Among the many new improvements in Acrobat 9 are a couple of not-so-obvious but powerful previewing and color conversion tools. These tools allow you to quickly and easily identify and evaluate color and other characteristics (such as resolution) of any color image in a PDF document. And then, if you want to, you can easily convert any color in your image to another color or color space of your choice.
STEP 1 Open and Duplicate a PDF
Open a PDF document containing text and at least one color image file and choose File>Save As to create a working copy of your original PDF. This will protect the integrity of your original PDF document. You could also simply make a copy of your PDF document through your operating system or Bridge interface. However, using Save As through Acrobat will simplify your PDF by removing any unused and unnecessary document components.
STEP 2 Launch Output Preview and View Colors
Choose Advanced>Print Production>Output Preview to launch the Output Preview dialog. When the dialog appears, you’ll notice a variety of settings you can choose from. First, let’s see what colors have been included in this document. Click on the Separations choice in the Preview area. In the Separations area you will see a list of all the colors assigned to this document when it was created. Here you’ll see there are process colors (CMYK) and a spot color, 576 C. Here the C designation indicates the Coated version of the spot color assigned form the Pantone list of solid spot colors. The inclusion of this spot color requires either that this spot color be separated and printed as a separate color or converted to CMYK for printing along with the other process colors.
STEP 3 Find Specific Colors
You can use the Separations portion of the Output Preview dialog to locate and view specific colors. Simply check the color to view it and uncheck to hide. If I wanted to view my spot color, I’d just check it. It would appear black because this is how it would print on a separated plate. The actual green spot color would be applied on press. If you have more than one spot color, each color will appear separately in the list and can be rendered either visible or invisible by checking its display checkbox.
STEP 4 View the Black Plate
Another very useful display capability is your ability to view just the black plate. To do this, simply uncheck all the plates except for black. All the text and objects containing black ink will be visible (not just those that appear black). You can also view any grayscale images or graphics in your PDF, such as the logos and bar code in this PDF. This black display is also useful for viewing the black ink contribution to color images that will be printing as CMYK. Here you can see how the black ink is concentrated in the silhouetted foreground portion of the cover image (on the right), as well as the shadow portions of the images on the back cover (on the left). You can also see the black ink contribution to the cover gradients.
STEP 5 View the Image Ink Values
You can also determine both the individual and the total ink values of any portion of any image or area in your PDF. First, make all of the color plates in the Output Preview dialog visible. Then, simply move your cursor around the text and images in your PDF to see the ink values appear in real time. In the example shown here, I placed the cursor over the silhouetted foreground vegetation in the cover image. Notice the CMYK values are displayed as C=95%, M=85%, Y=85%, K=85%. The added combination of these four inks, known and displayed here as Total Ink Coverage, is equal to 350%. This will confirm this area of the image will be printing as a high-density, rich black and will appear as a silhouette. You can determine the sample size of the measurement by clicking on the Sample Size menu and choosing Point Sample, 3 by 3 Average or 5 by 5 Average. (I set mine to 3 by 3 Average.)
STEP 6 View Excessive Total Ink Values
In addition to being able to view ink densities of specific locations in your PDF, you can also view all the areas that have ink densities that exceed a specific Total Ink Coverage. This is very useful for quickly determining which areas in your image will contain shadow detail and which will print without detail. To view the areas that will print without detail first, set the maximum value of Total Ink Coverage that can be printed and still show detail on the output device on which you will be printing your PDF. To do this check Total Area Coverage and enter your value in the text box. This value may be as low as 240 for some newspapers and presses and as high as 340 for a coated stock printed on a commercial sheetfed press. (We set Total Area Coverage to 300.) The areas in your PDF that exceed a Total Area Coverage of 300% will be highlighted in the color you choose from the color swatch to the left of the Total Area Coverage field value. (We used bright green.)
STEP 7 Previewing Overprints and Rich Blacks
You can also preview any objects in your PDF that will be overprinting and printing as rich blacks—which are areas that are assigned colors created with K plus another color to print with higher density. To view your overprints and rich blacks, select Color Warnings from within the Preview window. To view all objects that will be overprinting (printing on top of any colors that are beneath them), check Show Overprinting. All overprinting objects (such as the type in the Countryman Press logo in our example) will be highlighted in the Overprinting color (we used the default orange). Similarly, to display all of your rich black objects, check Rich Black. All rich black objects will be highlighted in the assigned color (we kept the default aqua). You can also specify a minimum ink value (we used 80%) above which an object will be considered a rich black. This ability to view rich blacks is useful for previewing those areas that will be printing as high-density areas with no detail.
STEP 8 Inspect Details of Color Images
In Acrobat 9, you can get information about the color, dimensions, and resolution of particular images or areas in your PDF by using the Object Inspector. To open the Object Inspector, choose it from the Preview window. Now, simply click on the object or image you’d like to get more information about. Details about the image appear in the large display panel located at the bottom of the Output Prevew dialog. In our example, you can see this is an RGB color space image (listed as Device RGB). You can also see this image has an effective linear resolution of 136 ppi.
Note: This tool is sophisticated enough to display a horizontal resolution that incorporates any changes to the resolution that result from scaling the image. For instance, the native Horizontal Resolution of this image was 100 ppi when it was placed in the layout. However, scaling it later to fit better increased the Horizontal Resolution to 136.04 ppi.
STEP 9 Show RGB Images
You also have the ability to locate and display all images and objects that have specific color characteristics. One common use of this capability is identifying RGB images and/or objects in a PDF destined for commercial printing—where you’d want to have all text, images, and objects specified as either CMYK or spot colors. To locate all RGB images and objects, choose RGB from the Show drop-down menu and Separations from the Preview window. Only the three RGB items—two images and the bar code—will appear in the PDF. To extract these items individually, select the TouchUp Object tool (Tools>Advanced Editing>TouchUp Object tool). Then Control-click (PC:Right-click) on the image and choose Edit Objects from the contextual menu. Next, choose and color converted or be converted as part of a document-wide conversion (See Step 12 below). Make note of the wide range of objects you can search for and display with this simple menu including solid color, text, and line art.
STEP 10 Simulate Print Appearance – Coated
Of all the previewing capabilities that Acrobat 9 supports, one of the most useful in terms of predicting significant changes that may occur during printing is your ability to simulate the effects of a printing environment, and especially the impact of choosing a specific paper stock. For example, let’s preview on screen how this PDF will print on coated stock with a standard commercial printing press in North America. From the Simulation Profile pop-up menu at the top of the Output Preview dialog, select U.S. Sheetfed Coated v2. This selects a color profile that contains characteristics that exist for printing on coated paper stock on a typical sheetfed commercial printing press. To finish up the simulation of the print setup, check Simulate Paper Color and Simulate Overprinting just below.This setup will now send display adjustment instructions that will attempt to simulate the appearance of the print onscreen to your monitor. With this setup, you’ll likely see a slight darkening and reduction of contrast onscreen. Toggle the Simulate Paper check box off and on to compare the difference.
STEP 11 Simulate Print Appearance – Uncoated
Now let’s change the print simulation conditions to uncoated stock. From the Simulation Profile menu select U.S. Sheetfed Uncoated v2. Be sure the Simulate Paper Color is checked. Now Acrobat and your monitor will simulate how this document will print on uncoated stock. Here you will likely see a significant difference in the display of the image. Any bright or highly saturated colors, such as the sunrise colors in the cover photo, may be significantly desaturated (bright saturated greens, oranges and purples will show the greatest changes), and the overall contrast will be reduced. As you can see, paper stock has a significant impact on the appearance of your print—especially your brightly colored and saturated images. If you’re viewing your PDF on a newer, calibrated monitor, your results will be more accurate than if your monitor is older and/or uncalibrated. Fully color-managed monitors can display surprisingly accurate simulated previews.
STEP 12 Convert Images Color Spaces
In addition to previewing colors and objects, you can also covert the color of images using Acrobat 9. One way to accomplish this is by using the Convert Colors command. Choose Advanced>Print Production>Convert Colors to summon the Convert Color dialog. You can use this dialog to accomplish a wide variety of color conversions. As an example, let’s see how we would convert all of our RGB images and objects to CMYK for commercial printing. Under Matching Criteria, set Object Type to Any Object and Color type to Any RGB. Now under Conversion Attributes, set Convert Command to Convert to Profile, Conversion Profile to to type of paper you’ll be using (we set ours to U.S. Sheetfed Coated v2), and Rendering Intent to Use Document Intent. To make sure you RGB blacks will be converted to good, high-density CMYK blacks, check Preserve Black under Convert Options in bottom-left corner of the dialog. Now Click OK. Note this process cannot be undone, so make sure you want to perform this conversion. To convince yourself that the conversion has indeed taken place, return to the Output Preview dialog box and choose Show>RGB. No RGB color space items will be displayed.
STEP 13 Convert grayscale to Rich Black
One very nifty printing use of this Convert Color tool is the ability to convert grayscale areas that are originally created with just black ink (K) into CMYK (rich blacks) so that they will print with more density. Typically large areas covered with just 100% K will not print with high density because the K ink is translucent. Making these areas rich blacks by added cyan, magenta, and yellow will dramatically enhance their density when they print. You won’t see a big change onscreen, but creating a rich black will make a big difference when you print. To convert gray scale areas to rich black, simply check Promote Gray to CMYK, also under Convert Options.
In these examples we have used the Ouput Preview and Convert Color Tools for print output. However, these tools are just as useful for other types of output, such as documents intended to be viewed on monitors or screens.