Photoshop offers a number of different ways to tweak your images. Some of these are as simple as creating a new layer and filling it with a color and then adjusting the blending mode and opacity (useful for adding or removing color casts). By filling a new layer with 50 percent gray and applying it through the color dodge blending mode, you can bring out detail in an image. This is a nice little nondestructive editing technique that can help improve the tonal range of your image. To fill a new layer with gray to increase the tonal range, follow these steps:

1. Create a new layer by choosing Layer Create New Layer.

2. Choose Edit Fill, and in the Fill drop-down box, choose 50% gray. Click OK.

3. On the Layers palette, change the Blending mode to Color Dodge.

4. Adjust Opacity as desired. I’d suggest bringing it down to 0 to see your original image and then sliding it to the right to see the effects.

5. Use the Eraser tool from Photoshop’s Tools palette (set to a soft-edged brush at a low opacity) to dial down the effect in areas that don’t need too much help.

6. Save a version of the image with layers intact so you can come back later and make changes if need be.

Contrast masking is an old conventional darkroom technique for pulling detail out of images shot under contrasty lighting conditions. This simple Photoshop technique gives you the same result that you would get in the darkroom, and you can convert it into an action for easy use. Follow these steps to use a contrast mask on your image:

1. Create a duplicate of your image layer by choosing Layer Duplicate. Alternatively, you can select the image layer with your mouse and drag it onto the new layer icon on the bottom of the Layers palette

2. Desaturate the new layer by choosing Image Adjustments Desaturate. This removes all color from the image because you’re going to use this layer to help create a mask of the image.

3. Invert the image by choosing Image Adjustments Invert. This places highlights over shadows and vice versa.

4. On the Layers palette, change the Blending mode to Overlay. Blending mode is the pull-down menu at the top of the palette. Its default is Normal.

5. Choose File Filter Blur Gaussian Blur to apply a Gaussian Blur filter, choosing a radius of about 40 (you can tweak this number as needed).

6. Adjust Layer Opacity as desired to tweak this effect. This is a subjective call, so experiment until you’ve made the image look the best you think you can.

Warming and cooling filters have always been useful tools for photographers trying to compensate for less than desirable lighting conditions. Photoshop makes it possible to solve the same problems back in the digital darkroom long after you’ve made the original image. To create a warming or cooling filter effect, follow these steps:

1. Create a new layer by choosing File Layer New Layer.

2. Use the foreground color picker on the Tools palette and pick the color you want to add to the image (orange for warming, blue for cooling). Just click on the foreground color on the Photoshop Tools Palette (it’s the upper square on the lower part of the palette), and it takes you to the color picker. Here you pick exactly the color you want to use.

3. Fill the new layer with this color by choosing File Edit Fill and then choosing Foreground color from the drop-down list.

4. On the Layers palette, change the Blending mode to Color. (Blending mode is the pull-down menu at the top of the palette. Its default is Normal.)

5. Change the Layer Opacity as needed. Usually it only takes a tiny fraction (10 to 15 percent) to achieve the desired effect.

Back in the days of the wet darkroom, dust was a nightmare. You either labored to keep the darkroom and its equipment as dust-free as possible or you resigned yourself to spending time using a camel’s hairbrush and special dyes to hide dust spots on your prints. The specks of dust on the negative would block light hitting the photographic paper, producing white spots. You’d dab the brush on the paper, gradually building up enough dye to get the spot to blend in with the surrounding image. Well, even in the digital age, dust is still a pain in the neck! It’s particularly bad for DSLRs and their interchangeable lenses. If dust gets into the camera body and lands on the imaging sensor (or the filter covering it), it shows up on your image as a black spot or streak. As you may have noticed, our working image has some ugly dust spots and streaks on it. It’s now time to get rid of them. Photoshop offers several different ways of dealing with dust spots and other dirt on the image. You can use the Cloning tool to paint over dust spots with similar areas of the image that are dust free. The program’s Healing brush offers an even more attractive alternative because it tries to keep some of the same underlying texture. Each tool has its advantages, and if you’re using an older version of the program, you may not even have the Healing brush available to you. Keep in mind, if you use the Cloning tool approach, adopt a nondestructive method. You can do this with the Cloning tool by creating a new blank layer above your image file, checking the Use All Layers box option in the Cloning tool and then cloning over the dust spots on the new layer. When you’re done, you can save a master version of the image as a PSD file with layers intact, that you can return to when needed, yet flatten the working version of the image for other uses. This solves the dust problem but still gives you an easy way to revert back to your original file. Here’s a technique I use when I have to remove dust from a particularly challenging image. This method takes advantage of Photoshop’s History palette and History brush. If the History palette isn’t visible when you open Photoshop, you can choose the Window tab on the menu bar and cursor down to the History option to open it. You choose the History Brush from the Photoshop Tools palette. To spot dust an image, follow these steps:

1. Open the Dust and Scratches filter by choosing Filter Noise Dust & Scratches. Begin with the Radius set to 1 pixel and the Threshold set to 0. Use the cursor to find and select the worst piece of dust or mark on the image. Click that mark to bring it up in the dialog box’s magnifier. I chose that ugly black streak in the lower right-hand corner of the image.

2. Slowly move the Radius slider to the right, pausing a moment at each increment. Find an amount that makes the streak disappear completely.

3. Move the Threshold slider to the right until the streak reappears. Then one level at a time, move the slider back left until the outline of the streak disappears completely. This is a particularly bad dust streak, so extreme settings were necessary. Click OK.

4. Go to the History palette and click the rectangle next to the Dust & Scratches event. This loads that event into the History brush.

5. Click on the event immediately before the Dust & Scratches event. Your image will return to its dusty, but clear state. Now select the History brush. (You can type the letter Y as a shortcut, and the program automatically selects the History brush.)

6. Select a brush size that’s just a little bigger than the dust spot you’re trying to remove. If it’s a scratch or hair, pick a brush that’s just bigger than the scratch is thick. Paint over the blemish. This should remove most dust spots and other marks, but may not work completely on really bad ones. Finish cleaning up everything you can with the history brush, then return to the remnants of the troublesome ones and use either the healing brush or cloning tool to finish up the job.

It’s not at all unusual for digital images to need some sharpening. Although many novice-oriented digital cameras perform their sharpening in-camera, you still may find the occasional photo that needs help. If you’re using a higher-end camera, odds are it will leave more of the decision in your hands, because oversharpening an image can degrade image quality. There are a number of ways to sharpen an image in Photoshop. The most basic method is to choose Filters ➪Sharpen and then choose one of the program’s sharpening tools: Sharpen, Sharpen Edges, Sharpen More, or Unsharp Mask.

The alternative method is to choose the Unsharp Mask filter. This is the only one of the four that lets you exercise precise control. Although this is not necessarily the best way to sharpen an image, the Unsharp Mask filter does a decent job. The Unsharp Mask filter has three controls: Amount, Radius, and Threshold. A simple method of sharpening with these controls is to take the resolution of the image, divide it in half, and move the decimal point two digits to the left. For example, here is how this would work for an image with a resolution of 300 ppi:

300 ppi ÷ 2 = 150.00
 Move the decimal point left: 1.5

Set the Amount setting to 100 percent, and then adjust the Threshold slider to tweak the overall effect until you’re satisfied. The lower the threshold number, the greater the sharpening effect. You can turn the preview box on and off by clicking the check mark. This helps you to judge the effect on the image. Also be sure to preview the effect at the actual print size of the image. This is at best a so-so method. Most images should be sharpened as the very last step before output, because the amount of sharpening necessary depends on the output resolution and how the photo is to be used. As mentioned earlier in this article, destructive editing methods—those that change the original pixels—are less desirable than those that don’t, and this technique falls into that destructive category.

Experienced digital darkroom workers frequently use Photoshop’s Unsharp Mask filter to “burn off” a sort of digital “haze” many images have. This application of the filter does nothing for sharpening, but many of us use it as an additional step in the editing process. It’s helpful enough that I’ve created an action (Photoshop’s form of a scripted mini-program) that allows me to apply this technique quickly whenever I need it. (Not every image benefits from this technique though, so be selective in its use.) Select the Unsharp Mask filter from the Filter menu and apply settings of Amount 16, Radius 40 and Thresholds 0. Click OK and you’re done. (Go ahead and try this technique on one of your own images and see the difference it makes!)

This technique takes advantage of a little used Photoshop filter known as the High Pass filter. Access the filter and apply this technique by following these steps:

1. Drag your image layer down to the New Layer icon on the bottom of the Layer’s palette. This creates a duplicate version of your image layer. (Or choose File Layer Duplicate Layer, which does the same thing.)

2. Set theBlending mode to H Light. (Soft Light will also work; you can experiment to see which effect you prefer.) Set the layer opacity to about 50 %. Don’t worry that it seems to have a strange effect on the image. The next step will fix that.

3. Choose File Filter Other High Pass to apply the High Pass filter to the new layer. Adjust the Radius slider to vary the intensity of the filter, turning the preview box on and off to get a sense of the effect. When you find a level of sharpening you like, click OK to apply the filter.

4. At this point, you can still further tweak the effect by changing the opacity of the high pass layer or even by changing blending modes. Best of all, you can turn this layer off and repeat the entire process for a completely different sharpening effect later on if that’s what you need. (Of course, you have to have saved the file with layers intact to have this option.) This is one of my favorite sharpening methods because it doesn’t change the original pixels, yet it leaves me the capability to change the amount and/or quality of the sharpening effect long after I’m done working on the image.

The easiest way to solve noise problems is to turn off the power to your teenaged kid’s stereo. That particular issue is beyond the scope of this article, so this article will actually deal with the issue of digital image noise. Noise is caused by individual pixels in the imaging sensor misfiring. This happens all the time, but less often at lower ISO settings and in better shooting conditions. Noise typically becomes a problem when you’re shooting in low light and have to crank up your ISO setting. As the camera sensor pumps up its sensitivity to light, it also causes more image noise. (Noise is characterized by off-color pixels—usually reddish to yellowish—in the shadow areas of your photo. There are several ways to deal with noise problems. One simple technique is to find the channel where the noise is the worst (usually the blue channel) and then apply a blur filter to that channel by choosing File Filter Blur Blur More. This softens the image a little, but you can correct for that during the sharpening process. Because noise is such a problem for digital cameras (particularly, consumer grade cameras with smaller sensors and lower maximum ISOs), a number of third-party options have shown up to help photographers deal with this problem. These options show up as Photoshop plug-ins, such as Nik Multimedia’s Dfine, which is a complete image-processing filter, and The Imaging Factory’s noise reduction and noise reduction pro filters. Some additional third-party options can be found as Photoshop actions such as those by Digital Deluxe. These applications try to simplify the process of dealing with this problem, and each does a good job of handling noise issues.