Photoshop is a wonderfully useful computer program if you need to make alterations to bitmap pictures, besides vectors, 3-D objects, and CAD. As it is so effective, the term 'Photoshop' has taken on the meaning of practically any photo-editing process, even if Photoshop isn't being used. This Entry is about the actual program Adobe Photoshop, although some things in similar programs may work the same or in a similar fashion. The problem is that it is not a very easy program to use if you know nothing about it. Although it is possible to figure out some features, it takes time, something many people don't have.

Tools

Selection Tools

There are several selection tools. The rectangular marquee tool is your basic selection tool, selecting everything within the rectangle on the layer you are on. It is, however, almost useless. You rarely need to select something in a rectangle.

The magic wand tool is one of the more useful selection tools but is the most unpredictable. At times it seems to have a mind of its own. It selects an area based on colour, or that seems to be the pattern. The lasso tool is the freeform selection tool, the polygonal lasso is similar to the lasso, but selects things in a polygonal marquee (left-click on mouse to place edge). The magnetic lasso is a precision version that clings to the edge of similar colours. When using the lasso tools you must close the lasso or else it goes crazy. When you select a part of an image you can freely move it, and any alterations of any type (including filters, which will be covered later) will only affect the selected area. You can also select everything that isn't currently selected by going to 'Select' and then 'Inverse' (hotkey Ctrl + Shift + I).

Editing Tools

'Editing tools' include the paintbrush, the paintbucket, and the blur tool. The paintbucket tool fills a specific area with the selected colour. If you turn off the anti-aliased option¹ on the paintbucket and use it in unison with a selection tool, it will fill only the selected area². The pencil tool adds colour, one pixel at a time. The blur tool does exactly what it says - it blurs an image. The burn tool is used to darken an image³.

The dodge tool does the opposite. The sponge tool either saturates or desaturates⁴. The smudge tool does exactly what it says: it smudges the image, virtually identically to the warp tool in the liquefy tool. The clone stamp tool is difficult to describe: the user selects a point (using Alt + left-click) to copy from. You then select a point to copy to. If you hold down on the left mouse button, the point it copies from moves in relation to the copy-to point (the point that it copies from and the point that it copies to are in the same place in relation to the respective points where they started from - this is the bit that's hard to describe).

There is a difference between the paintbrush tool and the airbrush tool. In later versions, starting in either version 7.0 or CS/8.0, the airbrush is an option of the paintbrush. The paintbrush applies colour directly over the area you move it over. The colour fades at the edges of the brush. The airbrush sprays a colour over the area. For example, if you set the foreground colour as black and click very briefly with the airbrush on a white background, it will appear grey. If you do the same with the paintbrush, it will turn out black.

The crop tool reduces the dimensions of the image by reducing it to just the selected area. It is used to help optimise the image without altering the size of the pixels.

Extraction Tool

Found under the image menu, the extraction tool is used to save a certain portion of an image and remove everything else. The remaining image can be moved over to another image (a classic Photoshopping task). While the magnetic lasso tool can be used for the same task, it can produce some unsatisfactory results. The extraction tool has the advantage of allowing previewing before you extract the desired part of the image. You get a window with the image in the centre, tools on the left and options on the right, such as brush size. You first use the edge highlighter tool to select the edges of what you want to extract. You can use the highlighting option (found on the option panel to the right or hold down Ctrl as you're doing it) to get more precise results. Then you use the fill tool to fill the area you want to select. You can then use the cleanup tool to remove unnecessary bits that decided to hang on and the edge touchup tool which restores edges that were not supposed to be removed.

Liquefy Tool

This is a very fun tool for messing with an image - such as one of your boss, for example. It allows for a high degree of distortion. It can be found in the image menu (in later versions⁵ it is found in the filter menu), and it brings up a window similar to the one that is brought up by the extraction tool. You get an array of tools in the window. The freeze tool 'freezes' the selected area. Frozen areas will not be affected by any liquefaction. To unfreeze an area you use the 'thaw' tool. The warp tool works exactly like the smudge tool, except you get the advantage of being able to freeze part of the image. The twirl clockwise/anticlockwise tools spin-smudges the selected area in the direction indicated by which one of them you are using. The reflection tool creates the reflection of the image of the same size of the brush. The bloat tool stretches the desired part of the image in all directions. The pucker tool narrows the image in all directions. The reconstruction tool can help undo unintentional damage.

Text Tool

Not much going on over here; it's for writing text into the picture. You can do the basics that practically every program allows you to do with text such as change font, style, size and colour. In addition, you can apply text effects that allows the type to be distorted. You cannot edit text if the file is not a PSD (PhotoShop Document, the standard save format for Photoshop).

Layers

Photoshop has a layer system, meaning that everything is present on a specific layer for organisational and artistic purposes as well as convenience. One thing that may get confusing is that you can only edit things that are on the layer that you are on, so keep checking to make sure you're on the right layer. The layers can take up a large amount of disk space if you're not aware of them. Every time you paste an image onto a document, that image gets its own layer. If you have multiple pasted images, it is suggested that you merge them onto a single layer once you get them into place. You can freely move a layer without selecting the desired part of the image. Of course you don't have to worry about that if you're going to save it as a jpeg. You can change the order of the layers ('Layer' to 'Arrange') and change the layer transparency to change how the pictures interact with each other. You can also give a layer its own effect(s) such as embossed textures and overlays under the blending options tool.

Filters

Photoshop also gives you an array of filters that apply a wide range of effects to an image such as distortion (giving it a hand-drawn look), blurring and others. Most of them do what they say. Some of them are more difficult to describe. If you don't know what certain effects do, just try experimenting with them.

Slice Tool and Saving for Web

The slice tool is used for web design. If you have dial-up Internet, you may have noticed that some images on websites will load in chunks. This is to speed up the load time of the images. The slice tool is used to do this.

To save an image for web you go to 'File' and 'Save for Web'. You can select the file format for each slice. It will give you several options for each format, a preview of the image, the file size and the load time (all under the current save settings).

Undo

It should be noted that early versions are incapable of undoing more than one action. In other words: if a mistake was made and you made another action before undoing, you would have to revert to the last save. If you didn't have a previous save, you would have to start all over again. This was a problem. To fix this, Adobe created a history window to enable multiple undos in one go. Multiple undos are only performable via the history window.