Project: The Value of Raw

RAW confers two main advantages in digital image processing: it enables the photographer to take advantage of the camera’s higher bit depth than the 8 bits allowed by a jpeg file but more importantly it allows the camera’s settings from the point of exposure to be adjusted in post processing.

The purpose of this exercise was to explore these advantages and at the same time, to put them in perspective. I chose these three images of Chepstow castle, taken during late afternoon sun, to explore this.

I used Photoshop to work up the jpeg, generally just adjusting the black and white points in the histogram. Then the RAW image was adjusted firstly in Photoshop’s RAW editor, then in Canon’s own software, Digital Photo Professional. The results are:

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Original Image

Photoshopped

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RAW Processed in PS

RAW Processed in DPP

Camera settings – f4.5, 1/1000 sec, ISO200, auto white balance, evaluative metering, aperture priority

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Original Image

Photoshopped

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RAW Processed in PS

RAW Processed in DPP

Camera settings – f4.0, 1/750 sec, ISO200, auto white balance, evaluative metering, aperture priority

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Original Image

Photoshopped

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RAW Processed in PS

RAW Processed in DPP

Camera settings – f3.5, 1/750 sec, ISO200, auto white balance, evaluative metering, aperture priority

In all of these, the most noticeable difference is the colour. The camera’s auto white balance failed to capture the warm tinge of the evening sun. I did not even attempt to correct this in the jpeg; it would have been possible but cumbersome involving adjustments of the three colour channels. With both RAW editors, it was a simple matter of dispensing with the camera’s setting and adjusting the colour temperature using a slider until it looked right. In the second picture I wanted to restore some detail in the foreground tree. In Photoshop I would have had to select it and lighten it, separated from the rest of the image. Both RAW editors gave me tools to do this much more easily.

The final image below was taken indoors and deliberately underexposed by 2 stops to give a more manageable shutter speed in the low light conditions:

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Original Image

Photoshopped

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RAW Processed in PS

RAW Processed in DPP

Again, the Photoshopped image was adjusted simply using the white point slider on the histogram. For the DPP processed image all I did was to restore the 2 stop underexposure. Comparing this with the one above it shows that not only is it a better exposure but there is more detail apparent in the dark areas around the dog’s eyes and nose. Trying to do the same with Photoshop’s RAW editor did not restore this detail and I had to use many more adjustments (colour temperature, black point, restore). The result is not as effective.

Doing this exercise has shown the advantage of using RAW. Well exposed images will not benefit as much, but ones taken in a more challenging environment will give more flexibility during post processing. There are differences in the software available and the ease with which they enable corrections to be made. Generally speaking I found Photoshop to be more usable and versatile but as the last picture showed, this isn’t necessarily so.

I am familiar and comfortable with using Photoshop to work on jpeg images and have developed a way of working which suits my style and gives me the results I want. With RAW I am at the bottom of the learning curve; I don’t really know what I am doing or feel comfortable that I am using the best methods or getting the best results. More practise and experimentation is required to develop the same level of fluency that I enjoy using Photoshop.

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