Wednesday, 31 January 2007
HDR.... fad or the future...?
HDR or High Dynamic Range is method of merging images taken at different exposure settings, such that both the highlights and shadows are maintained.
How many times have you tried to take a picture from inside a room and try to get the view out the window as well..? What normally happens is that you can get the view out of the window correctly exposed, but then the room is dark, or the room properly exposed and the view completely blown out. Thats because the dynamic range of your film, transparencies or CCD is limited, so it can't record the whole range of light values present. So you have to choose whether you want detail in the shadows, or in the highlights because you can't have both... until now... 'you mean I can have it all !!!'... well sort of....
You can now take three or more exposures covering the mids, highlights and shadows, stuff these images into a piece of software like Photomatix which then combines the images, performs tone mapping and gives you back an image with everything..... Sounds good doesn't it... so where's the catch ?? Well.... all your images have to be the same, pixel for pixel, so you need a tripod, then you have to adjust your camera up and down at least 2 stops. You now have to process 3 files instead of one and well... the tone mapping can give you some pretty funky results, very artistic but not exactly true to life... (I imagine sometime in the future all this will be done in-camera in the blink of an eye, but until then...)
The web is awash with interesting examples, like here and here. If you want to read a good tutorial, try this one... and have a go.. its lots of fun.