Bracketing and Layers to Cope with Contrast

Blazing Sunset

"Blazing Sunset"

The Nikon Coolpix 5000 has a very nice feature - Auto Bracket. It allows you to choose either three or five shots and intervals of from 1/3 stop to a full stop between shots.

The sky was heavily overcast with a small break at the horizon, and I thought that the moment the sun dropped low enough to illuminate the underside of the clouds there might be a reasonably dramatic sunset. In fact, there was.

I set the camera for a five-shot bracket at the maximum of a whole stop between shots. The sun did its part and set the clouds aflame. The .68x converter was on the camera, giving the equivalent of a 19mm lens on a 35mm camera. Camera was on tripod, and the composing was done on the CP5k's swinging LCD monitor.

When the light was at its most dramatic, it was just a matter of pushing the shutter five times or setting on Continuous Low and holding the button as the camera stepped through the exposures.

Once in Photoshop, the darkest exposure was assigned the role of background image. The next lightest exposure was layered over it, and assigned a layer mask.

When a layer mask is assigned, one can paint with any of the Photoshop tools and either black or white. Black renders the layer transparent and white renders it opaque, so if you get overly enthusiastic and blow away too much of the layer, you can just paint it back again with white. I use a Wacom Graphire pad and stylus that responds to pressure, driving the Airbrush tool, generally with a very soft edge.

There was detail along the horizon in the background shot with the exception of just a tiny bit blown out around the sun as would be expected. The top layer had a considerable band where there was no detail and this was painted away, revealing the horizon detail of the background image, while smoothly blending it with the soft brush.

The two layers were flattened and the middle exposure - the average was layered, and again the masking and painting out of the lost detail was done. Same with the next to lightest layer.

Finally the lightest exposure was layered on and the whole sky was removed. Levels was used to adjust the overall balance of the foreground, light enough to see detail, but not too light to be believed. A little additional painting was used around the trees to control a bit of flair and then the final layer was flattened.

The whole image was selected and the Distortion tool was used to deal with the foreshortening of the super-wide lens when tilted upward. Levels again was used to set the dynamic range of the whole picture, a small amount of unsharp mask applied, and the picture was reduced and saved with JPEG compression for the web. The original was shot and processed with the full 2580 x 1920 resolution of the 5MP camera.

Following are many examples of how this technique can be easily and effectively used in a goodly variety of situations.

Bracketing and Layering for Architectural Interiors

An even simpler process was used in the following illustrations. The Magic Wand was set to a tolerance of 16 and the brightest spot on the upper layer was selected with "Contiguous" turned off. The selection was expanded by 10 pixels and feathered by 15, and the delete key was used to reveal the detail below.

Not quite as precise as the layer mask/airbrush approach but much quicker. These figures were for full frame 5MP images. A bit of testing would be needed for other resolutions.

Note that while there is excellent shadow detail, only the very brightest lights are at the maximum lightness. Detail is retained in the signage.

See addendum below.



"Second Cup"

"Second Cup"

Food Court

"Food Court"

The Mask at the Mall

"The Mask at the Mall"

A huge Commedia dell'arte mask hanging the "Bourbon Street" area of the vast West Edmonton Mall. Five shot bracket at full 1.0EV intervals.

Prince House, 1894

"Prince House, 1894"

Shot at Heritage Park Historic Village, Calgary, Alberta Canada. Five exposure bracket at 0.7EV intervals.

Bracketing With People

I have pizza with a group each month at a Boston Pizza in Sherwood Park, Alberta Canada. The room is primarily lit with neon tubes and a few incandescent fixtures. There is a vivid display of signs in the kitchen area. I have been struggling to handle the contrast range with the RAW format it the past with less than spectacular results, though some gain over JPEG.

This time I shot with auto-bracketing over a five stop range. I had few expectations, but the results were very good - at least technically. While the tubes themselves will blow out, the surround was retained quite well and colour preserved.

Even with a shutter speed range of 1/15th of a second to 1/2 second at f-2.8, ISO 400, movement was not much of a problem, to my surprise.

It might be worth noting the extreme depth of field with the WC-E68 - 19mm equivalent - lens component on the CP5000. Everything from the table card in the foreground to the background is in focus - with the lens wide open!!!

Boston  Pizza, Sherwood Park
Boston  Pizza, Sherwood Park

Nights and Lights

First Lights-On

"First Lights-On"

Staying with friends who had just put their lights up ahead of a major snow storm. When the snow began to let up, and night fell, they turned them on for the first time this year. It is a five shot bracket at 0.7EV intervals. Note the delicacy with which it interprets the lights under the snow.

MGM Grand

"MGM Grand"

Three stop 1.0EV bracket. Shot from across the street from a room in the Monte Carlo.

Park at Nigh

"Park at Night"

A manual bracket of four stops with a full minute exposure for each. VERY DARK. It is mostly lit by the ubiquitous toxic-orange street lights, but the background is lit by a white security light as well. The white balance was set for the streetlight, so the security light recorded as bluish.

Addendum: Easy Masking, Scanning and RAW Image Format.

Addendum: May 5, 2005. I now have Photoshop CS and have changed my described technique above somewhat. I still use the Magic Wand to select the highlights, but now use a much higher value - generally 64 for the tolerance. I do not expand the selection and I set the feathering based upon the shape of the highlights. Trees against the sky receive almost no feathering, while large expanses of wall receive a lot.

I select my highlights in the top layer and then invert the selection and feather. All that is needed to generate the appropriate layer mask is to click the icon, with the top layer selected.

I have found that this approach works well with not only camera auto-brackets, but also with scans and RAW format shots. Photoshop CS supports most of the vital features in full 48-bit workspace, and that is how I work.

When a mask is generated, if there are not some pure whites in the background layer, the results may look dull and grey. Blocking those parts of the mask by using a soft edged airbrush and white will provide the brilliant highlights that are needed to make the image sparkle.

While the litany of digital photography is to preserve highlights and this is generally a good practice, it is impossible and undesirable to do so in all cases. When there are actual light sources in the image area or specular reflections off chrome and the like, these are pure white and should be.

As a general rule, there should be at least a bit of pure white - 255, 255, 255 - and pure featureless black in the image - 0, 0, 0 - or the image will look dull or muddy.

Photoshop CS provides a superb loader for RAW camera files. RAW has the potential for a significantly extended dynamic range. The loader has controls for setting the exposure after the fact, and the effects of an auto bracket can be simulated to some degree. Open the background layer with the highlight detail as you want. Duplicated it so it will be DSCNxxxx-copy.NEF, in the case of Nikon RAW files. Close the original. Unless you create the copy, Photoshop will not let you reopen the file.

Now you can reopen the file and layer as above until you get both the highlight and shadow detail you desire. I find that increasing virtual exposure at half-stop intervals produces a very smooth result.

When scanning a negative or chrome, I use the scanning software to produce a full scale image, with highlights as I want in the final image. With each succeeding scan, I clip more and more of the highlights, masking as above, thus stretching shadow detail to the point that I want.

Boston Pizza March 2005

"Boston Pizza - March 2005"

A RAW file shot under very dim lighting conditions, with far more intense light on the background than on the people. Layering and masking with repeated openings retained detail in the neon, and allowed recovery of detail in the people.

Oregon Beach

"Oregon Beach"

Shot on medium-format colour negative, scanned repeatedly to retain the subtle tones in the sky and still dig out maximum shadow detail in the severely backlit rocks.

©2003 Larry N. Bolch