Why shoot in 16 bit (RAW), rather than 8 bit (JPG)?

I’ve been asked this question  so much lately that I had to share – In this post, we’ve got two important questions (and two timely answers) as seen from a “post-processing” point-of-view

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Question #1:  

 From Kris K in Gilroy, CA:  

 “You’ve mentioned shooting in 16 bit RAW files, and I’ve always used 8 bit JPG’s.  What would be the advantages and disadvantages of using 16 bit versus 8 bit for a landscape architectural photographer?”  

Answer:

Before I can fully answer your question, Kris, allow me to put on my “propeller-head” hat for a bit, so if “technical” is not your thing, don’t tune out, as this is good stuff…ACR1_CS6_03-13

Let me introduce you to the concept of Tonal Compression. This is the inevitable reduction and degradation of the original scene from your eyes to the print. It’s pure physics – the range of colors reproduced shrinks throughout the process.    

Let’s say, for example, that our eyes see 100 shades of red.   The camera, shot in RAW (16 bit), may see only 70 shades. Then Photoshop may only see 50 shades of red, and the printer may only print 40 shades of the original 100 shades available.

If, however, you shoot in JPG (8 bit), tonal compression will limit you to only 10 or 15 printable shades of red – not good!

So, how can you minimize some of the effects of tonal compression?  Three things:     

1)  Shoot in RAW (or scan in 16 bit) – discussed below …

2)  Use a proper Color Working Space in Photoshop – I strongly recommend “Adobe RGB 1998”.

3)  Have your Color Management “house” in order (discussed in my free Color Management PDF – Download here…)

So, to answer your questions:

The advantage of shooting in 16 bit?  Simple – – more information equals better final output.  There’s power in a 16-bit workflow – it’s not just “double” the amount of information; it’s a hundred-fold increase.

Here’s where you’ll see problems in an image shot in 8 bit: Because of the effects of Tonal Compression, poor results will show up first in “gradients”, or “continuous-tone” areas where the tonal qualities change subtly – a perfect example is the sky.  Kris, since you’re shooting landscape and architecture images, the sky is a critical element, and it’s rarely the same shade or brightness of “blue” throughout your image.

A more specific example: Most sunset images shot in 8 bit have “banding”, posterization, and digital noise – they just look fake as the “gradient” changes, due to the effects of Tonal Compression.  That same sunset, shot in 16 bit, won’t have near as many problems with it.  In addition,  if you need to punch up the sky by increasing the “blue” saturation, chances are that you can do so in 16 bit without major problems – it just won’t happen effectively in 8 bit. 

The disadvantages?: In my mind, only two, neither one of them a “deal-buster” when deciding whether to shoot in RAW / 16 bit: Time and Memory – It takes a bit more time (and education) to work on your image in the Adobe Camera RAW plug-in, and a bit more space for file storage on your computer (but memory is really cheap right now)

Do I shoot in RAW / 16 bit for everything? Of course not; as much as I love my grandkids, I don’t shoot RAW when photographing them, as the “audience” for the final output are relatives and friends, who just want “snapshots”.  But for those images that are more than snapshots, I’ll shoot RAW every time.

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Question #2:

 From Bill S. in Seattle, WA:  

“I’m a rank amateur photographer and new to Photoshop.  I belong to a camera club, and all of my photographer buddies tell me to shoot RAW for my important work, rather than JPG’s – – Why?”   

Answer:

Your photographer buddies are right – You should be shooting in Camera RAW for your important work — the results are worth it!

A RAW file is different from a JPEG in 2 major respects:

1) There’s much more information in RAW (16 bit vs. JPG’s 8 bit)

2) There’s automatic “file compression & processing” built into the creation of a JPG, whether you want it or not.  The camera’s computer chip, essentially, is telling you what it thinks your image should look like.

 In addition, JPG has other limitations:

•  Every time that you open, work on, and save a JPG, there is degradation because the JPG compression scheme is not “lossless” – it dumps pixels, whether you want it to or not.

•  You cannot save a JPG in 16 Bit

•  You cannot save a JPG with Layers (critical in Photoshop)

But it really all boils down to “digital information” – the more you’re able to capture when you shoot, the more information you have to effectively create your image.

•  (JPG) 8 Bit: 255 values of each RGB color (255³)  = 17.7 Million combinations of RGB values

•  (RAW) 16 Bit: 65,000+ values of each RGB color (65,000³) = 281 Trillion combinations of RGB values  – a hundred-fold increase over 8 bit!

Why do you need all of this information? You’ll have a better chance of reproducing your original scene more accurately, because you’re capturing a greater range of colors and luminance.

RAW does have one “limitation”: You can’t open a RAW file directly in Photoshop. You must first work with it in the Adobe Camera RAW Plug-in (ACR) before “sending” it to Photoshop. By the way, ACR is a separate program, but included with (and “linked to”) Photoshop – you can learn more about working with RAW files in my Photoshop book: http://www.wattsdigital.com/photoshopebook.html

Also, if your Camera has the option of shooting “RAW” + JPG”, then you should do so – It takes up little in memory, and gives you a quick “look-see” image that’s been “processed” for contrast, color, etc (albeit by a computer chip!). Oh, and I frequently hear folks say “My JPG looks better!” – – once you learn how to properly work on a RAW file, you’ll never believe that again!

Questions?  Comments?  I’d love to hear from you …

Thx again, and cheers,

John Watts 🙂

 

3 Responses to “Why shoot in 16 bit (RAW), rather than 8 bit (JPG)?”

  • Myron Kuziak:

    I note that you refer to 16 bit RAW format. However, many other photogs who blog and blither [that is not an intended insult, just wry humor which applies to me as well] refer to most cameras as producing RAW output at 14 bit resolution, which is, of course better than 8 bit jpeg. Since I am not a photo science techie I don’t understand why this difference crops up from time to time. Do you have a clue? All the best to you. I enjoy your blog and occasional bits of wisdom.

  • Myron, you are correct in that depending on camera model they might capture RAW files in 12 or now 14 bit formats. If you shoot in JPEG that additional information is thrown away from the first and reduced to 8 bit.

    But when you open the RAW files in a RAW converter you have the option of opening them for editing in a 16 bit space. The converter did not ADD information but in put the files in a space where, during editing, it can be added. As editors like Photoshop work on the files and they are rendered following your editing operations, the hues and shades are now rendered in that 16 bit space. Your edited master file should contain every drop of data you can cram into it.

    It is true that many output needs will then require you to down res/ down sample the file. But the master might later be used for a serious print and if it is already a low res, low color space, low bit depth file you cannot regenerate the lost data. JPEG was designed specifically for quick file transfer over dial-up modems. It is NOT a good editing format because, as John noted, every time it is saved it re-compresses the image to, at the highest quality, a 4:1 compression. Open and save it again and it is now 16:1 from the original. Most humans can detect the compression artifacts at about 10:1, almost no one will have any trouble seeing them at 16:1.

    As John noted, if this is a snapshot destined for something like email or Facebook you’ll never see it; but if it is a serious shot and you want a top quality print from it you will have no trouble seeing it in the final.

  • Myron:

    Thanks for the explanation, David. Helpful. If you ask, you shall receive.

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