BRIGHAM YOUNG UNIVERSITY

  Humanities Technology and Research Support Center

Notes for Introduction to Photoshop tutorial.

Bitmap editor, not vector graphics editor(i.e., paint not draw; images not graphics)

Terminology

Antialias

Jaggie killer, line smoother. Smooths straight edges of a bitmap by adding shades of similar gray or color to the edges of the line.

Gradient

A smooth blending of shades from light to dark or from one color to another.

Aspect ratio

the ratio of the width to the height of an image, video, etc. 4:3 is a traditional aspect ratio for TV and computer monitors, but that's changing rapidly.

Alpha Channel

the portion of each pixel's data reserved for transparency. Enables varying levels of transparency in an image. Allows for semi-transparent shadows, highlights and other effects.

Important tools

Basic image manipulation

• Move - allows you to move a layer or selections to a new location on the canvas.
• Hand - Used to navigate through a large image, by "drag scrolling". Holding down the mouse and dragging brings other parts of the image into the viewable area of the window.
• Crop - Lets you delete parts of the image you don't want. Draw a box around the area you want to keep, adjust the box, then press return or enter to crop.

Selection tools

• marquee tool - selects rectangular or oval areas
• lasso tool - selects "freehand" areas that you draw with the cursor
• magic wand tool - selects pixels based on similar color

Selection modes (on toolbar at top)

• new selection
• add to selection
• subtract from selection
• intersect with selection

Painting Tools

• Paint Brush
• Pencil
• Color Picker/eyedropper
• Fill ("paint bucket")
• Gradient fill
• Text

Concept of layers

The way that Photoshop allows you to keep different bitmapped elements separate from one another, thus making it possible to edit elements separately.

Each layer can have various "Styles" applied that don't affect the other layers.

Layers and styles can be hidden and shown to create various "states" of the image.

History and undo

Undo the last action with Command (Control) - Z.

History palette keeps track of a limited number of changes (you can specify this number in Preferences.) Allows you to take out and restore any series of changes to compare to a previous state.

Photo touchup

• Image menu > Adjustment > Levels

  Lets you adjust tonal range and color balance of a photo by adjusting the intensity levels of the image's shadows (left slider), highlights (right slider), and midtones (middle slider.) Pull the sliders at both ends until they come to the first large change in the graph (histogram.) Move the center slider until you like the results in the midtones.

• Image menu > Adjustment > Hue/Saturation

  Lets you adjust the Hue (tone), Saturation (insensity), or Lightness of the image colors.

Choosing Colors

RGB vs. HSB vs. CYMK

RGB:

setting the Red, Green and Blue color channels to create the exact color you want. This is the most common method used for choosing computer screen (as opposed to print) colors.

HSB:

setting the Hue, Saturation and Brightness to create the exact color you want. It's an alternative method to RGB.

CYMK:

setting the Cyan, Yellow, Magenta, and Black (K) color channels to create the exact color you want. Used most commonly in the print world.

Drawing shapes.

Shape tools - 3 modes

• Shape layers: Path and filled shape (combo of the following two)
• Paths: path only (outline of shape with no visible manifestation; can be resized because it's a vector shape.)
• Fill pixels: a filled shape as a simple bitmap.

Drawing an unfilled shape - 2 methods:

Method 1. Using selection and stroke tools.

1. Use one of the marquee tools (rectangular or elliptical) to draw the desired shape.
2. Choose Edit menu > Stroke...
3. Set options: width, color, location blending. Click OK
4. Unselect (Cmd-D)

For rounded rect, after marquee tool, choose Select menu > Modify > Smooth. Choose radius, click OK. Then follow steps 2 - 4.
Drawback of this method: curved edges not smooth (not antialiased).

Method 2. Using the shape tool. A bit more complex, but produces antialiased edges.

1. Create a new layer (Layer menu > New > Layer).
2. Choose the rounded rectangle option of the shape tool.
3. Choose Fill Pixels mode on the toolbar.
4. On the toolbar, set opacity to 100% and check the antialias box.
5. Drag the mouse pointer to create the desired shape and size of rectangle.
6. In the layers palette, directly below the opacity slider, is the "Fill" slider. Set it to 0%.
7. Bring up the "Layer Style" dialog (usually by double clicking in an empty area on the layer.)
8. Select the "Stroke" option from the left menu, make sure it's checked. Adjust your stroke settings as desired.