Simple But Overlooked Adjustments For Best Fine Print Quality
By Sean Bagshaw
As a fine art landscape and nature photographer, one of my goals is to create the very best quality master files of my images that will produce prints with great detail, sharpness and clarity even at very large sizes. While the topic of how to create the highest quality prints in a digital workflow is deep and complex, I am going to share three simple RAW adjustments that are often overlooked but can make a big difference in the final quality of large format printed images.
Part of my ritual for creating the highest quality image files starts with capturing my photos in the RAW format. This gives me the greatest quantity of data to work with and the most latitude in the degree of adjustments I can make without sacrificing image quality. I pay careful attention to how I process my RAW files so they will give the best results as they continue on their way through various adjustments in Photoshop. My biggest priorities in making RAW adjustments, either in Lightroom or Adobe Camera RAW, are to get the white balance, highlights and shadows, exposure, contrast and clarity optimized for best results before moving on to Photoshop.
While many people are well educated on how to make these visibly obvious adjustments, I find that they often overlook three more subtle but equally important RAW adjustments; RAW sharpening, noise reduction and removal of chromatic aberrations. Making these three adjustments in the RAW portion of the workflow are important, even though they may seem minor and visually difficult to notice at this stage. Cleaning an image file up as much as possible in the initial RAW conversion means that there will be fewer unwanted artifacts to later be aggravated by additional adjustments in Photoshop and amplified when the image is enlarged for large format printing. If you use the Lightroom Develop module for your RAW file adjustments, Sharpening, Noise Reduction and Chromatic Aberration sliders are located a couple of levels down in the Details Tab. If you use Adobe Camera RAW, you will find Sharpening and Noise Reduction in the Details Tab and Chromatic Aberration in the Lens Correction Tab.
Let’s begin with RAW sharpening. Sharpening in general can be done at three different stages of the workflow with three different purposes. The two of these that most people are aware of are creative sharpening and output sharpening. Creative sharpening is done to enhance or draw the eye to a particular part of the image. Output sharpening is done to achieve the proper sharpness in an image for a particular final size and output, such as for web viewing or printing on one of a variety of photo papers. Every output requires a different degree of output sharpening for best results.
However, I find that many people don’t know or remember to make an initial sharpening pass in the RAW portion of their workflow. Even high quality digital sensors in top end DSLRs experience some loss of edge sharpness at the point of capture due to the way images sensors collect information. By applying a small amount of global sharpening in the RAW conversion your base image file can regain some of that lost sharpness. This will allow the retention of better sharpness throughout your workflow and the final image will respond better to output sharpening, particularly when creating large fine art prints.
In either Lightroom or Adobe Camera RAW, I find that setting the slider values to Amount = 50, Radius = 1.0, Detail = 50 and Masking = 50 provide just enough initial sharpening for most images. Since I use these exact settings so frequently I have created a preset for them so that I can apply them with a single click and then make minor adjustments if needed. It is important to note that to be able to see and evaluate such subtle RAW sharpening, as well as Noise Reduction and Chromatic Aberration adjustments, it is necessary to view the image at 100%.
Next, lets take a look at RAW Noise Reduction. Noise consists of digital artifacts or “grain” in a digital image. Certain workflow adjustments can introduce or enhance noise, but some degree of noise usually exists in an original RAW file, especially when shot at higher ISO settings or when aggressive shadow adjustments have been made. The most current generation of high end digital SLRs produce very low noise images even at higher ISO settings, so how much RAW noise reduction you do depends on the degree of noise in a particular image. Lightroom 2 and the current version of Adobe Camera RAW both do an excellent job of reducing noise and the word is that soon to be released versions will handle noise even better.
There are two sliders for noise reduction, one for color noise and one for luminance noise. Color noise can be identified as grainy spots of red, blue and green seen in an image when viewed at 100%. Luminance noise looks like color noise, but instead of spots of color it appears as spots of varying brightness levels…kind of like static with dark and light pixels. I usually start by adjusting for color noise, moving the slider until the noise has been removed as much as possible. Adjusting for color noise tends to have a lesser impact on image sharpness because it is reduced by changing the color values of the noisy pixels. If I notice additional luminance noise I will make adjustments with the luminance slider, being aware that reducing luminance noise comes at the cost of some image sharpness because part of the noise reduction involves blurring the noisy areas. That said, each new software version does a better job of reducing noise without loss of sharpness than the previous version. Also, third party software, such as Nik Define, can do an excellent job of reducing noise while retaining image sharpness. I use Nik Define for particularly problematic noise.
Finally, I make Chromatic Aberration adjustments if needed. Chromatic aberration is seen as a color fringe along high contrast edges when viewed at 100%. Different cameras produce chromatic fringing in varying degrees. With my particular cameras, the Canon 5D and 5DMkII, the greatest degree of chromatic aberration is seen near the outer edges of an image. If there are no high contrast edges in an image then there might not be any chromatic fringing to deal with, but I find it is always good to check carefully.
Chromatic fringe comes in two flavors, red/cyan and blue/yellow. There is a slider for correcting each one. My images most commonly suffer from red/cyan fringe and it looks just like it sounds, either red or cyan colored ghosting around high contrast edges. Move the slider until the aberration is neutralized. If you move the slider the wrong way you will see the fringe get bigger, or if you move it too far the correct direction you will see the opposite color fringe start to appear. In my camera the yellow/blue fringe is less common, but from time to time I will notice a hint of it after removing the red/cyan aberration. In such cases I follow the same procedure with the blue/yellow slider.
How important are making these three simple and subtle RAW adjustments? In images that will only be viewed on the web or printed at smaller sizes, they may not be very crucial. However, when mastering an image file for potential large format fine art printing I find that they are critical to obtain the highest quality print. I feel frustration of the hair pulling variety when I spend a lot of time getting the processing of an image just right, only to discover that when printed at 24×36 it lacks sharp details, has visible noise or you can see unnatural red and blue halos along tree branches or mountain skylines. No matter how well I have executed my processing for exposure, light balance, contrast and color I find that these small but visible problems with sharpness, unwanted noise and chromatic aberrations can really impact the finer qualities of a large gallery print.