Muir Woods is a beautiful place, but a tremendous challenge to photographers. The dynamic range of light is phenomenal: from brilliant sunlight to deep, deep shadows in redwood trees that are already quite dark on their own. Only HDR gives you the opportunity to simultaneously capture blue sky and the details of tree trunks in shadows. The above photo is a merge of seven separate exposures, each one f-stop apart. (Nikon D3S in DX mode at ISO 200, Sigma 10-20mm, f/4-5.6 at 10mm f/5.6) If you’re new to HDR, notice that the sky is blue, not an overexposed white, while you can still see detail in the darkest part of the tree trunks. If I didn’t tell you, would you know this was an HDR image? Does it have those weird artifacts you typically associate with HDR? Note that no masks were used. Only global Lab changes were applied. Below are the two extreme originals.

My workflow (as of today) for images like this is as follows:

• Import RAW images into Lightroom 3.
• Apply camera calibration. (I use ColorChecker Passport and create a new profile for each location.)
• Merge to HDR Pro in Photoshop.
• Use the ‘Flat’ or ‘Photorealistic Low Contrast’ preset. (It won’t look good yet!)
• Change the mode to Lab Color.
• Apply Dan Margulis’ ‘no brainer’ curve in an adjustment layer.
• Increase contrast in the ‘L’ channel.
• Make final color adjustments to the ‘a’ and ‘b’ channels. (The leaves are actually yellow, almost entirely in the positive values of the ‘b’ channel’)
• Save back to Lightroom 3.

I’ve developed (and am still developing) this workflow empirically, and I’m reverse engineering it to try and understand what’s really going on. The idea is to merge the originals into a rather flat (color-wise) image, then work in Lab to recover the colors. Lab is particularly good when starting with these flat, unsaturated images. This seems to avoid a lot of the artifacts that Photomatix and Photoshop HDR Pro create if you use them alone to render your final composite image. So far, so good.