11.2 Fixing Blown Highlights

Few things are more frustrating than taking a photo of a beautiful bird in a perfect pose, watching as the bird flies far, far away, and then looking at your LCD and finding that the photo was significantly over- or under-exposed.  If you’re following the ETTR or BETTR protocols described in section 6.2, then you’re more likely to over-expose than under-expose your images.  As long as no important details have been lost through clipping (section 2.7.4), over-exposure is always better than under-exposure, because under-exposure typically increases noise and posterization (via reduced photon counts), whereas over-exposure (as long as the highlights aren’t clipped and no additional feather glare is induced via overuse of flash) simply stores the information in a different set of bits inside the image file.  In this section we’ll address the issue of blown highlights.  In section 11.3 we’ll discuss exposure correction in the more general case.
    When you load your RAW image into Photoshop, it first goes through the Adobe Camera Raw (ACR) converter, as mentioned in the previous section.  The figure below shows an over-exposed image in ACR.

Fig. 11.2.1: Clipped highlights in Adobe Camera Raw.  The red areas indicate
regions that the software predicts will lose substantial detail during RAW conversion,
due to overexposure.  The small white triangle in the upper right corner of the screen
toggles the highlight alerts.  The Recovery slider can often reduce the incidence of
clipped highlights; in some cases it can eliminate them entirely, though in other
cases it can
t.  Reducing the clipping in the bird is most important; reducing it
in the background is typically less critical, though it
s still desirable if possible.

    The red areas in the above figure show the regions in which highlight clipping either has occurred
, or that the software predicts will occur during RAW conversion.  (To enable the red clipping indicators in ACR, you may need to click the small, white triangle in the upper right-hand corner of the histogram in ACR).  According to the BETTR philosophy (Bird Exposed To The Rightsection 6.2), the clipping in the background regions of the image may be somewhat acceptable, when they’re necessary for properly exposing the bird.  But the clipping inside the bird will result in loss of subject detail, which is far less acceptable.  In the case of this particular photo (above), the throat and chest region of this warbler will, if corrective steps aren’t taken during RAW conversion, end up largely as a pure yellow blob with no discernible detail.  Fortunately, many cases of slight clipping can be corrected, either in ACR or in Photoshop proper.
    In the main control panel of ACR you’ll see there is a slider called Recovery.  By slowly sliding this slider to the right you’ll see the red areas (indicating clipped highlights) contract and possibly disappear entirely.  (You might want to try holding the Option or Alt key while doing this, to mask out everything but the red).  The figure below illustrates this for another warbler photo that has been over-exposed.  In the top pane is the original image, while the bottom pane shows the effect of increasing Recovery to 34%.  As you can see, the red areas have been substantially reduced, though not completely eliminated.  That means some clipping is bound to occur during RAW conversion, which we
ll need to correct in Photoshop proper using other methods.

Fig. 11.2.2: Reducing clipping of highlights via the Recovery slider in Adobe
Camera Raw.  Increasing the Recovery setting reduces the extent of the clipping
in the image, though there is usually a point of diminishing returns.  Setting
the Recovery slider above about 50% or so often decreases overall image
brightness without reducing the clipping region appreciably.

     For this particular image, increasing Recovery past 34% does not reduce the red areas significantly; past this point it simply darkens the overall image without reducing clipping in any appreciable way.  You’ll generally want to find the smallest Recovery amount that maximally reduces the clipping without darkening the image too much.  Though you can also reduce clipping by decreasing the Exposure or Brightness settings, these have a more pronounced effect on the overall brightness of the image, whereas moderate Recovery settings generally improve clipping with only the most subtle effects on overall image brightness.
    Once you’ve found a good setting for the Recovery slider and adjusted any other settings in ACR (such as noise reduction
section 11.1) as desired, you can proceed with the RAW conversion and open the image in Photoshop proper (remembering to do so in 16-bit1).  Highlight clipping will no longer be shown in red, but by inspecting your image carefully you may be able to discern a lack of detail in the remaining clipped regions (those that Recovery couldn’t fully fix).  In the figure below, the left pane shows the warbler photo from the previous figure, after RAW conversion.  Notice the homogeneous yellow regions above and below the eye and below the cheek patch.  These were the regions that remained red (indicating clipping) even after using the Recovery slider in ACR.  In the right pane is the result of using the Shadows/Highlights tool in Photoshop proper.

Fig. 11.2.3: Restoring details in bright regions via the Highlights tool.
Left: the original image.  Right: the image after applying Highlight reduction.
The bright yellow areas around the bird’s eye and lower cheek have been
darkened in the right image, and may contain a slight bit of additional
visible detail.  It’s usually best to apply Highlights to just the regions of
the image that clearly need it (via an appropriate selection tool).

     The figure below shows the Shadows/Highlights tool in action.  In section 11.3 we’ll explore the use of this tool in greater detail as we consider the more general problem of correcting overall exposure and lighting patterns.  For now, we’ll limit our attention to the Highlights portion of the tool.  For clipped highlights in bird photos, a highly effective way to use this tool is to first select the bird (or even just a portion of the bird containing the blown highlights) and then invoke the tool via the menu option Image > Adjustments > Shadow/Highlight (on my computer I have this set to the keyboard shortcut Cmd-H, since I use it so much).  I recommend starting out with a small radius and a small tonal width, and then aggressively increasing the Amount slider (in the Highlights pane).  The goal is to reduce the highlights until details start to emerge in the areas where the highlights are (nearly) blown.  In extreme cases you may need to set the Amount slider to 100% and then increase the tonal width until you notice a change.  Beware that if you apply this procedure too aggressively, you’ll notice unpleasant image artifacts, such as excessive gray in white areas.  Also, if you set the radius too small you’ll usually obliterate details rather than enhancing them.

Fig. 11.2.4: Applying the Shadows/Highlights tool to just the bird.
By first selecting the bird (using your favorite selection tool), you
can limit the effect of the Shadows/Highlights tool to just the bird.
It's usually best to keep the Radius and Tonal Width small, and to
explore increasing values for the Amount slider.  Sometimes you
may need to increase Tonal Width to see any effect.  Using a
Radius of zero often obliterates detail rather than restoring it.

     If the Highlights tool doesnt give you the effect you’re trying to achieve, you can sometimes get what you want by instead adjusting the Output Levels white point in the Levels tool.  This is the small white slider at the bottom-right corner of the Levels window, in the Output Levels pane.  Decreasing this slider usually has the same effect as using the Highlights tool, but when Highlights misbehaves (for example, when it wont allow subtle adjustments, or when it induces saturation or contrast artifacts) its worthwhile trying this alternative method. 
    Note that accentuating highlights is best performed before reducing the image size.  If your primary use for your images is to post them on your web page or to distribute them compactly on the internet, you probably reduce most of your images to 25%-50% (or less) of their original size before posting them, so that they fit more easily into the viewer’s internet browser window.  Using the Highlights tool (to accentuate details at the extreme white end of the spectrum) prior to reducing the image size is generally more effective than doing it after resizing, because it brings out more details that can be retained during the interpolation phase of the resizing algorithm.  I always apply the Highlights tool before resizing (downward) if there
s even a hint of blown highlights in the image.  Also, aggressively applying Highlights to a reduced-resolution image can induce a halo around the selected region, while applying it to the full-resolution original before downsizing usually doesn’t.
    Obviously, the Highlights tool (and the Recovery slider in ACR) can’t magically re-create details that were obliterated by clipping.  In the cases in which these tools do seem to be effective, what they are actually doing is merely emphasizing details that are otherwise too subtle to see on your screen, most likely because of a narrow color gamut (see section 5.2.2) or due to other conditions affecting rendering or viewing of the image.  That is, the details were indeed present before you used the Highlights or Recovery tool to bring them out, but you couldn’t see them (well) because either your screen is limited in its ability to render extremely fine differences in color, or your eyes are similarly limited in their ability to discern such differences when faithfully rendered.  In the case of the Recovery slider in ACR, you’re also preventing details from being lost during RAW conversion (i.e., during translation between color spaces and/or bit depths).
    The bald eagle head in the figure below illustrates this well.  Because bald eagles (Haliaeetus leucocephalus) have white heads (as adults), it can be very difficult to discern feather detail in the bird’s head—even if that detail is indeed present in the image (i.e., even if the highlights haven’t been blown).  In the figure below we’ve applied the Highlights tool to accentuate the fine differences in different shades of white in the bird’s head, thereby making it easier to see the minute details in the white feathers.  Note that this process tends to give an overall grayish cast to the bird’s head, which previously was closer to pure white.  This is the cost of this technique, and is largely unavoidable if you want to bring out details in a pure white bird, since shades of white are by definition shades of gray.

Fig. 11.2.5: Restoring visible detail in the white head of a bald eagle.
White subjects are always difficult.  If you expose to the right without
triggering the highlight alerts, you’ll retain all the details in the bird
but you may still need to apply some postprocessing to make those
details visible to the human eye.  Left: original image.  Right: after
applying the Highlights tool.  The right image is grayer overall,
but gives the perception of increased detail, due to fine-scale
contrast in the white areas.

    In those cases in which the Highlights tool fails to bring out enough detail (because the detail simply no longer exists in the image), a common remedy is to clone in detail from a different part of the image (or from a different image of the same bird or species).  This can be accomplished very simply, as follows:

1. Use your favorite selection tool to select a small region of the bird having (roughly) the same color as the area where the highlights are blown (but more texture and details):

2. Convert that selection into a layer, via the key combination Cmd-J or Ctrl-J:

3. Invoke the Move tool (by pressing the V key):

and then use your mouse to drag the cloned piece so that it covers the area of blown highlights:

4. In the Layers pane, set the Blend Mode to either darken, multiply or linear burn, and then reduce the opacity until the new layer blends in well with the original image (typically 20%-50%), leaving only its texture showing through:

The figure below illustrates the effect of this technique.  The left part of the figure shows the original image which has been treated with the Highlights filter.  The bright yellow areas around the eye and the lower cheek still lack detail, so we’ve used the above procedure to c some of the texture from other parts of the bird’s head onto these blown regions.

Fig. 11.2.6: Creating the illusion of detail via texture cloning.  In the left image,
the bright yellow areas around the eye lack detail.  In the right image, these
areas now appear to have texture.  This texture was cloned in from other
parts of the bird’s head.  The texture layers were given a low opacity so as
to blend in with the base layer.  Saturation was also reduced, since the
texture layers had a strong olive cast.

Notice in the right panel of the figure above that the cloned-in textures impart a slight olive cast to the areas where they were superimposed.  This can be rectified by reducing the saturation (of just those regions) via the Saturation filter (Image > Adjustments > Hue / Saturation). 
    A refinement of the above technique allows you to precisely match the sizes and shapes of the source and target areas.  First, select the target area (the area lacking texture).  Then invoke the menu option Select > Transform Selection.  This will allow you to drag the selection to the source area without actually copying any pixels (just be careful when using your mouse, that you don’t distort the boundary; you need to click on the interior of the selection, rather than on the boundary itself).  Once you’ve got the selection boundary positioned in the source area (an area with good texture), just press Enter or Return to anchor the selection there.  Now you can proceed as above: press Cmd-J / Ctrl-J to copy the source pixels to a new layer, use the Move tool (press V) to drag the new pixels to the destination area, and then adjust the opacity as desired (in the Layers panel).  You may also need to de-saturate and adjust Levels to get a perfect blend.  Merging the new layer into the old is optional at this point.
    The next two figures provide another example of the above techniques.  In the first figure below, notice that the bird’s chest contains some very bright white patches (left pane).  The right pane shows the effect of using the Highlights tool on just the bird’s chest, followed by the use of the Levels tool (see section 11.3) to darken the blacks in that region.  Although the new image looks better, the whites in the chest still lack detail.

Fig. 11.2.7: Reducing brightness in regions with blown highlights.
Left: original image.  Right: after reducing brightness of the bird’s
chest via the Highlights tool.  The contrast was also increased by
increasing the blacks using the Level tool.

In the figure below, we’ve additionally applied the cloning technique to add some false detail to the bird’s chest.  The left pane duplicates the image from above (i.e., after use of Highlights and Levels).  The right pane shows the result of cloning in texture from the bird’s chest.  A moderately-sized area of the bird’s chest was cloned and repositioned very slightly (with a low opacity); this was repeated several times with random positioning of the cloned layer, but always in the chest area.  The effect is subtle, but you should be able to see that the bird’s chest has fewer areas of solid white lacking any detail. 

Fig. 11.2.8: Cloning in detail to fix blown highlights.  Left: original
image after applying Highlights and Level tools to the bird’s chest.
Right: after cloning detail from some parts of the bird’s chest to
other parts of the same region, with a low opacity.  Areas that
were previously pure white now have some streaking, to create
the illusion of detail in areas where detail was lost due to blown

     The Highlights tool described earlier can also be used to remedy a problem related to that of blown highlights: feather glare.  In the figure below, the top image suffers from severe feather glare in the bird’s flight feathers and on the bird’s lower back, as well as in the middle part of the chestnut band running down the bird’s chest.  The bottom pane shows the result of applying the Highlight tool to just these areas.  As you can see, the glare has been reduced a bit, though it has not been completely eliminated.  Feather glare is a very difficult thing to fix in postprocess; the best defense against it is to be careful when using flash, especially at close range, to avoid inducing a glare in the first place (unfortunately, bright sunlight also induces feather glare).

Fig. 11.2.9: Reducing feather glare.  Top: original image.  Bottom:
after selecting the regions with extreme feather glare (flight feathers
on the wing, and the bird’s rump and part of its chestnut side).
Highlights were reduced via the Highlights tool.  Some contrast
was also added by increasing the blacks via the Level tool
(moving the leftmost histogram boundary slightly to the right).

If you do need to correct feather glare after the fact, the Highlight tool and a cloning technique similar to that described above can be useful.  For feather glare, you can select the region of the glare, copy it to a separate layer, and then (without moving the layer) set the Blend Mode to multiply, darken, or linear burn with an opacity of 30% to 50% or thereabouts.
    Finally, note that, as with any form of image manipulation, the techniques described above are intended only to improve the aesthetics of the image.  Once you start cloning feathers from one part of the bird to another, your image is no longer strictly a photograph of the bird, but rather more of an artistic rendering.  It’s conceivable that in extreme cases you could end up making changes that are even misleading, especially to viewers hoping to use your images for the purposes of field identification or documentation of migration patterns (e.g., your bird, of one particular subspecies, might start to look more like that of another subspecies which doesnt normally occur in the place where you photographed it).  In my opinion, there is absolutely nothing wrong with manipulating your images in any way that you like for the purpose of creating artistic renderings—just so long as long as you don’t misrepresent a manipulated image as a raw photograph to be used for scientific or documentary purposes.  If anyone accuses you of doctoring your photos, you can simply point out that your images are meant to be artistic renderings of birds, not as tools for identification or scientific documentation.  To the extent that the majority of us lack Leonardo da Vinci’s expertise with oil and canvas, or Audubon’s skill with watercolors, images captured with a digital camera and subsequently manipulated on the computer provide the only opportunity for many of us to create exquisite avian art.  Various crabby and argumentative people (so-called purists) will argue that digital manipulation is dishonest, lazy, and probably even unpatriotic.  I recommend ignoring them, with the caveats given above.

1In Adobe CS3, you can open a RAW file in 16-bit by clicking on the information line at the bottom of the Adobe Camera Raw window, which will bring up the Workflow Options window, and then changing the Depth setting to 16-bit.  All images will then default to 16 bit in ACR until you change the setting back to 8-bit.