Digital Photography
Introduction
How Traditional
Cameras Work
Advantages
of Traditional
Photography
Disadvantages
of
Traditional Photography
Advantages of
Digital
Photography
The Digital Difference
Quality Questions
Why Go Digital?
Monitor Calibration
Printing Resolutions
Cropping
Composition
Introduction
Some people may be experts in the field of emulsions, f-stops
and exposure
settings, but maybe they don't have as firm a grasp on computers.
Things
like RAM, floppy discs, or bit depth don't interest them as much. On
the
other hand, there is an equally large number of people who know lots
about
computers and how much RAM their system has, but need to know more
about
the world of photography. Some photographic tricks of the trade are
given,
but in a way a computer guru would understand.
With traditional photography, an image can be judged on it's
own merit.
It's good, or it's not . . . . . and that's pretty much it!
With digital photography, a screen image cannot be judged on
it's own
merit because that image is only one part of a larger system. It's one
link in a chain. Other links in the digital "chain" are the camera (or
scanner) that digitizes the image; the CPU that processes the image,
the
monitor that displays the image, and the output device that prints the
image. A bad or inaccurate screen image means there's a deficiency in
at
least one link of the chain. This emphasizes the need for having a
"calibrated"
system in order to make effective image quality judgments. There are
numerous
techniques, programs and devices available to help calibrate your
system
so that what you see on the screen matches well with your output. Calibrating
your monitor is a critical step in this process.
How
Traditional
Cameras Work
With a traditional camera, light comes through the lenses and
strikes
the emulsion, or special silver halide coating, on the film. The
brighter
the light, or the longer the film is exposed, the darker the image. The
film is "developed" using chemicals, creating either a negative (where
light parts of the image show as dark, and dark parts show as light) or
a slide positive. Prints are then made from the negative.
Advantages
of Traditional Photography
The 35mm camera is still the standard for high-quality
photography,
providing the best resolution at an affordable price for the
entry-level
user to the professional photographer. Traditional film-based
photography
has become so affordable, portable and easy, taking pictures does not
have
to intimidate even the most novice user.
The latest in one-touch cameras and advanced technologies such
as APS
(Advanced Photo System) make photography accessible to everyone,
allowing
amateur photographers to take high-quality photos without the
complication
of figuring out focus, f-stop and other unlimited terminology and
techniques.
However, the professional photographer can still take advantage of
other
technologies that provide control over every element of taking the
perfect
picture.
Disadvantages
of Traditional Photography
Despite all the physical controls a photographer can have over
the camera
and development of film, traditional photography does not allow the
same
flexibility and immediacy as digital photography. With a traditional
camera,
the photographer has to wait until the film is developed to know
whether
or not the picture is acceptable. A photographer could waste a lot of
expensive
film, developing costs, time and energy trying to take the perfect
picture
with a traditional camera.
Advantages
of Digital Photography
Affordability. With digital photography, there are no film
costs or
processing expenses (paper, chemicals or development costs). If a user
makes a mistake or just does not like the image that was taken, the
reusable
PCMCIA cards or digital film allows the user to erase the picture and
simply
reshoot it.
Communication. Digital photography makes communication a
simple process.
A photo can easily be saved to a digital format, put into an Internet
Web
site, sent as email, or even included as part of an electronic postcard
sent to friends from far away.
Control. Digital cameras, combined with image manipulation
software,
let users resize, rotate, cut and paste, recolor, and otherwise
manipulate
their photos.
Deletion. The PCMCIA cards, or digital film, standard with
digital cameras
allow users to immediately determine if a picture is appropriate and
simply
delete it to make room for another picture.
Duplication. The image can be duplicated over and over without
any degradation
of picture quality.
Ease of use. With digital photography, there's no fuss, no
muss. If
a photographer doesn't have time or space or interest in mixing
chemicals,
the same effects can be achieved using a computer as a digital
darkroom.
Image storage. PCMCIA cards, or digital film, allow users to
store anywhere
from 18 to 3,000 images at one time depending on the resolution of the
image and the compression used.
Immediacy. A user can snap a photo, immediately see it on the
digital
camera's LCD screen, then instantly transfer it into a computer using a
serial or parallel cable or removable PCMCIA cards. Digital images can
be produced immediately, either printed or electronically distributed
over
the Internet.
The
Digital Difference
Digital cameras "paint with light" in a similar way, using a
lens, aperture
and shutter. But digital cameras use their electronic image sensors
(known
as CCDs, or charge-coupled devices) and signal processing technology to
convert the light into electronic or digital information. This
information
(the image) is then compressed so many images can be saved onto the
camera's
storage device, such as a removable hard drive or memory card. Once
saved,
it can then be transferred to a computer for manipulation, printing,
transmission
to another computer via modem or archival storage.
In place of conventional film, 1MB of internal memory can
store up to
18 images and can store up to 72 images with an optional 4MB compact
flash
memory PCMCIA card. An optional 170MB hard disk drive PCMCIA card makes
it possible to store up to 3,000 photos at 832 x 608 resolution.
Unlike conventional film, the PCMCIA cards are reusable once
the images
have been downloaded and erased.
Once the image is in the computer, the user can manipulate it
with image
manipulation software, like Adobe Photoshop.
Quality
Questions
Digital photography is suited for many uses, but users should
not expect
Ansel Adams-like print quality from entry-level models. These cameras
are
best used for small photos, such as Web images. Traditional film
cameras,
especially large format cameras, are better suited for large, detailed
portraits.
Digital cameras have a narrower exposure latitude than film,
and at
present, image quality is still lower than that of film-based
photographs.
The cost of digital imaging equipment is still high, and additional
equipment
(like a personal computer) is often needed to view the images.
But digital photography is evolving, just as desktop
publishing did
in the 1980s. Desktop publishing (DTP) was once "good enough" for
newsletters,
then became widely used for magazine publishing. Digital cameras are
following
the same arc in enhancing quality, while lowering costs.
Why Go
Digital?
Digital photography is not a replacement for traditional
photography,
but an additional tool. Think of a toolbox: most people have both a
flathead
and a Phillips-head screwdriver in it. One is no better than the other,
but each has a different application.
Monitor
Calibration
The basic approach to calibrating a monitor is to acquire and
print
an image and then adjust your monitor so it matches that image as
closely
as possible. There are technical reasons why you can't get a perfect
match,
but the closer you can get, the more accurate your daily work will
be.
A monitor's "bit depth" is another characteristic that will
affect the
perception of image quality on-screen. Each pixel on the screen is
composed
of three separate dots of color -- red, green and blue. Your brain
"sees"
them as a single colored dot. Monitors can display different bit
depths,
and the greater the bit depth, the more shades of color the monitor can
display. Typically, monitors can display 8 bit color (256 shades), or
16
bit color (over 65 thousand shades) or 24 bit color (over 16 million
shades).
To display photographic quality images on screen you need to be working
with 24 bit color. The trade offs for working at this bit depth are
slower
image processing and the need for more memory on your video card. It's
not uncommon for those working with large photographic quality images
to
use accessory video and graphics cards with extra memory and
accelerated
image processors.
Having a calibrated monitor and using 24 bit color provides
the necessary
environment for working with high quality images using sophisticated
image
editing software, however, 24 bit color isn't necessary for all
projects.
For many projects, 8 or 16 bit color may actually be preferable. For
example,
most internet pages (like the one you are reading) are designed in 256
colors(8 bit). This de facto standard has designers turning their
possible
monitor colors down from millions to 256. Setting your monitor like
this
can greatly improve the performance and re-draw speed of your computer.
You'll have to make that judgment and equip yourself accordingly
depending
on your needs.
Besides monitor calibration and bit depth, other variables to
consider
in a monitor are size, image sharpness, compatibility with your
computer
system, distortion, color spectrum of display, resolution, and controls
available. All of these factors will affect the digital image displayed
on your computer.
Printing
Resolutions
Understanding resolution is important. Resolution affects the
quality
and file size of your images. Select the resolution or picture quality
setting on your camera based on your intended output. Example of camera
picture quality settings:
· Best
- 1600 x 1200 pixels
· Fine
- 1024 x 768 pixels
· Good
- 640 x 480 pixels
Minimum Suggested Printing Resolutions
|
Resolution
|
Number of Pixels
|
Size
|
Maximum Print Size
|
| 640x480 |
307,200
|
900K
|
1¾x2½ - inch
|
| 800x600 |
480,000
|
1.38mb
|
2½x3½ - inch
|
| 1024x768 |
786,432
|
2.25mb
|
4x6 - inch
|
| 1156x864 |
998,784
|
2.86mb
|
5x7 - inch
|
| 1536x1024 |
1,572,864
|
4.5mb
|
8x10 - inch
|
| 2700x1800 |
4,860,000
|
14mb
|
12x18-inch
|
| 3000x2400 |
7,200,000
|
20.6mb
|
16x20-inch
|
| 3600x2400 |
8,640,000
|
24.8mb
|
16x24-inch
|
| 3600x3000 |
10,800,000
|
30.9mb
|
20x24-inch
|
| 4500x3000 |
13,500,000
|
38.7mb
|
20x30-inch
|
| 4500x3600 |
16,200,000
|
46.4mb
|
24x30-inch
|
| 5400x3600 |
19,440,000
|
55.7mb
|
24x36-inch
|
| 6000x4500 |
27,000,000
|
77.3mb
|
30x40-inch
|
Full Frame Pixels Per Inch
|
Effective MegaPixels
|
0.31
|
0.79
|
1.23
|
1.92
|
3.15
|
3.76
|
4.92
|
| Image Size |
640x480
|
1024x768
|
1280x960
|
1600x1200
|
2048x1536
|
2240x1680
|
2560x1920
|
| 2x3½ |
183 |
293 |
366 |
457 |
585 |
640 |
731 |
| 3½x5 |
128 |
205 |
256 |
320 |
410 |
448 |
512 |
| 4x5 |
120 |
192 |
240 |
300 |
384 |
420 |
480 |
| 4x6 |
107 |
171 |
213 |
267 |
341 |
373 |
427 |
| 5x7 |
91 |
146 |
183 |
229 |
293 |
320 |
366 |
| 8x10 |
60 |
96 |
120 |
150 |
192 |
210 |
240 |
| 11x14 |
44 |
70 |
87 |
109 |
140 |
153 |
175 |
| 16x20 |
30 |
48 |
60 |
75 |
96 |
105 |
120 |
| 20x24 |
24 |
38 |
48 |
60 |
77 |
84 |
96 |
| 24x30 |
20 |
32 |
40 |
50 |
64 |
70 |
80 |
Red: Largest recommended print size.
The following chart lists the minimum recommended DPI setting
your original
should be scanned at to produce the desired print size in your order.
Minimum Recommended Scanner DPI Setting for
the following
Print Sizes:
| Original Size In Inches |
2½x3½
|
3½x5
|
4x5
|
4x6
|
5x7
|
8x10
|
| 2x3 |
250 DPI |
300 DPI |
350 DPI |
400 DPI |
500 DPI |
800 DPI |
| 2½x3½ |
200 DPI |
250 DPI |
300 DPI |
350 DPI |
450 DPI |
600 DPI |
| 3½x5 |
180 DPI |
200 DPI |
250 DPI |
300 DPI |
350 DPI |
450 DPI |
| 4x5 |
130 DPI |
150 DPI |
200 DPI |
250 DPI |
350 DPI |
400 DPI |
| 4x6 |
100 DPI |
140 DPI |
190 DPI |
200 DPI |
250 DPI |
380 DPI |
| 5x7 |
90 DPI |
120 DPI |
170 DPI |
180 DPI |
200 DPI |
350 DPI |
| 8x10 |
80 DPI |
95 DPI |
100 DPI |
120 DPI |
140 DPI |
200 DPI |
| 35mm Slide or Negative |
1000 DPI |
1200 DPI |
1400 DPI |
1500 DPI |
1800 DPI |
2000 DPI |
If there is a chance you will have to resize or edit the
image, you
should either:
· Save
image in TIF format (if the camera supports it).
- or -
· Open
JPEG in photo editing software and Save As a TIF.
Only save a JPEG.file once!!! Jpeg. files become more and more
distorted
every time you save the file.
Since an image file can be any size at all, we’ll speak in
terms of
printing resolution, expressed as pixels per inch, or PPI. As you’d
expect,
"pixels per inch" is just a measure of how "big" the pixels of our
images
will be on the printed page. For example, a 640x480 pixel image printed
at a size of 6.4 x 4.8 inches has a printing resolution of 100
PPI.
DPI: Equals 'dots per inch'. DPI always represents dots per
linear inch
on media. It can be used to denote how many dots are used to produce a
printed page or DPI can be used to scale a document for scanning to a
required
resolution or pixel size. As an example if you scan a 4X6 photograph at
150 dpi, the resulting digital image will be 600 pixels wide by 900
pixels
long. The math as follows: 4 inches times 150 dpi = 600 and 6 inches
times
150 dpi = 900. Using the math in reverse with our 600 by 900 pixel
image
and printing it at 150 dpi gets us back to our original 4X6 inch print
size.
Cropping
To insure you have the best picture to print you should always
get as
close to the subject as possible. Cropping a digital photo takes away
valuable
image data important to printing. So zoom in and keep shooting!
Optical zoom is much better than a digital zoom. If the lens of the
camera zooms in to the subject for the photo then the resolution will
be good. If the zoom is a function of the camera capturing a portion of
the image then the resolution will be lower.
Composition
Simplify: move in close, have a strong center of interest, a
colorful
subject and choose a simple background. Control the placement of
subject
within the frame, have subject off center, use lines to lead viewer to
subject, use foreground to frame subject and to add depth try unusual
camera
angles. Add energy and depth, use dramatic lighting, early and
late
in the day, sidelight and backlight. Strong shadows diagonal lines and
patterns can fill an image with energy so use foreground to build depth
and perspective.
Back to photography tips main page.
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