Sunday, February 13, 2011

Ex. 11 Raw

As a matter of principle I only ever RAW, the availability of modern workflow tools such as Lightroom mean that I can process a RAW image as quickly as I can a JPG, plus I get all of the flexibility that RAW delivers.  As an example, the camera I mostly use for this course, my Canon 5D Mark II now has 24,123 shutter releases, of which 13 were JPG's and those mostly for comparative tests or by mistake.  Ultimately most images that I use in one form or another end up as JPG, either for Web or for book publishing, however, I like to start with the raw material.  This fixation on RAW came about due to my initial photographic interest of shooting underwater, an environment notoriously confusing to a cameras in built White Balance prediction.  Underwater it only makes  sense to shoot RAW.

Having completed this exercise I am still convinced of the value of RAW although I have to say the difference between the RAW capture and JPG was smaller than I expected.  I took my 7D, this time, for a walk down town looking for a variety of scenes that would stress the difference.  The sky was overcast and very bright, so any outdoor shot would inevitably include a good contrast ration. I shot all images as RAW + Large JPG.

My first image is a middle contrast photograph, shot in an Italianesque monument near the river in central Munich.  I found the perspective and framing interesting, with natural and muted colours

Across the river this shot of the Bavarian national museum offered greater contrast, although it is perhaps not quite HDR, but offered a richer pallette of colours to work with:

My high definition image, is this one in the main railway station, with strong contrast between the natural lighting and the dim interior

Finally the following image is lit with fluorescent lighting.

I processes the JPG and RAW in parallel for each trying to achieve more or less the same tonality and colour balance.  The first most notable difference was on opening the images, the JPG was almost a half stop brighter than the RAW image, requiring me to first brighten the RAW to obtain a comparable image.  Lightroom 3 now offers the ability to set white balance on both RAW and JPG using an eye dropper tool, removing some of the constraints of JPG processing.  Thus for all images I used the eye dropper tool to set WB from the same location in the photograph.

I found the following differences:

  1. The reds in the RAWs were richer and deeper than in the JPGs, no matter what adjustments I made
  2. The colours in the RAW images looked richer, although this is far more subjective
  3. The RAWs had a better gradation of colour
Clearly a 14 bit file will contain greater depth than an 8 bit file.  Sadly there was no blue sky, so one of the key tests of a file, banding in blue sky was not really possible.  When I moved from a 12 bit to 14 bit camera, one of the most significant improvements was better handling of blue gradients, either sky or ocean.

My final check was to print them side by side, two to an A4 sheet.  I was quite surprised not to be able to tell any difference, other than those due to slight variations in the processing - clearly for a small print RAW or JPG makes no appreciable difference.

As the text suggests the differences are smaller than I expected, but I still feel more comfortable shooting RAW.

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