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Sally Jane Photographic Art

Adobe Photoshop Tutorial

 

RAW!

 

Introduction - What is it and why should I use it?

It has taken me a long time to work out how to introduce the topic of RAW to you so in the end I thought I would start by answering the two questions most people have regarding it who have not already 'seen the light'. In a nut shell, RAW is a safety net. If all the photos you took were always perfectly exposed and always have the correct white balance set it's likely you might find RAW a waste of file space and effort. Having said that, there are still useful features that even the most perfect photographer could find useful. In practice, all the top professionals use RAW so if they do, then the rest of us certainly should.

Well, that's all well and good but I still haven't answered the questions. So, what is RAW? You may well have heard the analogy that RAW is the nearest you will get to a digital negative. That's a pretty good description. When a digital camera 'sees' an image it 'sees' far more information than can be displayed on a PC monitor or printed. The camera uses the settings you have selected for exposure and white balance and makes a judgment as to what information to keep and what to throw away. The kept information is saved usually as a jpeg image which holds a maximum of 8bits of data per channel. With the average point and shoot or compact digital camera there is no other option and all the excess data is lost forever. This isn't normally a problem unless the exposure is incorrect. If you have a poorly exposed jpeg image in order to correct it you will have to edit it in some image editing software such as Photoshop. I have said many times that editing in this way is destructive. You cannot put back anything that isn't there you can only remove data you don't want. If your image is under-exposed and it is very dark you can adjust it in photoshop with the levels slider to lighten it but all that results in doing is spreading the remaining information out more thinly. Often this will show up as noise or poor colour graduations in the shadows.

Where you have a camera that offers RAW capability when it is selected, instead of tech camera making the decision about what information to keep and what to weed out it simply records it all or nearly all. It is still limited a bit but it can now record up to 12 or in some cases 14 bits of data per channel. This might not sound a lot until you work it out. Each 'bit' of data is a state that is either on or off i.e. a state of 2. When we say 8 bits of data we are saying 2 to the power of 8 (2x2x2x2x2x2x2x2=256). That's 256 different light values per channel. 12bits is 2 to the power of 12 = 4096. That's a huge difference. Of course, this extra data can't be displayed in a single image but now when you need to lighten an under-exposed image, instead of stretching out the usable information you have to produce a balanced image the software can instead replace the information with other information that was otherwise hidden. In doing this you are no longer degrading the image and the result can be as good as if you had taken it correctly in the first place.

"Are, but what about file sizes?" I hear you say. It is true, a RAW image creates a huge file compared to a jpeg so you might only get a fraction of the images on a memory card that you would if you shot in jpeg but lets face it, memory cards these days are cheap. Bye several and always keep plenty of spares with you. It's cheaper than messing up an important shot.

If you have RAW capability on your camera my advice is to use it all the time. There might be an exception to this. My previous camera was a point and shoot Nikon Coolpix E8800. That had RAW capability but it was extremely slow in writing the data to the memory card as it didn't have much of a buffer. This meant I could only use RAW effectively when shooting still life shots. Most cameras that offer RAW now, however, don't have this problem so fill your boots! You won't regret it.

Ok, so enough of the chatter, lets see some examples!

under-exposed shotHer is a shot I took yesterday of my sister who is due to give birth in a couple of weeks. I was using a speedlight SB600 but it hadn't had a chance to charge up after the previous shot so only partially fired. Hence the resultant image is very under-exposed.

Since I always shoot RAW I knew there was a good chance of saving this image. It actually was a case of serendipity as I was already planning this tutorial and needed a good example image to use. Thankfully my sister is a good egg and gave me permission to use this shot.

First I converted it straight into this jpeg image without any alterations to show you what it would look like if I had shot it as a jpeg rather than RAW. I can't show you the RAW image direct because unless you have the right software you would not be able to see it.

 

 

 

8bit converted imageNext I edited the 8bit jpeg image in Photoshop using the levels adjustment. At first glance this doesn't look too bad. The next image below was crated by adjusting the exposure and contrast in Adobe's RAW converter. Again, at first glance there isn't much difference between them except that I probably reduced the contrast a little too much and flattened the skin tones.

 

 

 

 

 

 

(8 bit jpeg conversion)

 

raw converted imageViewed at this size you might be wondering what all the fuss is about. Remember I said it is the shadows that really show up the problems on under exposed areas? The next two images are full size crops of the bottom left hand corner showing just a section of the wooden cupboard door.

 

 

 

 

 

 

(12 bit RAW conversion)

 

The detail section below is from the 8 bit jpeg converted image. Notice the harsh graduations in colour from the greyish browns to the maroonish reds.

detain from the 8bit converted image

The below detail is from the 12 bit RAW converted image. The harsh colour graduations have been smoothed out completely.

detail section from the raw conversion

N.B. Although working in RAW allows you to make far greater changes than you would normally you can still go too far and cause the image to appear noisy or blocky or both. for that reason it is always best to pay attention to setting your exposure settings correctly before taking the shot. See the tutorial on camera settings for more information on this. The good thing is that no matter what changes you make to the RAW file the data stored there is unaffected and you can go back as many times as you like a tweak your settings will no ill effect. Also, even if you do go beyond the boundaries of the available information within the RAW file the noise effect will not be as bad as it would if you had made these same changes in Photoshop or any other image editing program.

 

RAW - Camera Settings

Importing RAW files with Bridge

Adobe Camera RAW Interface Explained.

Creating and Applying Presets

ACR Basics & Exposure Tools

ACR Sharpening & Noise Reduction

ACR Curves tools

HSL/Grayscale tools (Hue, Saturation and Luminance)

Split Toning tools

Lens Correction tools

ACR Top Menu Bar (Crop, rotate and blemis removal etc)

Saving your settings and converting your RAW files

Bridge and Converted RAW Files

 

 

Recommended Further Reading for Photoshop

Return to introduction & contents page

"A-Z of Digital Editing"

  

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