DSC_3460 - Version 2 - Version 2

We return to San Francisco for today’s post, and probably not for the last time because, let’s be honest, who wouldn’t take a LOT of photographs when given the opportunity to take a helicopter tour of the city?  Unlike the previous images that I’ve posted from that tour, this one has undergone a conversion from colour to black and white with the intention of making it all about the form of the buildings.

One of the things that prompted me to post this shot today is so that I can enter it in this week’s Photo Friday challenge which has the topic “Urban Landscape”.   Some of you will be visiting my blog for the first time having read my article on the Digital Photography School website, and you may have seen another article there by a fellow photographer with tips to keep your creative juices flowing.  The idea behind the Photo Friday challenges are to do just that, though when I participate in those, more often than not I tend to dip into my image library for a shot to post rather than take my camera out with the intent of capturing a shot for that week’s theme.

The creativity for me then is often found in the processing I do on the shot, which is why I spent more than the usual amount of time playing around with today’s photo in Aperture.  While I’ve done monochrome conversions before obviously, I wanted to try something different for this image, and was struck by a question I saw online where someone asked about black and white HDR techniques.   As is clear from some of my more recent posts, in the last couple of weeks I’ve been playing with HDR, but always in colour.  I thought this shot might be a chance to try something in black and white.

The original shot was a JPEG (I wasn’t shooting RAW back in 2007 when I took this), and just a single exposure, but I decided to see what would happen if I duplicated it in Aperture and pushed the exposure up and down to create 3 exposures of the same scene.  Unlike with RAW, where all the information is in the 12-bit file to allow you create 8-bit exposures anywhere within 2 stops of the in-camera exposure, for JPEG the software needs to interpolate for any exposure other than the in-camera one, so you are effectively losing some information and creating other information when you alter the exposure in software.  As a result this is not a true HDR technique, but I could still see, when I merged the three shots in Photomatix, that alot more detail came through – particularly in the sky.

That consistency that I’m finding with HDR’s ability to bring out detail in the sky is fast making it one of my go-to techniques for images where the sky is flat.  I’m sure it won’t work well all of the time, but it’s a quick process (that I suspect I could automate in Aperture) so it’s certainly worth a try.

For this shot I did all of the HDR processing in colour before converting the result to black and white.  There are a number of ways to do a conversion like this – the simplest being to desaturate the image completely, the better but more complicated way being to use the channel mixer to control how much each colour in the image is filtered during the conversion process.  That’s the approach I took here, and I like the result.

For comparison I performed a black and white conversion of a non-HDR version of the original JPG and could see that the image above had more detail, suggesting that this approach has merit for at least certain shots.  I wonder if doing the conversion before, instead of after, the HDR processing would yield a very different looking image?

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