“Instant HDR”: How to spruce up your image with tone mapping


By Alex Stepanov (www.astepanov.com)

I’m sure you know what instant coffee is – drop a spoonful (or two) into the cup, pour in some boiling water and voila! Personally, I can’t survive without that brown stuff. It’s not nearly as good as the “real” brewed coffee but when you don’t have time and/or energy to go out and seek the properly prepared coffee, then this instant mix maybe just “good enough”…

Single image tone mapping is just like instant coffee – it does not produce as good an image as the “full-blown” HDR process would but it may help to spruce up your image with very little time and effort.

Most often, the term “tone mapping” is brought up in connection with HDR photography. Even the Wikipedia article on tone mapping, defines it as “a technique used… to map one set of colors to another in order to approximate the appearance of high dynamic range images in a medium that has a more limited dynamic range”. While tone mapping is certainly a key part of the HDR workflow process, it is often overlooked that the key concept of tone mapping is “recalculating the colors” and HDR is just one of the applications. In other words, you can just as well “tone map” colors of an “ordinary” non-HDR image and often times produce quite remarkable results!

First things first

Before we begin, I’d like to say that in order to fully benefit from tone mapping, you need to start with a good well-exposed image in the first place. Don’t expect to salvage a shot that belongs in the trash bin – more often than not, it won’t happen. Also, tone mapping is more of an art rather than precise science – you need to play with it a little bit to get the feeling and figure out your own personal parameters.

For the purpose of this article, I used Photomatrix 4.2.2 but any other version better than 3.0 will do fine. In fact, if you use some other HDR software, check out the menus – there is a good chance you will find the “tone mapping” tools tucked in somewhere.

Step by step

First, I started with this image of the City of Arts ad Sciences in Valencia (below) that I took last summer.
I use Lightroom plugin as a shortcut (it saves me a few clicks) but you can achieve the same results by starting Photomatrix and loading the file (File -> Open…) and then clicking the “Tone Mapping” button (see the inset below).
The plugin automates all those tasks for me, so once I export the image to Photomatrix, I drop right into the image processing area. Now, Photomatrix comes with a truckload of presets of all sorts but for the purpose of this particular task, I ignore all of them except what is now called “Photographic” (used to be known as “Compressor Default” in the previous versions). Once you click on the preset, the Tone Compressor parameter palette will pop up and at that point, you basically have to start “playing with the dials” and see whether you like the outcome.

A couple of points that are worth keeping in mind while tweaking the image:
* Tone mapping often times increases the graininess of the image so I always check the “loupe” view just to make sure I don’t get some crazy harsh grain
* Usually, I increase (move to the right) the “Compression” slider, while decreasing (moving to the left) the “Brightness” slider. My personal preference is to produce a slightly “under-exposed” image rather than blow away highlights or increase grain to the levels when it is impossible to rid of. The third slider (“Contrast Adaptation”) mostly controls the color intensity and it is up to you how far you’d like to go on that – much like salt and pepper, everyone has a different taste for that. Personally, I try to go rather conservatively.

But let’s get back to our image. Once I’m done playing with the dials and the resulting image looks OK, the final parameter set will look somewhat like the one on the right. Again, every image is different so play away!

At this point, I click on ‘Save and Re-Import’ button, which brings the tonemapped image back to Lightroom for final adjustments. Of those, you may need to bump up the noise suppression a notch or two in order to combat with the increased grain and maybe add some sharpening so that the final image does not become too soft. In my case, I added about 25% of Luminance noise reduction and about 30% sharpening at 0.8 with 40% masking to deal with the increased “softening”.

Once everything is done, we get our final image. Looks not too shabby! And the best part – it took us about 15 minutes from start to finish.

That’s it for now. Have fun with tone mapping and never stop experimenting!

Cheers,
Alex Stepanov, Photographer

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