Written by Chris Oaten Friday, 25 February 2011 14:15
There's one thing I really hate in a photo: blown highlights. Big splotches of white where there should be some detail. Aperture users have a few tools at their disposal to deal with over-exposures when they occur.
Careless exposure is one common cause of blown highlights but there are situations where even with careful metering and thoughtful exposure choices, you still end up with splotches of formless white in your image.
The thing to remember if you're shooting RAW files, and I strongly recommend you do for this very reason, is that Aperture's rendering of your RAW file may well show blown highlights. On closer inspection, however, this may not actually be the case. There may be detail in the highlights areas that you can bring out.
Remember that Aperture, when it renders your image on screen, is only interpreting the RAW image data and often it's not truly revealing all the image data available for you to work with. There's a lot more you can do to massage the image into shape — indeed that's exactly the beauty of shooting RAW.
If the analogy helps, the way Aperture renders RAW image previews is like a darkroom-era proof sheet, which comprises an average representation of all the negatives on a strip of film, all exposed to the paper at the same time with no headroom for shadow or highlight detail. When you print a negative, you fine-tune the exposure and other parameters to get the best from the negative. Previews in Aperture's browser/viewer are just like a proof sheet.
There are photographers who regard the post-processing of a RAW file as cheating. Such people tend to believe that if you can't get it right in-camera then you must be some kind of failure as a photographer. Well … bollocks. If you understand the latitude that a RAW file delivers when it comes to post-processing, you can shoot to take advantage of it.
In this first picture of two tennis players shaking hands with Apple's default preview render, you can see the highlights are formless. They are white. White is good, but white without detail, without texture, is bad. Let's fix it up.
Before we do fix it, let's see just how much detail there is in the highlights. By using Aperture's exposure slider to under-expose the image, you begin to understand the exposure latitude in a RAW file while revealing the detail in the players' caps.
But this is not what we want. So let's dial the exposure back up again and this time use the Recovery slider to squeeze those details out while leaving the mid-tones and shadows alone. Like so:
There are other tools to help control highlights and recover details in bright areas of the image. One of these is the Highlights slider, which pairs with the Shadows slider. In the last picture here, I've used that slider just to get a little extra texture in the players' caps. You want to be careful with this tool, because it simply clips tonal values across the board and you can quickly find yourself with a very grey image if you push that slider too far to the right. Of course, if you know what you're doing, or are willing to learn, the Curves tool can fix a lot of these highlight/shadow detail issues, too.
Other adjustments to the final image, below, were: boosted vibrancy, a slight tweak to the white balance to warm the players' skin tone, some boosting of shadows to bring out the blues in the shirt on the right, a slight vignette, and the Dodge tool was used to lighten up the shadow from the cap on the face of the player on the left.
How well I've got my message across may depend on your monitor, so if you're scratching your head wondering where these highlight details are, perhaps your monitor is too bright.
In any case, the tools that Aperture offers for controlling highlights and recovering detail mean you can confidently do what so many digital photographers do — which is to "shoot to the right" or deliberately overexpose the image, a handy strategy when shooting RAW images with harsh daylight, though by no means one you should subscribe to slavishly.
So when Aperture renders your RAW files, just remember when it comes to blown highlights that not being able to see any detail doesn't mean it isn't there.
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