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Technique PHOTO SCHOOL
Everyone has to start somewhere, even pros, and here we look at the core skills you need. Thismonth: how to read a histogram for better exposures, and use Lightroom’s Adjustment Brush Camera class
Words & pictures by Kingsley Singleton
n How to read a histogram Like any exposure tool, the histogram is there to ensure that the picture looks the way you want it, so broadly speaking there’s no one ‘perfect’ histogram to aim for. For example, if you see a large clump at the left of the chart, indicating lots of black in the scene, that could be good or bad depending on the type of shot. If you’re shooting a dark scene or a silhouette, it’s okay. But if you’re shooting a subject where you want lots of midtones instead of black areas, it’s not so good and your shot is likely to be underexposed. n What is clipping? If an RGB histogram hits either end of the chart, parts of the image are ‘clipped’, and have lost any variation in the tones. Therefore there’s a loss of detail and most of the time that’s to be avoided. If you’re viewing a colour histogram, you’ll see that it’s possible for one colour to be clipped, but not the others, and so long as not all the colours are clipped there’ll be some detail retained. n How to improve exposures Having read the histogram, it’s time to adapt your shooting settings, for example using exposure compensation via the ‘+/-’ button. So, if the picture is too dark dial in a positive amount, like +1 EV, and check again. If it’s too light, do the opposite.
Lightroom local adjustment tools, but the Adjustment Brush is the most versatile, letting has several you make a variety of selective enhancements. Unlike the Graduated Filter and Radial Filter, the Adjustment Brush can be used in a completely unrestricted way. This means you can literally paint in the changes right where you want them, for example making the picture lighter or darker, or more or less colourful. You can adjust the brush’s size, the hardness of its edge and how rapidly your adjustment is applied to the picture. You can also use multiple brushes to build an effect. You’ll find the Adjustment Brush icon in the Develop module, underneath the Histogram, or access it quickly with the K shortcut key. The brush features most of the same adjustments as the Basic tab, but it’s important to set it up correctly before you jump right in. Here’s what to look for. Software technique The Adjustment Brush ADOBE LIGHTROOM n What is a histogram? A histogram is a chart that displays precisely the tonal values in the image or the scene. In its most common form, the horizontal axis illustrates the lightness of the tones; from pure black at the far left, through the shadows, midtones and highlights, to pure white at the far right. The vertical axis shows how many pixels are grouped in each of those zones – the higher the level, the greater the number of pixels of that shade in the scene. On many cameras you can also get a colour histogram, showing the brightness of the individual red, green and blue channels within the picture. The most significant improvement of digital cameras over film versions is the screen. Not just because it lets you compose and review pictures, but because you can assess whether the exposure is correct via the histogram. A histogram is the closest thing you have to a ‘true’ reading of the scene; unlike your eye, it’s not subjective or fooled by ambient conditions. So if you’ve ever shot something you thought was fine only to find out it’s over or underexposed later, then a quick glance at the histogram could have told you already. You can bring up the histogram for images you’ve already shot, and on some cameras add it to the screen or viewfinder while you compose, letting you assess the scene in real time.
HISTOGRAM biased to the left (underexposed)
HISTOGRAM in the centre (correct exposure)
HISTOGRAM biased to the right (overexposed)
NEXTMONTH: More easy-to-follow camera and Lightroom tips to improve your shots.
BRUSH SETTINGS At the bottom of the palette are the Brush settings. You can have two brushes on the go at once, using the A or B options, to swap quickly between them. You can also delete or fade out edits you’ve made using the Erase option. The Size control governs how big the brush is, and Feather sets the softness of its edge (you’ll usually want this set high so your edits blend well with the rest of the picture). ticked, will use edges within the picture to guide the brush, making it easier to adjust complex areas. In the example here, see how the mask has stuck to the shape of the hill, making it easier to apply changes there. To see where you’ve brushed, turn on the Mask Overlay with the shortcut key O, and cycle through the overlay colours using Shift+O. MASKING OPTIONS The Auto Mask option, if
FLOW& DENSITY Flow allows you to build up your adjustments quickly or slowly, depending on the setting. Doing this slowly looks more natural, so unless you want the whole adjustment to take place with one brush sweep, set this to a low number. Density caps the overall amount of adjustment applied. So if you were applying +2.00 of Exposure and set the Density at 50 you’d only get +1.00 in total. BRUSHES & PINS The Brush has an inner and outer circle, illustrating its Size and the amount of Feather. Each time you paint with a new brush you’ll get a ‘pin’ and you can click between these to make adjustments (use Show Edit Pins under the image preview if you can’t see them). You can increase or decrease the overall adjustment you’ve made by clicking a pin and dragging left or right.
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Issue 18 | Photography News
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