Adobe Photoshop 4.0 Is a Program of Many Layers Oliver Thomas

Adobe Systems recently unveiled Photoshop 4.0, the latest incarnation of 
its digital imaging software. The new release introduces many features 
and even a few new technologies. Key additions include adjustment layers, 
an Actions palette, and enhanced Web support. However, the focus of this 
release is on streamlining and refining existing features. Adobe has greatly 
improved the handling of layers and updated the user interface with a Navigator 
palette, guides and grids, and a standardized toolbox.

Big Program, Big Appetite
Photoshop 4.0 is very demanding of system resources. In both Macintosh 
and Windows versions, it requires a minimum of 16MB of application RAM 
(32MB recommended) and 25MB of hard disk space for installation. An 
additional 20MB of hard disk space is required during operation to 
accommodate the scratch disk. 

RAM requirements for opening large files have been reduced. However, for 
optimum performance you still need about three times as much RAM as the 
size of the image being edited to avoid hitting the scratch disk.
 
Layers upon Layers
Perhaps Photoshop 4.0's most noteworthy new feature is the 
implementation of adjustment layers. Accessible through the Layers 
palette, adjustment layers let you apply color and levels corrections 
without changing the underlying image data. This effectively adds 
unlimited undo capability with no image degradation. Adjustment layers 
can be moved up and down in the Layers stack, hidden, and discarded. You 
can apply adjustments to a set of layers, producing compound effects.
 
In general, Photoshop 4.0 relies much more heavily on the use of layers. 
Text, for example, is now automatically placed on a separate layer 
rather than inside a selection on the current layer. There is increased 
control over merging layers and drag-and-drop support for combining 
selections and images.

To help speed the redraw of high-resolution images in such operations as 
layering, compositing, and color adjustments, Photoshop 4.0 implements 
image caching technology. The program uses a low-resolution version of 
an image to update the screen display. Settings for tweaking the image 
cache can be found in the Preferences menu under the File menu.
 
A New Look and Feel
Some of the most visible changes in Photoshop 4.0 are interface changes. 
The program now implements context-based menus - a feature familiar to 
users of Windows 95. A Control-Click (Macintosh) or Right-Click (Windows) 
opens a pop-up menu with items appropriate to the current location of the 
mouse pointer.

Many of the icons in the Toolbox have been consolidated into pop-out 
menus that allow access to related tools. For example, the crop tool has 
become part of the marquee selection tool set, and the Path tools have 
been moved from the Paths palette to the Toolbox. The crop tool now 
includes a rotate feature, so you can crop and rotate an image in a 
single step.
 
The new Navigator palette lets you move quickly to any part of an image, 
as well as change magnification by manipulating a thumbnail of the image. The 
zoom indicator in the lower left of the image window has been  changed to an 
editable text box, so that you can type in an arbitrary magnification factor 
(0.2% - 1600%).
 
Many of the transformation tools have been combined into a Free Transform 
command that lets you move, scale, skew, rotate, and add perspective in one 
operation. Guides and grids are another welcome addition. Selections can 
finally be snapped to a grid and aligned with user-positioned vertical and 
horizontal guides. You can adjust grid and guide settings through the 
Preferences menu.
 
Photoshop 4.0's redesigned interface offers a cleaner, standardized work 
environment. Adobe plans to implement this interface across all of its 
graphics applications.

A Trove of New Filters
Photoshop 4.0 comes with 48 new effects filters, bringing the total to 
90. One of them, the Digimarc filter, offers copyright protection by 
embedding digital watermarks in images. To use this filter, you must 
pay an annual fee. For more information, see
 
http://www.digimarc.com/

Actions Palette, Web Support 
Photoshop 4.0 introduces limited scriptability through the new Actions 
palette. While not as powerful as a scripting language such as 
AppleScript or VisualBasic, the Actions palette lets you define simple 
macros that can be executed on a single image or applied to all of the 
images in a folder. Six Actions - including Drop Shadow and Vignette - 
are built into the palette.

Actions can be especially useful in preparing images for publication on 
Web pages. You can, for example, record a macro to scale an image to 
thumbnail size, sharpen it, reduce the number of colors, and save the 
result. This Action can then easily be applied to an entire folder of 
images.
 
Photoshop 4.0 also supports three additional file formats used on the 
Web: Portable Document Format (PDF); Progressive JPEG; and Portable 
Network Graphics (PNG).

Availability and Help
Macintosh and Windows versions of Photoshop 4.0 are available at the MIT 
Computer Connection (W20-021) for $230. Photoshop 3 owners can upgrade 
to 4.0 at reduced cost by contacting Adobe directly at 1-800-492-3623.

Photoshop 4.0 comes with a user manual, tutorial CD, and online help. 
Adobe also provides a valuable collection of Photoshop material online 
at

http://www.adobe.com/prodindex/photoshop/main.html