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So, you have your digital dslr. You know how to measure the white balance, and you know how to set the exposition right. Do you? I am almost certainly sure that in 99% of the cases you don’t. Just like me. Just like most of the semi-pros out there. Like most of the lazy people. But you have RAW images to help you. What is RAW?
Let’s imagine that you want to cook a soup. Chicken soup. You have two ways: you can buy a stock cube which will substitute the meat and some of the vegetables. You can buy a piece of the chicken and some fresh vegetables on the market. In both of these cases, you can boil it and you’ll have a chicken soup. Which one will be better? Well, you don’t need to be Jamie Oliver to examine this. Now please imagine, that the stock cube is the software embedded in your camera - this bit of programming code which will digest all the fresh data captured by the camera sensor, “optimize it” and spit out the JPEG file - your final picture, the soup. And the chicken is the same fresh data - but it’s you who will decide how to cook it :)
Ok, let’s leave the chicken-carrot rubbish behind. So what exactly this RAW is, you will ask? The answer is simple. RAW is pure, almost un-manipulated, clean data coming straight from the sensor. It’s like a digital negative (in fact, one of RAW specifications is even called “Digital Negative”). It’s something which comes from most of the dslr cameras as .CRW file (Canon), .NEF (Nikon), .MRW (Minolta) and so on. It is compressed with the loseless algorithm (unlike JPEG - this means that nothing is missing from the information registered in the first instance) and it is not processed by your camera software, which means it’s also probably looking like sh*t before you’ll edit it with a RAW processing software :)
With RAW you can manipulate white balance, sharpness, exposition, colour and contrast much more easily than with JPEG - due to the fact of its loseless compression (look on the previous paragraph). Any disadvantages? Yeah, a few: files are bigger than JPEG, so less continuous shooting, they need a special editing software (there’s plenty of free, very good alternatives for multiple platforms though), and most of all: editing RAW needs more than basic understanding of image acquiring and processing techniques. But it’s the closest to the old fashioned, fully controlled and totally super-duper analogue photography you will ever get with your digital camera.
So attack! Forget JPEG, shoot RAW. And discover whole new world.
This is personal blog of Wojtek Kutyla - Photographer based in Sheffield, South Yorkshire. Photography, Internet, music, naked girls, alcohol, food and travel. All in one.
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March 30th, 2007 at 12:25 pm
I have seen the light (but managed to reduced the blooming highlights)…
The first thing that seriously annoyed me is that so-so support for RAW, especially amongst consumer level image apps. I found that when I plugged my camera into my PC, the PC wouldn’t see any photos on the camera. Now that is just bad!
The size of RAW can be crippling if you don’t have plenty of memory cards, or big ones.
I always found that I could manipulate images to account for even quite serious errors in exposure etc, so I didn’t think RAW was worth the effort.
Time to U-Turn!
I went back to RAW when support for the format improved. Having played with RAW much more I realise that anyone who is serious about photography can’t afford to gamble on the chicken soup.
April 2nd, 2007 at 7:03 am
You didn’t mention why it’s possible to correct exposition and/or white balance and get good results when using RAW. It’s not because some extra data are stored in EXIF/whatever. It’s not because RAW hasn’t been manipulated (on my dslr you can use the setting which automaticaly saturates images a little bit). Most of the same action as setting white balance or changing exposition in your software/plugin for manipulating RAW you can achieve using .jpg and a graphic program (gimp, photoshop).
The real difference is the colour depth. In jpg you have 8 bits per channel which gives you 256 levels of red, 256 of green and 256 levels of blue. Is it a lot? Not.
If you try to correct exposition (photo is underexposed so you want lighten it) you will stretch the information stored in eg. 200bytes to 256bytes.. So you will end up with 200 bytes of information per channel (only the max value will be now eg. 255). When you modify white balance you will loose another data. The results can be really rubbish ;>)
What about RAW? In most cameras it’s 12bit/channel which gives you 16 times more information (4 096 levels per channel). And that’s real difference.
When you want to loose even less data you can convert your 12bit RAW into a 16 bit image and then make manipulations. Because manipulation not always stretches the information but also narrows (eg. when correcting white balance or lightness/contrast) less data will be lost. Of course if you don’t see a dfference between images manipulated at 12bits and 16bits (in print of course - if you have LCD then probably it will be hard to see difference between 8b and 12b) then you don’t need another extra 4bits per channel.
Anyone understand anything or I’ve just really twisted a quite simple concept? ;>)
Time to get back to work.. that was a nice, lazy weekend ;>)
April 2nd, 2007 at 8:45 am
Well, as usual I got bored in the half of writing so I didn’t finished. :)) Thanks Calek ;)