4th June 2015 – On High Dynamic Range Imaging and Marmite questions.

HDR Imaging. What does it mean to you? Horrible Disastrous Rubbish? Highly Desirable Representation? Something in between? Our much welcome and returning speaker, David Southwell ARPS would admit that there is a lot of the former around but if done properly, High Dynamic Range images are an important tool in the photographers tool box. Most of his ARPS panel consisted of them taken in the demanding situation of the interior of Bristol Cathedral. Thoughts were certainly provoked and the discussion afterwards was more animated than usual which would suggest that this is a bit of a Marmite question, “Love, it hate it, you can’t ignore it” as per the advertising slogan. We will return to this later, for Marmite questions have a hidden truth within them.

David did an excellent job of explaining the technical origins of HDR, essentially boosting the fixed capabilities of digital images to catch a range of 6 – 6.5 EV at best (depends on the sensor construction and other factors), or about one half that of the human eye (10-14). Using software and exposures of the same scene metered between exposure for shadow detail to exposure for highlight detail and the range in between (see here for a much more detailed explanation and on how to go about creating a more natural version of the effect) a single image is produced capturing the entire range of luminosity values in the scene. There is a more technical and vastly more expensive way to create HDR using oversampled binary image sensors. Here is what Wikipedia has to say about that and for the rest of us, rest assured they will be coming to high end mobile phones in the near future.

Some DSLR’s, CSC’s, Mobile Phones have an HDR facility built in, but this will almost certainly work with JPEG’s which have a more limited dynamic range than versions of RAW or Tiff. Handled carefully they can be effective, but as always there is the question of how much control is needed, required or is desired by the photographer. The camera processor and choice of jpeg format mean that certain assumptions have been made at the coding stage you do not have an input to. David left us in no doubt that, whereas process can be automated, shoot in RAW (preferably 16 bit, but 8 bit has got him some spectacular results). Your standard 8 bit image (as used in JEPGs and a lot of cameras shooting RAW) gives you 16.8 million colours (more than you can see) and 16 bit 281 trillion (far, far, far more than you can see). 16 bit gives you far more subtlety to play with, whereas 8 bit tends towards grouping colours into bands rather than representing them as subtle variations of colours. In a not particularly accurate but certainly useful way of looking at it we can say the difference is in the ability to reproduce shades, though the human optical processing system does vary from individual to individual. David asserts that 16 bit is the future and for those interested in HDR and, eventually, all photography, so now is a good time to start working in it as far as you can.

But why bother if all we want is the picture that represents a decent looking image of the widest possible range? Well now this is the tricky bit and where its detractors get dismissive of the technique. Before we touch on that, and we can only really touch on it here for reasons of time, space and the need to preserve a semblance of sanity, we need to deal with that problematic idea that you can only make art through fine motor skills. We have treated with this before (27/11/14) so I am not going to go into it again, but part of the attraction of HDR is to make the photograph look more like a painting. OK this is a gross simplification, a minority point in a minority interest, but that does not undermine its validity. Photography’s inferiority complex has existed since print 1 frame 1 in the history of photography. Both are trying to make that emotional connection with the viewer. If that is absent it doesn’t matter how good the draughtsmanship, the image does not work.

David made the point that it is, despite his determined advocacy of the technique, only ONE tool in the box, a very important point. We all have our favourite tools. He gave an estimate of about 3% of his own photography – and this coming from a man who needs 16 TB storage space in his computer system and a high end spec to match in terms of graphics and processors, memory and monitors. To give you an idea, that’s about 640,000 25mb raw images, if my maths is right, so 20,000 ish frames to make up his HDR section when full – with David spending up to 8 hours getting it right on each one! Slightly more involved than Justin Quinnell’s equipment needs, for sure, but they are two ways of making an artefact, two different ways of making a connection. The other 97% isn’t and that is the point. There is no technique that suits all horses on all courses but the more techniques a photographer can master the more complete that photographer will be. Not in pseudo competition with fine art, but in terms of their own personal development and capabilities. HDR has a role to play in getting emotion into an image, certainly it gets a reaction like no other photographic technique I have come across. That’s the art of photography.

OK let’s not tot up the cost of the sort of system David is talking about, he is a very experienced photographer with deep roots in computing. Looked at that from that perspective it just puts the technique out of the range of most of our pockets in the club. HDR can be done on a laptop using programmes that aren’t Photoshop. David reckons that layers and blending, cloning and careful metering are the basics and they can be practiced in any number of ways. Indeed Photoshop isn’t fully 16 bit yet and the vast majority of monitors out there cannot handle 16 bit data and the ones that do will cost you about the equivalent of the average UK wage. Start in 8 bit and make your way up. Practice, practice, practice the basics. Be critical, seek criticism, put the feedback into your practice. The same points were made by the last speaker.

So let’s come back to the Marmite question again. “Love it, hate it, you can’t ignore it”. That is simply not true. Looked at logically the vast majority of the British public remain in denial that Marmite is a big issue facing the United Kingdom. It’s a clever ruse to sell a strong tasting edible (or inedible depending on your view) spread. If a Marmite insurrection has sprung up then it has passed me by. HDR certainly provokes strong opinions, but in ten years time it may be a capability so ubiquitous in photographic equipment that we give it no thought, in exactly the same way as most people do with most Marmite questions. Depth of field may be going the same way, where the out of focus becomes a filter you apply. The technology has been around for a while, only now it’s electronic. Those that do tend to feel strongly about this sort of thing, feel very strongly indeed, how do you like Marmite?

N E X T  M E E T I N G

Your Picture Your Way – Architecture & Artistry. Bring an image or two on these themes and give us some insights on the who the what, the why, the where, the when and the how!

A N N O U N C E M E N T S

Monday June 15th – peaking between 00:30 and 02:00 The Milky Way.