Working with Raw Format

RAW images contain unprocessed image data straight from the camera’s image sensor. Since the data isn’t processed on the camera you must do it yourself on your computer in order to get it into more usable formats like TIFF or JPEG.
.raf (Fuji)
.crw .cr2 (Canon)
.kdc .dcr (Kodak)
.mrw (Minolta)
.nef (Nikon)
.orf (Olympus)
.dng (Adobe)
.ptx .pef (Pentax)
.arw (Sony)
.x3f (Sigma)

Cameras that support raw files typically come with proprietary software for conversion of their raw format to TIFF or JPEG.

However, Canon decided not to add support for their D30 DSLR in their latest release of their Digital Photo Professional software, and Nikon removed features of their own RAW converter Nikon Capture and added the encryption of features in Nikon’s D2x digital camera RAW format (NEF). As a response to this, on March 10th, 2005, OpenRAW (a Working Group of photographers and other people interested in advocating the open documentation of digital camera RAW files), coordinated by Juergen Specht, has been created.

Also, Microsoft’s Digital Image 2006 is able to recognize and organize RAW image formats such as .crw, .cr2, .tif, and .nef, which are file formats produced by Canon and Nikon. Picasa, a free image editing and cataloguing program from Google, can read and display many RAW formats, but like iPhoto (the Apple release), Picasa provides only limited tools for processing the data in a RAW file.

There is no single RAW format: different manufacturers use their own proprietary formats, which are collectively known as RAW format. Raw files contain pixel data from the image sensor usually at 12 or 14 bits per individual sensor bucket. These pixels are a mosaic of either red, blue or green values. o retrieve an image from a RAW file this mosaic must be converted into an RGB image (Demosaicing). RAW Data is preserving the maximum amount of original image data and offers greater creative control with digital images.

The contents of RAW files are often considered to be of ‘higher quality‘ than the RGB converted results, because you have finer control over the white balance, brightness, contrast, colours and saturation.

Note: RAW files are sometimes referred to as CCD-RAW

If understanding RAW is still difficult after what I said before, take a look at the following images from photo.net.




The 3 most known RAW formats are CRW, CR2, NEF, and DNG. A few words on them:

The Canon RAW (CRW, CR2) File Format
Canon uses two different RAW formats, and some camera models produce CR2 instead of CRW files and other models can use bouth. The Canon CRW file format is type of RAW file format and It has a structure that is fundamentally similar to TIFF. CRW files are written in Camera Image File Format (CIFF).
For extremely detailed informations about the structure of a CRW see this article.

The Nikon RAW (NEF) File Format
Nikon RAW Format is known as Nikon Electronic Format (.NEF). Nikon offer their pro SLRs with PictureProject software that includes limited control over the RAW file conversion process, and then offer the more feature-rich Nikon Capture conversion software for an added cost. Nikons policy was to encrypt the white balance data in order to sell their software, so with other available programs the management of .nef files is limited. While Nikon Capture does indeed offer excellent capabilities for people to manipulate images saved in NEF formats, many photographers prefer Adobe Photoshop and from now on Adobe Lightroom.

The Adobe RAW (DNG) File Format
Adobes Digital NeGative format, indicated as .dng, is an open standard file format available to all, without secrecy, seeking to become the next overall universal format. A quote from OpenRaw: DNG is not an open standard in that it does not document all the essential information contained in current RAW format files like NEF and CR2. In many ways, DNG can be viewed as simply yet another RAW format with undocumented information – except that DNG has the added risk that information can be lost during conversion to/from DNG and other RAW formats.

Now that you know what RAW is, let’s see some adjustments over a .nef file.
Picasa is a free software from Google which I found useful and helpful in many photographic situations, but when it comes to RAW editing, its very basic. If you take a look at the first image down here, youll see that raw editing is split into 3 categories: Basic Fixes, Tuning and Effects. Basic Fixes solves most of the editing necessities but is not flexible as Adobe Photoshop contrast, brightness, and curves: practically you only got Auto Contrast and Auto Color. Croping is useful and nicely done and Straighten is a function I really admire Google for the idea: it saves a lot of time compared to manually straighten that usually requires a lot of steps.

Basic:


Tuning goes deeper into the lighting adjustments, conferring the possibility to darken the shadows, lighten the highlights and adding overall atmospheric light to the RAW picture. While I consider this still pretty basic fixing, choosing the neutral color and color temperature is a little bit more than that. Picasa did a fine job with the colors, and, if you still think about improvements, in the Effects menu you got Saturation, Warmify, and Glow for further color adjustments. Sharpen, Film Grain and Blur are also present but, again, in a much more inflexible and basic form than Adobe Photoshop.

Advanced:


Between B&W and Filtered B&W I prefer filtered. Sepia and Duotone (here called Tint) are also present in the menu. By the way, I like very much the preview thumbs of the menu that helps deciding what effect to chose. Graduated Tint was a pleasure surprise from Google. For this kind of picture, like the one in my example: where a good part of it is the sky, this effect really works amazing – it gives a darker tint to the sky but no dark tint over the buildings.

Results: