photoshop doc1

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many leaets can be found at:

http://www.cam.ac.uk/cs/docs

70 penceOctober 2003

Computing Service

M440

Adobe Photoshop 7.0:

the basics


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M440/October 2003 5

Adobe Photoshop: basic techniques

Lesson 1: Scanning, saving and set-up

To scan images into your computer, you need a scanner attached to your computer

and scanning software installed onto your computer. Scanning software is supplied

with the scanners, often Photoshop. You can also buy Photoshop independently.

To scan a picture

1. Place the original material on the scanner glass. It should be face-down. Your

scanner manual will tell you which way round to put it.

2. Launch the scanning software: Photoshop, Photo Deluxe, ScanWise, etc. If you

already have Photoshop running, you can launch the scanning package from

within Photoshop by choosing File > Import > and select the scanning package

(eg ScanWise).

3. Your software may automatically preview (scan) your document so that it

appears on the right hand side of the scan window. If not, you will need to click

a Preview button to pre-scan the document.

4. The scanning software will automatically select options for destination, image

settings, file format, etc. You may change this if you wish from the buttons on

the left hand side of the scan window.

6. Click the Scan button.

7. Save the image in the desired format (see page 7). If your scanning package waslaunched from within Photoshop, your image will automatically appear in a

Photoshop window.

What scanning software is installed on the PWF Macs and PCs?

Graphics; Agfa ScanWise (can also be invoked from within Photoshop)

Text; TextBridge Pro (full-featured), OmniPage LE (basic, limited features)

See page 28 for details of Computing Service leaflets on using the PWF scanners.


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Lesson 2: Tools, palettes and the mouse

Tools and palettes

Todays course covers those tools shown in bold type below. To use a tool,

single-click it. Most tools have options, eg tool thickness and opacity can beset in the palette which runs along the top of your screen. This palettechanges according to which tool you have selected.

History paletteThe History palette keeps a step-by-steprecord of every operation you perform in

Photoshop. You can undo any number ofsteps by clicking on the white tab for which-ever change you wish to go back to.

Rectangular/elliptical marquee

Lasso (selection, as is marquee)

Crop

Healing brush

Clone stamp (duplicating items)

Eraser

Blur

Path Component Selection

Pen

Notepad

Hand

Tools

Move (layer or selection)

Magic wand (select similar pixels)

Slice

Paintbrush(drawing tool)

History

Gradient

Dodge/burn/sponge

Type (add text)

Rectangle

Eyedropper (pick a colour)

Zoom (in or out)

Foreground and

background colours

QuickMask mode

Screen modes

Jump to ImageReady mode


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Lesson 3: Selections, Channels and LayersSelection: a selection is any highlighted area defined by a moving, broken line(marching ants). Selections occur when you use a selection tool (rectangular,

elliptical, crop) to select parts of your image. Selections are temporary. Selections

work on layers (see below).

Channel: all documents opened in Photoshop have one or more channels. A channelrecords information of a specific colour (eg. red, green). Most common are Bitmap

(one channel in black on a transparent background which will give black on white if

printed onto paper), RGB (three channels, Red, Green and Blue, which are overlaid to

give other colours) and CMYK (four channels, Cyan, Magenta, Yellow and Black

which are also overlaid to give other colours). CMYK is not available in Photoshop

LE.

Channels can be adjusted (see 22) or switched off to create different colour effects.

To switch a channel off, click the eye icon alongside the channel name in the Channelpalette.

Layers: a document usually begins with just one layer. Imagine the layer as a sheetof clear acetate with the picture printed on it. Whenever you use drawing tools or

copy and paste selections, you can choose to do this on a new layer. Gradually you

can build up a composite image (see page 26) of several layers. Clicking the eye icon

alongside the layers name will hide that layer to give a different effect. Layers are a

bit like collages, they are a way of building up the picture by adding more contents to

it. The order of layers can be changed by dragging layers within the Layers palette to

bring some items to the front or to send others to the back.

Documents containing two or more layers are larger than one-layer documents,especially when open (see page 11) so it may be a good idea to flatten (merge) all the

layers into one when you have finished editing the document (see page 18).


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Lesson 14 Adjusting colours and contrast

The brightness and contrast, amount of true whites and blacks in an image, can be altered

in several ways.

The Adjustments > Brightness/Contrast panel from the Image menu. This givesblanket results across the entire image. For finer control, use one of the two methodsbelow.

LevelsChoose Adjust ments > Levels from the Image menu.

The graph shows the range of tones, from darkest (left) to lightest (right). The left pointerindicates the point from which true black starts. All tones to the left of this point are black.

The right pointer indicates the point from which pure white starts. All tones to the right ofthis point are white. The middle point indicates the mid-gray point.

So, move the left and right pointers to decrease or increase the purity of white and black,and contrast. Move the middle pointer to determine the overall brightness and darkness.

The Channels option on the Levels window also allows you to change the tones withinindividual colours (eg for RGB you will also find Red, Green and Blue channels). Thisenables you to remove or create colour casts on your documents.


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Leaet number: M440.

2003 University of Cambridge Computing Service. May be reproduced only with permission.

The information in this document may be available in other forms. Please telephone the Information

Group coordinator on 334598 or e-mail [email protected] to discuss what is available,

any special requirementsfor presentation and how we could meet them.


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