Art 100

Introduction to Digital Photography

Digital Processing II: Advanced Issues

The PhotoShop Layout

Before we get started, we need to observe some standard features of PhotoShop. Thus far, we have been using the Main Menu Bar which runs horizontally across the top of the PhotoShop desktop. This is where the Image, Filter, and View menus are located. Directly underneath the Main Menu Bar is the Options Bar. [If you don't see it there, click on the Window menu and select "Options".] Also, vertically, along the left hand margin of the desktop is the Tools Bar. [Again, if you don't see it there, click on the Window menu and select "Tools".] Next, notice that, when you open one of the tools in the Tools Bar by clicking in the box, the Options Bar changes appropriately and gives you all of the options that are available for that particular tool. For some of the tools, if you click-and-hold in the box, a popout menu appears and gives you some choices. [Click-and-hold in the Marquee Tool (the square with dotted-lines) and notice that there are four choices.]

The group of six tools at the top of the Tools Bar are all designed for selecting portions of your image. The next group down (8) are designed for making various changes directly in the image. Below these are four tools designed for adding text or drawing. Below these are various utilities. We will work with most of these tools at some point in the discussion below.

For now, click-and-hold on the text tool (the large "T") and select either horizontal or vertical text from the popout menu. Set the cursor where you want the text and click; then type what you wish. Now, click on the "move tool" in the upper right corner of the Tools Bar and go back to your text. Click-and-hold the move tool on the text and slide the text around until it is exactly placed, as you wish. How does this happen without disturbing the image itself? When you use the text tool (or any of the other tools in this group), it opens a new "layer" and places the text or drawing in that layer separate from the image (background) layer. Click on the Window menu and select "layers". This opens the Layers window which allows you to see the layers you have. At this point, you should have only your background layer (in which the image is located) and the text layer (in which you'll see what you typed). You select the layer in which you are working by clicking/highlighting it. The Layer Window itself contains a number of tools relating to how layers work with each other. One of these is an "eye" at the far left. When the eye is there, you can see the contents of that layer on the screen. Click the eye on the text layer and notice that, when the eye disappears, you can no longer see the text in the image. There is a trash can at the bottom right of this window. If you decide that you don't want a layer, click on it and drag it to the trash or click the trash can.

Another very useful window that you can open out of the Window menu is the History window. This lists every action that you have taken since you opened the image file. If there is anything you did that you now regret, regardless of whether it is in the image layer or another layer, you can delete it by clicking on the action and then clicking on the trash can at the bottom right. A safety message will ask to confirm that you want it deleted. Close the window when you no longer need it.

Alternatively, you can create new layers by simply clicking in the Layers menu (top row) and choosing one of the options. Select "duplicate layer", for instance, and give your image copy a name. In the layer window, click to select your duplicate layer and then do something to it like adjusting the color saturation by some extreme. Click the eye on this layer to see the original image; then, click to return the eye so you see the composite of both images. With the duplicate image selected, click the "opacity" tool in the upper right and use the slider. Notice, as you slide back-and-forth, that you see different combinations of the two layers; hence, you can apply degrees of some action performed on the duplicate layer to the resultant image.

There is much more to all of these tools and windows, but we're now at the point where we can start with some specific moves.

The Clone Tool

The clone tool is very useful if you need to clean up your digital image. The only question is how far do you go when you "clean something up"! I took a mountain landscape picture that included part of an alpine lake. Later, I noticed that there was a fisherman in a float tube out in the lake. I thought he ruined the sceen so I cloned a portion of the ripply water and blotted him out. During the recent campaign, one of the enthusiastic workers for the Republican Party cloned a group of soldiers and created a whole audience for a Bush speech. Unfortunately, some Democratic Party staff people noticed the repetition of soldiers' faces in the "audience". So somewhere there is a limit to what you should do with the clone tool. You'll have to find that yourself.

When you have selected the clone tool (it looks like a rubber stamp), the clone options appear in the Options Bar. The first option available is the brush option. You'll find a staggering number of brush shapes and sizes. If you click the tiny arrow in the upper right corner of the brushes box, it will offer even more options. Next option is "mode" and after that is "opacity", etc.

The clone tool is the weapon of choice if you simply want to clean up splotches in your image. Digital SLRs get dirty because dust particles and grit fly into the camera body every time you change lenses. When you take a picture, the open shutter curtain allows particles to travel back toward the CCD. Eventually, micro-particles deposit on the filter covering the CCD. Since these are opaque, they show up in your image as black splotches. They are easy to spot and they are in the same place in every picture you take until you clean them off the CCD. To eliminate these splotches, zoom in enough that you can see them clearly and pan back-and-forth or up-and-down to locate them. When you find a spot, open the clone tool by clicking it in the Tool Bar. The cursor is now a circle of some size. You can change the size by clicking in the "Brush" menu in the Options Bar and selecting a smaller or larger radius. For smallish spots against plain backgrounds, choose a circle that will just cover the spot. For more complicated situations, it is better to work with a smaller circle and do multiple clones. Having chosen the circle size, move the cursor off the spot onto the background and click the cursor while holding down the Option key (MAC) or the Alt key (PC). Then move the circle over to cover the spot and click once more. A miracle! The portion of background has been transplanted over the spot. [In some situations, you may want to change the opacity or mode to create effects other than simply replacing the spot as we did here.]

The advantage of using the clone tool is that it picks up patterns of pixels and reproduces them. Thus, you replace a splotch with an authentic segment of the actual background. It fits right in. You can also use it to cover up offending power lines --- sometimes even that offending post coming right out of a person's head.

Selecting Parts of an Image for Adjustment

Three of the uppermost tools in the Tool Bar offer ways of selecting portions of the image. The most straightforward of these is the "marquee" tool. When you click and hold on this tool, you will be able to choose a rectangle, oval, or single row frame going either horizontally or vertically. After opening the right tool, click at a point in the image and drag the rectangle or oval out wherever you like. Having selected that portion of the image inside your rectangle or oval, you can now make most of the adjustments previously discussed on that part only. [You can also copy or cut-and-paste the selected part to another canvas or even another part of your image.]

There are some obvious limitations to the marquee tool. First of all, it can only select one of these standard shapes. Second, once you un-click the image, the shape is frozen to that spot; you cannot change the shape or size though you can use the "lasso" tool (below) to move it around. A more useful tool is the "lasso" tool, which also comes with a few options. With this tool, you use the mouse (clicked and held) to draw a closed curve around some part of your image. (It is the fine lower end of the lasso that draws.) This is easiest to do if you zoom in on your image. One of the options for this tool is a "magnetic lasso" which, if you can trace reasonably close to the edges of an object, will re-draw the curve for you at the object's exact edge. Very useful!! Once again, after un-clicking, the portion of the image inside the closed curve is selected and any adjustments performed will be applied only to that part.

The final word in selecting a part of your image is the "magic wand" tool. When this tool has been opened, you can click it in a general area that you want to select. It will draw a closed curve around that part of the general area that it "sees" as all the same color. You can adjust the wand's tolerance for color in the Options Bar at the top. Usually, what you get will be a first approximation and you will either want to remove some portion or you will want to add more. If you simply want to add more, hold down the Option key (MAC) or Alt key (PC) and click in other areas. They will be added to the original selected contents whether or not they are connected. In the options bar you will find ways of adding to or subtracting from the selected area. Also, if you uncheck "contiguous" it will select all parts of the image with the color you initially click into. [If you wanted to desaturate the blue in all of the snow appearing in your picture, you could click in any snow with the "contiguous" unchecked and the wand will surround everything it sees as snow. Adjust this by adding or subtracting portions. Then, use the Image menu, "adjustments", "hue/saturation" to desaturate in the blue channel.]

One of the problems with adjustments performed on a selected area is that a harsh boundary line may result on the image between the adjusted and non-adjusted area. You can avoid this, after selecting an area, by going to the Select menu and choosing "Feather". In the popout menu, choose the amount of feathering you want in pixels (starting with about three). This will diffuse the boundary.

Compensating for Poor Exposures

In the previous discussion, we adjusted the overall qualities of the image in order to bring them to an optimum effect. Unfortunately, this doesn't always solve the problems. The contrast range in the image may be way too great to enable us to print an attractive picture. Worse yet, the actual subject of the picture may be in one of the high contrast areas --- usually the shadows. This is where you should have used a light reflector or a fill flash --- but, alas, you didn't. Now the person's face is a dull grey at about Zone III and the background is a vibrant Zone VII. Another example, by the way, is the the standard duo-tone landscape --- a brilliantly illuminated sky (with or without clouds) and a morbidly dark foreground of grass and trees.

Solving these problems requires substantially more ingenuity. Here's an example of a landscape in which the sky is blown out and the main subject, the meadow, is underexposed. We proceed by using the Image menu and opening the Adjust/Levels. You'll notice that the histogram for an image like this has pixels ranging from the lowest black to the highest white so there doesn't seem to be any space for adjustment. No matter. Slide the right arrow to the left almost past the pixels representing the sky and the granite cliffs. Then, slide the middle arrow (the midtone output) to the left to lighten the foreground until it seems reasonable. In the process, you have completely blown out the sky and the cliffs, as shown. Click OK.

Now use the Window menu and select the History window. It shows two entries --- "open" and "levels". Select the "open" and you'll see the image return to the original unadjusted one. Click in the left hand box of the "levels" history state and a paint brush appears. This is the "history brush". Now, go over to the Tools Bar and select the History Brush tool. It's next to the clone tool. Looking at your original image and using a fairly large brush size, paint over the entire foreground with the History Brush, watching it become lighter. For now, avoid the boundary areas. The history brush is literally applying the results of your levels-adjustment to the specific parts of the image that you paint over. To get the boundary areas, you'll either need to use a very small brush and go over it very carefully or, better yet, you can use the Magic Wand tool to select that boundary. Then, click inside the foreground area with the history brush and swipe the brush up to the boundary. Note that you can be very careless about this because the brush will only change whatever is inside the selected area! Here's the resulting image.

If you are lucky enough to be working with PhotoShop CS, you can achieve essentially the same thing by using the Adjustments//Shadow/Highlight tool out of the Image menu. In the Shadow/Highlight dialogue box, click on "show more options" to get the full set of tools. Start with "tonal width" of 33% and pixel "radius" of 15. Also start with the "amount" set at 0%. This shows your original image. Starting from the same original landscape image, move the "amount" button for the highlights to the right until you are happy with the resulting darkened appearance of the sky and granite cliffs. Then, move the "amount" button for the shadows to the right until you are happy with the resulting lightened appearance of the meadow and trees. You may wish to change the color saturation and to adjust the midtone contrasts before you are finished. Click OK when your image looks right. Here's an example with both "amounts" set to 39% and a small increase in color saturation.

Other Adjustment Tools Relating to Exposures

No matter how well we think our way through the camera work leading to an image, there is almost always some part of the image that can be improved. Ansel Adams's work is a good example. While people think of him as a "realist nature photographer," he engaged in darkroom manipulation of images constantly. [Much of this is discussed in his books, especially Examples: The Making of 40 Photographs.] In effect, Adams was always "shaping" the light so as to bring forward the most dramatic image possible. This was done in the chemical darkroom by "dodging" and "burning" his prints, usually employing both techniques on different segments of the same print.

The basic principle of dodging is to withhold light from a portion of the print for some period of time while the enlargement time as a whole is elapsing. This is done when some portion of an image would otherwise print too dark relative to other portions. Suppose that a doorway is in deep shade but that all the rest of a image is perfectly exposed. You can print the image at the appropriate exposure time for the normal parts and still get the details of the door to show by dodging the door. In the darkroom this is done by inserting a shading device (usually a small opaque figure on a wire handle) into the light path and feathering it so that it doesn't create a hard outline anywhere on the print. The amount of dodging (in percentage of the total printing time) is determined by experiment.

When dodging in PhotoShop, you begin by selecting the dodging tool from the toolbar. It looks just like the darkroom dodging tool. (If you click-and-hold, a popout menu shows you a selection of dodging, burning, or sponging.) When you place the cursor on the image, you will see the pattern and size of the brush currently selected. You can adjust these in the options menu above. It is best to select a largish fuzzy brush. The dodging tool can be applied simply by clicking on an area of the image or by gliding it across an area. You should be very careful not to over-dodge. Use "range" and "exposure" in the options bar to limit the effect of the dodging tool. The PhotoShop tool is not as clean as a standard darkroom dodging instrument but you can immitate the darkroom more nearly by dodging very lightly multiple times with different sized brushes. If the boundaries are complex, it may be helpful to select the appropriate area for dodging with the magic wand tool and dodge within the selected area.

"Burning" is also a standard darkroom technique and it is the opposite of dodging. Occasionally, when making a print, you have to time the print to stop so that most of the image is comfortably exposed. However, you may find that certain highlights or bright areas have not been printed long enough to bring out the detail. A very light shirt shows no texture or folds. The sky shows no clouds even though they were there. Sometimes this can be solved by burning in the area, that is, by exposing that area for a longer time while leaving the rest of the image alone. PhotoShop has a burning tool and a similar brush adjustment. Again, you need to be cautious and use such tools carefully and sparingly.

If you make a mistake and go too far with any tool, use the Window menu and select "history". You can delete one or more of the burn-tool applications.

In his book on PhotoShop CS, Scott Kelby describes another technique for burning and dodging. Open the Layers window and click on the "New Layer" icon at the bottom. Change the mode to "soft light" and confirm that the paint brush tool is showing in the window to the left of the new layer. With the new layer still selected, go over to the Tool Bar and select the paint brush tool. Adjust the opacity to 30% in the Options Bar and select the size and style of brush you want to use. Now, use the eyedropper to select white as your foreground color and return to the paint brush. [You do this by clicking the eyedropper on the overlying square just below the eyedropper in the Tools Bar. Click the white (upper left) corner and click OK.] Now, paint all the sections that you want to dodge. In effect, you are painting soft white light in the masking layer you have created, using your image as guide. Switch the foreground color to black and paint all the areas you want to burn. Your masking layer is now a soft replica of black and white patterns that represent the dodging and burning for this image. Click the eye to the left of the new layer and you'll see the original image. Click the eye back and you'll see the result of your burning and dodging. You've made no changes to the image itself so you can toss out the new layer and start over if you need to. Before you save the file or print it, you'll need to "flatten" the image in the Layer menu.

Making Color Corrections

First of all, follow the instructions given by Scott Kelby on pp. 116-117. Set the color "working space" for PhotoShop as "RGB (1998) as the default. This is the standard working space for photographers. Also, reset the eyedropper tool to a 3 by 3 average sampling rather than a point sampling. In the following, I will summarize Kelby's chapter on color corrections (pp. 118-125).

We are going to use the "Curves" tool under the Image/Adjustments menu in order to correct the color in an image. First, we need to calibrate the eyedropper tools in the curves dialogue box as directed by Kelby on pp. 118-121. Once the eyedropper tools are set, we can use them on the image. Click on the black eyedropper tool first and then find the darkest shadow in your image. Click the eyedropper on that shadow. Next, click the white eyedropper and find the brightest white in your image; click the eyedropper there. You will usually see small changes in the image when you do this. Finally, find the section of your image that is as close to "middle grey" (Zone V) as possible and click the midtone eyedropper there. (If there is no grey in your image, you'll have to leave this step out. At the end, click on the middle of the curve itself and drag it up or down to lighten or darken the midtones to your taste. Click OK. What you have achieved through this process is an elimination of the color casts that tend to lurk in the shadow and highlight regions of digital photos.

Creating Black & White Prints

Digital photography does not equal "color photography"! You can create black and white images from any digital file. Better yet, since you don't have to select either black and white or color film at the beginning, the data you've collected can be used in either or both ways. The big challenge is interpreting in color what will make a good black and white image. That, of course, is the challenge that black and white photographers learn to overcome at the point of camera work, when viewing a colored scene and then exposing a black and white film. Digital black and white photography simply defers this interpretation to the time of file manipulation.

Kelby describes a simple technique for grayscale conversion if all you want to do is emphasize the existing contrasts. First, convert the image to "Lab Color" through the Image/Mode menu. Then, open the "Channels" window from the Window menu. Select the "lightness" channel and you'll see your image in grayscale. Use the Image/Mode menu to select "Grayscale" and the other channels disappear, leaving your grayscale image. Click on the Layers tab to the left of the Channels tab and select the grayscale image, which is your background layer. Duplicate this layer and select the duplicate layer. Now, click on the menu just below the Layers tab (currently reading "normal") and select the mode of this layer as "multiply". The image darkens considerably! The copy layer is multiplying the contrasts in the image. Use the opacity slider at the top right to dial in the right amount of contrast for your black and white image. Flatten the image in the Layers menu before saving or printing.

Black and white photographers often use colored filters in the field to change the contrast relationships within an image. For example, it is often standard procedure to keep a yellow filter on the camera because yellow and blue are complementary colors. The yellow filter blocks some of the intense blue from the sky and darkens the sky in the print. As another example, suppose that you are picturing some green grass against the side of a red barn. Using a green filter will admit the green light but block the red since red and green are complementary colors. As a result the black and white image shows very light grass against a dark background.

With a digital camera there is no need to use filters; you can add color adjustments to your image in PhotoShop. After you open your file, decide on a color adjustment strategy. If you are using PhotoShop CS, you will find a "Photo Filter" option under the Image/Adjustments menu. You can choose "Photo Filters" that replicate what the black and white photographer would have done in the field. You must do all of this in RGB mode before you use the Image menu to select Mode and change to "Grayscale". The result will be the same as though you had taken the picture with a filter on your camera lens.

Kelby describes another technique that uses the Layers window. Open the Layers window and click on the "adjustment layer" icon at the bottom. (It's the black&white circle.) In the dropdown menu, select "channel mixer". This will create a new layer and open the "channel mixer" dialogue box. You can slide the outputs for the RGB channels to different levels; just make sure that they sum to 100%. You are composing your own camera filter and you can watch the color of the image change. When you are satisfied, click the "monochrome" box at the bottom left to see the resulting grayscale image.

Once you have a grayscale image, you should process it in the same way that you would any other image --- correcting levels, sizing, sharpening, etc. You will want to print your black and white image at high resolution on matte paper with a high quality printer set to black-only printing.