News and Views from Dave Wilson

Archive for February, 2011

HDR Tip #1 – HDR From A Single Raw

by on Feb.28, 2011, under Photography

This week, HDR aficionados Rick Sammon and Trey Ratcliff are offering a week of HDR tips so I figured what better time to throw out a few tips of my own. I can’t promise to write one each day but I’ll try to get as close to this as possible. Without further ado, here’s tip number 1.


Caerlaverock Castle

Most of us who do HDR find ourselves in a situation once in a while where we would love to produce an HDR image but only have a single raw image to start with. Common causes for this are that we didn’t bracket when we originally shot the image we want to process now or that we want to take a picture that contains a lot of movement. In these situations, we can, however, still make use of Photomatix to produce an HDR-like image from that single original exposure and the results can often be very appealing. The image above, for example, was generated from a single exposure I shot while on a tripod-less trip back to Scotland a four years ago.

Many people, including several photographer friends whose HDR work I respect enormously, produce HDRs from single raw files using a workflow that goes something like this:

  1. Create 3 virtual copies of the original image in Lightroom.
  2. In the develop module, pull the first image exposure up by 2 stops so that it is brighter.
  3. Again in the develop module, pull the last image’s exposure down by 2 stops so that it is darker.
  4. Export all 3 images to JPEGs (hence creating the bracketed set you need to create an HDR).
  5. Open Photomatix and merge the 3 JPEGs together to give an HDR image which you can then tonemap and process as normal.

This sounds reasonable, doesn’t it? To create an HDR, you need a set of brackets and this gives you that set of images so all is well.

What these folks don’t realise, however, is that they are wasting about 20 minutes per picture and likely ending up with an image that is not as good quality as it should be.

Why not try this instead?

  1. Open Photomatix.
  2. Choose “File/Open…” and point it at the single RAW file you want to work on.
  3. Process as if you just merged a bunch of brackets.

“That can’t be right – it’s far too easy!” you are likely shouting by now. The truth of the matter is that this is likely to give you a better result than the long and complex “generate your own fake brackets” approach described above. The original raw file has at least 2 stops and most likely at least 3 stops more information in it than the JPEGs you create in the awkward workflow. The JPEGs you export there throw away all but 8 stops (8 bits) of the data so by using exposure modification to generate your pseudo-bracket,all you are doing is deciding whether you throw the information away from the highlights or shadows in the different JPEGs. You then open these in Photomatix and have it try to reconstruct the very same data that you were so careful to throw away in the export step.

Photomatix is perfectly capable of extracting all the information from your single raw file so why not have it do the work instead of trying to help (but actually making Photomatix’s job more difficult)?

People who have heard me talk about this before may note that I’m breaking one of my golden rules here which is never to have Photomatix process my raw files. HDRSoft themselves admit that Adobe Camera Raw (the raw file processor inside Photoshop and Lightroom) does a far better job of rendering a raw file than their processor so I always use Lightroom to export my brackets to Photomatix. If you want the best possible quality, you can do the same thing here as long as you remember one very important choice. When you export your single image from Lightroom to send to Photomatix (which, incidentally, you can do via the standard Photomatix plug-in by just highlighting a single image rather than a whole bracketed set), make sure you select “TIFF 16-bit” as the output format. A 16 bit TIFF file allows you to save every bit of dynamic range information from your original raw file and pass it over to Photomatix. If you select JPEG at this point, Photomatix will only receive 8 bits of information and can’t, therefore, pull out any extra dynamic range since you’ve already thrown all that data away.

Next time you are tempted to muck with your exposures in Lightroom and create a fake bracket, give this a try and see what you think. I’m confident you will see that in this case the easiest approach can also be the best!

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Talk at CapMac Photo SIG this Thursday

by on Feb.20, 2011, under Photography

I’ll be giving a talk on HDR photography this coming Thursday evening at the Austin CapMac Advanced Photography SIG meeting. Come along to the parish hall of the Episcopal Church of the Resurrection at 6:30pm and join the fun.

My plan was to revamp the talk and update it so that anyone who had previously heard it at Hill Country Photography Club or Austin Shutterbugs would find new material to listen to and new pictures to see but my laptop hard disk decided to die yesterday so I may be dragging pictures from Flickr and winging it if Dell doesn’t come through on their “next business day” service promise or I don’t manage to get my backup restored in time. My fingers are crossed!

As another upshot of this failure, the photoblog is going to be quiet for the next few days. The failure occurred as I was exporting a batch of images for the next week’s posts so, unfortunately, they will be delayed until I get everything back up and running too.

I can’t help noticing the irony of me having a catastrophic PC hardware failure (in a 1 year old drive – I’ve never had a hard disk fail in less than 5 years before) the very week I’m supposed to be speaking to a Mac user group. Oh well…

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Guest Post on ScottWyden.com

by on Feb.15, 2011, under Photography

A couple of months ago, New Jersey-based photographer and HDR aficionado Scott Wyden invited me to write an HDR tip for an ongoing series on his blog. The article was published today and you can find it here. I would love to hear what you think so please leave a comment over there and let me know.

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Chromasia Workshop Debrief

by on Feb.13, 2011, under Photography

Daisies

Last weekend saw the culmination of about 5 months work for me with the arrival of David Nightingale in Austin to give two workshops at Dragonfly Gallery. David is author of the popular “Practical HDR” and is widely known for the gorgeous, subtle images he publishes on his photoblog at chromasia.com. He spent a week in Austin and taught two workshops, a one day “HDR Crash Course” and a two day “Creating Dramatic Images.”

Despite the weather trying its hardest to thwart our plans – the temperatures dropped into the teens the day after David arrived and sat there rather stubbornly until the afternoon of his first workshop four days later, resulting in a couple of weather-related cancellations and us having to put the class start time back two hours – things ran smoothly and the students, myself included, got a great deal out of the weekend.

I didn’t learn a great deal during the “HDR Crash Course” though it was interesting to see how someone else goes about teaching the topic since this is a class I have taught at the gallery in the past. David’s approach was very much more “hands on” than mine with the emphasis on the behaviour of all the Photomatix tone mapping settings and with plenty of time for people to process the images shot during the outdoor portion of the class. Due to the late start, we abandoned plans to visit the State Capitol and, instead, shot exercises in the vicinity of the gallery. This worked beautifully since we saved at least 40 minutes that would otherwise be taken up in travel yet we had no shortage of great subjects in the architecture around the area and the park behind Central Market on the opposite side of Lamar Boulevard. The upshot of this was that everyone had a lot more time to process pictures and I’m pretty sure I’ll carry this forward to my own classes in future.

The highlight of the weekend for me was the “Creating Dramatic Images” class taught on Saturday and Sunday. David’s approach to post-processing is dominated by the use of Photoshop’s Curves adjustment layers so much of the first day was spent explaining the potential of using Curves and illustrating how they can be used for global and local contrast adjustments. The second day expanded on this, with Curves-based colour adjustment and correction introduced and moved on to consider various other tools that can be used for colour control – the Channel Mixer, Black and White, Hue/Saturation and Selective Color adjustment layers. We also spent some time working in LAB colour mode and explored the possibilities offered via the Curves layer here for saturation control and hue alteration. Although I’ve been using Curves for several years, I’ve been rather conservative and tended to use it solely for local contrast adjustment so this class really opened my eyes to a lot of new uses and left me with plenty of new tricks to play with!

Overall, then, I would rate the visit a great success and I very much hope that David will return next year to teach a few more classes at the gallery. That said, I’m hopelessly biased but perhaps some of the folks who attended the class will comment and offer some independent opinions.


Wrecked Fire Engine, Johnson City, Texas

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