adobe photoshop cs5 – illustrated unit b: selecting pixels

Adobe Photoshop CS5 – Illustrated

Unit B: Selecting Pixels

Objectives

Use the Marquee toolsUse the Lasso toolsUse the Magic Wand toolSave and load selections

Adobe Photoshop CS5 - Illustrated

Objectives

Work with and save alpha channelsUnderstand anti-aliased edgesWork with a feathered edgeRefine selection edges


Using the Marquee Tools

First select pixel to modifyMarquee tools Most basic tools for making selections Rectangular Marquee

• Rectangular or square selections Elliptical Marquee

• Oval or circular selections

Pixels Can be added or removed from a

selection using quick keysAdobe Photoshop CS5 - Illustrated


Tool icon black triangle indicates additional hidden tools Located beneath currently displayed tool

If unhappy with selection Deselect selection Start over



Positioning the first piece

Repositioning the circle piece


Using the Lasso Tools

Three types of Photoshop Lasso tools Lasso, Polygonal Lasso, Magnetic Lasso

Lasso tools: make free-form selections Click and drag anywhere on the canvas

to create section of pixels• Complex shapes: easier to make small

selections and add to them with Shift key

Polygonal Lasso tool Uses straight lines for geometric shapes


Using the Lasso Tools

Selecting the interior of the object

Positioning the fifth piece


Using the Magic Wand Tool

Magic Wand tool is powerfulClick any canvas pixel Tool selects other pixels based on

tolerance Greater the tolerance value, tool selects

more pixelsOptions bar contiguous check box Selects only contiguous (touch) pixels Or selects similar pixels throughout the

imageAdobe Photoshop CS5 - Illustrated

Using the Magic Wand Tool

Once needed pixels are selected Can modify in many ways

Zooming in on selected image areas Helpful when making selections,

including colors, using the Hue/Saturation dialog box


Using the Magic Wand ToolSelecting the white pixels

Selecting pixels without the Contiguous option

Results of changing the hue of selected pixels


Saving and Loading Selections

Making selections Complex and time-consuming work

Saving selections Smart idea Can easily access selection in the future



Swatches panel Changes foreground/background colors

Click swatch and foreground color changes Click Eyedropper tool, sample any pixel

from the imageSaving created colors Float pointer over a white area of the

Swatches panel



The finished project

Pure Yellow Orange swatch on the Swatches panel

Save Selection dialog box


Working with and Saving Alpha Channel

Alpha channels Saved selections Listed on Channels panel Displayed as black and white thumbnail

images Selected areas represented by white Areas not selected represented by black Not automatically saved when the file

saved Must specify when saving a file


Working with and Saving Alpha Channel

The Dark Gray alpha channel

Save Alpha Channels option in the Save As dialog box


Understanding Anti-Aliased Edges

Edge: outline of a selectionEdge types of a selection Aliased: hard edge

• Very blunt and obvious Anti-aliased: crisp but smooth edge

Anti-aliased edge Creates a smooth transition between

edge and background• Uses many shades of edge pixel colors


Understanding Anti-Aliased Edges

Pixels: squares and a soft edge Cannot be made with squares Illusion created using anti-aliasing


Viewing the anti-aliased edge

Viewing the aliased edge

Working with a Feathered Edge

Feathered edge: blended edge Settings available for controlling blend

length at the edge Feather value: equal to feathered edge

• Edge equally distributed inside and outside selection edge

Vignette: visual effect with feathered edge• Image edge: usually oval, gradually fades

away


Working with a Feathered Edge

Drawing the feathered oval selection

The selected pixels relocated


Refining Selection Edges

Refine Edge dialog box Offers useful options for viewing and

refining the edge of a selectionTwo key options in the dialog box Feather slider

• Dynamically feathers a selection while previewing the result

Contract/Expand slider reduces enlarged selection• Useful for removing halos from the edge of a

selectionAdobe Photoshop CS5 - Illustrated


The Refine Edge dialog box

Selection

The silhouette of the eagle against black


Summary

Marquee and Lasso tools Provide different ways to select image

pixelsMagic Wand tool Selects other pixels based on tolerance

Save selections Easy to access selection in the future

After sampling a selection color Color can be saved in the Swatches

panel Adobe Photoshop CS5 - Illustrated

Summary

Alpha channels Must specify saved selections as an

alpha channel when saving fileImages edges: made up of square pixels Blunt square edge: aliased edge Anti-aliased edge: made to look like a

smooth edgeEdges Feathered and refined


adobe photoshop cs5 – illustrated unit b: selecting pixels

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