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Introducton to Adobe Photoshop
Selecting Things  

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Well, the irony of yesterday was that in the introduction we said that Photoshop was not really a painting program yet we spent the rest of the day learning how to paint on our canvas.

Well, that is because you needed to learn the fundamentals of Photoshop before you could move on to the more exciting features. Today we will go into some of those more exciting features. In particular, for the first half of the day we will work with "Selections".

Selections are areas within the canvas that you set apart from the rest which you can apply special effects to or other wise modify, copy, cut, flip, move, rotate or scale.

It is important to understand that Photoshop is different from other programs in which you select things. For example, consider your word processor. Most likely, when you want to select a word, you double click on that word. Your word processor knows to select the word because letters are isolate objects.

Photoshop does not have that convenience. When you scan in a picture of a face, Photoshop has no way of discerning between the eyes and the nose on that face. This is because images are pixel based rather than object oriented. Photoshop can manipulate those pixels, but it cannot intelligently differentiate between them in terms of the overall meaning of the picture.

This is a good thing because otherwise, there would be little use for you. Fortunately, you are needed to decide which pixels belong to which meaningful part of a picture. For example, you might want to select a pair of glasses on a face in order to change the color of the frame. Typical reasons to make selections include

  • Editing a portion of your canvas
  • Creating a mask or layer
  • Cropping
  • Applying filters and special effects to portions of your image

To select a portion of your canvas, you will have to use one of the selection tools that we will discuss more later. But all selection tools do the same basic task, they draw an outline around some bit of your canvas with a little flashy marquee that looks like a dashed line or a row of little parading ants.

Once you have selected an area, you can manipulate that area in many cool ways. We will do a lot of manipulation of selections over today and tomorrow, so it is crucial that we get a good sense of how to select areas.

Modifying a Selection  
We will talk about several tools to make an initial selection however we should mention here that all selections share several properties.

For one, any selection can be deselected just by clicking outside of the selected area or choosing SELECT --> NONE from the main menu

Another such property is that you can edit a selection. This is a good thing because it would suck to create a detailed selection only to realize that you missed one small piece. Fortunately, you can easily add to a selection, remove from a selection or create selections from intersections of other selections.

To add to a selection, simply hold down the SHIFT key and use the selection tool to add to the existing outline.

To subtract from a selection, hold down the OPTION or ALT key (depending on operating system) and use the selection tool to remove from the existing selection

To create an intersection selection, simply hold down the ALT and SHIFT (OPTION-SHIFT) keys and use a selection tool to deselect all but the overlapping portions of two selections.

You can also hide the selection outline if it is getting in the way of your concentration by hitting CONTROL-H

Further, you can inverse the selection, thus selecting everything that was not selected by your selection by choosing SELECT --> INVERSE from the main menu.

There are also several built in selection modification tools int he SELECT menu item. These include Grow, Similar, Border, Smooth, and Expand/Contract. These all modify the selection in predefined ways.

Okay, that is a run down of the qualities shared by all selections. Now let's take a look at the list of tools that you can use to create selections.

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