Issues in HDR Tone Mapping

Candyland Sky
©Joe Bridwell
Convoluted, chocolaty red rock shapes contain subdued white sandstone stringers. Long sky cloud stringers subtly emphasize the point-counterpoint red rock surface. I find God's handiwork quite artistic...

What's the Best HDR Software for Noise Reduction and Chromatic Aberration? We've compared Photomatix and CS4 for Magic Hour HDR. When you use Lightroom to remove noise and chromatic aberration before HDR, Photomatix returns an image with chromatic aberration - though you requested it be removed.
CS4 provides a clean image; although processing may be more convoluted, when the end result is printed on large printer, I feel it's worth using CS4.
We describe the entire CS4 process to achieve complete tone mapping. It's an experimental but reproducible process; one where you learn more and get better as you do more of it.

HDR Capture
Five high dynamic Range images were captured at +/- 2EV. The negative EV range contained Noise; images also contained Chromatic Aberration. One might expect such behavior when shooting at Magic Hour, that hour around dawn and dusk.

CS4 vs. Photomatix
With Lightroom 2, we globally eliminated dust smudges, reduced noise, and reduced chromatic aberration for each image before submitting them for high dynamic range processing.
When Photomatix created a 32-bit Tone Compressed HDR result from these images, chromatic aberration was present. When CS4 created a 32-bit Local Adaptation HDR result, chromatic aberration was absent.

Tone Mapping in Several Stages
When CS4 receives images to Merge to HDR from LR2, it may take a little while to create a 32-bit file. We recommend you save that 32-bit file because you may want to work with it later.
Image> Mode> 16 Bit brings up the HDR conversion routine in CS4 to create a 16-bit tif file. Use the drop-down menu to choose Local Adaptation, set Radius about 90 pixels, choose Threshold about 1%, and carefully map the Tone Curve. Martin Evening has pointed out that tone curve mapping of an HDR image is both complicated and different from the normal tone curve choices for a single image.
The HDR result may same bland; little distinctive color, sort of soft.

Mask Sky and Ground with Color Range
Magic Hour is enhanced by dramatic clouds. It's usually easier to select sky and clouds to create a mask between sky and ground. For this task, I use Color Range. By setting small values for Fuzziness and Range, the mask selection usually fits the boundary fairly well.
It's a very good practice to examine the image at 2:1 (200% zoom). Although keystroke techniques differ between LR 2 and CS4, this scan size lets you look for various effects which would be immediately apparent on a large print. In particular, you quickly get to see if Color Range selected portions of the sky and ground which need to be corrected in the mask.
When you've completed the Sky mask, duplicate channel, invert the channel, and name it Ground.

Hue/Saturation Color Adjustments with Masks
Create 2 adjustment layers using Hue/Saturation. Attach the Sky mask to one, then find the right sky color using Hue. Attach the Ground mask to the other, then find the right ground color using Hue.
When appropriate colors are found, vary Saturation and Lightness until the colors reflect nearly true colors from the 0 EV image on the initial capture.

Final Tone Mapping in Lightroom 2
Lightroom 2’s close connection with Adobe Camera Raw provides easy Basic, Tone Curve, and Details tabs for final, accurate touch up. We pay particular attention to contrast, clarity, and vibrance. We apply the landscape preset then carefully enhance the masking portion of sharpening to finalize our image.

Finale…
I thank Bob Weber for a very enlightening session where, among many other topics, we dealt with fringing and correction of chromatic aberration. It prompted me to prepare a more detailed workflow describing how to use LR 2 and CS4.

Enjoy…

Bosque Delight

Serendipity

©Joe Bridwell
Sandhill Cranes seek night’s peace as they land and settle in for dark. Our result is a soft, cloud capped sunset where cranes seem to stand silhouetted in orange bas relief… The Bosque del Apache is world famous for such views.
Nikon D300, 24-105, 105 mm, iso 200, f6.3, 1/50, 1/100, 1/25 ~ 14-bit
We captured 3 HDR raw files three minutes after sunset, then processed in Photomatix and Lightroom 2.

Camera v Eye
Our eye sees much better than a digital camera. We instantly record all nuances in a scene, yet our camera only captures a limited portion of scene. When we automatic exposure bracket, we capture a range of contrasting light which is called high dynamic range HDR. With software, our computer can ‘add’ these images together to produce an approximation of what our eye saw.

Photomatix
Most digital HDR shooters use Photomatix Pro. It adds two images together, then asks you to Tone Map. There are 2 variants; Detail Enhancer (DE) and Tone Compressor (TC).
This is a Magic Hour shot (that hour around dawn and dusk); strong dark foreground and light sky. Of course, its complicated by water’s reflection – but it’s this enclosing reflection which adds so much to the sandhill’s charm.

When one compares histograms, Detail Enhancer gives one HDR histogram profile – this profile is not in concert with the 0EV manual capture histogram from the 1st HDR image. Basically, DE moves the original histogram capture from Shadows to Lights – seeming to blow out the HDR compilation.
Tone Compressor gives a histogram pattern similar to 0EV capture.



We save the 32 bit TC file as a 16 bit tif for further clarification in Lightroom.

Photomatix provides global controls for changing luminosity, tone, and other parameters. Because subtle light variations can decidedly enhance this HDR image without making it ‘science fiction’ in appearance, we will only take the TC product and more subtly tone map it in Lightroom.

Lightroom 2
Lightroom 2 allows local brush control on restoring the resulting HDR image to what our memory saw by eye.
We begin by making Virtual Copies of our HDR tif file (Ctrl-‘) – to allow future growth. Each change we wish to make in Lightroom becomes its own slightly improved baby; for me, my mind changes over time and software improves over time, so this is a good workflow.
With our Tone Compressed file, we change exposure then added clarity and virbance using Lightroom sliders in the 1st copy. Copy 2 allows us to make Medium Contrast using Tone Curves. Copy 3 lets us work with graduated filters. Copy 4 lets us try to reduce bird motion caused by the time difference in taking individual HDR images using the local adjustment brush. This last step is like burning in the shadows left when birds move their heads in search of food. Copy 5 lets us sharpen the result.

Final Image
After we complete Lightroom's Develop module steps, we return to the Library Module and Export the ‘final’ image as both a DNG and jpg file. Meanwhile, our Catalog contains all history changes for each copy. Both files are placed in a laptop portable Catalog we used for this particular project development.

We developed this HDR workflow approach based on knowledge of how histograms reflect the reality of capture, what different global tone mapping tools might or might not do, and the marvelous precision attained with new local, nondestructive brush tools in Lightroom. We executed our local Tone Mapping changes on a Wacom Pen Tablet using current upwardly mobile software tools – which we expect to only improve.
Enjoy…

New Lightroom Plugin for Photomatix Pro

You can now perform a seamless HDR image construction between Lightroom 2 and Photomatix…

When Matt Kloskowski, NAPP, recently began the crusade to get Lightroom and Photomatix to really communicate, we had v 3.1.2 Photomatix and a plugin which would take files into Photomatix, but not return them to LR. This left it up to us to move such files back into our working catalog.

Most of us are used to LR2 sending a file out to Photoshop then seamlessly getting the result back. The guys and gals at HDRsoft promised to remedy the ‘dangling file’ situation post haste.

With advent of 3.1.3 beta4, Photomatix now has a new plugin to integrate with Lightroom It only runs on the new beta vice 3.1.2. When you select 3 or more images to process for HDR, Photomatix brings up a dialog box. At the bottom, this box asks you if you want to return the result and stack it with your original images. You may choose either 8 bit jpg or tif formats. You may also choose a 16 bit tif (my normal choice since I shoot raw).

So you will want to download the new beta to speed your HDR processing.

Tony Hillerman, 1925-2008

From my vantage point along the ancient dike, the Sun had dropped below the western horizon, casting long shadows down its backside. Yet, direct sunlight was reflecting from Ship Rock. A slight front was trending southeastward from Utah, up north past Four Corners. Highest cirrus clouds, seeming to consolidate the eye, jaded from Ship Rock's beauty, trailed to the edge of the world.

The basalt dike, Mother Nature's bold brickwork wall, trending from the upper right edge toward distant Ship Rock, acted as an arresting lower frame for our image. Magic Hour's shifting sunset pastel lights, some direct, some reflected, add a softer, evocative upper element.

Ship Rock, that ancient almost Gothic spires lit by the setting Sun's golden hues, assists with the same silent wonder, bears prolonged silent witness to man's wanderings across this dry, semi-arid desert. The distant Roman nose shape of Sleeping Ute Mountain is another famous, dominant Four Corners landmark.

"I love the place," Tony Hillerman wrote of vast tribal lands that span the northeast corner of Arizona and straddle the borders of New Mexico, Utah, and Colorado. "I need only drive west from Shiprock into that great emptiness to feel my spirit lift."

Over 10 years ago, Hillerman penned The Fallen Man…

They could see the snowcapped top of Mount Taylor looming over Grants, New Mexico, about 80 miles to the east, perched on one of relatively few outcrops of basalt in what Ship Rock climbers call Rappel Gulley. On the way up, it was the launching point for the final hard climb to the summit, a slightly tilted but flat surface of basalt about the size of a desk-top and 1721 feet above the prairie below. If you were going down, it was where you began a shorter but even harder almost vertical climb to reach the slope that led you downward with a fair chance of not killing yourself.

Whiteside slid along the wall, getting closer. He was moving slowly along the cliff, body almost perfectly vertical, toes holding his way on perhaps an inch of sloping stone, his fingers finding the cracks, crevices, and rough spots that would keep him balanced if the wind gusted. He was doing the traverse perfectly. Beautiful to watch. Even the body was perfect for the purpose. Just bone, skin, and muscle, without an ounce of surplus weight, moving like an insect against the cracked basalt wall.

And 1000 feet below them - no, a quarter of a mile below him lay "the surface of the world." Almost directly below, two Navajos on horseback were riding along the base of the monolith - tiny figures that put the risk of what Whiteside was doing into terrifying perspective. If he slipped, Whiteside would die, but not for a while. It would take time for a body to drop 600 feet, then bounce from an outcrop, and fall again, and bounce and fall, until it finally rested among the boulders at the bottom of this strange old volcanic core.

It was late afternoon, but the autumn sun was far North and the shadow of Ship Rock already stretched southeastward for miles across the tan prairie. Winter would soon end the climbing season. The sun was already so low it reflected only from the very tip of Mount Taylor. Eighty miles away early snows already packed the higher peaks in Colorado's San Juan's. Not a cloud anywhere. The sky was a deep dry-country blue; the air was cool and, a rarity at this altitude, utterly still.

The silence was so absolute one could hear the faint sibilance of Whiteside's soft rubber shoe sole as he shifted a foot along the stone. A couple of hundred feet below them, a red-tailed hawk drifted along, riding an updraft of air along the cliff face.

Whiteside moved, and stopped, and looked down.

"There's more honeycomb breccia under the overhang," he said. "Lots of little erosion cavities. It looks like some pretty good cracking where you can see basalt." He shifted again. "A pretty good shelf down about _"

Silence. Then, Whiteside said, "I think I see a helmet."

"What?"

"My God!" Whiteside said. "There's a skull in it."

Tony Hillerman, 1996

Over the past 20 years, I've read and reread Hillerman's fascinating novels of the Four Corners. I was deeply captivated with Tony's description of Skinwalkers, Navajo tradition, and the land he so deeply loved. At times, cassette tape players spun breathtaking tales of Leaphorn and Chee as I trekked repeatedly into those beloved wilderness lands Hillerman brought to life in his novels.

Tony... your full life, your incredible ability to tell stories, your writing - I'm simply much the better because you took me far beyond just the land, invested me in the spiritual, and deeply intrigued me with Navajo myth, tradition, and mystery.

A week ago, I captured this HDR image of Ship Rock, knowing then it was very simply one of my better efforts. After Hillerman's recent passing, I found a deep, compelling need to complete the image, whose stories so helped invest me in our gorgeous Four Corner myths and legends.

I dedicate this gorgeous Ship Rock image to you!

"I need only drive west from Shiprock into that great emptiness to feel my spirit lift." Tony, I truly understand…

I suspect your spirit may have joined that of other Navajo spirits atop Ship Rock... may you continue in hozhó. May you walk in peace, harmony, and beauty… !