cores indexadas

8/7/2019 Cores Indexadas

1/14

Part One of a two part article. Click here to read Part Two.

By Scott Fresener

Printing detailed, photorealistic images on dark shirts has always been the ultimate goal ofmost garment screen printers. Yes, the bread and butter is in basic images (for most printers),

but there is nothing like lifting the last screen and seeing a masterpiece on the garment. It canbring tears to your eyes!

But there is nothing like lifting the last screen and breaking down in tears because theimage just doesnt look right and you have no idea what to do next..AND, the customer is

due to approve the print in ten minutes.

This article will detail how to do very respectable color separations and photorealistic printson dark shirts. I use the word respectable because no matter how much time I spend going

over the steps, there is still a learning curve. All of us who do high-end printing have learnedthrough years of trial and error and through many failures. If you follow these steps you will

be on your way to creating high-end prints. You just need to remember that with each job,

you will gain knowledge about what is important and what is not.

While this article will deal with some color theory, it is designed more as a primer to help the

average printer achieve results in a short time period without having to go back to college art

class.

What is Simulated Process Color?

This term has been around for a long time. In simple terms, it is a method of printingphotorealistic images without using the standard CMYK separations. I like to say the image

looks like process color (CMYK), smells like process color but it isnt process color. In

fact simulated process color uses off-the-shelf inks that are standard opacity plastisolsprinted on top of high opacity plastisol as a base or underbase (see Figure 1).

Why is it so hard?

It is hard because again, we are trying to use standard inks and make the image print like

process colors. We are also printing on a base of white and trying to be faithful to the originalartwork. A tough task. One of the secrets of great simulated process color is that the print

needs to stand on its own. This means that while it might be faithful to the majority of theoriginal art, it should be bright and detailed. How many times have you seen the original

artwork when you view the coveted Golden Image winners at the SGIA show? Never. Ithink you might be shocked at the difference on some prints. Others, might match the original

but what you DONT see are the three or four attempts and screen re-burns it took to get tothat point.

I know this sounds negative, but it is the reality of working with so many variables like shirt

composition, ink opacities, poor original artwork and worst of all, high customer

expectations.

OK, enough of this negative talk. Lets get down to specifics. We will look at artworkrequirements, image adjustment and color separations, screen, ink, press setup and printing


2/14

requirements. This article was originally written in 2005 using Photoshop 7.0. Dont worry.None of the steps have changed. Photoshop of cours is the program of choice for image

manipulation and color separations. All steps here will work with any version of Photoshop.

While it is nice to know how to do these things and this article deals with a LOT of items like

getting the image looking good before you separate it many artists just dont want to

remember all the steps and have opted for plugins for Photoshop that do this with the push ofa button. Check out my plugin T-Seps here if you want to see all these steps happen in a flash

before your eyes. Yes, this is a blatant plug. But you will learn a lot in this article about the

process, prepping artwork and more. This article is a must read if you plan to do higher end

photorealistic work.

This one is sometimes a real joke. How many times have you gotten a low quality JPG image

from a web graphic and been expected to us it as the artwork. Better yet, they give you the

CD label and want it on a shirt. When you see a magnificent print that has detail and edge

definition, it came from a magnificent original that had detail and edge definition. If you take

the 72dpi image that is the size of a wallet photo and blow it up to 200 dpi, you will have a

soft 200 dpi image.

I deal with sample files from customers and students every day and I have to always ask, is

this all you have to work with? The answer is always, thats it!

Figure 1 - Click on images to see larger version. Use the BACK button to return to article.

Figure 2

Your original image should be from a good graphic, photograph, illustration, or image

created in a drawing program like Corel, Illustrator or Photoshop, that is the final image size

at a resolution of 200 to 250 dpi. Yes, it can be lower resolution but hard edges will be softer

(see Figure 2).

Photoshop Setup


3/14

We will be using Adobe Photoshop to do the separations and it then stands to reason that wewill use Photoshop to do the pre-separation image adjustment. In order to not make this

article an entire book, the following steps assume that you have done a monitor calibration(detailed in your Photoshop manual).

Also, in order to preview the individual alpha channels (separations) correctly you must tell

Photoshop to display the image with the proper dot gain.

Go to Edit/Color Settings and underWorking Space, set Spotto 30%. UnderRGB, set the

monitor profile to Apple RGB (see Figure 3).

Image Adjustment Improve contrast

The best images for dark shirts have good contrast. If the image has what appears to beblack areas, make sure they ARE dead black by checking them with the Info Palette

(Window/Show Info). Dead black is 0 levels of RGB (see Figure 4).

It is also helpful to improve the contrast by applying an S Tone Curve adjustment

(Image/Adjustments/Curves) (see Figure 5). Photoshop has a feature called Auto Color

(Image/Adjustments/Auto Color). Auto Color improves contrast and color saturation (see

Figure 6). Very nice!

Poor quality JPGs

If the image did come from a low quality JPG image, the boxes that are created by the JPGroutine averaging the color in areas will be GREATLY enhanced when you do color

separations. If your image does have blocky areas, you might actually have to soften theseareas before color separating (see Figure 7).

Photoshop has routines designed to improve/enhance JPG images and there are inexpensiveprograms on the web called JPG Enhancement programs.

Keep edges hard

If you created the image in a vector program, make sure to NOT use Anti-Aliasing when

importing the image. The edges will become soft and this will show up in the final print (seeFigure 8).

Figure 7


4/14

Figure 8

Figure 3

Figure 4

Figure 5


5/14

Figure 6

Use Unsharp Masking

Most images supplied by the customer need to be sharpened. I recently worked with images

from a well known theme park company who supplied images for cartoon characters to a

printer in Mexico City. All of the images were very soft and needed major unsharp

masking applied to them. The printer assumed that the customer knew what they were doing

and I had to work hard to convince them that typical artists dont really know what a screener

needs.

I rarely work on a design without first seeing if the image needs Unsharp Masking

(Filter/Sharpen/Unsharp Mask).

OK, the name seems wrong, but Unsharp Masking sharpens areas of high contrast. Start with

settings of Amount 150%, Pixel Radius of 1 and Threshold of 5 (see Figure 9).

Then take the Amount slider all the way to 500%. You will be SHOCKED at the

improvement to some images. Others will get very grainy over 200%. Be bold here.

Two Versions of Artwork Needed

If the image is going on black or dark shirt colors you will need TWO versions of the file.One version is the normal image with white as the canvas or background. The second

version of the artwork has black around the image in the canvas areas (see Figure 10). This is

called a masked file and will be used for the underbase and highlight.

I spent a lot of time trying to explain why you need two versions of the artwork. The simple

answer is that to pull the colors from the image, you MUST have the background or canvas

white. Otherwise you would not be able to create the color portions of the separations.

If the image is on a shirt color, the shirt color really has nothing to do with the color

separations.

In order to make an underbase of an image, the canvas areas MUST be black because you

will be making a grayscale of this image and it will be inverted. You dont want to print asolid block of white around the image. Just buy into it and trust me on this.

The easy way to create two versions of the image is to build the image in Layers in

Photoshop and then create one version with a black background and another with a white

background (see Figure 11). Flatten the image and you are ready to separate.


6/14

Another method is to airbrush around the image with black or use the Magic Wand and selectthe areas around the image and fill these areas with black. If at all possible, YOU WANT TO

GET THE ORIGINAL ARTWORK IN LAYERS from the customer if possible so you havemore control over these things.

Color Separations Are Critical

Figure 9

Figure 10

Figure 11

I like to joke that if the seps are done correctly, the printing is easy! Although this article

details how to do the separations, there are a number of automated color separation programson the market that do this for you. Many of these programs do a great job and will save youhours of trial and error. In fact most go through hundreds of complex moves that would be

impossible to teach in a short article. Even if you have an automated color separation

program I think it important that you understand the basic steps so you will be able to know

about the inner workings of this process.


7/14

Keep in mind that color separators (myself included) who learned this process using filters ina camera (years ago!), often like to use each of the Red, Green and Blue channels of the RGB

image and each of the Cyan, Magenta, Yellow and Black channels of a traditional CMYKimage to build an image using all or parts of those channels for each color separation when

creating simulated process separations.

If you have a lot of experience, you can look at the individual RGB and CMYK channels anddetermine if it in fact has the color information you need. As an example, the Black channel

of a CMYK image might be good enough (probably too weak) for the black plate of your

separations. The cyan channel probably has the blue areas. The yellow and red channels

might have information that can be used to make browns, etc.

Also, experience separators and the automated separation programs use the Photoshop

Calculations command to combine, exclude, subtract and do other manipulation of the

individual RGB channels (I will touch on this briefly later). This requires a lot of work, much

trial and error and a good experience level (can you say lots of failures?). With that in

mind, this article will detail the easiest and quickest method to use and one that requires

much less experience.

Contrary to what you might think, the original image must be in RGB mode. You should

have the image open and the Channels Palette visible when doing the color separations.

Underbase and Highlight White

Images that go on dark shirts need an underbase of white ink (generally NOT a solid image),

and a Highlight White that is typically printed last. Yes, you need two whites but this is a

must.

Creating Highlight White

Open the masked version of the artwork (black around the image). Using Color Range

(Select/Color Range) select just the white in the design with the eyedropper. Use the

Fuzziness slider to determine how much white you want. Remember, this just needs to be the

whitest parts of the image. It is a judgement call (see Figure 12). Too much and you will mute

down the colors when you print the image. Make sure Invert is checked. Say OK to the Color

Range window.

Save this selection as a channel (Select/Save Selection). Name this channel Highlight White

by double-clicking on the Channel Header (see Figure 13).


8/14

Simulated Process Color Separations for

Screen Printing Part Two

By Scott Freseneron Aug 15, 2009 with Comments 1

Part Two Simulated Process Color Separations for

Screen Printing. Click here to read Part One.

By Scott Fresener

Creating Underbase White

If you are going on a black shirt you will need an

underbase white. The underbase is the key to the image. If

it looks GREAT when printed, chances are the image will

look great! Working with the same file that has the new

Highlight White channel, select the entire image

(Select/Select All). Copy this selection to Clipboard

(Edit/Copy). Make a New Spot Channel (Horizontal

arrow in Channels Palette). Select new channel and Paste

(Edit/Paste). Deselect the image (Select/Deselect), and

then Invert the new channel(Image/Image

Adjustments/Invert).You will now have a grayscale of the

full image along with the highlight white channel (see

Figure 14).

Enhancing the underbase

We arent done with the underbase yet. A good underbase

is high contrast. Apply an S tone curve

(Image/Adjustments/Curves) to darken the shadows and

lighten the highlight areas. Play with this to give the

image good contrast (see Figure 15).

Your underbase channel is now a respectable underbase

Figure 14

Figure 15


9/14

but not yet complete. It will be flat and lack intensity

under certain colors like red and blue. You will need to

increase the density of the underbase under these colors.

For each top color you want to boost in the underbase, use

the eyedropper to select that color. As an example, for

red, go to Select/Color Range and select the red in the

image. Adjust the Fuzziness slider to pull the amount ofcolor you need (see Figure 16). Say OK to the Color

Range window.

Next, Inverse this selection (Select/Inverse Selection) and

then apply the selection to the Underbase Channel

(Select/Save Selection/Choose the new Underbase

Channell/Addto Channel) .

You can see that you now have much more white in the

underbase channel where the red of the image is (see

Figure 17).

Do the same for darker blue areas of the image. The

yellow, light blue, and green areas of the image should

have enough white under them without boosting these

areas.

This is what the underbase will look like when printed

(see Figure 18).

Separating Individual Colors

You will need to open the version of artwork that haswhite in the canvas area for the next steps. There are two

different approaches to pulling the colors. The easiest

method is to use the Color Range tool to pull a color. This

works for many colors and also works well for non-

standard colors like browns, grays, and flesh tones.

The second approach works well for red, green, light blue,dark blue and yellow.

Figure 16

Figure 17

Figure 18

Using Color Range

The Color Range tool is extremely powerful. Yes, it does

have limitations on colors that have many extreme shades(greens and browns are VERY hard), but all in all, you

can use Color Range to pull specific colors.

As an example, to just select the red of our sample image,

go to Select/Color Range (make sure Invertis checked)

and use the Eyedropperto select just the red from the

image. Use the Fuzziness slider to determine the amountFigure 19


10/14

of red you think appropriate (see Figure 19).

Yes, another judgment call. Say OKto this window. Save

this selection (Select/Save Selection) as a new channel

(see Figure 20).

In order to build the separations and preview thembefore you go to press, it is important to apply the

appropriate color and ink opacity to each channel as youmake the color separations.

To apply a preview color you can either double-click on

the channel header and assign the proper Pantone(r) coloror you can hold down the ControlKey (PC) orOptions

Key (MAC) and double-click on the new channel header

(make sure that RBG is selected and that you have not

deselected the marching ants). This will bring up the

ChannelOptions box. Click on the colored box and then

sample the color you selected from the image at the

ForegroundColorbox on the Toolbar. CheckSpot Color

and set Solidity to 5% (see Figure 21).

Why 5%? We are trying to simulate on the monitor how

the image will look when printed. Standard opacityplastisol has an opacity of about 5%. Use this as a general

opacity level for most colors. Use 100% opacity (solidity)

for black. Trust me on this

You can now continue to build the rest of the separations

this way.

Select the RGB, use Color Range to pull a specific color,

make this selection a Channel, apply the appropriate print

color and ink opacity to the channel.

Separating Browns and Flesh Tones

These are hard colors. Browns can be yellowish, redish,

dirty and more. Flesh is based on the persons skin colorand to do it correct you generally need to pull more than

one shade.

Browns

As you can see in Figure 22, the horses have yellow

brown, dark brown, etc. It will be almost impossible touse just one brown. If you can only print one brown, try

using Color Range to pull the main brown, but add to theselection by holding down the Shift key and select other

shades of the brown with the eyedropper. The other

Figure 20

Figure 21

Figure 22

Figure 23


11/14

option is to print more than one brown.

Flesh

Flesh is the same way. Use Color Range to pull the mostdominant flesh color. Use Color Range to pull a darker

flesh from the shadows of the image (see Figure 23).

When you see a great print with realistic flesh tones, theyhave printed two and maybe even three shades of flesh.

Using the Automated Color Range Feature

The Color Range command will also automatically

choose the red, yellow, green, cyan, blue, and magenta

colors in the image. Go to Select/Color Range and drop

down the Selectwindow. You will see a color list. Choose

Red. You will note that you now do not have any controlover the amount of red Fuzziness is not available. Make

sure Invertis checked and then say OK to this window.

Again, make this selection a channel (Select/SaveSelection). Notice that the red you pulled using the normal

Color Range/Fuzziness feature lacks a little of the detailthat the automated Color Range feature pulled. See Figure

24.

You can use the Automated Color Range feature to pull

the other colors. The cyan will be the same as light blue.

The magenta can be used for purple.Using Calculations

If you want to play with the Calculations command

(Image/Calculations), open the RGB image and for the

Yellow separation, subtract Green from Blue, for Red,

subtract Red from Green, for Blue, subtract Blue fromRed (see Figure 25). This method will create a new

channel that will need to be inverted. You can start toapply masks to channels and a lot more.

Putting It All Together

OK, now you have the underbase, highlight channels as

part of the masked version of the artowork and all the

other colors as part of the unmasked version. You can

build the entire separation that allows you to preview the

image in Photoshop.

You can drag channels from one file to the other in


12/14

Photoshop. Open both of your working files. Select the

masked version with the underbase and highlight white

channels. Click on the underbase channel and drag it to

the unmasked file. Do the same for the highlight white.

Assign the underbase channel white as a display color,

and give it a solidity of 85%. White is NOT 100% on ablack shirt.

For the highlight white, assign it white as a preview color

and an opacity of 90%. This is about as white as it will getwhen printed on the flashed underbase (see Figure 26).

Click and drag all the channels to the correct print

sequence. The underbase should be first (after the RGB

which we are done with). Next, put the yellow and then

go light to dark. Place the highlight white last and the

black channel next to last.

Make a channel for the Shirt Color.

Create a New Spot Channel and assign it the appropriateshirt color. You will need to fill this channel with Black

(Edit/Fill/Black) for the shirt color to display in color.Move the Shirt Color channel to above the underbase

white.

By clicking on the eye in the channel header, the

channel will display with the appropriate color (see Figure

27).

Tweaking the Image

The image should preview pretty much the way it will

print. We have told Photoshop to display the channelswith 30% dot gain applied to the display and we have

dialed in the appropriate ink solidity. If the image looksweak with the eyes turned on, dont be shy. Select the

channel you think is weak and apply a Tone Curveadjustment to it (Image/Adjustments/Curves). By simply

clicking and dragging the mid-tone area of the curve, you

can increase or decrease the density of the color (seeFigure 28).

A good separator tweaks all the colors. Remember, you

will get more visible dot gain from darker colors (reds,

blacks, etc.) so the final print may end up darker than

what you see on the monitor.


13/14

Outputting Films

You can print out each channel directly from Photoshop

or you can take this entire set of channel separations

into Corel, Illustrator or Freehand by saving it as a DCS

2.0 file.

Everyone has their favorite screen frequency and angles. I

like to use an angle of 25 degrees for ALL the channels.Again, trust me.. You can use a frequency of 55 lip for

manual printing and 65 lpi for automatic presses. SeeFigure 29.

Screen Making

For best results use a pure Photopolymer or Dual-Cure

emulsion applied with just one coat on each side and

correct exposure. Use properly tensioned screens.

Put the white underbase and highlight white on a 180-230(70-90 cm) mesh (the lower mesh is easier for manual

printing) and the top colors on a 280-355 (110-140 cm)mesh. If you have limited experience printing with

halftone dots, make sure to hold all the dots on the films.This may mean lowering your standard exposure time

when using the high mesh counts. Compare the films tothe exposed screen.

Printing

Print the top colors with all purpose inks and theunderbase as a high opacity. Flash after the underbase.

Print everything else wet-on-wet. Print the highlight whitelast with an all purpose mixing white (high opacity will

also work). The print sequence of the colors should belight to dark. Of course dominate colors might need to go

later in the sequence.

Your underbase print needs to be clean. It may not be asbright as you think. This is NOT athletic printing. Detail

and smoothness is the key. The highlight white will help

boost the white where needed.

Also, keep the top color prints clean. We are printing

halftone dots through high mesh counts.

Summary

If you work with a good piece of artwork, follow the

separation suggestions and print using the proper mesh


14/14

count and technique you should have a respectable print

the first time out of the box (see Figure 30). If the job is

critical and you have a lot of colors to match there may be

compromises. Obviously the more colors you can print

the better.

Good luck.

Note: allimages shown in this article are copyright ortrademark their respective owners andare show here for

illustration purposes. The author wouldlike to thankpeople who has sent shirt samples over the years of

outstanding workdone using the authors techniques orsoftware.

cores indexadas

Documents