Digital Editing in the year 2008
By Glenn Bartley
These days the majority of nature photographers capture their images using digital photography equipment. Digital photography has opened up a whole new realm of possibilities, made learning, while out in the field, much more intuitive, and in my opinion, made photography a lot more enjoyable. The ability to take hundreds, if not thousands, of images in a single day has certainly increased the potential for capturing a pleasing image. However, for many photographers the digital darkroom is still a somewhat scary place. Sorting through gigabytes of images, figuring out which software programs to use and trying to establish a digital workflow can be daunting tasks. This article is intended to provide a solid foundation for editing your images from initial capture to final output.
Getting Started Right…Literally:
Learning how to effectively edit digital images can add the “pop” or “wow factor” that many photographers are looking for. Post processing, however, is a lot like the proverbial “icing on the cake”. Effective digital editing can certainly make an image look better. Nevertheless, in order to create the best images possible it is absolutely essential that, before any post processing is considered, that you first begin with the best quality digital file. There are several ways in which to do so.
To begin with, it is important to ensure that you are shooting in your cameras RAW shooting mode. If you are serious about creating the best images possible, this is an absolute necessity. Shooting RAW offers the greatest amount of flexibility as it retains all of the information captured by your camera. No data is lost through file compression and you are free to make a variety of adjustments to this “digital negative” file. Many photographers are reluctant to shoot RAW because doing so adds an extra step of post processing. This is because the RAW files must first be converted into either a .tif or .jpg file before they can be edited in a program such as Adobe Photoshop. The reality is that with the powerful RAW conversion software programs that are currently available, shooting RAW can actually save you time in the digital darkroom as many adjustments can be made directly to the RAW file, resulting in much less time editing in Photoshop.
A second in-camera adjustment to consider is to always set your camera to the lowest ISO setting possible in a given situation. Modern digital cameras such as the Canon 40D or Nikon D300 produce remarkable quality, noise free images up to about ISO 400. Personally, I almost never use ISO speeds higher than ISO 400 as I feel that above this setting the image quality begins to sharply decline. Choosing what ISO speed to use will have to be a decision that is made based on the available light, the depth of field desired and the shutter speed necessary to create a sharp image. The point I am trying to make here is to drop the ISO speed when you have lots of light and raise the ISO speed only as high as is necessary.
Once you have your camera settings dialed in, it is time to start capturing images. The most important consideration at this point is to create images that are well exposed and that capture the greatest amount of information possible. The best rule to remember is to “expose to the right”. What this means is that when looking at the histogram on your camera’s display that you are adjusting your exposure settings to make sure that there is data captured leading all the way up to the right side of the histogram – but that no data has been clipped (see figure 1). If there is a spike at the end of the histogram (on either the right or the left) it means that data in either the shadows or highlights has been lost. Although shooting RAW enables you to recover some detail in shadows and highlights there is a limit to what can be saved. As a result it is always best to start with a properly exposed image.
The histogram on the left is from an image that has been overexposed by approximately 1/3 of a stop. The histogram on the right shows a properly exposed histogram with data leading up “to the right” – but where no data is clipped.One final technical consideration before editing an image is to make sure that you are viewing your images on a properly calibrated monitor. You have to ask yourself the question – am I seeing on my monitor what everyone else would see on their own personal computer? The answer, unless you have calibrated your monitor, is probably not. It doesn’t make much sense to spend hours out capturing and then editing images only to realize that the way they look on your screen is not what they actually look like. To solve this problem of the digital age there are a variety of companies that offer calibration products. These products include a device that attaches on to your monitor and a software package that, after walking through a variety of steps, creates a custom ICC color profile for your monitor. The result is that an image displayed on your monitor would look about the same as it would on my computer, or on the photo lab’s computer. These products range anywhere from around $100 to well over $1000 dollars. For most people a basic unit will work just fine. Personally, I have been very pleased with the "Gretag Macbeth Eye-One Display" unit.
It is perfectly alright to do some quick editing or “chimping”, as it is often referred to, by reviewing images in the field. Flipping through your images is a good idea to make sure that you are getting your exposure settings correct. As you browse through images feel free to delete any that are obvious "throw-aways". This is a great way to save time when downloading images to your computer.
Once you have downloaded your images it is time to begin critically editing them. At this stage the goal is to eliminate any images that have flaws, compare similar images to determine which may be slightly better, and refine the day’s collection of images to only the absolute best. To accomplish this task it helps to have a program that allows you to quickly, but critically, sort through your images. You can use programs like Adobe Bridge, Adobe Lightroom or Mac’s Apeture – but I have found these to be extremely slow on my machine. My favorite program for this stage of editing is called Breezebrowser Pro. This software program is very quick to generate preview images and allows you to easily compare, rename and delete image files. After reducing the number of images down to a manageable number, it is time to convert the RAW files.
There are a number of RAW conversion software programs to choose from. All digital SLR cameras come with their own proprietary software – and most to (do) a pretty good job of basic conversions. The problem is that they tend to be quite clunky to use and are often very slow. More powerful tools such as Adobe Camera Raw (which acts as a plug-in to Adobe Photoshop), Adobe Light Room or Mac’s Aperture allow for maximum flexibility in RAW conversion. Because (since) there are so many tools out there, I will not be discussing specific details about how to make conversions as they are called by different names in different programs. Instead I will attempt to walk you through the basic steps of a RAW workflow.
One of the best things about shooting RAW is the ability to make subtle adjustments to the exposure settings of an image. While I generally do not push the exposure beyond a third of a stop outside of the original settings, even these seemingly minor adjustments can make or break an image. I find that in all aspects of digital editing the “less is more” rule usually applies – especially if you got the exposure right in the first place!
The second step in my RAW workflow is to adjust the black and white points of the image. At this stage, you are essentially making adjustments to the darkest blacks and the brightest whites. This point is represented visually by the far left and right sides of the histogram. If there is a gap between where the histogram data meets the left side of the image, it is often desirable to “pinch” in the black point so that the darkest parts of your image are truly black. Alternately if there is a spike at the end of the histogram, it means that data has been “clipped” from the image and may need to be recovered. Almost all RAW conversion programs offer some type of highlight and shadow recovery tool. These are often powerful applications that can work wonders on over or underexposed portions of an image (see figure 2). There are of course limits to what can be recovered. This is also the point of the workflow when additional exposure adjustments can be made, such as a “curves” adjustment, to either boost or reduce contrast in the image.
The above images illustrate the opportunity to recover highlight detail when shooting RAW. Note that the histograms in figure 1 are associated with these two images.
The third stage of my RAW workflow is to make adjustments to the white balance and color saturation of the image. Shooting RAW enables complete freedom when it comes to setting the white balance of an image. I simply leave my camera on its “auto” white balance setting and then adjust accordingly. Usually I find “auto” to do a pretty good job. The most common adjustment I will make is to “warm up” the white balance slightly by moving the slider to the right. Once this is accomplished I will make adjustments to the saturation of the photo. Usually this involves boosting the saturation of the image, or of certain colors within the image (see figure 3). I find this to be an area where there are large differences in the degree of flexibility offered by the various RAW conversion programs. Some software programs only allow for crude alterations to the overall saturation while others, such as Adobe Camera Raw, allow the user to adjust the saturation of individual colors within an image. If using a program that does not offer a great deal of control, I would suggest leaving this step to be accomplished in Photoshop.
Adjustments to the white balance and saturation can restore or enhance the rich colors that many nature photographers strive to capture. Notice that the tip of a second birds’ beak has been removed from the image on the right using the “clone stamp” tool in Photoshop.
Most RAW conversion programs allow the user to reduce the noise and also to apply sharpening to an image. Personally, I prefer not to make these alterations “globally”, that is, to the entire image. The reason for this is that noise removal generally involves a certain amount of detail loss. The areas with the greatest noise tend to be areas such as dark backgrounds or shadows. Correcting the noise for these areas would mean losing detail from the actual subject where there may be little, if any, noise. Alternately, applying sharpening to an image usually exaggerates any noise present. While it is almost always desirable to apply some sharpening to the main subject of the image there is generally no advantage to sharpening the background. Furthermore, sharpening is best applied for final output. For example, the amount of sharpening required for a 700 pixel web-resolution image and for a 12x18 inch 300ppi print would be drastically different. As a result, I choose to apply both noise removal and sharpening “locally” based on the final output size in Photoshop. Sharpening is done using the intuitive controls of the “Unsharp Mask” filter.
The final stage of my RAW workflow is to convert the image to a .tif file at the camera’s native resolution. I output my files at 300 pixels per inch. You can determine the size of the file in inches by dividing the number of pixels on each side of the image by 300. For example, the files from my Canon 40D are 3888 pixels by 2592 pixels. This results in a 300ppi image of 12.96 by 8.64 inches.
A great deal of digital editing can be accomplished through the RAW conversion process. In fact, the more adjustments that can be made to the RAW file instead of the converted .tif file the better! There is, however, a number of editing steps that I prefer to make in Adobe Photoshop.
The first thing that I do upon opening an image file in Photoshop is; to determine whether any image rotation or cropping is required. I almost always maintain the standard 3:2 aspect ratio in my images when cropping. To do this I simply select the “crop” tool, type in the native size of the image files from my camera (12.96 by 8.64 inches) and compose the image as desired. Once the image has been cropped, I generally re-size the file back to 300 ppi using the “bicubic smoother” option checked in the image size dialog box.
Generally speaking, the exposure of the image has been sufficiently adjusted at this point through the RAW conversion process. I will, however, sometimes make slight changes using the “levels” dialog box. Most often, this involves shifting the middle slider slightly to the right, to add contrast in the mid-tones of an image. I will also often utilize the “shadow / highlight” tool at this stage in order to make any further adjustments to the brightest and darkest areas of an image.
If you have not applied additional saturation to the image, or to certain colors within the image, this can easily be accomplished in Photoshop at this stage using the “Hue / Saturation” command. You can choose to apply saturation to the entire image or to user-definable color ranges within the image. Generally, I find that I bump up the saturation to the point where a given color range is looking over-saturated and then select this color range and selectively de-saturate this portion.
In past versions of Adobe Photoshop, the “Brightness / Contrast” tool was very unsophisticated and overly aggressive. As a result, I almost never used it. However, with the release of Adobe Photoshop CS3, this tool has been drastically redesigned. Now, I find that I often raise the contrast of an image by as much as 15 points.
At this stage, the major image editing process is complete. However, you may wish to “clone out” certain undesirable elements within your image. For example, if your digital camera’s sensor has any dust particles or if there is a distracting element in the image (such as in figure 3). To accomplish simple cloning jobs, I use a combination of the “clone stamp” to paint over areas and the “patch tool” to smooth out these areas. The idea with cloning is to make the image appear natural. If you can tell that something had been there before then you have not done a good job. With a little practice, these tools can be easily mastered for simple cloning jobs.
The final edit that I make to many of my images is to apply selective noise removal to the background. To accomplish this, I simply select the background using either the “magic wand” or “lasso” tool, feather the selection to create a smooth transition area, and apply the “reduce noise” filter. This technique allows you to remove noise from the grainiest areas of your image while retaining all of the detail in the main subject areas.
At this point, you can save your image and rename it if you have not yet done so. I always save my images as 16 bit .tif files to maintain the maximum tonal variation and image quality. You may choose to convert the images to 8 bit .tif files and save the images using the LZW image compression option. This form of lossless image compression reduces the file sizes of your images tremendously. If storage space is an issue – I would recommend this option to maintain a balance of extremely high image quality and manageable file size.
Digital photography has opened up a whole new world of possibilities for nature photographers. But to take advantage of these opportunities we must equip ourselves with the proper tools and skills. With a little bit of knowledge, the right software and an efficient editing workflow; digital editing can help to give your images that "wow factor" you’ve been looking for.