Benny Gettinger: Photo-Graphic Artist

The RAW Format Cube Principle

Midway is a cute little town in Central Kentucky.  We have a railroad track that runs right through the middle of downtown, so it has been a popular location for train photo shoots.  This is a “Pseudo HDR” of a cute little building there.

Midway HDR

"Pseudo HDR" taken in Midway, KY

I took this photo in RAW format which means that the camera records all the image exposure data coming through the lens without compressing it to a JPEG.  I like to describe a RAW file as a cube of image data, whereas a JPEG is a plane within that cube.

RAW format as a cube

A RAW file is like a cube of exposure data, and a JPEG is a sample from that.

Photoshop and Lightroom are used to process RAW files.  When you adjust the exposure, you’re essentially moving that plane back and forth within the cube.

This principle relates to HDR photography techniques.  Traditionally, a photographer will shoot a scene in JPEG format at several different exposures to create this range of exposure data. Using special software like Photomatix the images can be blended together. But it can also be done using a single RAW file.  Essentially, for each pixel in the image the software will search the dynamic range for a midtone and use that exposure setting for that pixel.  So in other words, it’s adjusting the exposure for each pixel.  With this method, shaded areas are exposed properly and bright areas are exposed properly.

I always shoot in RAW format.  I don’t always make HDR images with them, but it’s very practical to be able to tweak exposure and contrast in a way that is more effective than just darkening/lightening pixels.  Shooting in RAW has saved my bacon on more than one occasion!

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One response

  1. Excellent way of putting it. That metaphor is both visually and conceptually helpful for a beginner like myself.
    Thanks Benjamin.

    September 23, 2010 at 8:55 am

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