Before I dive into today’s test, it’s important to talk about a critical aspect of image capture: dynamic range. Both traditional film and modern digital imaging mediums have measurable dynamic range – or, to put it differently – they have dynamic range limitations.
So what is dynamic range? Generally speaking, dynamic range is the difference between the brightest and darkest portions of an image. If you’ve ever shot someone standing in front of a sunset, chances are you have experienced the frustration of dealing with the (in)ability of your camera to record information from both highlights (the sun) and shadows (your subject).
There are hardware remedies to dynamic range problems, but for now we’re just talking about software. We want to see how much better a RAW recording format can capture highlight information than a JPEG format can.
This original image was taken a few years ago of a sunset in a local park. You can see very clearly just how broad the dynamic range of the original scene was. Unfortunately, capturing all of that highlight and shadow information was not possible with just one shot. If I had underexposed much more, the foreground would have been too dark. If I had overexposed any more, the sky would be white. With that said, I picked a shot for this test that had been slightly overexposed – the exaggeration makes the difference more palpable.
After loading the original shot, I took each into Photoshop and attempted to balance the exposure by pulling up the shadows and pulling down the highlights. Not surprisingly, the RAW image blew the JPEG out of the water. Between the highlights and shadows I would estimate that the RAW image contained roughly 2.5 stops more dynamic range than its JPEG counterpart. And that’s to say nothing of the color information that was quite clearly discarded during JPEG compression.
Again, the detail shot makes the difference clear. In the JPEG version there was no color information in the darkest spots of the trees; attempting to pull up those shadows was interpreted as making black into dark gray. The highlights in the sky fared no better; photoshop can do nothing with blown highlights other than make them light gray. Of course, the even the RAW version could not pull all of the information out of the highlights. But it makes a valiant effort.
Be sure to check out the other blog posts in our RAW vs. JPEG series: