Wednesday, 22 February 2012

A quick HDR tutorial

Love it or hate it HDR photography has become a highly popular technique and is seen by many as an essential tool for getting the best from certain scenes. For quite a long time I wasn’t too keen on the HDR ‘look’ and often wondered why I would want to ‘ruin’ my images by processing them in that way.  I’ve come to realise however, that when the photographer has an in depth knowledge of how to use their software the results can be stunning. The only reason I hadn’t thought this way before was simply because I hadn’t seen any ‘good’ HDR samples. It’s easy to go in all guns blazing and HDR everything you see and while this is a good way to learn (you’ll make all of the mistakes early on!) it’s the reason the technique has got a bit of a bad name.
For those who have viewed my Flickr stream you’ll know that recently I’ve been trying my hand at interior, architectural photography and what I’ve become aware of is that if there’s one thing that HDR’s well- it’s low light shots inside a building with character. I’ve been exploring both old and new designs and one place I knew would be screaming for tone mapping is the auditorium of the Gala theatre in Durham City. It’s a modern building with a slightly futuristic plan and the auditorium is great mix of rustic and new. Since gaining permission took a little effort and I didn’t know if I’d be back any time soon I erred on the side of caution and took more images than less for each bracket. I was also on a time limit so made do with 5 exposures (it’s still better than three).
I merged the shots in Photoshop CS5’s Merge to HDR Pro software which is renowned for delivering nicely natural results; although this time I was looking for a something a bit more artistic. Since a few people have asked me how I process my HDR shots I thought I’d run through my workflow for the Gala auditorium shot from start to finish. So here goes:-
 I started my downloading the bracketed series onto an external hard drive (it’s better to merge from copies rather than originals as always to avoid corrupting your files) and since they were RAW files I accessed them through Adobe Bridge. I selected all five shots and went to Tools>Photoshop>Merge to HDR Pro.
This then gets Photoshop CS5 to merge all of the brackets into one image for tone mapping. After a while (and it can seem an age!) the HDR Pro dialogue pops up. As you can see the initial attempt PS made in its default settings doesn’t look that inspiring, but you’re presented with the series of sliders you can see here and we’re going to play with those in a moment.

Since I’ve already done the tone mapping for this image I saved all of the settings I chose as a preset; I called it Gala Auditorium1, so that I could call them all back later (which I guess came in kinda’ handy for this blog post!) Presets are awesome because they save you so much time playing with the sliders, trying to remember what you used before. I’ll often scroll through my list of presets and see how they look on a new image; even if they don’t work out of the box they may still get half of the work done for me.

I really was after bringing out all the little details in the wood panelling and the ceiling so here I’ve pushed the Detail slider all the way to 300% but compensated for the over-the-top look this could have given me by keeping the Radius and Strength sliders over to the left and pushing the Gamma to the right slightly to even out the balance of highlights and shadows. Speaking of these I brought out the shadows by pushing the shadow slider to 100 but also nudged the highlights to the right to keep a bit of overall contrast. I didn’t want to overdo things so kept the Saturation low and used a higher Vibrance amount to pick out the under-represented colours.

Lastly I did a quick S-Curves adjustment to kick the contrast a little further. That’s it for tone mapping- I hit ok and CS5 merged the shots for me.

The shot wasn’t quite there yet though- it was a bit flat and needed some more tweaking. For most of the editing in this case I used Adobe Camera Raw, applying some contrast using the Fill light and Blacks sliders and bringing out some more detail using Clarity and by sharpening. ACR’s adjustment brush came in handy for applying localised adjustments, whilst leaving other parts of the image untouched. I love sharpening here because you can really push things to the extreme without introducing any nasty halos and you can easily mask out any flat tones using the masking slider to avoid accentuating noise. There’s also the Detail slider here which can work wonders for bringing out textures such as in the panelling and the curtains around the stage. 

I then opened the image in regular Photoshop for some additional Levels, Curves and Colour Balance tweaks and for cropping. This time I chose a panoramic crop to emphasize the ‘ultra-wide’ feeling, using a 12in x 6in preset that I made. Since this was a theatre I thought it would be a nice touch to add a border above and below the image, simulating letterbox movie film dimensions (even though 12x6 isn’t officially a standard movie aspect ratio). I did this by expanding the canvas [Image>Canvas Size] and adding 15% to the Height field.

That’s it, done. There are plenty of other examples I could have shown you but this is as good as any! A lot of perfecting your HDR workflow and favourite ‘looks’ is down to experimentation and trial and error. I strongly recommend saving your settings as presets since you can always use these as a starting point for every image you tone map and you won’t have that frustrating experience of struggling to remember what you used before. There are a number of software packages to choose from- I just used Merge to HDR Pro because it comes with Photoshop. Why not try Photomatix or Nik software’s HDR Efex pro and see what you prefer?



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