Photoshop CS3 for Screen Printers- P15 pdf

A Little about Alpha Channels You can save a selection as an alpha channel mask.. A new channel called Alpha 1 appears, which can be renamed.These alpha channels can be deleted, added, a

2 Choose Layer>Add Layer Mask>Reveal All to reveal the entire layer or Layer>Add Layer Mask>Hide All to hide the entire

layer

To create a layer mask that hides or reveals a selection only:

1 Select the layer to which you want to add the mask in the Layerspalette

2 Make the selection for the mask using a selection tool

3 Choose Layer>Add Layer Mask and either Reveal Selection or Hide Selection Only the selection will be hidden or shown, and

this selection can be edited independently of the other parts of theimage

To work with layer masks that have been created:

1 Select the layer in the Layers palette that contains the mask youwish to edit Click once on the layer mask thumbnail to make itactive

2 Select an editing or painting tool

3 Paint with white to subtract from the image, black to add to it, andgray to partially hide the layer You can switch to using the fore-ground and background colors in the toolbox and revert to theoriginal black and white there too

4 When complete, you can either apply or discard the mask by holdingdown the Shift key and clicking once on the mask in the Layers pal-ette A red X indicates that the mask is discarded

Using layer masks allows you to separate and control specific parts of animage by producing a stencil of a selection This stencil can be alteredbut the area around it is protected from change These selections canthen be saved for later use by saving the mask in an alpha channel This

is briefly detailed next

A Little about Alpha Channels

You can save a selection as an alpha channel mask Saving the selection

as a mask will allow you to keep your work for later use Alpha channelsare storage areas for data, like selections When a selection is saved as amask, this channel is created automatically

You can also save a selection manually First, open the Channelspalette using Window>Channels With the selection active in the image,choose the Save selection as channel icon at the bottom of the Channelspalette A new channel called Alpha 1 appears, which can be renamed.These alpha channels can be deleted, added, and edited using thepainting and editing tools, and opacity and other mask options can be set.Alpha channels can also be converted to spot color channels for spotcolor separations.

Once the mask has been saved as a channel, you can paint with white

to erase part of the mask, black to add to the mask, or gray to apply ity to the mask There is more on alpha channels in the next chapter,

opac-“Spot Color Separations.”

Summary

In this chapter you learned a little about paths and how to draw curves

as well as straight lines To create paths, you used the pen tools Youlearned to fill and stroke paths and how to save them for later use Youlearned that paths can be useful for tracing around objects that would beharder to deal with using other tools, and that paths can be saved asselections for various other applications and purposes

Vector masks and layer masks were also introduced These can beused to control what parts of a layer will be hidden or revealed Themasks can have special effects applied or they can be inverted for moreeffect and usefulness Paths, layer masks, and vector masks are a quitepowerful and complex feature of Photoshop This chapter introduced onlythe basics, but with this knowledge you are well on your way to uncover-ing the magnificent power of these tools

Separations

399

Spot Color

Separations

Of all of the types of color separations that you can perform in

Photoshop, spot color separations are the easiest You’ll use spot colorseparations when there are only a few colors in the artwork and thosecolors are distinct Spot color artwork usually contains 12 or fewer dis-tinct colors The fewer the better though, since each color must bechosen and separated manually

Spot color separations where the colors fade into one another orhave highlights or shading must be printed with halftones output by a

PostScript printer True spot color images, those whose colors are few

and distinct and do not fade into one another or have highlights, can beprinted using an inkjet or laser printer and film or vellum without half-tones If you print T-shirts using a four- or six-station press to print truespot color, remember that you can print only as many colors as you havestations on the press

Besides allowing you to color separate different types of spot color

images, Photoshop also makes it easy to create spot color artwork, thus

allowing you more options when creating artwork for clients Creatingyour own artwork for clients can be both profitable and rewarding andcan help you expand your business by allowing you the ability to offer artservices

401

Building Your Own Design

Photoshop makes it easy to create your own design from hand-drawn lineart If you have line art that you’ve drawn or artwork that a client hasdrawn, you can scan an image as line art at 600 dpi and fill the areas ofthe image with the color As detailed in previous chapters, the PaintBucket can be used to fill any area with color, brushes can be used to addhighlights, and the Magic Wand can be used to select areas in the

scanned line art quickly for other editing tasks

6 Caution!

You can’t fill a grayscale bitmap image with color using the Paint Bucket

without first converting it to RGB mode Use Image>Mode>Grayscale andImage>Mode>RGB Color to convert modes

You can also use Photoshop to open or scan a client’s colored spot colorimages and separate them in-house Finally, you can use clip art and text

to create designs

True spot color designs are ideal for shirts for local sports teams,staff, family reunions, school choirs and bands, police and fire depart-ments, and any other group or organization looking for a fast,

inexpensive, and effective design stating who they are Figure 22-1shows some examples

. Note:

These examples are JPG files because they were recently e-mailed to clientsand were pulled from our “E-mailed to Clients” folder We send files as

JPEGs for several reasons, including but not limited to, the image’s smaller

file size They also prevent clients from editing our work or taking our work to another screen printer for easy color separation and editing

art-] Tip:

Practice creating spot color designs in Photoshop; my clients are always

amazed when I import some clip art, add some text, and say “Do you like

this?” They almost always do

Prepare Photoshop

Before performing any kind of color separations, make sure your monitor,printers, and scanners are calibrated, along with any other equipmentthat offers calibration options Also, check the Edit>Color Settings dia-log box to verify that the settings there are appropriate for the ink, mesh,dot gain, color working space, and other options These settings werecovered in Chapter 5 Figure 22-2 shows the settings that I configuredregarding my shop, ink, and equipment; yours might be different If indoubt, return to Chapter 5 and work through the projects

Figure 22-1: True spot color designs

. Note:

Depending on your system, you might configure your color settings to

include an Apple RGB working space, a specific ink brand, specific settings

for manual and automatic presses, and dot gain of 35 percent for CMYK and

30 percent for spot color

Prepare the Image

You’ll get images in many forms, some of which were discussed in ters 13, 14, and 15 Images that you’ll get from clients can be from digitalcameras, CDs, DVDs, via e-mail, or they can be originals that need to bescanned The following offers a brief compendium of the information cov-ered in those chapters but is by no means a complete account:

Chap-Figure 22-2: The Color Settings dialog box

n If you have to scan a colored, spot color image, scan it at 225 to 250dpi or greater.

n If scanning black and white line art, scan at 600 dpi

n Scan the image at 100 percent, unless you need it to be larger thanthe image given to you, in which case you should upsample it on thescanner by choosing 150 percent or so

n Turn off anti-aliasing if the file size is too large

n Always scan in RGB mode

n If prompted about an Embedded Profile Mismatch when opening afile, choose Convert Document’s Color to the Working Space andclick OK

n If the file is an older CorelDRAW or Adobe Illustrator file, export it

as 225 dpi with anti-aliasing turned off

With the image now showing on the screen, save the image If this were

a photograph, you’d most likely need to perform some additional ments With spot colors though, there isn’t much to do You can deleteareas of the image if they aren’t needed using the Clone Stamp tool topaint over the unwanted part with the color of the background, or you canerase backgrounds that you don’t want using the Magic Eraser You canalso select areas to perform edits on using the Magic Wand

adjust-Figure 22-3 shows two images The image at the bottom is from aclient who wants this design printed on a light blue T-shirt The clientadded the background in light blue so I’d know that’s the color shirt hewants The background isn’t needed in the actual print and needs to beremoved or changed to white so that it won’t print when you create thevellum for the screen Clicking once on the background with the MagicEraser tool removes the background (Now remember, the colors a clientsees on his computer monitor probably aren’t what you’ll see on yours.I’d take special precautions when ordering his shirt In fact, I’d ask him tocome by the shop to hand pick the color from the catalog himself.)

. Note:

Once the image is complete and ready for printing, save the image

About Pantone Colors

When you perform a spot color separation, you can match the colors inthe image with the closest Pantone colors Pantone colors are industrystandard colors that are represented by names and numbers Clients willoccasionally give you a specific Pantone color number to use, and you canpurchase inks based on specific Pantone colors

The Pantone Matching System (PMS) is an ideal way to ensure truecolors when you print Pantone colors include Pantone Yellow, PantoneRed, Pantone Purple, etc., and various shades in between with nameslike PMS251 and PMS262 Keep in mind that the color of the shirt orsubstrate can have an effect on the final color once the ink has set, soalways perform test prints if perfect color is an important issue

Figure 22-3: Prepare an image by removing the background or changing a

colored background to white

Alpha Channels

When performing spot color separations, you’ll work with RGB channelsand alpha channels Channels and alpha channels are represented in theChannels palette, which is shown in Figure 22-4

In Figure 22-4, the composite channel (the first channel) and each of thethree channels for Red, Green, and Blue are selected The RGB channelsare in grayscale and created automatically when a file is opened You willcreate additional channels called alpha channels to specify the plates forprinting spot color images

Figure 22-4: The Channels palette

Getting to Know the Channels Palette

To familiarize yourself with the Channels palette, open any RGB file andthen open the Channels palette using Window>Channels If you want,open the file Wade.jpg file from the Chapter 22 folder on the companion

CD Familiarize yourself with the Channels palette by doing the

following:

n If the channel in the Channels palette is blue (as are the channelsshown in Figure 22-4), the channel is active By default, all channelsare selected You can select a single channel by clicking on it in thepalette To select all of the channels again, select the compositechannel (the topmost channel)

n When adjustments are made to an active channel, the adjustmentsare applied only to that channel For instance, if you select only theRed channel and use Image>Adjustments>Curves to adjust theimage, the changes are only applied to that channel

n Remove the eye icons from channels to remove them from view

n When printing separations, use the eye icon in the alpha channelsthat you’ll create to tell Photoshop which channels to print Thereare no alpha channels in Figure 22-5

Figure 22-5: Adjusting a single channel

n Change how you preview the channels from the additional options inthe Channels palette You may want to choose the largest options.That’s it! Let’s get busy color separating.

Performing Spot Color Separations

There are several ways to color separate a two- or three-color spot colorimage like the ones shown earlier in Figure 22-1 However, most imagesaren’t just two or three colors, and recreating the image or performingcolor separations by hiding colors or using other tricks is not very effi-cient! There is a specific way to perform spot color separations in

Photoshop that will work for all spot color images; this is the task athand In Project 22-1, we work with a simple, two-color separation andlearn the basics This process can be used to perform spot color separa-tions on images with more colors simply by repeating the steps listedhere

Project 22-1: Performing a Spot Color Separation

To perform a basic, two-color spot separation, follow these steps:

1 Open the file Fire.psd from the Chapter 22 folder on the companion

use the Eyedropper tool, also selected in this dialog box See Figure22-6

4 Use the Eyedropper cursor to click on the red part of the image.

5 Adjust the Fuzziness slider to pull the amount of color you want.Because the image is only red and black, you can move the slidermost of the way to the right You want to select all of the red, but youdon’t want the edges to be too hard (170-200 is a good value for thisimage)

6 In the Selection Preview choices, select Grayscale Notice how the

image changes What you see here is only what is red, and will beseparated You can use this preview to see if the Fuzziness setting isgood or needs to be revised Change Selection Preview back to

None and click OK.

7 The red part of the image has been selected You can see the ing ants outline around the red in the image In the bottom of the

march-Channels palette, click the Save selection as channel icon ( )

A new alpha channel will be created (from the selection), as shown inFigure 22-7

Figure 22-6: The Color Range dialog box settings

8 Hold down the Ctrl key on a PC or the Cmd key on a Mac and

double-click on the new alpha channel The Channel Options dialogbox appears (The red in this dialog box has nothing to do with thered in the image; it’s just a default color for the channel.)

9 As shown in Figure 22-8, select Spot Color and change the solidity

to 100 percent (Do not press OK just yet!)

. Note:

Solidity values can be between 0 and 100 percent This option lets you late on your computer monitor how solid the printed color will be Zero

simu-percent is used for transparent inks, while 100 simu-percent is used for more

solid inks These settings only affect the on-screen image and do not have

anything to do with the printed separation So, it’s okay if you aren’t quite

exact here!

Figure 22-7: Saving a selection as an alpha channel