The two most common digital image formats on a camera are TIFF and JPEG. However, many cameras are now offering the ability to save your images in a RAW format. This, as the name suggests, is the format in which the image is captured, before in-camera processing.
The subject of RAW files generates perhaps more controversy and confusion in digital photography than any other. Exaggerated claims are made for RAW’s advantages and it certainly has great merits, but working in RAW slows down operations and there’s potential for misjudged conversions.
Below is an example of a RAW photograph and a JPEG photograph, taken from 10000birds.com website. The photographer quotes, “Also I found that by taking the photos in RAW mode produces better results, especially in low light conditions. The RAW format has more information and you can get more noise out of the photo and the resulting colours are more vivid. Here is a photo comparing jpg vs RAW at ISO 3200, 1/500th sec, f 5.6, with a 100-400 mm zoom.”
A RAW camera file contains
- Minimal processed data
- The complete loss of data from the camera’s sensor
- Higher in dynamic range, (ability to display shadows and highlights)
- Lower in contrast ( flat, washed out)
- Not as sharp (details)
- Not suitable printing straight from the camera, ((Will need processing before printing)
- At least 8 Bits per colour
A simple way of explaining RAW is to think of an image that is waiting to be analysed. Imagine that you have just completed a survey, you have piles of data to analyse before you can draw any conclusions. Crucially, someone else could study your data and research differently to you, leading to different conclusions. A RAW file is essentially the same, the data is waiting to be processed, but different processes can extract different results, some obtain better colour or more detail and so on.
There are two main reasons for shooting in RAW format. The first is that as modern high-quality camera sensors operate at a higher bit-depth from the JPEG or TIFF that is created and saved, they have the potential to capture a wider range of brightness. This is not as great as many manufacturers and some people claim it to be, but nevertheless, there is at least a small advantage, perhaps one or two F-stops.
The second reason, of real practical value, is that the original, camera settings, such as white balance and contrast, are saved and kept separate from the original capture data. With a JPEG or TIFF, the camera’s processor applies the settings you choose and throws away the other possibilities, but with a RAW file, you can go back and select any setting you like later, on the computer.
Taken from Digital Photography Masterclass book, We have seen that whenever you want the greatest flexibility with an image, the best strategy is to set your camera to record RAW files. You work with the larges file your camera can muster, and don’t commit to white balance, colour space, or sharpening. Some cameras store RAW data with more detail than the usual RGB file, that is, with 10 or more bits of data instead of 24. This again allows more room for manipulation.
However, the files are much larger than even the highest quality JPEG equivalents, slow when recording in RAW. In short, the flexibility gained from working with RAW files is balanced by the slower and more labour intensive workflow.
The need to convert RAW files before the images can be viewed is a nuisance. To work around this, many cameras save a small JPEG version alongside the RAW file, to allow you to view it on the LCD screen or your monitor. This preview image applies standard camera settings and, typically, the result is bright and cheerful, in contrast to the unadjusted RAW image, which may give the impression that the JEPF file is superior to the RAW file.
Processing RAW images:
To make the most of RAW files, you need to convert them into a standard image file, in TIFF or JPEG. When you shoot a RAW image, your computer will process the image, creating an image file, rather than the camera. Therefore, you will need processing software. RAW converters vary greatly in their performance, not only in obvious features such as ease of use and speed, but also the quality of image they produce, their interpretation of the RAW data varies.
One vital thing you should remember is that the original RAW files should remain untouched throughout all of your changed. When you save them, it must always be to a new file, the processed image. It is at this point that you tell the file which colour space to operate in. This means you can return to the original RAW file and make new adjustments without fear that your earlier adjustments, such as choice of colour space, may have compromised the integrity of your image data.
I have arranged a trip in October, to go on the severn valley railway steam train, from Kidderminster to Bridgnorth. I will read through all of my exercises for this set of work, and the final assignment. I will plan each exercise, and the final assignment around my trip. I want to keep the same theme of trains and this train trip for these exercises and for the assignment.
Digital Photography Master Class, Tom Ang, Dorling Kindersley Limited, London 2008. Page 184-187.