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Hue Shifting and Colorizing

This section covers commands designed to change the distribution of colors in an image. You can rotate the hues around the color spectrum, change the saturation of colors, adjust highlights and shadows, and even tint an image. Four of these commands — Hue/Saturation, Selective Color, and the new Photo Filter and Match Color commands — are applicable exclusively to color images. The other two — Replace Color and Variations — can be applied to grayscale images but are far better suited to color images. If you’re more interested in editing grayscale photographs, refer to the Levels, Curves, and new Shadow/Highlight commands, all of which I discuss toward the end of the chapter. For those of you who want to correct colors, however, read on.

Using the Hue/Saturation command

The Hue/Saturation command provides two functions. First, it enables you to adjust colors in an image according to their hues and saturation levels. You can apply the changes to specific ranges of colors or modify all colors equally across the spectrum. And second, the command lets you colorize images by applying new hue and saturation values while retaining the core brightness information from the original image.

This command is perfect for colorizing grayscale images. I know, I know, Woody Allen wouldn’t approve, but with some effort, you can make Ted Turner green with envy. Just scan him and change the Hue value to 140 degrees.

When you choose Image Adjustments Hue/Saturation or press Ctrl+U (z -U on the Mac), Photoshop displays the Hue/Saturation dialog box, shown in Figure 17-10. Before I explain how to use this dialog box to produce specific effects, let me briefly introduce the options, starting with the three option boxes:

Figure 17-10: The Hue/Saturation dialog box as it appears when editing all colors in a layer (top) or just a specific range of colors (bottom).

Hue: HSB” section of Chapter 4. You can adjust the Hue value from –180 to +180 degrees. As you do, Photoshop rotates the colors around the Hue wheel. Consider the example of flesh tones. A Hue value of +30 moves the flesh into the orange range; a value of +100 makes it green. Going in the other direction, a Hue of –30 makes the flesh red and –100 makes it purple.

Saturation: The Saturation value changes the intensity of the colors. Normally, the Saturation value varies from –100 for gray to +100 for incredibly vivid hues. The only exception occurs when the Colorize check box is active, in which case saturation becomes an absolute value, measured from 0 for gray to 100 for maximum saturation.

Lightness: You can darken or lighten an image by varying the Lightness value from –100 to +100.

Edit: The Edit pop-up menu controls which colors in the active selection or layer are affected by the Hue/Saturation command. If you select the Master option, as by default, Hue/Saturation adjusts all colors equally. If you prefer to adjust some colors in the layer differently than others, choose one of the other Edit options or press the keyboard equivalent — Ctrl+1 (Win) or z -1 (Mac) for Reds, Ctrl+2 (Win) or z -2 (Mac) for Yellows, and so on.

Each Edit option isolates a predefined range of colors in the image. For example, the Reds option selects the range measured from 345 to 15 degrees on the Hue wheel. Naturally, if you were to modify just the red pixels and left all nonred pixels unchanged, you’d end up with some jagged transitions in your image. So Photoshop softens the edges with 30 degrees of fuzziness at either end of the red spectrum (the same kind of fuzziness described in the "Using the Color Range command” section of Chapter 9).

Color ramps: You can track changes made to colors in the Hue/Saturation dialog box in two ways. One way is to select the Preview check box and keep an eye on the changes in the image window. The second way is to observe the color ramps at the bottom of the dialog box. The first ramp shows the 360- degree color spectrum; the second ramp shows what the color ramp looks like after your edits.

Color range controls: You can use the color ramps also to broaden or narrow the range of colors affected by Hue/Saturation. When you choose any option other than Master from the Edit pop-up menu, a collection of color range controls appears between the color ramps. The range bar identifies the selected colors and also permits you to edit them.

Figure 17-11 shows the color range controls up close and personal. Here’s how they work:

Figure 17-11: After defining a basic range using the Edit pop-up menu, use the color range controls to modify the range or the fuzziness.

Drag the central range bar to move the entire color range.

Drag one of the two lighter-colored fuzziness bars to broaden or narrow the color range without affecting the fuzziness.

Drag the range control (labeled in Figure 17-11) to change the range while leaving the fuzziness points fixed in place. The result is that you expand the range and condense the fuzziness, or vice versa.

Drag the triangular fuzziness control to lengthen or contract the fuzziness independently of the color range.

Eyedroppers: To lift a color range from the image window, click inside the image window with the eyedropper cursor. (The cursor automatically changes to an eyedropper when you move it outside the Hue/Saturation dialog box.) Photoshop centers the range on the exact color you clicked.

Load/Save: As in all the best color correction dialog boxes, you can load and save settings to disk in case you want to reapply the options to other images. These options are especially useful if you find a magic combination of color correction settings that accounts for most of the color mistakes produced by your scanner.

Colorize: Select this check box to apply a single hue and a single saturation level to the entire selection or layer, regardless of how it was previously colored. All brightness levels remain intact, although you can adjust them incrementally using the Lightness slider bar (a practice that I strongly advise against, as I mentioned earlier).

Color ranges are not permitted when colorizing. The moment you select the Colorize check box, Photoshop dims the Edit pop-up menu and sets it to Master.

Restore: You can restore the options in the Hue/Saturation, Levels, and Curves dialog boxes to their original settings by Alt-clicking (Win) or Option- clicking (Mac) on the Reset button (the Cancel button changes to Reset when you press Alt or Option). Or you can simply press Option-Escape on the Mac.

Figure 17-12: When you move the eyedropper outside a color adjustment dialog box and into the image window, the Info palette lists the color values of the pixel beneath the cursor before and after the adjustment.

Remember, you don’t have to settle for just one color readout. Shift-click in the image window to add up to four fixed color samples, just like those created with the color sampler tool, described in Chapter 4. To move a color sample after you’ve set it in place, Shift-drag it.

In the case of the Hue/Saturation dialog box, you can set color sample points only when the Edit pop-up menu is set to Master. After you set the samples, select some other options from the pop-up menu to modify a specific range.

Adjusting hue and saturation

All right, now that you know how the copious Hue/Saturation options work, it’s time to give them a whirl. Go ahead and turn to Color Plate 17-3, and maybe keep a finger wedged in there as you read on here; we’ll be making frequent references to that color plate. The subjects in our sample photo are yours truly (right) and my Little Puppet Friend (left), whose encyclopedic knowledge of digital imaging and dashing good looks have enlivened several of my video training series.

Changing hues

When the Colorize check box is inactive, the Hue slider bar shifts colors in an image around the color wheel. It’s as if the pixels were playing a colorful game of musical chairs, except none of the chairs disappear. If you select the Master option and enter a value of +120 degrees, for example, all pixels stand up, march one third of the way around the color wheel, and sit down, assuming the colors of their new chairs. A pixel that was red becomes green, a pixel that was green becomes blue, and so on. Color Plate 17-3 shows the results of my +120 degree Hue shift in full color.

Figure 17-13: Comparing the before (top row) and after (bottom row) of a +120-degree Hue shift, you’ll see that the red and green channels are identical, as are the green and blue channels and the blue and red channels.

Changing saturation levels

When I was a little kid, I loved watching my grandmother’s television because she kept the Color knob cranked at all times. The images leapt off the screen, like they were radioactive or something. Way cool. Well, the Saturation option works just like that Color knob. I don’t recommend that you follow my grandmother’s example and send the saturation through the roof for every image, but the option can prove helpful for enhancing or downplaying the colors in an image. If the image looks washed out, try adding saturation; if colors leap off the screen so that everybody in the image looks like they’re wearing neon makeup, subtract saturation.

Color Plate 17-3 shows a Saturation value of 40 percent.

Figure 17-14: The difference between a Saturation increase of 20 percent (top row) and 60 percent (bottom row) on a channel-by-channel basis.

Now that we have some idea of how the Hue and Saturation parameters work, let’s try applying them to the practical goal of trying to give my Little Puppet Friend a slightly rosier glow. The first thing you need to know is that if you adjust the Hues of an image with any Edit option other than Master, the musical chairs metaphor mentioned earlier breaks down a little. All pixels that correspond to the selected color range move while pixels outside the color range remain seated. The pixels that move must sit on the non-moving pixels’ laps, meaning that you sacrifice colors in the image.

For example, in the middle-right image of Color Plate 17-3, I switched the Edit menu from Master to Cyans and then performed my Hue shift and Saturation increase, and then repeated this with Edit set to Blues. All pixels that fell in the cyan and blue ranges shifted to new hues; all non-cyan and non-blue pixels remained unchanged. Although the effect is subtle, my Little Puppet Friend does appear a little rosier than in the upper-left image. Then again, so do the blues in my shirt.

The Saturation option is especially useful for toning down images captured with lowend scanners and digital cameras, which have a tendency to exaggerate certain colors. Back in the early years, I used to work with an Epson scanner that would digitize flesh tones in varieties of vivid oranges and red. For the life of me, I couldn’t figure out how to peel the colors off the ceiling until I tried the Saturation option in the Hue/Saturation dialog box. By selecting the Red color range and dragging the slider down to about –50, I was usually able to eliminate the problem, and so can you.

Correcting out-of-gamut colors

Chapter 4, many colors in the RGB spectrum are considered out-of-gamut, meaning that they fall outside the smaller CMYK color space. Photoshop provides a means for recognizing such colors while remaining inside the RGB color space. Choose View Gamut Warning or press Ctrl+Shift+Y(z -Shift-Y on the Mac) to color all out-of-gamut colors with gray (or some other color that you specify using the Preferences command). The pixels don’t actually change to gray; they just appear gray on-screen as long as the command is active. To turn View Gamut Warning off, choose the command again.

How do you eliminate such problem colors? Well, you have three options:

Let Photoshop take care of the problem automatically when you convert the image by choosing Image Mode CMYK Color. This tactic is risky because Photoshop simply cuts off colors outside the gamut and converts them to their nearest CMYK equivalents. What was once an abundant range of differently saturated hues becomes abruptly flattened, like some kind of cruel buzz haircut. Choosing View Proof Setup Working CMYK gives you an idea of how dramatic the buzz can be while permitting you to continue working in the RGB color space. Sometimes the effect is hardly noticeable, in which case no additional attention may be warranted. Other times, the results are disastrous.

Another method is to scrub away with the sponge tool. In Chapter 5, I discussed how much I dislike this alternative, and despite the passage of a dozen chapters, I haven’t changed my mind. Although it theoretically offers selective control — you just scrub at areas that need attention until the gray pixels created by the Gamut Warning command disappear — the process leaves too much to chance and frequently does more damage than simply choosing Image Mode CMYK Color.

The third and best solution involves the Saturation option in the Hue/Saturation dialog box.

No doubt that last item comes as a huge surprise, given that I decided to broach the out-of-gamut topic in the middle of examining the Saturation option. But try to scoop your jaw up off the floor long enough to peruse the following steps, which outline the proper procedure for bringing out-of-gamut colors back into the CMYK color space.

STEPS: Eliminating Out-of-Gamut Colors

Create a duplicate of your image to serve as a CMYK preview. Choose Image Duplicate to create a copy of your image. Then choose View Proof Setup Working CMYK. Alternatively, you can press Ctrl+Y (Win) or z -Y (Mac) to invoke color proofing. By default, Photoshop selects the working CMYK space. This image represents what Photoshop does with your image if you don’t make any corrections. It’s good to have around for comparison.

Return to your original image and choose Select Color Range. Then select the Out Of Gamut option from the Select pop-up menu and press Enter (Win) or Return (Mac). You have now selected all nonconformist anti-gamut pixels throughout your image. These radicals must be expunged.

To monitor your progress, choose View Gamut Warning to display the gray pixels. Oh, and don’t forget to press Ctrl+H (z -H on the Mac) to get rid of those pesky ants.

Press Ctrl+U (Win) or z -U (Mac) to display the Hue/Saturation dialog box.

Lower the saturation of individual color ranges. Don’t change any settings while Master is selected; it’s not exacting enough. Rather, experiment with specifying your own color ranges and lowering the Saturation value. Every time you see one of the pixels change from gray to color, it means that another happy pixel has joined the CMYK collective. You may want to state, in your best monotone, “Resistance is futile,” if only to make your work more entertaining.

When only a few hundred sporadic gray spots remain on screen, click the OK button to return to the image window. Bellow imperiously, “You may think you have won, you little gray pixels, but I have a secret weapon!” Then choose Image Mode CMYK Color and watch as Photoshop forcibly thrusts them into the gamut.

Mind you, the differences between your duplicate image and the one you manually turned away from the evils of RGB excess are subtle, but they may prove enough to produce a better looking image with a more dynamic range of colors.

Avoiding gamut-correction edges

The one problem with the preceding steps is that the Color Range command selects only out-of-gamut pixels without even partially selecting their neighbors. As a result, you desaturate out-of-gamut colors while leaving similar colors fully saturated, an effect that may result in jagged and unnatural edges.

This solution isn’t perfect — ideally, the Color Range option box wouldn’t dim the Fuzziness slider when you choose Out Of Gamut — but it does succeed in partially selecting a few neighboring pixels without sacrificing too many of the out-of-gamut bunch.

Colorizing images

When you select the Colorize check box in the Hue/Saturation dialog box, the options perform differently. Returning to that wonderful musical chairs analogy, the pixels no longer walk around a circle of chairs; instead, they all get up and go sit in the same chair. Every pixel in the selection receives the same hue and the same level of saturation. Only the brightness values remain intact to ensure that the image remains recognizable. The bottom-left example of Color Plate 17-3 shows the results of shifting the hues in an image using the Colorize option.

In most cases, you’ll only want to colorize grayscale images or bad color scans. After all, colorizing ruins the original color composition of an image. For the best results, you’ll want to set the Saturation values to somewhere in the neighborhood of 25 to 75.

The final image in Color Plate 17-3 shows my last valiant attempt to give my Little Puppet Friend (otherwise known as “LPF”) a rosy glow. This time I started by making a selection using the Color Range command. Then I applied Hue/Saturation with Colorize turned on, and with the same settings as in the bottom-left image. It’s a stronger effect than I got with just shifting the Hue in the cyan and blue ranges, as in the middle-right image. It also played havoc with the blues in my shirt, but I could have tidied up my Color Range selection in the quick mask mode to isolate LPF’s skin tones. (Or perhaps that should be “fleece tones.”)

Shifting selected colors

The Replace Color command allows you to select an area of related colors and adjust the hue and saturation of that area. When you select Image AdjustmentsReplace Color, you get a dialog box much like the Color Range dialog box. The Replace Color dialog box, shown in Figure 17-15, varies in only a few respects. It’s missing the Select and Selection Preview pop-up menus, and it offers three slider bars, taken right out of the Hue/Saturation dialog box.

Figure 17-15: The Replace Color dialog box works like the Color Range dialog box described back in Chapter 9, with a few Hue/Saturation options thrown in.

In fact, this dialog box works the same as selecting a portion of an image using Select Color Range and editing it with the Hue/Saturation command, as I did previously. You don’t have as many options to work with, but the outcome is the same. The Replace Color and Color Range dialog boxes even share the same default settings. If you change the Fuzziness value in one, the default Fuzziness value of the other changes as well. It’s as if they’re identical twins or something.

So why does the Replace Color command even exist? Because it allows you to change the selection outline and apply different colors without affecting the image. Just select the Preview check box to see the results of your changes on screen, and you’re in business.

Shifting predefined colors

The Selective Color command permits you to adjust the colors in CMYK images. Although you can use Selective Color also when working on RGB or Lab images, it makes more sense in the CMYK color space because it permits you to adjust the levels of cyan, magenta, yellow, and black inks.

Choosing Image Adjustments Selective Color brings up the dialog box shown in Figure 17-16. To use the dialog box, choose the predefined color that you want to edit from the Colors pop-up menu and then adjust the four process-color slider bars to change the predefined color. When you select the Relative radio button, you add or subtract color, much as if you were moving the color around the musical chairs using the Hue slider bar. When you select Absolute, you change the predefined color to the exact value entered in the Cyan, Magenta, Yellow, and Black option boxes. The Absolute option is therefore very much like the Colorize check box in the Hue/Saturation dialog box.

Figure 17-16: Select a predefined color from the Colors pop-up menu and adjust the slider bars to change that color.

If you examine the Selective Color dialog box closely, you’ll notice that it is very much like the Hue/Saturation dialog box. You have access to predefined colors in the form of a pop-up menu instead of radio buttons, and you can adjust slider bars to alter the color. The two key differences are that the pop-up menu lets you adjust whites, medium grays (Neutrals), and blacks — options missing from Hue/Saturation — and that the slider bars are always measured in the CMYK color space.

Filtering colors

Since the dawn of color film, photographers have used different filters and balanced film stocks to correct the color balance in their photos. Different types of light sources produce a variety of color temperatures: Natural daylight generally takes on a bluish cast, or a higher color temperature, whereas artificial light often produces more shades of reds and yellows, or a lower color temperature. When not shooting on film that has been prebalanced to account for these casts, photographers will often place a color filter over the lens to compensate — adding blue to an indoor scene will counteract the yellows, for instance. It’s similar to how folks who work in video need to set the white balance on their cameras before they shoot.

Filter: The Filter pop-up menu includes four specific filter options followed by a list of colors you can use to fix various color casts on your image. The first two options, Warming Filter (85) and Warming Filter (81), simulate filters that a photographer would use when the color temperature is too cool, or bluish. Warming Filter (85) produces an orange color cast, and Warming Filter (81) adds more of a tan tint to your image. Conversely, Cooling Filter (80) and Cooling Filter (82) add to your image a dark and rich cast of blue or a light cast of blue, respectively, to account for the yellows of artificial light. The rest of the options in the pop-up menu are different color presets that let you achieve photographic effects similar to those provided by some real-life filters.

Color: You can also specify any color and use it as though it were a filter. This is a great way to compensate for an unusual color cast, such as a color light source in a scene that you’d like to neutralize. Click the color swatch to open the Color Picker and select a color. Alternatively, once the Color Picker is open, you can click anywhere in your image to choose a particular color.

Density: The Density slider adjusts the amount of color correction that the Photo Filter command will apply. You can also manually enter a value in the option box above the slider. Remember, you can always adjust the amount of correction after you click OK by choosing Edit Fade Photo Filter and changing the Opacity value.

Preserve Luminosity: Select this check box to ensure that the brightness values will not be darkened by your color adjustments.

Using the Variations command

The Variations command is Photoshop’s most essential color correction function and its funkiest.

On one hand, you can adjust hues and luminosity levels based on the brightness values of the pixels, something Hue/Saturation cannot do. You can also see what you’re doing by clicking on little thumbnail previews (see Figure 17-18), which takes much of the guesswork out of the correction process.

Figure 17-18: Click the thumbnails to shift the colors in an image; adjust the slider bar in the upper-right corner to change the sensitivity of the thumbnails; and use the radio buttons to determine which part of an image is selected.

On the other hand, the Variations dialog box takes over your screen and prevents you from previewing corrections in the image window. Furthermore, you can’t see the area outside a selection, which proves disconcerting when making relative color adjustments.

The Variations command is therefore best suited to correcting an image in its entirety. Here’s how it works: To infuse color into the image, click one of the thumb- nails in the central portion of the dialog box. The thumbnail labeled More Cyan, for example, shifts the colors toward cyan. The thumbnail even shows how the additional cyan will look when added to the image.

Notice that each thumbnail is positioned directly opposite its complementary color, with the Current Pick between them. More Cyan is across from More Red, More Blue is across from More Yellow, and so on. In fact, clicking on a thumbnail shifts colors not only toward the named color but also away from the opposite color. For example, if you click More Cyan and then click its opposite, More Red, you arrive at the original image.

To control the amount of color shifting that occurs when you click a thumbnail, move the slider triangle in the upper-right corner of the dialog box. Fine produces minute changes; Coarse creates massive changes. Just to give you an idea of the difference between the two, you have to click a thumbnail about 40 times when the slider is set to Fine to equal one click when it’s set to Coarse.

The radio buttons at the top control which colors in the image are affected. Select Shadows to change the darkest colors, Highlights to change the lightest colors, and Midtones to change everything in between.

The Saturation radio button lets you increase or decrease the saturation of colors in an image. Only one thumbnail appears on each side of the Current Pick image: One that decreases the saturation and another that increases it. The Variations command modifies saturation differently than Hue/Saturation. Hue/Saturation pushes the saturation of a color as far as it will go, but Variations attempts to modify the saturation without changing overall brightness values. As a result, an image saturated with Hue/Saturation looks lighter than one saturated with Variations.

As you click the options — particularly when modifying saturation — you may notice that weird colors spring up in the thumbnails. These brightly colored pixels are gamut warnings, highlighting colors that exceed the boundaries of the current color space. For example, if you’re working in the RGB mode, these colors extend beyond the RGB gamut. Although the colors won’t actually appear inverted as they do in the dialog box, it’s not a good idea to exceed the color space because it results in areas of flat color, just as when you convert between the RGB and CMYK spaces. To view the thumbnails without the weirdly colored pixels, turn off the Show Clipping check box. (Incidentally, this use of the word clipping has nothing to do with paths.)

Using the Match Color command

There are a bunch of scenarios in which you might want to resolve the color cast of one image to match another. Say, for instance, that you’re presenting a series of outdoor photos you took over the course of one day. Every time the clouds passed over the sun, the rich colors faded and the world of your image became a little gray-ish. With but one click in the dialog box, Match Color does a pretty impressive job of eliminating these disparities. Or, for instance, say you want to combine two photos of people, shot under different circumstances, into one image. An inconsistency in the color cast of the skin tones can be a dead giveaway on an otherwise expert composite. Although there are ways to fix problems like these manually, Photoshop CS has made it a whole lot faster and simpler with the Match Color command.

Begin by opening both the image you want to adjust and the image whose color you want to match. If you want Match Color to base its analysis on a particular part of the image, such as skin tones, select the colors you want to isolate in both the source and destination images. Make sure the destination image is in the active image window and choose Image Adjustments Match Color to display the dialog box shown in Figure 17-19.

Figure 17-19: The Match Color command in Photoshop CS lets you adjust the color cast of one image to match another.

The following list explains the options available to you in the Match Color dialog box:

Target: The Target is automatically and unalterably set as whatever image was active when you chose the command. If your destination image contains a selection, the Ignore Selection when Applying Adjustment check box is available. If you don’t select this check box, the effect will apply to only the selected area in your image, which is rarely the desired result. If you’ve made a selection in your destination image, you’ll most likely want to click this check box. Doing so applies the altered colors to your entire destination image.

Image Options: The Image Options let you make adjustments to the lightness, saturation, and strength of the Match Color command. The Luminance slider defaults to a value of 100 and lets you increase or decrease the brightness of your destination image. Color Intensity works much like the Saturation slider in the Hue/Saturation command. The Fade slider saves you the step of applying Match Color and then choosing Edit Fade Match Color. Increase this value to gradually bring in color elements from your unaltered destination image. A value of 100 will exactly match your pre-Match Color image.

Image Statistics: These options let you specify a source image and determine how it is interpreted. The source can be any other open image, or even a layer within the destination image itself. The latter is particularly useful if you’re trying to composite, say, a person from another photo on a separate layer into your destination image. If your source image contains a selection, click the Use Selection in Source to Calculate Colors check box to only analyze the statistics, or characteristics, of the selected region. When this check box is turned off, Match Color determines the statistics of the source by looking at all the pixels in the image. Similarly, turning on the Use Selection in Target to Calculate Adjustment check box makes changes to the target image using colors found in only the selected area of that image. If you selected similarly colored areas in both your target and source images, it’s a good idea to leave both of these boxes turned on.

Use the Source pop-up menu to choose the source image from among all open images. If you select None, you still have access to the Neutralize check box and other Image Options settings. If you select a source with more than one layer, you can specify the layer from which you’re culling statistics in the Layer pop-up menu. You also have the option of choosing a merged composite of all the layers in the source image.

Finally, the Match Color dialog box offers you the option of both saving and then loading the statistics it has calculated from a source image. This can be useful in a couple of ways. First, it means you don’t need to have a source image open when applying the Match Color command. It also means you can save the statistics of an image and use them to adjust an unlimited number of other images, on other machines, long after the original source image is out of the picture.

If you’re curious to see the Match Color command in action, check out Color Plate 17-4. It shows how I used the command together with a good photo of my son Sammy to fix the flawed color in a second, otherwise adorable image of my kiddo. It required a bit of trial and error, but as I’m sure any proud parent would agree, the result was well worth the effort.

Enhancing colors in a compressed image

Now that you know every possible way to adjust hues and saturation levels in Photoshop, it’s time to discuss some of the possible stumbling blocks. The danger of rotating colors or increasing the saturation of an image is that you can bring out some unstable colors. Adjusting the hues can switch ratty pixels from colors that your eyes aren’t very sensitive to — particularly blue — into colors your eyes see very well — reds and greens. Drab color can also hide poor detail, which becomes painfully obvious when you make the colors bright and vivid.

Consider the digital photograph featured in Color Plate 17-5. Snapped several years back in Boston’s Copley Square using a Kodak DC50 digital camera, the original image at the top of the color plate is drab and lifeless. If I use the Hue/Saturation command to pump up the saturation levels, a world of ugly detail rises out of the muck, as shown in the second example. (Obviously, I’ve taken the saturation a little too high but only to demonstrate a point.) The detail would have fared no better if I had used the Variations command to boost the saturation.

Unstable colors may be the result of JPEG compression, as in the case of the digital photo. Or you may have bad scanning or poor lighting to thank. In any case, you can correct the problem using our friends the Median and Gaussian Blur commands, as I explain in the following steps.

STEPS: Boosting the Saturation of Digital Photos

Select the entire image and copy it to a new layer. It seems like half of all Photoshop techniques begin with Ctrl+A and Ctrl+J (z -A and z -J on the Mac).

Press Ctrl+U (Win) or z -U (Mac) to display the Hue/Saturation dialog box.

Then raise the Saturation value to whatever setting you desire. Don’t worry if your image starts to fall apart — that’s the whole point of these steps. Pay attention to the color and don’t worry about the rest. In the second example in Color Plate 17-5, I raised the Saturation to +80.

Choose Filter Noise Median. As you may recall, Median is the preeminent JPEG image fixer. A Radius value of 4 or 5 pixels works well for most images. You can take it even higher when working with resolutions of 200 ppi or more. I used 6. This destroys the detail, but that’s not important. The color is all that matters.

Choose Filter Blur Gaussian Blur. As always, the Median filter introduces its own edges. And this is one case where you don’t want to add any edges, so blur the heck out of the layer. I used a Radius of 4.0, just 2 pixels less than my Median Radius value, to produce the third example in Color Plate 17-5.

Select Color from the blend mode pop-up menu in the Layers palette.

Photoshop mixes the gummy, blurry color with the crisp detail underneath.

My image was still a little soft, so I flattened the image and sharpened to taste. The finished result appears at the bottom of Color Plate 17-5. Although a tad too colorful — Boston’s a lovely city, but it’s not quite this resplendent — the edges look every bit as good as they did in the original photograph, and in many ways better.