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Photographic images are often as important
a component of office documents as text and graphics.
The level of support that computers
give for computer graphics has increased substantially
in the last few years, as has the degree of computer graphics
package integration with the operating system.
This has made it much easier for people
to develop new graphical applications because they
don't need to start from scratch anymore.
In addition to new applications, new user interfaces
have been developed for existing systems in order to make things
easier for the novice user.
The support for photographic material
has not reached the same level of sophistication, though.
Typically, the level of support for this kind of data
is much more primitive, slow, expensive,
and resource-intensive with protocols that are not so
clearly defined.
If the level of support for photographic material
could be raised to the same level as graphics material,
a whole range of new applications and modes
of interaction would emerge.
One can think of many examples where
easy manipulation of photographic material
would be a great benefit, particularly
in the areas of design and planning.
For example, in landscape design,
you could visualize your garden with the plants
at various stages of maturity or see
the effect of moving plants, shrubs, and trees from place
to place.
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In house design, proposed modifications
to existing structures could be shown
that can provide a much better indication
of the result than, for example, an architectural plan.
This might be particularly valuable in communicating
design ideas to planners, zoning officials, or your neighbors.
In the same vein, it's possible to experiment
with interior design in places where
color, texture, and detail can make all the difference.
You can see the total effect of changing color or design,
or of adding different styles of furniture.
In a few minutes, you can take the designs
you have in your head and get them down on paper
without spending a penny.
Some people might find it more entertaining to experiment
with their own appearance.
Certainly, doing it this way would
be faster, less risky, less expensive, and more amusing.
Clearly, there are at least as many opportunities
for this technology as there are for photography itself.
There are several systems on the market already
that digitally manipulate photographs.
They have several disadvantages.
For example, some of the best cost millions of dollars.
Others are targeted at scientific applications rather
than the office, while a third kind is just
too difficult for the average person to use.
But in my view, most importantly, most systems
lack a programming interface upon which
new or different applications can be built by third parties.
In addition to meeting this complex requirement,
a generally useful digital photography system
needs to be inexpensive, simple to use,
ubiquitous, and well-integrated with the general information
processing environment.
This seems difficult to achieve.
And if we attempt to provide a full range
of photographic editing facilities, it clearly is.
However, our study suggests that for many applications,
a large proportion of the photo manipulation tasks
can be accomplished with a relatively small set
of well-chosen functions.
In order to test this assumption,
it seemed necessary to build and distribute
an experimental prototype.
It was hoped that experience with this prototype
would shed light on both the user
interface and architectural requirements,
particularly those areas where hardware support would
be appropriate.
So more formally, we set ourselves to project goals.
First, identify a small set of image manipulation functions
that are sufficiently powerful to meet
most of the needs of office users
yet remain simple to understand and easy to use.
Second, implement those functions
on a general-purpose workstation in a manner that
encourages general use.
In our environment, this means that, ideally, it
should require no special hardware support.
In short, we'd like to do for photography
what the word processor did for document creation.
This sort of system has come to be known as a digital darkroom.
As we said earlier, our study suggests
that users can accomplish a great deal
with a small but powerful set of functions.
There are seven functions in our digital darkroom.
The first is rather obvious.
It's necessary to provide facilities for scanning images
from a variety of sources--
from paper, 35-millimeter slides, or a video source,
including the new medium of still video.
On this digital darkroom package,
images obtained from different media
can be combined in a seamless manner--
that's to say, combined so that you can't detect that they
came from different media.
The second function is at the other end of the production
process--
namely, the ability to print.
Transferring video images to a color printer
is both complex and expensive.
Many new types of color printers are emerging.
For example, some thermal sublimation printers
provide such excellent spatial and gray resolution
that they outstrip the capabilities of the display.
Clearly, it would be unfortunate if the digital darkroom
constrained the quality of the output
to the resolution of the display.
For this reason, our system maintains image data
at original scanned resolution and makes
full use of this information during printing.
Often, this results in the printed image
having more visible detail than the screen version.
Four editing functions can be distinguished
that cut, paste, filter, and geometrically transform images.
Cutting out images is typically a tedious, error-prone, and
often unsatisfactory task, which is
particularly difficult on low-resolution images.
Such images may afterwards exhibit fringe or halo
artifacts.
It's important to be able to extract the desired
features of an image with the minimum amount of effort
and with a natural-looking result.
In the digital darkroom, the user roughly
outlines the edges of an object to be
cut out using a fat paintbrush.
The AutoMask function then estimates the exact position
of the edge, removing background color from transparent regions,
unblending edges, and restoring transparency.
The complementary function to Cut is called Paste.
It merges images together while performing the correct blending
functions at the edges and transparent regions
to achieve a result that is often undetectable.
Scaling, rotating, and stretching
are the most important geometrical transformations.
But more complicated distortions are surprisingly useful.
Filters allow the user to make non-geometric transformations
to images.
Filters are attached to images.
And then their shape can be adjusted
to confine their effect to appropriate regions
of the underlying image.
Several filters can be stacked on top of one another
to produce more complex effects.
Most filters have associated controls
that can be manipulated to vary the effect the filter produces.
One kind of filter adjusts color characteristics.
Most images require some adjustment
to their color balance to obtain satisfactory lightness,
contrast, saturation, and cast characteristics.
This is particularly necessary when
images are obtained from input devices
with different sensing or sampling characteristics.
In that case, some image components
may need to be adjusted to bring them into conformity.
Another desirable image filtering operation
adjusts the resolution characteristics.
If a high-resolution image and a low-resolution image
are on the same page, the low-resolution image
looks relatively blurry.
And the high-resolution image looks sharper, and therefore
more focused or closer.
This produces depth-of-field characteristics which
may or may not be desirable.
Lastly, and perhaps most importantly,
the system must support Undo and Redo.
These two functions allow the user to correct mistakes easily
and to experiment painlessly with design ideas.
In conclusion, our digital darkroom
provides support for a wide range of simple applications
that are required to manipulate photographic material.
The system is in an early stage of development.
But results gained so far are encouraging and have
led to proposals for several novel applications.
It's clear that with even very limited functionality,
a great deal can be achieved.
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