JPeg or RAW
25/01/12Jpeg or Raw? That is the question. If you don’t know the difference, then read on.
First of all, many of you will have, at some time in your life, taken all your photographs on film. If you haven’t, then you will no doubt have heard about film, how you have to load it in a camera and once exposed, send it off or take it to Boots to be developed. Using film, the actual film type will be chosen according to your requirements. For rich colours for landscape photography, something like Fuji Velvia, a slide transparency film will be chosen. In contrast, if you want more neutral colours for natural history for example, then Fuji’s Provia, again a transparency (slide) film would be the one to go for. Velvia was initially rated at ISO 50 with Provia at ISO 100 or ISO 400 if you wanted to use commensurately faster shutter speeds. Similarly, if you wanted to shoot even faster, then a faster film would be used rated at ISO 800 or even higher. The downside to these higher speeds is an increase in the grain size used in the emulsion on the film, which also shows as an increased grittiness in the developed film and subsequent print. If the film was black and white, this grittiness may add to the effect of the print, but if not, it may become a distraction - one of the downsides of fast, higher rated ISO film speeds.
In the digital age, this is no different in this aspect with higher ISO’s being achieved by effectively amplifying the signal. However, this increases the digital noise shown in the final image. Noise reduction software either built into the camera or external software, may be used to reduce the effect, usually at the further expense in terms of image resolution, sharpness or dynamic range – the number of tones that are captured at one time.
What has this got to do with raw and jpeg? It may be useful as a comparison and analogy.
With film, you took your photographs. You then either had your film developed or developed it yourself. If the latter, you could alter the contrast of the image through the choice of chemicals used in combination with the time of development. Once developed, you would get your prints made. Now, again, you could create different prints according how they were printed. If you were printing the images yourself, you could have ‘dodged or burnt’ the print, by varying the amount of light used on the print. In our most basic of choices you could choose what paper the image was printed on, gloss or matt?
Having retrieved your prints fully dried and admired them, you may decide to get some reprints to pass on to family and friends. At this point, what would you do? Take your beloved print back to Boots for a reprint? No, you would take them the negative. That way, a far better print could be made from the original information.
As for the analogy, the print is the Jpeg and the negative is the RAW. The Jpeg is the finished image, it has already been processed. Now, some of you may say, “I never use Photoshop to process my images, they’re straight out of the camera.” That may be so, but if you take your pictures in Jpeg mode, then whilst you are not using Photoshop to alter the image, your camera is doing it for you, oh yes. So, you take your image using the digital camera and it produces an image, a RAW file of basic data, which is converted so that you can see the image using relevant conversion software. If you have JPEG selected or used by default on your camera, that RAW information is assessed by the camera’s computer, with information programmed on it probably by some whizz kid in Japan, to produce the final Jpeg image. On most cameras, you have the ability to alter the Jpeg parameters set by the whizz kid in the camera, by increasing or decreasing such things as colour saturation and contrast, sharpening and a monochrome as opposed to a colour image. Once you have taken the Jpeg image, and the on-board computer has made its adjustments as programmed by the whizz kid, or adjusted in camera by you, the information is then compressed to make a smaller file size. From this point, as all the original information recorded when you squeezed the shutter release has been manipulated by the camera and then compressed, thus removing some of the original information, any further alteration to the image will degrade it in some way. Therefore, this Jpeg image out of the camera should not be manipulated further and is, effectively the final processed image to be duplicated onto a screen or printed paper only.
Compare this to shooting RAW. With the raw image, you can keep going back to all the basic information as captured by the camera. You can process the image in different ways. Note that I say ‘you’, because it is you that has to do it. You have to adjust the contrast; you have to increase saturation; you have to sharpen the image; you have to apply noise reduction etc.
There are other benefits of course. Let’s take the information differences to highlight the point. A jpeg image is produced in 8 bit. That means that the information is compressed to 256 colour tones for each of the three colour channels. Still plenty of information to produce an amenable finished print. However, compare this to any modern DSLR which, in all likelihood, will take images in 12 bit. That is 4096 individual tones for the same three colour channels. Some cameras can take the images in 16 bit, which is over 16000 tones for the three channels. There is so much more information that your graduations of colour will be much, much smoother and you far more information to play with. Don’t forget, even if the camera is capable of shooting in 14 bit, if you have chosen Jpeg, the information is compressed down to 8 bit and just 256 colour tones .
Take another scenario. As software develops and improves, you can take your RAW image and reprocess it using more modern software. I have in fact gone down this route. I have re-processed an early RAW image it using modern software. This has dealt with the early noise issues apparent, far better than the first time round, to produce a much cleaner image. I couldn’t have done that to the same extent if it had been shot as a Jpeg image.
Okay, why would you want to do all this? Why would you like to choose to do all this extra work? Personally, I want to make my images. I don’t want to rely on the skill s of the whizz kid to process my images. He isn’t around when I took the picture. When I am doing so, I am visualising the finished print; how it will look; where I want viewers to look; how I want to show the atmosphere in the picture. No one, however good, can determine those feelings because they are mine. No, I hate spending so much time in my darkroom, which now inevitably is the digital darkroom, but, just like Ansel Adams in the last century, I want the print to be processed and developed as I want it to be.
It is your choice. Mine is RAW.
Keep practising, I am.