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Train of Thought...
September 2008 -Idle Thoughts?

The interesting thing about writing a column with a monthly deadline is the problem of finding the inspiration, the kernel of an idea on which to base your column. Usually I am able ti draw on an incident from the previous month, but having been away for 2 weeks out of the last month, the potential sources of inspiration are dramatically reduced. Returning from leave, as we all know, is not recommended for maintenance of sanity, as we deal with the nonsense that accumulated whist away. The environment is certainly conducive to a case of writer's block.

Ahah! I hear from around the traps, we are going to be spared this month! Whilst in Singapore, I decided to shoot photos with my camera recording RAW files rather than the usual JPEG files. For those who are not into photography the difference is that a RAW file has all the information generated by the digital sensor while the JPEG file is a RAW file that has been processed by the camera software to create a file that can be viewed in full colour. In processing the RAW file, the camera will set the whitest and blackest part of the image and decide what the colours are automatically. A significant amount of information is then discarded before the file is saved. A JPEG file will also only be 8 bit in terms of colour depth (ie 256 levels of intensity). A RAW file, on the other hand is 16 bit so has 65,536 levels of intensity. Furthermore, there is NO information discarded in storing the file. The downsides of a RAW image is that the files are very much bigger and you need to do the processing that the camera would have done automatically if capturing JPEG images.

When looking at a high quality JPEG or RAW captured image of an average subject, it would be very difficult to tell which is which. As soon as you view a subject where there is a high contrast (sky and shadow), or where there is a wide range of subtle colour differences (eg flowers) the benefits of RAW capture become very apparent. In processing you area able to recover much more highlight and shadow so have a much greater tonal range than in JPEG and you are better able to optimise the image colours as you have a much more gradual colour gradient to work with. You are better able to deal with sensor noise and image sharpness.

It is not a case of one capture method being inherently better than another, but rather choosing the appropriate method for the subject you are shooting. It is the more difficult or more complex cases where RAW capture excels.

What has this to do with things Respiratory? Possibly not a whole heap. I am, however, frequently asked for advice about what sort of spirometer to buy and I have been thinking that there are some parallels here perhaps. I have always been nervous about automated diagnostic equipment. I believe that the more decision making that is taken away from the scientist/technologist the chance of getting poor quality output rises. I would suggest that the automated spirometer that spits out or displays only numbers is akin to shooting in JPEG capture format, sometimes highly compressed JPEG for that matter. If the person doing the testing is really experienced, and the subject really compliant, then the quality can be good. The more complicated the situation, the more difficult it is to get top quality. Performing spirometry with good real time screen displays and being forced to choose the data for reporting is akin to shooting in RAW capture. Yes there is more required of the scientist/technologist in processing the information, but the output will be better quality. The more difficult the case, the greater the difference will be.

So there you are, idle thoughts perhaps but maybe I will encourage someone to experiment with RAW capture in their photography, even if I don't change the way they look at spirometers!

'til next month

K.

PS Singapore was great, food fantastic and the orchids out of this world. And its closer than Sydney!

September, 2008

kevin.gain@health.wa.gov.au

 

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