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hand-blending high dynamic range (hdr) images using luminosity masks



The Magic Brush

This was a first attempt at hand-blending HDR exposures using luminosity masks and luminosity painting. It took about 30 minutes to figure out, but now that I have a feel for the method, it should go faster next time. It certainly turned out much better than my previous attempt (Figure 21), which was done without the benefit of luminosity painting. For easy comparison, rollover this image with your mouse to see the much improved new version.

Figure 21
Figure 15

I've not run these images through Photomatix or any of the other HDR programs to see if I could get better results. To me this new version looks quite natural and is very much Photoshop-ready. It'll be easy to work with the blended image to improve the overall color balance, saturation, and contrast that I do with all images.

One thing that I especially like about this method is that instead of sliding sliders and typing numbers in control panels in HDR software, I am able to paint the effect exactly as I want it. There is almost a tactile quality to this in that I immediately see on my monitor what my painting does to the image. I can add more or less paint as desired and I can easily reverse what I did. Nothing is permanent with the masks. As the image develops in Photoshop, I can even return and update the blending masks if need be.

As mentioned previously, because the selection of a luminosity mask completely controls which tones get painted, even if I'm careless with the brush, the results turn out well. I've started to think of the paint brush in luminosity painting as something almost magical. It's impossible to paint "outside the lines" because the brush actually creates the lines as it paints. This magic brush is the key to allowing the user to create the specialized masks for blending the different HDR exposures. And the magic isn't only in the way that luminosity painting picks out just the right tones to paint. It's also in the way that it allows the painter to touch the light in a very individualized manner. HDR exposures provide a lot of tones to work with. Luminosity painting provides the control to blend these tones into an image that expresses the photographer's personal feelings for the scene. In creating customized blending masks, the photographer's own hand is determining how the blend the occurs and how it will look in the end.

While I've not experimented with enough images to check out other possible workflows, I think the steps performed on this image would be a good starting place for anyone wishing to try this technique, though different masks in the Lights- and Darks-series may need to be used. In summary, the steps are:

  1. Stack the images on the Layers palette with the darkest exposure on top and the lightest on the bottom.
  2. Create a Hide All (black) layer mask on the layer with the Underexposed image and paint white through a Light-series mask to reveal the lighter tones of this layer.
  3. Create a Reveal All (white) layer mask on the layer with the Normal exposure and paint black through a subtracted Darks-series mask to conceal the dark mid-tones on the Normal exposure in order to allow the lighter tones from the Overexposed image on the bottom layer to show through.

I'm certainly going to try this again and hope you will too. It's still pretty new to me, so I would enjoy hearing about your experiences in using luminosity painting to blend your HDR images. You can always with any comments, questions, or suggestions. An eBook of this tutorial is available as part of the  Special Offer