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发信人: killest (矛盾), 信区: Graphics
标  题: PHOTOSHOP-Appendix A:Improving Performance(3)
发信站: 紫丁香 (Sat May 16 12:18:34 1998), 转信

screen frequency you will use to print the image.
See [screen frequency sidebar in chapter 3] for
more information.
If you are preparing images for color separation,
it抯 also a good idea to work in RGB mode until you
are ready to print RGB images. RGB images are
approximately 75% the size of CMYK images.
Also, merge layers and delete channels as you no
longer need them. Layers and channels may add
significantly to the size of the file.
Clear data from RAM
The images and selections you cut or copy to the
Clipboard or that you define as patterns or snap-shots
are stored in RAM. Keeping large amounts of
data in RAM can significantly degrade Adobe Pho-toshop抯
performance.
To clear cut and copied data from RAM:
Choose Edit Purge and then choose an option
from the submenu: Undo to remove from RAM a copy of the image
before the last-performed operation. Clipboard to remove from RAM any data copied
or cut from an image. Pattern or Snapshot to remove from RAM any
defined patterns or snapshots.
Note: To avoid filling the Clipboard with data, use
the program抯 drag-and-drop capability to drag
elements (images, selections, channels, layers, and
paths) from one file to another or from the Layers,
Channels, or Paths palette to another file.
Turn off palette previews
The preview thumbnails on the Layers, Channels,
and Paths palettes can be turned off for a slight
performance improvement. To turn off these pre-views,
choose Palette Options from the palette
menu and select None from the Thumbnail Size
options.
Use shortcuts
Learn to use the command shortcuts that appear
to the right of the commands in the menus. These
are especially useful for operations that you per-form
frequently, such as displaying a specific com-mand抯
dialog box or adjusting color levels. You
can also select frequently used commands or sets
of commands or show and hide palettes by clicking
buttons in the Actions palette. Buttons can easily
be added to the button display of the Actions
palette.
For complete information on shortcuts, see the
Adobe Photoshop Quick Reference Card.
Save selections in channels
Get into the habit of saving complex selections in
channels until you have finished editing a file. You
can then easily load the selections without rese-lecting.
If you have many selections in a channel,
copy the channel containing the selections either
by dragging the channel to the New Channel but-ton
in the Channels palette or by choosing Dupli-cate
Channel from the Channels palette menu. By
loading the channels as selections from this second
file, you can keep the file size manageable.
APPENDIX A 370
Improving Performance
Make complex selections in Grayscale
mode
Making complex selections in Grayscale mode can
save processing time, because grayscale images are
about one-third the size of RGB images. Save the
selection in a channel, and then copy the channel
by dragging it from the Channels palette to the
open color document. Note that if you increase the
contrast of a grayscale image, it抯 easier to select
shapes of different colors. When you抮e working
with selections in Bitmap mode, it抯 even faster to
save a complex selection as a path.
Apply filters to individual channels
Some Photoshop filters, such as the Distort filters,
work only in RAM and don抰 use Photoshop抯
scratch disk. If you抮e having problems applying a
filter to a color image, try applying it to each color
channel individually. (Use Command/Ctrl+F to
reapply a filter with the same settings.) Applying a
filter to a single channel requires significantly less
memory. (In a flattened file, each RGB channel is
equal to about one-third the entire file size; a
CMYK channel is about one-fourth the size of the
entire file.)
Working in two windows
You can save time by using the View > New View
command to open a second window for a docu-ment.
For example, you can work on a magnified
version of an image in one window while viewing
the entire image in a second window, or you can
use two windows to view the results of color cor-rections
in the composite color channel and in an
individual channel of an image.
Use QuickEdit
You can significantly decrease the time it takes to
open large high-resolution files, especially files
larger than 4 MB, by opening and editing parts of
the file using the Quick Edit feature. The feature is
also useful when you don抰 have enough RAM to
open the entire file or when you want to speed up
processing while trying different painting tech-niques
or special effects. The Quick Edit module
opens Scitex CT, uncompressed TIFF files, and
Photoshop 2.0 files (Macintosh only). For more
information about using the Quick Edit module,
see 揂cquiring Quick Edit Files� on page 57.
Work on low-resolution copies of files
Another way to save time and space is to create a
low-resolution version of your file. Be sure to give
this copy a unique name when you create it so that
you don抰 overwrite your original high-resolution
image.
A low-resolution image is useful for making initial
editing and color corrections. If you抮e adjusting
color, save the settings by using the Save buttons in
the color-adjustment dialog boxes. Once you
know which features and dialog box settings pro-duce
the results you want, open the original file
and repeat the steps; then use the Load button to
apply saved settings to the original file.

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