It can be loads of fun taking pictures, but the resulting images can be disappointing. We are lucky we live in the digital age: computer software can now rescue those disappointing images–and even improve the keepers. Once the images have been taken and processed, they can be optimized for monitor display and integrated into a slide show. In this article, I will discuss my work flow for slide show development. This will include the following:
- a discussion of software used to build the slide show,
- a discussion of image problems that need correction,
- a discussion of Photoshop techniques for problem correction, and
- a discussion of how the slide show is assembled.
Although there are other programs with many of the same features, I use Adobe Photoshop CS2 for my image processing. All of my images are captured in the Camera Raw format. Using this format, I can adjust things like exposure before I open the image in Photoshop for normal processing–while preserving the original image data at all times. A good book on Adobe’s Camera Raw is Real World Camera Raw with Adobe Photoshop CS2 by Bruce Fraser.
Camera Raw also allows me to take advantage of special techniques, such as Luminance Masking, which can help preserve detail in shadows and highlights that might otherwise be lost. Once the image processing is done, I use WnSoft’s PicturesToExe to create the slide shows and, as a side benefit, screen savers.
There are many problems that can affect the visual quality of a slide show image. Problems that can show up in images include the following:
- loss of shadow detail,
- white, overexposed areas,
- dust spots,
- a crooked horizon,
- wide-angle lens distortion, and
- distracting flash reflections.
Why do these problem show up in images? If you are like me, sometimes you just want to point-and-shoot. I do not always fuss with camera settings–or sometimes I just forget a critical camera setting. For instance, overexposure can usually be avoided by setting the camera to underexpose images by -1/3 to -1 stop: if this is done, detail in bright highlights are not likely to be lost. The camera’s exposure compensation is adjusted to do this. Do I always do this? Nope! That is one reason I need a program like Photoshop. Unfortunately, once highlight detail exceeds the dynamic range of the camera, the detail is lost forever. What can be done in this situation? Appropriate sky background from another image can be used to replace a blown-out sky. Pasting in replacement background is also a good corrective solution to eliminate a flash reflection. I do alter my images in this way, when necessary, to make them more closely resemble the scene as I actually experienced it. However, on my web site, I make it clear that I do so.
Exceeding the dynamic range of the camera’s sensor can also cause posterization effects. In order to cure this problem, the affected areas can be treated with a dose of saturation and/or hue adjustment.
In low light situations, when I do not use a tripod, I do the best I can with an externally-mounted flash unit. Even so, distant image detail is sometimes shrouded in darkness. Fortunately, the shroud can usually be lifted using Photoshop’s Shadow/Highlight adjustments. Lifting image detail out of the shadows can be particularly rewarding–and is made easy in Photoshop.
To correct lens distortion problems, Photoshop has a couple of great tools: the Lens Correction filter and the Free Transform command. With these tools, camera lens distortions can be corrected, and crooked horizon lines can also be corrected.
Other Photoshop tools, such as the Clone Stamp and Spot Healing tools can be used to correct problems such as the dust spots caused by a dirty lens.
As suggested above, some image problems are due to the high contrast of the scenes we want to capture. Where the dynamic range of the scene is likely to cause loss of detail in either the highlights or shadows, a digital darkroom technique called “Luminance Masking” can be used to help preserve this detail.
Luminance Masking can tame a high-contrast scene and help reduce loss of highlight and shadow detail. This technique works with images saved as RAW images (.CRW files). Briefly, the technique is analogous to taking two images: one image is exposed for the highlights and another for the shadows. The images are then combined in the digital darkroom to take advantage of the best of both.
After image selection and correcting image problems, I look at each image and decide how I’ll use it in the slides show. Generally, I like an image to be a full screen image for the show. Since I design my shows for a 1024 x 768 pixel screen resolution, I will sometimes crop to this size before spending a lot of time correcting image problems in parts of the original image that won’t be seen in the slide show. At other times, especially when the image is a portrait (taller than wide) rather than a landscape (wider than tall) and I want to use the entire image, I need to enlarge the canvas so that I can crop out a 1024 x 768 pixel slide.
Once I have selected the images, corrected any image problems, and cropped the images, I can build the slide show.
There are many programs that can be used to produce slide shows. PicturesToExe is the first program I used to create my slide shows and screen savers. I have never felt the need to learn another program for these tasks. As with most programs I use, PicturesToExe has more features than I am likely to use.
For me, the critical settings are the display time, the transition type, and the transition duration. I like a slide to display for 15 seconds. This is long enough to have a good look at the slide. I prefer the simple fade in/out transition type and I set the transition time between slides for about 4 seconds. I include a slide caption in the upper left corner using Arial Bold, color white, and size 12. I have not advanced to providing music along with the show yet, although PicturesToExe can do this.
With PicturesToExe, it is easy to add control buttons to the slides. The default method of terminating the slide show is with the ESC key. It is probably a good idea to include, at least, an exit button so that there is an plainly visible way of exiting the show.
Sometimes, I just arrange my slides so that the show is aesthetically pleasing to me. At other times, the slides tell a story. My last show chronicled a day in Seattle, Washington. For this show, I organized my slides to show my activities, which included a ferry trip to Seattle, a walk along the Waterfront, and visits to The Pike Place Market, the Seattle Aquarium, and the Boeing Museum of Flight.
Once the slides are assembled and captioned, I preview the show from start to finish. When I am satisfied with the slide show, I save the slide-show project–with all of the included images–on a CD. If I have already created an executable slide show and/or screen saver, this also goes onto the CD.
When everything is ready to go, I create the slideshow.exe program and screensaver.scr. I burn these files onto a CD along with a small file that causes the slide show to autorun when it is inserted into the CD drive.
As a finishing touch, I print a CD label with my color laser printer. I use an image from the slide show as background for the label. On the label I include the slide show title, the date, and a list of included files. When I send the CD out, I include a letter discussing the show along with information as to how the show and screen saver can be installed on the PC.
Digital photography can be fun, and viewing the captured images in a slide show or screen saver can be rewarding. At first, not every image I take looks like a keeper. The good news is that modern software for the digital darkroom can often convert even throwaway images to keepers–and improve the keepers, too!
Copyright © 2006 Royce Tivel
Preparing Digital Images for a Slide Show, November 20, 2006