Photoshop

Two Dimensional Painting/Image Manipulation

2D graphics programs represent and manipulate images based on pixels. They are often refered to as raster or bit mapped graphics applications. Adobe Photoshop is by far the most popular 2D image manipulation program.

Adobe Photoshop

Photoshop is an application made by Adobe. This section describes the workings of the program. It is not intended to be exhaustive. The points covered here are those that I think are most important and useful.

What kind of program is it?

Photoshop is a photo-manipulation tool. It gives you many techniques for manipulating photographs and graphics. It is also used to create text to be integrated with graphics. Photoshop is not a painting program in the sense that it is not designed to do computer painting from scratch.

How Does it work?

Photoshop allows you to manipulate and combine parts of images based on a grid of dots (pixels), each of which can have a colour.

• Selection

  One of the powerful features of Photoshop is the ability to select different areas of an image based on area and/or colour, then move or manipulate that selection. A selection in Photoshop can be any combination combination of areas and/or any combination of colours. Areas are selected with the Marquee and Lasso tools and colour is selected with the Magic Wand tool.

• Layers

  Photoshop allows an image to be constructed with several layers combined in various ways. Imagine many acetate sheets overlayed and the idea of trasparency being extremely flexible.

• Painting

  Photoshop has many brushes and type tools to manipulate and add to an image.

• Filters

  Filters are what has made Photoshop really famous. Essentially they are the ability to do very complex manipulation on a part of an image. These manipulations are usually pre-programmed.

The Tools

Most tools have options available by double-clicking on the tool in the palette.

• Selection Tools - These tools allow you to select a part of the image based on area or colour. Each tool can have its boundary tolerance adjusted.
  • Marquee - Used for regular area selections such as rectangle and elliptical.

  • Lasso - Used for selecting an arbitrary area.

  • Magic Wand - Used for sececting regions of colour.

  • Move - Used for moving a selection.

• View Manipulation Tools - These tools allow you to change the way you are viewing the image.
  • Hand - Used when part of the image is not visible to drag the image around.

  • Zoom - Used for zooming in and out. Hold down the option key to zoom out. You can tell how much you are zoomed by the numbers in the title bar. 1:1 means actual size, 2:1 means double size and 1:2 means half size.

• Crop Tool - Used for cropping part of an image, removing the remaining part.

• Paint Tools - These tools allow you to paint on an image.
  • Type

  • Paint Bucket - Pours paint onto the canvas.

  • Gradient - Creates a blend from one colour to another.

  • Line

  • Eyedropper - Changes the current foreground colour to the colour over the cursor.

  • Eraser

  • Pencil

  • Airbrush

  • Paintbrush

  • Rubber Stamp - Easily duplicates part of an image.

• Image Manipulation Tools
  • Smudge

  • Blur/Sharpen

  • Dodge/Burn/Sponge

The Menus

• File - The standard file manipulation commands.

• Edit - The standard editing commands

• Mode - This menu contains commands to change the way colour is being represented. Most often work is done in RGB mode. Work is sometimes converted to indexed colour.

• Image - This menu allows adjustment of the standard aspects of an image. Map and Adjust allow relative adjustments of pixel density such as contrast, brightness, hue, saturation... Flip, Rotate and Effects manipulate the image with straightforward transformations.

• Filter - Compex manipulation options.

• Select - Adjustment of the selected part of an image.

• Window - Zooming and palettes.

Scanning

You can scan an image into Photoshop by choosing the appropriate scanner in the Acquire item in the File menu. This can of course only be done if you are at the computer with a scanner connected to it.

A General Guide:

1. Turn the scanner on?!!
2. Place paper/object on glass of the scanner. If using paper make sure it is square with the edge.
3. Choose the scanner in the Acquire item in the File menu.
4. Press Preview. This gives an approximation of what is one the glass.
5. Select the area that you want to acquire.
6. Choose the settings you want/need.
   • Resolution: Use 72 dpi (dots or pixels per inch) for the web and Director.
   • Bit depth (# of colours): probably millions (24 bit) or grayscale
7. Press Scan.
8. Save the image

Changing the Size of an Image

Image Size

Use Image Size in the Image Menu to change the size of the image. This will scale the image larger or smaller based on the numbers you enter.

Canvas Size

Use canvas size to change the size of the canvas. This will change the size the canvas. If you enlarge the canvas the current image will be placed in the center of the new canvas. If you make the canvas smaller, you will cut out part of the image.

Cropping

You can crop an image in two ways:

1. Select an area using the marquee tool, choose crop in the edit menu.
   
2. Select an area using the crop tool, then confirm with the gavel.

Zooming

Use the zoom tool to zoom in on an image. Hold down the option key and click to zoom out. You can also zoom in and out using the window menu. Or you can use the command key equivalents: cmd + and cmd - .

You can tell how much you are zoomed by the numbers in the title bar. 1:1 means actual size, 2:1 means double size and 1:2 means half size.

Map and Adjust in the Image menu

• Posterize - reduce the number of colours
• Brightness/Contrast
• Hue/Saturation
• Variations - Allows you to adjust colour and brightness very conveniently.

Palettes

Photoshop has many small floating windows called palettes. The tool palette is one used most often. Others include:

• Colour picker
• Swatches
• Scratch
• Brushes
• Options
• Layers
• Channels
• Paths
• Info
• Commands

Tips

Revert and Undo

Revert - Use revert in the file menu to revert to the version last saved.

Undo - use undo immediately if you have made a mistake. One more click and the last move becomes permanent.

Working image/Final image

You only need to save an image as jpeg, GIF or PICT when you are ready to use it on the web or export to another program. At all other times you should save your images as Photoshop 3.0 files. Doing this preserves the information about layers in your image so it is easier to edit them. I might have an image called: wallgraf that is a Photoshop 3.0 file I have worked on for a while. When I am ready to use it on the web I might save it as a JPEG and name it wallgraf.jpg

Using Photoshop for images on the web

There are many details to be aware of when working with Photoshop for a specific purpose. Being aware of them will make your life easier!

I find it most useful, when working with the web, to refer to an image's size in pixels because of the direct relationship to the screen.

Resizing and extending a selection

Use the shift key with a selection tool to add to a selection.
Use the command key with a selection tool to subtract from a selection.

Valid for Fall/Winter 2003-2004

The material contained in this site is copyright and owned exclusively by Don Sinclair and members of the FACS teaching team.

Last modified on 14-Nov-03 at 9:28 AM.

I am in the process of overhauling this section. Many pages are outdated. - don

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Photoshop

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