Raw or JPG, Which Format Is Right For You?

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One attraction of the FujiFilm® FinePix® E900 over some other digital compacts is that it offers the option to save RAW data files. RAW data is information collected by the CCD sensor before it is processed in any way. This means that this data has to be made readable on a computer, where depending upon the software used, you may be able to make adjustments to it before saving it as a .JPG, TIFF, or some other format.

Making such conversions is a slow, labour intensive process, especially if your computer is dated. I’ve just bought a new computer because converting RAW took too long on the old one!

A JPG, [or JPEG], is the kind of file that digital compacts use as their default file format. All digital cameras offer this format as an option because it’s an efficient way to store images. The camera RAW data is rapidly converted by the E900 into .JPG files, making it possible to bracket exposures, or take a burst of up to 40 frames at a speed of approx. 0.5 FPS.

The FinePix® CCD Sensor and RAW Files

FujiFilm® Super CCD sensors have octagonal pixels. These enable pixels to rest closer together and to be arranged in diagonal arrays. The pixels are also closer together than would be possible than were square pixels used.

Conventional sensor arrays are
arranged as a grid. But your since eyes are wired to
recognize differences in vertical and horizontal banding,
your recorded image appear more busier than
if they were arranged in diagonal arrays.

FinePix® sensors are arranged like a honeycomb. This
enables the pixels to be arranged closer together
and also in diagonal arrays.

The Super CCD-HR sensor in the FinePix® E900 uses two kinds of pixel diode. Highly sensitive S-Pixel diodes produce impacted highlights, whilst smaller R-Pixel diodes increase the dynamic range of your images. FujiFilm® claim that this combination mirrors the structure of colour negative film.

The physical size of the sensor itself is tiny ~ it’s just 8mm x 6mm. This isn’t unusual for any digital compact camera, but it’s a considerably smaller sensor that placed in a digital SLR. Remarkably the tiny sensor in the FinePix E900 will yield 4864 x 3648 pixels in RAW mode. If you multiply these figures you will arrive at a total of 17,743,872 recorded pixels. This explains why a RAW file from the E900 requires 18 megabytes of storage space.

RAW images usually have 12 bits colour information per pixel. Image editing software uses 8 bits, or 16 bits so RAW data is always converted before editing takes place.

The 12 bits per pixel data from a RAW file seems more accurate than the 8 bit format of a .JPG, but the JPG’s 8 bits contain various corrections that haven’t been performed in the 12 bit RAW file.

JPG Images

The default setting for the FinePix® E900 will save your images as ‘normal’ JPGs. In fact there is no such entity as a ‘normal’ JPG. Really a certain amount of compression is being applied to your JPG file in order to save storage space on the XD media card. This also decreases the file write time enabling several exposures to be made as a burst.

If you know that you will use your image as an illustration on a web site, or you can be sure that you won’t want to enlarge and print it to a larger dimensions that 10″ x 8″ then ‘normal’ compression may provide adequate quality for your images.

But if you’re like me you probably have no idea just how large a print will be required the next time you pick up the camera. For this reason I always shoot 9 mega pixels in the ‘fine’ quality mode. This produces an image of 3488 x 2616 mega pixels that I inevitably crop to a 3:2 ratio, [the same as a post-card, or 35mm slide].

Since I like the 3:2 ratio you may wonder why I don’t shoot using the pre-programmed FinePix® 3:2 mode? This provides a wider JPG measuring 3696 x 2464. I used the setting for a while but found two disadvantages to it. Firstly it is only available at the ‘normal’ JPG compression mode, so the ultimate quality isn’t quite as good as in ‘fine’ mode. Secondly I found that when using the optical viewfinder it was confusing to be composing in a 3:4 viewfinder space in the knowledge that a 3:2 image was being made in the camera.

It’s long been claimed that the RAW format offers the ability to correct defects such as under, or over exposure, colour balance and other problems. Most, if not all, of the adjustments that can be made to CCD RAW images may also be made to .JPGs. The difference is that you are making the adjustment after various non-linear corrections, such as setting the image gamma, have been made by the camera.

The easiest way to make such adjustments is to use the PowerRetouche suite of filters, which work with Adobe Photoshop as plug-ins, or other image editors as a stand alone product.

JPG, [not the little used JPG 2000 version, which is a different format], is an industrial standard means of exchanging digital picture files.

I have little doubt that software will be able to read JPG files in the future. RAW files, however, are predicated upon the design of the camera CCD, [or CMOS], sensor. Every sensor is different and every upgrade results in a slightly modified version of a camera’s RAW file.

Adobe® are encouraging manufacturers to standardise their RAW formats and have suggested their own Adobe RAW as a suitable alternative to all the proprietary RAW formats that different cameras produce. Although many manufacturers have expressed interest it’s difficult to see how this might benefit them, especially is using Adobe RAW would compromise their sensor designs.

RAW formats, including CCD-HR RAW, always runs a risk of redundancy in the future when newer computers may not be capable of running today’s software. Such obsolescence is unlikely to occur with images stored in either .TIFF, or .JPG formats, so even if you shoot RAW it makes sense to archive your images as .TIFF, .JPG, or .PSD [Adobe Photoshop], files. Of the three .JPG images are the smallest.

Lossless and Lossy

JPEGs save more file space than other digital image file formats because they combine a number of file saving algorithms.

Your eyes see the world in a certain way and a .JPG sets out to compress the file in ways that the eye is unable to easily detect. For example .JPGs tend to compress the colour channels over the detail [Luminance-Chromanance], channel. Because of this you notice less of the compression because the structural detail of the image is preserved.

But when high levels of compression are applied increasingly fine detail is sacrificed, and some corruption will be detectable at higher magnification.

Compression that gives rise to artifacts, [corruption of the image], is known as lossy compression.

The .JPG format is a lossy storage format, and once the clarity of your image is lost it cannot be restored.

The .TIFF format, by contrast is the standard format used by the print industry. Like .JPG a TIFF file can be compressed, but the compression method is different and no loss of detail is apparent. This kind of compression is known as lossless compression.

Summary

The format you choose to take your images depends very much on the purpose for which you wish to use the final image.

.JPG images from the e900 will allow you to make very large pictures, [enlargements], especially when you use the ‘Fine’ setting.

If you think you might want to make poster sized images then you should consider taking your photographs in the RAW format.

RAW files take considerably longer to process, but probably no longer than were you making hand prints from colour negative film. Nevertheless if speed of workflow is an issue, then a .JPG file will be much faster from first image to colour correction.

RAW files should be archived in a generic format such as .JPG, .TIFF, or .PSD.

Regardless of whether you shoot in RAW, or .JPG the most important elements of the photograph are its composition, and subject matter!

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