For years, Adobe has heard the pleas of researchers, scientists, and other highly specialized users of Photoshop to include features that fulfill their
needs. Finally, Adobe has been able to provide the tools these specialists need. But rather than just adding them into Photoshop CS3 and making
everyone pay the costs for developing these features that few will use, Adobe packaged them as a separate, higher-priced version of the software.
“Let those who need the new features subsidize their costs!” was the decision And, in my opinion, it was a fine decision. As I explain, these extended
features don’t really have a place in the workflow of most Photoshop users. That doesn’t mean that if you do have Photoshop CS3 Extended that you’ll never use any of these features!(“How do I know which version I have?” Watch as Photoshop starts to see which splash screen appears.

Even if you didn’t specifically purchase the Extended version (it might have been part of a package deal), you might someday decide to
work with 32-bit, high dynamic range images. Or you might find a need to calculate a height or a distance using the measuring tools in Vanishing
Point. But unless you actually work directly in one of the target fields for the features of Photoshop CS3 Extended, you’re not likely to miss the additional capabilities at all. Another clue that you’re working in Photoshop CS3 Extended is that you can see the Analysis menu, which holds commands related to working with the new measuring capabilities Read the rest of this entry »

The behavior of some tools changes when you add one or more modifier
keys (Ô, Shift, and Option for the Mac; Ctrl, Shift, and Alt for Windows).
As an example of how modifier keys can affect tool behavior, consider the
Rectangular Marquee and Elliptical Marquee tools :

• Hold down the Shift key while dragging. Normally the marquee selection
  tools are freeform — you drag however you like. When you hold
  down the Shift key while dragging, on the other hand, you constrain the
  proportions of the selection to a square or circle (rather than a rectangle
  or ellipse).

• Hold down the Option/Alt key while dragging. When you hold down
  the Option/Alt key while dragging a marquee selection tool, the selection
  is centered on the point where you first clicked. Rather than being a
  corner of a selection, that starting point is the center of the selection.

•  Hold down the Shift and Option/Alt keys while dragging. You can
  select from the center while constraining proportions by using the Shift
  and Option/Alt keys together.

Have you ever created something that was just wonderful, then forgot how you did it? Or someone asked you how you did something and you couldn’t remember all the steps? Wouldn’t it be great if you could have a complete history of every editing step performed on an image? With the History Log in Photoshop CS, now you can! Besides being helpful for your own use, it can be used to record time-tracking information for client work, to create a legal record, and for training purposes.The History log is disabled by default. To turn it on, go to Edit > Preferences > General (In Mac OS, Photoshop > Preferences > General). In the lower section of the dialog box, click the check box to enable History Log. You can choose whether you want the information embedded into the file as metadata, stored in a text file, or both.If you pick the text file option, you will need to click “Choose…” and tell Photoshop the name and location of the file where you want the data saved.Under “Edit Log Items” you have three choices:

1. Sessions Only - only records when Photoshop is opened and closed and when each file is opened and closed. Useful for time tracking.
2. Concise - records Sessions information, plus the text that appears in the history palette.
3. Detailed - records all of the above, plus the text that appears in the actions palette. This essentially tracks the complete history of editing for the file.

History data can be viewed in the metadata panel of the File Browser, or from the File Info dialog. Be careful storing the history log in the metadata–it can increase the files size and reveal editing details that you’d prefer to remain undisclosed.