PROJECT: THE VALUE OF RAW

Now, in my mind we are getting down to the nuts and bolts of things as understanding RAW and its properties and possibilities is something I have been looking forward too as well as to the opportunity of researching the differences between the different file formats used in photography.

I resisted shooting in RAW for years because I was convinced that editing RAW files would be more complicated and time-consuming than editing JPEG’s.  Grogan (2013, p.1)

I can identify with this comment and in fact can build on it further by stating categorically that I had avoided using RAW up until recently due to the ease of manipulation available to these kinds of files.  Over the years of my study I have banged on about the authenticity of images, and this is the fundamental reason for my learning to shoot ‘in-camera’ so no manipulation was needed to my shots, producing a true representation of what I see within a scene.  I am going to stop here, as I know this will be covered later in this module, so back to task in hand.

File Format

There are many different kinds of file formats used within photography; RAW, JPEG and TIFF are the most common, therefore most of us are aware of these and probably use one or all of them to capture the many different forms of Digital Media we use today.

To add confusion to this, each camera manufacture also produces their own version of a RAW file, for example Nikon, my choice of camera, uses .NEF as their RAW file format, over Canon who produce .CR2, Pentax .PEF and Sony who have a choice from .ARW .SRF and .SR2, these are to name just a few.  On top of this, the applications we use to work on our images (such as Photoshop and Aperture) also produces a native RAW file format, which is probably not compatible with other software, but is used internally by the application during processing procedures; Photoshop’s file extension is .psd.

JPEG

JPEG is the acronym of Joint Photographic Expert Group and is probably the most commonly used file format in photography.  Not only has the JPEG file format been around for some time, but it also has properties that are useful to photographers such as a) JPEG files are readable and interchangeable within all imaging software packages, b) they are optimised for digital transmission, so are easily used in emails as well as for uploading onto the internet and c) JPEG images are considerably smaller than all other file formats, so they take up less storage space on computers and camera memory cards.

Cambridge in Colour states that:

JPEG files achieve a smaller file size by compressing the image in a way that retains the detail that matters most, while discarding details deemed to be less visually impactful.

However, the compression within JPEG files does come with a price as ‘lossy’ compression is employed whereby, the file size is reduced with some loss of image data over a lossless compression, where the data file is re-written more succinctly so that only file size is compressed with no changes made to the quality of the image.

JPEG takes advantage of the way the human eye notices differences in brightness over differences in colour therefore, the amount of an images compression is dependent on both the options set within your camera (basic, normal or fine image capture) as well as the type of image being captured; for example, high contrast images with lots of detail (and the potential for noise in the darker shadows) are not as easy to compress as those images with little texture and smooth surfaces.  However, to overcome some of this loss, by choosing a low compression, high-quality setting in camera (if it allows), and image degeneration is usually undetectable.

Other disadvantages of using compressed JPEG images is that they only allow for fundamental changes to be made in post-production, so what you shoot is basically what you get and during compression, as the information is squashed into a smaller space, they can also produce noticeable artifacts such as noise, blooming or moiré patterns, and the higher the compression, the more noticeable the image discrepancies can appear.

TIFF

TIFF is the acronym for Tagged Image File Format and is the standard file format in the worlds of publishing and printing.  Considerably larger than JPEG files, TIFF files can be either uncompressed or compressed using lossless compression (whereby the file size is reduced without the loss of image quality).

Another advantage of choosing TIFF as your image capture format is that, unlike JPEG it has a bit depth and the ability to capture in either 8-bit or 16-bit channels; TIFF also has the ability to store multiple layered images in a single file, allowing for more post processing to be achieved if required and as there is no compression within the file, no image artifacts are produced.

As previously discovered while looking at Camera Sensors and Histograms in the last module, bit-depth describes the degree of colour accuracy in a digital image.

Freeman (2011, p.41) states the following:

One bit (a basic computing term for a unit) is either on, or off – black or white.  A byte is a group of 8-bits, and as each of these bits has two states (on or off), one byte has a possible combination of 256, meaning 256 values from black to white.  An RGB image has three channels (Red, Green Blue), so at 8-bits per channels, has a colour accuracy of 256 x 256 x 256 this is 16.7 million possible colours.

This is way beyond the abilities of the human eye, and is the industry standard, so why the need to increase the bit-depth to 12-, 14- or even 16-bits per channel?  There are two reasons for this; firstly higher bit-depths produce better graduation of tones making the transition between each smoother and less disjointed in our images and secondly, there is an improved accuracy of interpolation during manipulation.

Finishing off my findings on TIFF files; using a TIFF/JPEG shooting combination is an excellent way to archive images that may need editing at a later date as due to their lossless compression, smaller storage requirements are needed, although they will take up considerably more room than JPEG images.  However, and if you are looking for a more superior image editing solution then a shooting combination of RAW/JPEG will suit you better as although the RAW files are bigger still than TIFF, RAW images are far more flexible.

RAW

RAW is not an acronym of any specific file format, but digital photography’s equivalent of the negative used in film photography, containing image data, straight from the camera’s sensor, that has yet to be processed and is completely uncompressed and untouched; this file contains one red, one green and one blue value at each pixel.

RAW is the most versatile file format, and as we saw above, is unique to each make of camera, although commonly camera’s records lots of additional information, available when a picture is taken (metadata) so will save this separately from the RAW data.   Ignoring white balance, contrast, hue adjustment, sharpening etc. when the RAW data is opened in the RAW editing software package relevant to the camera manufacturer, the file is read and used to display an image using the captured RAW information, which is then manually adjusted to produce an image we are happy with.

When capturing an image, our camera will use the RAW data to produce either a JPEG or TIFF image to be stored on our memory card; this image is also used on our camera’s display screen.  Our camera will make several interpretive decisions during the development of this RAW data, to produce an image it thinks best represents the data it is presented with, which may not quiet be what you expect it to be.

Of course there are pros and cons for using RAW, the advantages are:

  • The production of a lossless image means more control over White Balance, Contrast, Saturation etc.
  • As no image data has been lost, we get the full range of data as recorded by the camera sensor
  • We have control over how an image looks
  • We can make multiple changes to our images, as the RAW data is never altered

Disadvantages include:

  • Increased file size due to the amount of data being recorded and stored
  • RAW files can be time consuming to adjust
  • Camera processing can be slower due to their working with large amounts of data
  • More powerful processing is needed due to the size of the RAW data file

The Internet has provided lots of information about file formats and there is lots of discussion about which is best and what we should be using to capture our images.  Our shooting preference should come down to the requirements of our photography as there is good and bad to be had in all of the file formats we have looked at.  Personally, I like to shoot using a combination of RAW and JPEG as this allows me the freedom of quickly turning around images in social media and with family (JPEG) and the ability to make improvements to my shots where necessary (RAW).

Source:

Reference:

Cambridge in Colour.  (n.d.) Image Types: JPEG & TIFF Files [Online Article.  Available at: <http://www.cambridgeincolour.com/tutorials/imagetypes.htm&gt; [Accessed 5 July 2013].

Freeman, M.  (2011) The Digital SLR Handbook.  Revised 3rd Edition.  East Sussex: The Ilex Press Limited.

Grogan, P.  (2013) Not sure what to read first?  Photography Week.  Issue 33; 09-15 May 2013. p.1

Bibliography:

Atkins, B.  (2008) RAW, JPRG and TIFF [Online Article].  Available at: <http://photo.net/learn/raw/&gt; [Accessed 6 July 2013].

Cambridge in Colour.  (n.d.) Image Types: JPEG & TIFF Files [Online Article.  Available at: <http://www.cambridgeincolour.com/tutorials/imagetypes.htm&gt; [Accessed 5 July 2013].

Cambridge in Colour.  (n.d.) RAW File Format [Online Article.)  Available at: <http://www.cambridgeincolour.com/tutorials/RAW-file-format.htm&gt; [Accessed 6 July 2013].

Cooper, K.  (2012) The RAW digital image format [Online Article].  Available at: <http://www.northlight-images.co.uk/article_pages/why_use_raw.html&gt; [Accessed 6 July 2013].

Freeman, M.  (2011) The Digital SLR Handbook.  Revised 3rd Edition.  East Sussex: The Ilex Press Limited.

Grogan, P.  (2013) Raw Made Easy.  Photography Week.  Issue 33; 09-15 May 2013.  p.2.

Miller, E.  (n.d.) JPG Files [Online Article].  Available at: <http://graphicdesign.about.com/od/Definitions/g/Jpg-Files.htm&gt; [Accessed 5 July 2013].

Photoxels.  (2004) Understanding RAW File Format [Online Article].  Available at: <http://www.photoxels.com/tutorial_raw.html&gt; [Accessed 6 July 2013].

Rowse, D.  (n.d.) RAW vs. JPEG  [Online Article].  Available at: <http://digital-photography-school.com/raw-vs-jpeg&gt; [Accessed 6 July 2013].

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