JPG vs RAW part 3

In the last blog, we ended with "Now that we know what RAW is, we can go on to explain why you'd want to use it...."  I guess that the difference between JPG and RAW is akin to the olden days when you could take pictures with 35mm film or use a Polaroid.  The Polaroid gave you a nice picture, but if you wanted to change it - well it was WYSIWYG (what you see is what you get).  However, if you shot the image with 35mm film, you had control over the processing and post-processing.  The film captured data and when developed, you could edit it for exposure, colour saturation, colour temperature and imperfections.

I suppose these attributes of film were of more interest to professionals, but even casual photographers could go to a local lab and get their negatives cropped, corrected and printed.

Although there is software that permits basic editing of JPG images, we have to understand how a JPG is created.  Your digital camera comes packed with very sophisticated computer technology.  When you capture a JPG image, your camera's image processor evaluates it and determines (for you) what data to retain and what data is unneeded.  Shades and fine details are averaged and much of the data is discarded when the image is compressed.  Thus a JPG is a compressed image and is referred to as a "lossy compression".  To understand this, think of an image with a bright background and a darker foreground.  If the foreground has detail in the shaded areas, it will be averaged and the resulting image will contain very little of what your eyes saw.  

The final JPG image is great for snapshots and family photos, but not so good for "serious" photography.  In the next instalment, we'll delve into the technical aspects of RAW....