Not a day goes by that I don’t get a call about how to use Adobe Photoshop. Actually, the phone call starts with something like “I have Corel Photopaint, can’t I use it?” After my usual, NO, with a smile, I say that “the world” uses Photoshop so it is the one to learn. Then the question goes something like “I have Corel Draw. Why can’t I just use it?” I then tell them that Corel and Photoshop are two different types of programs and each have their strengths.
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1. Photoshop is a pixel based program. |
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2. Photo-realistic images are Photoshop’s strong suit. |
Why Photoshop
First, let’s clear the air about Photoshop. It is a pixel based program that creates an image by making it consist of millions of pixels (figure 1). Unlike Corel draw or Adobe Illustrator, which are vector based programs that excel in spot color images and images with hard edges, Photoshop LOVES images that are more photorealistic (figure 2). In fact, it is THE program that “the world” uses to color separate process color, simulated process color and index color. If you don’t know these terms, checkout the article titled Simulated Process, Index or What? on this site.
In this short article, it will be very hard to tell you everything you ever wanted to know about Photoshop. My goal here is to get you up to speed and at least out of the box with the program. Like other programs, Photoshop can be OVERWHELMING and very intimidating. Just keep in mind the age old 80/20 rule. As it applies to Photoshop, you will use 20% of the program 80% of the time. It is actually more like the 90/10 rule.
Where to get Photoshop
Photoshop is the flagship product of Adobe Systems at http://www.adobe.com. It retails for around $650 and as of this writing, version 7.0 just shipped. It is always nice to have the lastest and greatest version, but frankly, you can do everything I show here (using version 6.0) with version 5.0 or higher. If you are a student, teach, or work for a school, you may be eligible for an “educator version” from places like http://www.softwareshowcase.com.
Photoshop File Types and Resolutions
Photoshop will let you “Open” a wide variety of files including, TIF, JPG, GIF, EPS, PSD, AI and others. If you open a file that is vector based like one from Adobe Illustrator, Photoshop will convert the file from mathematical vectors to small pixels. This is called Rasterizing a file.
The important point here is to keep the file resolution high enough for the image to remain sharp. It is generally taught that a file needs to be at 300 dpi at the final size in order for it to remain crisp. In T-Shirt printing, you can get away with file resolutions of 200 to 250 dpi at the final size. The default setting for opening vector files in Photoshop is 72 dpi. Figure 3 shows a magnified view of a file that is 300 dpi and one that is 72 dpi. Obviously, the 72 dpi file will be softer.
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4. Keep your Palettes organized for optimal work area. |
Photoshop Basics
Let’s start with some basics. I will assume you have installed Photoshop and followed the steps in their excellent manual. The program also comes with tutorials and my website has many excellent articles on specific uses of Photoshop.
You will notice Photoshop has a variety of items on the right of the screen that have divider tabs on top. These are called Palettes and you can “hide” them or “show” them. If you go to the Window pull down menu you will see the Palette list. You don’t need all of the Palettes open for basic work. In fact, the one’s I like “show” are: Layers, Channels, History, Actions, Info. The rest you can close by clicking in the upper right X in each Palette. You can group Palettes together by “docking” them. You can also click and drag on a Palette name and “undock” it. The idea here is to keep the working area clear of clutter. Keep the Palettes docked and to the right of the page (figure 4).
The top Menu bar has lots of “Pull Down” menus and there is a typical “Toolbar” on the right.
Let’s “Open” a file. Go to the File menu and then to Open. Search your hard disk for a test file, or if needed, find the Samples folder that comes with Photoshop. Open or load a file. If the file is an EPS or AI (Adobe Illustrator) file, you will be asked what resolution you want to open the file. Remember, keep the file around 200 dpi the final size.
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5. Check your File Mode. |
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6. Check your Print Size. |
Check File Mode
This is where beginners go wrong. You open a file and don’t bother to learn about the file. At this point, the file should be RGB and not CMYK. Yes, Photoshop will do process color separations called CMYK, but for file manipulation and adjustment you should work in RGB mode. To see the Mode of the file go to Image/Mode. If CMYK is checked, click on RGB. The file should also be 8-bit. See figure 5.
Check File Size and Resolution
Next, you MUST know the actual resolution and size of the image. Otherwise you could be working on a very small file and not know it. Go to Image/Image Size. The resolution should be 200 dpi or higher in pixels per Inch. If it say pixels per CM, change this to inches. The physical size should be the final print size (figure 6).
What if the file size and resolution is not correct? This is where it gets hard. Let’s say your file is only 5″ in width and 72 dpi, AND you want it to print 10″ wide. In the Image Size window, under Document Size, if you uncheck Resample Image, you will see that all three windows are now “locked” together. If you change the file size to 10″ notice that the resolution changed to 36! 36 dpi is a LONG WAY from 200.
The problem you have is the file is very low resolution. Your only real choice is to check Resample Image and change the width to 10″ and the resolution to 200. Photoshop “upsamples” the image. But, it has to guess at where to place all the extra pixels and what color to make the pixels. Images can get softer when upsampled. If this is the only thing you have to work with then so be it. If you can get a higher resolution file from the client, by all means to it.
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7. The Gamma Wizard is your friend. |
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8. Use the Tone Curve to avoid muddy prints. |
How Does The File Look?
Next, let’s look at the file. How does it look? How do you know that what you are seeing on your monitor is actually what the file really looked like on your clients monitor? An easy way to get close is to do a Monitor Calibration using a program supplied with Photoshop called Adobe Gamma. You can access it on Mac and PC through Control Panel. Adobe Gamma let’s you adjust your monitor to display the image more accurately. It has a step- by-step Wizard that guides you through the changes (figure 7).
Let’s assume the monitor is calibrated. How does the file look? Typically, there are two basic adjustments you do to a file. Make it lighter, and make it sharper.
Using the Tone Curve
In screen printing, images tend to get muddy when printed. If you have a file with lots of detail in the shadow areas, this will probably be lost when screen printed. Now is the time to adjust the “density levels” of the file. Go to the Image pull down menu and then to Adjust/Curves. The Tone Curve is a very powerful tool. It lets you adjust specific tonal areas from the lightest “highlights” to the darkest “shadows.” By placing your cursor in the middle of the curve “midtones” and dragging the mouse up or down, you can lighten and darken the medium or midtones in an image (figure 8). By clicking on the very top corner and dragging the mouse in, you can make the highlights lighter. Play around with the Tone Curve and see what happens.
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9. Preview Sharpened images and compare to the original. |
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10. “Marching Ants” show selected areas. |
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11. Layers are an invaluable element of Photshop. |
Sharpening Images
Typcially, an image can be made sharper. Even if the file came from an agency or large licensed job, don’t assume that their artist knew your needs. Images that are screen printed, not only get darker but they get softer. You MUST make them as sharp as possible.
Go to Filter/Sharpen/Unsharp Masking. Don’t let the “unsharp” term fool you. This term came from the old process camera days and basically means is only sharpens areas of high contrast. It sharpens but keeps it less apparent that you have sharpened the image.
Set the Amount slider to 200, the Radius to 1 pixel and the Threshold to 8. How does the image look? To compare the original to the sharpened version, uncheck the Preview check box. Click it on and off and compare the results (figure 9). If you can’t see much difference, move the Amount slider higher. Go all the way to 500% if you need. Don’t get the image too grainy. Remember, Photoshop displays images a little sharper than they really are which means you can go a little too far and be OK.
Working on Select Areas
If you want to apply a Tone Curve adjustment or apply Unsharp Masking to select areas, you can choose these areas with one of the Selection Tools on the Toolbar. Click on the tool that looks like a Lasso – yes it is called the Lasso Tool. Now, simply hold the mouse button down and draw around an area you want to change. When you release the mouse, you will have little moving dashes, commonly called “marching ants” (figure 10). You have just Selected an area. Now, anything you do ONLY happens to this area. Think of this like “selecting” an object in Corel or Illustrator. To remove the marching ants, go to the Select pull down menu and to De-Select. If you want to select square or round areas, the top left tool is called the Marquee Tool. It does the same thing as the Lasso tool only it does it to square or round areas.
Channels and Layers
If you setup the working space the way I showed, you should have the Channels Palette and Layers Palette open. People always get these confused. Here are the rules. The Channels Palette is used to create color separations that can be output. Channels print. The Layers Palette is used to create or build the image. You use the Layers Palette to put various components together including adding Type to an image. Layers don’t print. Simple.
You will notice that your Channels Palette shows four channels. RGB, R, G and B. Your test file probably shows only one Layer called Background.
Figure 11 shows a design that is made up of lots of layers. Images on a layer can be moved around, effects added to them, Tone Curve adjustments made, etc. When you click on a Layer, you make it “active” and available for changes. You can also select areas for adjustment using the Marquee or Lasso tools.
Other Adjustments and Effects
In this short article, there isn’t space to cover all the tools in Photoshop. Here are a few:
Dodge/Burn Tool
If you want to lighten or darken select areas of an image, select the “lollipop” looking tool. This tool with lighten areas of an image. Before you use many of these tools, you need to know what “size” brush is applied to the tool. Thin of the Brushes like this. If you want to draw a small line on a wall, you need a very small brush. If you want to paint a large two foot path of paint, you would need a very large brush (or have to do LOTS of strokes with a small brush). Many of the “painting, drawing and adjustment” tools in the Toolbar can have a Brush tips assigned to them. In Photoshop 6.0, the Brushes Palette is available from the top menu. In earlier version, you have to “Show” the Brushes Palette.
To lighten a large area of an image, choose a brush of 200 pixels. Hold down the mouse button and move the mouse around over the image. To darken an image, hold down the Alt key on the PC or Option key on a MAC. This changes the tool to the “burn” tool. Do the same movements and watch the area get darker.
Airbrush Tool
If you need to paint areas of an image, you can “spray” color out of the airbrush. The Toolbar has two color squares near the bottom. The color “in front” is called the Foreground color. It is a color you paint with any of the painting tools. The color behind is called the Background color and is the color that you “replace” in an image when you erase or delete areas.
If you click on the Foreground color, you get a window called the Color Picker. Simply pick the color you want to paint and say OK. You will notice that the Foreground color is now the picked color.
To use the Airbrush tool, pick a color, choose a brush tip and hold the mouse button down and start to move the Airbrush around. Fun!!
Filters
A filter is actually an effect. The name is confusing. There are hundreds of filters in Photoshop. You can apply most filters to entire images or just to selected areas. Try this. Use the Lasso tool to select an area of an image. Go to Filter/Adjust/Twirl. Set the Angle to 100 and see what happens. Neat!
Color Separations
This article is NOT about doing color separations. That is the next step.
Summary
So, what have we learned. We know that if we use a client’s file or scan directly into Photoshop, the image should be 200 dpi or higher at the final size. Upsampling is not always a great solution. If the image is too dark or light, use the Tone Curve or the Dodge/Burn tool to fix the entire image or select areas. If the image is soft, use Unsharp Masking to fix it. You can build an image using Layers.
La Perse Journal - Transcript 