Trapped Photons

Thanks to PhotoSIG, I started to look more critically at my photos and did not like what I saw: it seems that I have trouble getting the most basic technicalities such as exposure right. Determined to learn more about exposure, I started reading various articles on the Internet and found that overexposing is a big issue in digital photography. I decided that I will focus on getting the exposure right for now and this photo of the Stata Center at MIT is one of my first attempt where I was very careful choosing the right exposure settings. Basically, I used the camera’s histogram function to use as much of the sensor’s dynamic range while avoiding overexposed/blown out areas.  Unfortunately, I had to learn that the histogram function of the Pentax K100D apparently does not show the complete “picture” - this image still has some blown out regions, even though they are only in the red channel.  I guess this is due to the reddish light during sun set.

This is also the first time I used the RAW format to capture the image and spend a lot of time exploring post-processing options.   I love black and white photos and the RAW format gives a much better dynamic range for the B&W conversion.  Unfortunately, none of the open-source RAW format photo tools seems to support B&W conversions.  Luckily, Bibble Labs produce an excellent RAW converter Bibble for Linux users (and yes, it also runs on the Mac and Win$). The pictures shown here were made using the trial version of Bibble Lite.

I explored several post-processing options.  The main result shown on top was converted to B&W by “hand” using the channel mixer, toning down the blue channel and emphasizing red&green. I also gave the fancy B&W film simulator a try, see photo on the right. If you compare the results, you can see that the result of the film simulation has much more contrast, emphasizing the shadows more.  While this makes the photo moody, I personally prefer the more balanced result of the channel mixer.  Last but not least, there was also some color to be seen ;-)  In all three cases, I used Bibble’s highlight recovery to reduce the effect of the blow-out red channel (though you can still see some loss of detail on the bright brick wall on the left) and a neutral density gradient filter(also in post-processing) to make the blue sky look darker.

I captured this image in Boston at the demonstration for a free Tibet on March 30th 2008. Note how tight this gentlemen grasps the US flag.

Red line subway train crossing the Longfellow bridge between Boston and Cambridge.

I am experimenting a bit with converting my photos to black and white lately and chose this one for the nice contrast. However, I am still at odds with the dynamic range of my camera. If you look close, you will notice that some of the highlights are blown out, something that is much more severe in digital photography compared to film. Makes me wonder if I should try shooting a few rolls of b&w film.