Tuesday, July 10, 2007

RAW vs JPEG


The following tip on RAW vs JPEG
So, you’ve forked over at least $600 (but probably $1000) for your first DSLR camera. You have more buttons, dials, and menus than you know what to do with, even after reading through the fat booklet that came with your camera and explains its usage in ten differnent languages.
It’s all you can do to understand ISO, shutter speed, and how less is more when it comes to aperture. This beast of a camera can produce files in a Raw format, whatever that means, but it also has the nice comfortable JPEG format that we all know and love.
Like me you probably happily shoot in JPEG for quite awhile - getting used to the myriad of options available to you. One day you look at that Raw setting and ask, “should I be using Raw for the best quality? What is Raw, exactly?”
Excellent question.

A Raw file is…

• not an image file per se (it will require special software to view, though
this software is easy to get).
• typically a proprietary format (with the exception of Adobe’s DNG format
that isn’t widely used yet).
• at least 8 bits per color - red, green, and blue (12-bits per X,Y location),
though most DSLRs record 12-bit color (36-bits per location).
• uncompressed (an 8 megapixel camera will produce a 8 MB Raw file or larger).
• the complete (lossless) data from the camera’s sensor.
• higher in dynamic range (ability to display highlights and shadows).
• lower in contrast (flatter, washed out looking).
• not as sharp.
• not suitable for printing directly from the camera or without post
processing.
• read only (all changes are saved in an XMP “sidecar” file or to a JPEG or
other image format).
• sometimes admissable in a court as evidence (as opposed to a changeable
image format).
• waiting to be processed by your computer.

In comparison a JPEG is…

• a standard format readable by any image program on the market or available
open source.
• exactly 8-bits per color (12-bits per location).
• compressed (by looking for redundancy in the data like a ZIP file or
stripping out what human can’t perceive like a MP3).
• fairly small in file size (an 8 megapixel camera will produce JPEG between 1
and 3 MB’s in size).
• lower in dynamic range.
• higher in contrast.
• sharper.
• immediately suitable for printing, sharing, or posting on the Web.
• not in need of correction most of the time (75% in my experience).
• able to be manipulated, though not without losing data each time an edit is
made - even if it’s just to rotate the image (the opposite of lossless).
• processed by your camera.
These differences lead implicitly to situations that require choosing one over
the other. For instance, if you do not have much capacity to store images in
camera (because you spent all your money on the camera body) then shooting in
JPEG will allow to capture 2 or 3 times the number you could shooting in Raw.
This is also a good idea if you are at a party or some other event afterwhich
you want to share your photos quickly and easily.

On the other hand, if capacity is not an issue at all (1 GB and 2 GB flash
cards are getting cheaper every week) you might consider shooting in Raw +
JPEG, just to cover all the possibilities. If you cannot or do not want to do
any post processing, then you simply have to shoot in JPEG. Taking a picture
in Raw is only the first step in producing a quality image ready for printing.
If, on the other hand, quality is of the utmost importance (like when you are
shooting professionally), and you want to get every bit of performance your
DSLR can offer then you should be shooting in Raw.
That being said, I know many professional photographers who do not shoot in
Raw for one of two reasons: 1.) they don’t know how, or 2.) they don’t want to
take the time to process the images afterwards.

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