Many years ago, I was in an office of desktop-publishing authors, and the running joke was how a program needed a Make Better button. Very amusing, until software like Apple’s iOS Photos app added an Enhance button that often just made things better. Using a reasonably sophisticated analysis of an image, a single click could reshape an image’s tones to make it an objectively more fuller-toned version of itself.
But “better” is often not good enough, and if you’re willing roll your sleeves up a tiny bit, the new Photos for OS X app includes substantially more refined, more granular, and easier-to-use tools than iPhoto. They’re also quite speedy to preview and apply in comparison.
(If you have iCloud Photo Library enabled, any edits you make are synced to other Photos libraries, including in iOS. On the Mac, the original version and applied edits are synced, so you can revise changes. In iOS, the original and a changed version are synced, but you can’t modify the adjustments.)
Why edit an image at all? You’re typically trying to fix a problem:
The edges of the tonal range. The highlights (lightest areas) appear blown out or fully white with no range. Or the shadow detail (darkest areas) is too black, making it hard to distinguish what’s depicted.
White balance. The image has the wrong color cast.
Noisiness or blurriness. The image was taken in low light and is full of noise or lacks sharp definition.
Overall muddiness with tones lumped in the middle without good differentiation.
A lack of snap, where a picture seems to leap off the screen.
Photos offers overlapping tools that help with each of these problems. Double-click any photo in the app until it’s shown at full size, and then click the Edit button at the upper-right of Photos window. (When you’re using iCloud Photo Library and have the preference set to optimize, if this image isn’t stored at full resolution on your Mac, Photos will download it for editing.)
Tip: To get the best results when editing, shoot in RAW mode on your camera. RAW isn’t a single format, but a way for cameramakers to store unadjusted photo data that contains more information than a JPEG or other format that is made in the camera’s software. This preserves more tonal information. Every camera that supports RAW has a different way of enabling it, and the files are much larger than an equivalent JPEG, so consult your manual.
The Edit view changes the white background to dark and adds a row of editing options at the right: Enhance, Rotate, Crop, Filters, Adjust, and Retouch. A Red-Eye control appears when Photos thinks you’re working on faces, but you can force it to always show up via the View menu. I’ll be covering just Adjust in this article.
When you click Adjust, you’ll see just a subset of all the available controls. Click the blue Add button at the top, and you can select to show or hide any control one at a time. When you’ve figured out the right combination, choose Add > Save as Default, and that will be your automatically displayed adjustment set. My default set includes everything but Vignette and Black & White, which I don’t routinely use and can show as needed.
One tricky element: when you select an item from the list, Photos applies it. So if you select Vignette, you will suddenly see a softly feathered edge haloing your entire image. Click the bluecheck checkmark next to the Vignette item, and it’s disabled.
Each item appears initially in its “collapsed” form with a slider showing a numeric display or an array of image variations, except for White Balance and Levels. Hover over an item, and you’ll see an Auto button appear. Click the Auto button, and Photos applies its best algorithmic adjustment.
But each adjustment—except Definition, Noise Reduction, and Levels—also hides more detail. Again hover near the adjustment’s name, and you’ll see a downward-pointing expansion arrow. Click it, and more detailed settings appear.
For most photos of people and landscape, the goal of image adjustment is to either bring something closer to reality, by matching tonal range, color, and clarity to what you saw; to enhance it, and bring out details that might have been invisible or underemphasized in person; or to stylize the image data to bring out an aspect or set a mood.
You might associate adjustments only with the first two items in that list, and think of using Effects to achieve the last. But while some effects use an algorithm or mask to apply a treatment, others are essentially a set of adjustments applied together.
Let’s start with the first two cases, in which an image remains realistic. The goal is not have an even tonality from white through highlights, midtones, and shadows to black. Rather, you want a distribution that allows detail to be seen throughout without making it unnatural. (High dynamic range or HDR images often look supernatural because they are able to preserve so much tonal variation across the entire range.)
Light is the single most important correction you can make, and it’s often paired with Sharpen, Definition, and Noise Reduction to produce a more balanced and crisp image. White Balance is often less important, because the automatic white balance in many cameras provides the best match. The Auto option in Photos seems to handle cases that don’t, such as when a photo is shot with indoor lighting but a camera is set to sunlight conditions.
Drag the slider back and forth on the main Light visualization and you can see, sometimes with a short lag, how several aspects of the image change at once. Now click the expand arrow to the right of its label, and you’ll see six separate sliders: Exposure, Highlights, Shadows, Brightness, Contrast, and Black Point. Watch the associated video for an interactive look at these controls.
Dragging the main Light slider changes each of those settings according to an algorithm that rebalances tones. You can view these changes, too, in the Histogram display at top, which shows the distribution of color (as red, green and blue) and the overall tonal range (as gray) from darkest at left to lightest at right. The histogram shows the percentage of color at each tonal value on the scale.
Most photos are either too light or too dark, but Brightness and Exposure by themselves can’t solve that. Both are coarse tools: Exposure moves all the tones in an image towards the brightest point, or white; Brightness largely makes the darkest tones lighter. Both controls can blow out the lightest parts of a photo, eliminating detail. It’s best to use Exposure rather than Brightness, and to use a light (ha ha) hand, moving it up just slightly. Highlights redistributes the
Contrast is a linear adjustment, increasing or reducing the distribution of tones in the middle. Move Contrast lower, and tones spread out, becoming muddy; higher, and they move to either end, becoming stark.
It’s often the case that if you need to bump Exposure, you back off on Highlights, as the Exposure has already pushed up the lightest values. Going below the zero point on Highlights brings some detail and range back. Likewise, the Shadows slider can be bumped above zero to pull out detail hidden in darkness. Too far, however, and camera noise, which is prevalent in the darkest areas, starts to show up, as well unwanted detail.
The Black Point lets you set a cutoff point for the blackest part of an image. Move the control to the left, and midtones become grayer; move it right, and midtones transform into black more and more.
The Sharpen, Definition, and Noise Reduction commands work as as set. Sharpening increases the contrast between adjacent pixels that are already some tonal value different, like turning a shallow dropoff into a cliff. Definition reduces muddiness or the sense of “haze” across the entire image. Noise Reduction smoothes patterns that are typically artifacts of the limits of camera sensors—adjacent pixels that are radically different in color or tone.
Most images benefit from some sharpening, because our eyes are terrific at recognizing edges between distinct tones; emphasizing that makes an image seem more “real.” Hazy images can do with an increase in definition as well, but it typically works best with nature rather than people or objects, where too much definition makes a subject look unnatural, ironically. Reducing noise in any image in which you can see speckling in the dark or light areas will reduce its artificiality as well, but too much can introduce an uncanny valley of smoothness.
One final tip: When you’ve found an optimum adjustment for one photo and you want to fix similar ones, you can choose Image > Copy Adjustments on the modified photo (Command-Shift-C), and then on any other photo, select Image > Paste Adjustments or press Command-Shift-V.
Photos rewards experimentation in a way that iPhoto didn’t. iPhoto had some of these controls, but not all, and they didn’t provide the same feedback and interaction. In just a few weeks of using Photos, I’m making much more effective adjustments in Photos, although Adobe Lightroom remains the gold standard for extremely fine-grained control.
If you find you’ve made an error, Photos has a very deep level of Undo, although I couldn’t find the bottom, if there is one. All adjustments are reversible through sliders as well, or by clicking a Reset Adjustments button to revert to the original. Even clicking Done doesn’t doom you to changes: you can always click Edit again and reverse or change any manipulations.