is also used in someone else’s

project? Images that have their usage rights managed cost

signiﬁcantly more. A rights-managed image has restrictions

placed on who can use the image for a certain time period.

In contrast, a royalty-free image is purchased once and can be

used as many times as the designer desires.

•

Quality: Expensive doesn’t guarantee better, but it does
increase your chances. More expensive sites often have a better

selection of images (the best photographers charge more, go

ﬁgure). If you are on a budget, prepare to spend more time

searching for an image. There’s a line often used in the profes-

sional creative community: “Good, Fast, Cheap… pick two.”

It seems appropriate here as well.

36 Chapter 3 Acquiring Digital Images

STOCK PHOTOS ONLINE

Several stock photo sites are available to choose from. Here are some
that offer high-quality images. Be sure to compare prices and usage
rights to ensure they work for your project.
• istockphoto: (pay per image and subscription) www.istockphoto.com
• AbleStock: (subscription) www.ablestock.com
• Photo Objects: (subscription) www.photoobjects.net
• Photos.com: (subscription) www.photos.com
• Comstock Images: (pay per image and subscription)
www.comstock.com

Public Domain Images
I’d say, “The best things in life are free,” but that wouldn’t be ac-
curate here. More appropriately, “Why pay twice? ” The United
States has several federal agencies that document their work and
make it available to the public. This work was paid for with tax
dollars, and the people of the United States own the work. For-
tunately, through the Internet, the U.S. government is willing to
share much of it with the world.
I’ve created a portal page on my blog that points to the best
government sites. These pages offer print-resolution images that
you can use. Nearly every image is copyright free, but you may
be required to cite the source. Be sure to look at the terms of use
posted on the site. Take the time to fully explore each site; you’ll
be surprised by the wealth (and diversity) of available images.
Visit www.rastervector.com/resources/free/free.html.

Public Domain Images 37

THE FAIR-USE MYTH

A popular myth in academic cultures is fair use. The doctrine provides

situations where copyrighted works can be used without paying. It

places restrictions on:

1. The purpose and character of the use, including

whether such use is of a commercial nature or is for

nonproﬁt educational purposes

2. The nature of the copyrighted work

3. The amount and substantiality of the portion used

in relation to the copyrighted work as a whole

4. The effect of the use on the potential market for or

value of the copyrighted work.

Students and teachers alike get caught up in ex-

emption number one. It is true that in a classroom

situation you can use virtually any image you want

for practice or class exercises. However, here is the

problem: As soon as a student wants to start looking

for a job and builds a portfolio, those images are being

used for ﬁnancial gain. If you are a student, you need

to build work samples that help you get a job. Use

images that you have the rights to (or that you have

photographed).

The other clause that is often seen as a loophole is

For more on copyright and fair-use

number four. People often think that because their

doctrine, visit www.copyright.gov.

project was small or personal that damage cannot be

claimed. It is relatively easy for a copyright holder to claim damages

or lost revenue. Even though they may not go after you, why take the

chance? As a content creator, you should respect the law and the wel-

fare of your fellow designers and photographers