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is my 16bit edit pointless
I have been using PSE 1 with various free add on tools for a good few years now, and this combination has served me well for my needs..

I recently purchased my first DSLR(EOS400D) and at the same time decided to upgrade my software and got myself PSE 6. I am also playing around with a demo of PSPX2 and both seem to be very good.As most of my images are for on screen viewing my usual workflow is1 shoot raw2 adjust w/b and exposure in DPP and save as 8bit TIFF3 edit in photoshop and save as high quality jpeg..

However, for images I want to print, or just spend a bit more time over I export fromm DPP as a 16bit TIFF. When editing in PSE(or PSPX2) I can perform contrast and colour adjustments but there then comes a point where I need to convert to 8bit to enable me to access various functions. ie cloning, spot healing etc..

Does converting to 8bit throw away any extra detail I may have retained by doing my initial corrections in 16bit mode..

In short, would I be just as well starting in 8bit mode from the moment I convert from raw..

Comments (11)

Hmmm. According to a random trawl using google, the human eye can perceive at most 10 million different shades of colour, which sounds a lot. But three colour channels (R/G/B) at 8-bit resolution (0 - 255 on each channel, apparently fairly crude) gives a total of 256 cubed different colours, or nearly 17 million..

Using 16-bit resolution gives (65536 cubed) = close to 300 TRILLION different shades, which is millions of times more more than the most optimistic estimate of how many different shades of colour the eye can perceive..

On that basis, I'd say that 8-bit is fine....

Best wishesMike..

Comment #1

Short answer yes..

Longer answer - still yes but not quite as clearcut..

Basically you should put off using an 8-bit format as long as possible. You can ( and I do ) edit 8-bit images quite happily in a graphics package, but using a 16-bit package ( i.e. a package that can operate on data with 16-bits per component ) gives you more control and will allow smoother colors and less e.g. posterization and color shifts. Cumulative changes are more accurate..

So ideally stay in 16-bit as long as possible. Drop to 8-bit if you have to..

Important. If you start from 8-bit still try and convert it and work on it as 16-bit, because you still get the benefits of cumulative changes which are more accurate..

StephenG.

Pentax K100DFuji S5200Fuji E900PCLinuxOS..

Comment #2

My understanding is that certin Pshop functions (clone and stamp tool for example) produce smoother and more artifact free results when done to 16bit files. I do them before converting. Good Luck..

Comment #3

Mike703 wrote:.

Hmmm. According to a random trawl using google, the human eye canperceive at most 10 million different shades of colour, which soundsa lot. But three colour channels (R/G/B) at 8-bit resolution (0 -255 on each channel, apparently fairly crude) gives a total of 256cubed different colours, or nearly 17 million..

Using 16-bit resolution gives (65536 cubed) = close to 300 TRILLIONdifferent shades, which is millions of times more more than the mostoptimistic estimate of how many different shades of colour the eyecan perceive..

On that basis, I'd say that 8-bit is fine....

Best wishesMike.

Yea good point...actually very good point!.

Roy Niswanger http://www.motleypixel.com..

Comment #4

What are you doing with your images? or to put it another way....

Is the way you output your images able to take advantage of the extra 16bit information?.

If the answer is yes then use it.

If it's not, then you should be questioning why you are using information that can't be displayed...Keep the RAW files for the future tho ;0).

For me and my work the CMYK print process cannot display all the information found in a 8 bit jpg straight from the camera, so for me shooting in RAW is pointless from the outset. However there are many photographers out there for whom shooting RAW is part of their working process. You have to decide what's right for you..

=-=-=-=-=-=-=-=-Always give the client a vertical-=-=-=-=-=-=-=-http://grahamsnook.wordpress.com/..

Comment #5

Lextalionis wrote:.

On that basis, I'd say that 8-bit is fine....

Yea good point...actually very good point!.

Well, actually it sort of missed the point all together. While it is indeed true that the human eye will have real trouble discerning a broader tonal range than what can be expressed in an 8-bit image, that's pretty much academic. It's why our monitors are generally 8-bit devices. And our printers..

The advantage in editing is that with a 16-bit image file (which in actuality is seldom more than a 12-bit file in a 16-bit wrapper) we have a much broader pallete of tones and colors from which to choose from when deciding exactly which ones will finally end up in that 8-bit JPEG or print. This can present all sorts of advantages, from increased highlight and shadow detail, to smoother gradients throughout..

It's the same 12-bits that the camera uses when applying the settings that were in place at the time of capture to any JPEG's that are output directly. The camera is able to use those extra bits to good advantage, there's no reason why we shouldn't be able to as well..

Whether editing 16-bit files is a waste of time for you is pretty much up to you. A lot of people are perfectly happy sticking to 8-bit files and for the most part perfectly good results are obtainable, even if the editing options are somewhat limited by comparison..

'Here, look at the monkey. Look at the silly monkey!'.

Tom Younghttp://www.pbase.com/tyoung/..

Comment #6

On that basis, I'd say that 8-bit is fine....

Yea good point...actually very good point!.

Well, actually it sort of missed the point all together. While it isindeed true that the human eye will have real trouble discerning abroader tonal range than what can be expressed in an 8-bit image,that's pretty much academic. It's why our monitors are generally8-bit devices. And our printers..

The advantage in editing is that with a 16-bit image file (which inactuality is seldom more than a 12-bit file in a 16-bit wrapper) wehave a much broader pallete of tones and colors from which to choosefrom when deciding exactly which ones will finally end up in that8-bit JPEG or print. This can present all sorts of advantages, fromincreased highlight and shadow detail, to smoother gradientsthroughout..

Thanks Tom, that makes very clear sense. LIke the OP I had wondered about why anybody would bother with 16-bit when 8-bit apparently offers all that the eye needs..

Best wishes.

Mike..

Comment #7

Lets suppose that you have a camera that has a 9 stop dr (Lucky you) and that your workflow is as follows in Raw+ACR+Photoshop CS3..

Well first of all, with most cameras (DSLR's) you can take 12 bits RAW's, then pass them to ACR in 16 bit format and then whatever is your workflow in Photoshop you should also keep them in 16 bits RGB..

A camera with 9 stops of DR and 12 bits of data path makes pictures that are as follows: 2, 4, 8, 16, 32, 64, 128, 256, 512 shades of grey. the first 3 (2, 4, 8) are you shadows, then come your midtones (16, 32, 64) and then your highlights (128, 256, 512) for a total of 1024 shades of grey for each color (RGB)..

That means that as soon as you go down to 8 bits you're losing a lot of detail all over the spectrum.In 8 bits you have 4 shades for shadow, 28 for midtone and 224 for highlight..

In 16 bits (Really 12 bits out of camera like somebody said before) you've got at least: 14 shades for your shadows, 112 for your midtones and a huge 896 for your higlights..

Remember that a camera's ccd is not like our eyes as it percieves light in a linear fashion, that means that each stop lets in twice the light as the one that follows it.Imagine when we get real 16 bit RAW output from a camera's ccd..

Like somebody told me a few years back "garbage in , garbage out" the longer you keep your edition in 16 bit format, the better your final pictures will look even in 8 bit format.Forgive my bad spelling as I'am Spanish..

Comment #8

Forgive my mistake: wherever I say 1024 shades of grey I meant to say 4096 shades of grey which is what comes out of a 12 bit raw capture..

That means that your shadows have 8, 16, 32 shades of grey (From darkest to lightest) your midtones 64, 128, 256 (from darkest to lightest) and your hightlights 512, 1024, 2048 shades of grey (from darkest to lightest).Sorry for the mistake...

Comment #9

16 bits file (which actually is a 12 bit file but c9onverted to 16 due standars) works perfect if you will do a heavy manipulation to your image, like expanding the dynamic range of the photo. After processing, you can convert it to 8 bit, but always keep the 16 bit one..

Try this:.

1) Open a 16 bits native image file in photoshop.2) Duplicate it and convert it to 8 bits..

3) Grab the 16 bits one and apply a heavy contrast increment using levels, hit ok..

4) Refresh the Histogram's Cache (a yellow triangle with an ! in the histogram window).5) Do the same with ten 8 bits file.6) Compare the histograms.

You will see the 8 bits one will look jagged. That's caled posterization/banding and probably, will show artifacts..

If you wanna smooth manipulations, use 16 bits, even if you like hard contrasted images, use 16 bits, they will look more professional instead blown pixels-like .

I'm freaking crazy, so what!!!..

Comment #10

As others have said, keep your file 16-bit as long as possible, but on the other hand don't worry about dropping it to 8-bit for final editing or printing. The reason for this is data precision converting down from 16-bit to 8-bit is like rounding a number off. Which is fine when done in moderation but results in error compounding if you begin to adjust that number..

Imagine giving someone directions and telling them to drive 100 feet down the road when the real value is 95 feet. Either way the number is good enough for the purposes at hand (just like 8 bit per component is good enough for human visual systems), 5 feet of difference is insignificant. The problem occurs when you compound the estimation over a number of calculations... say you know they need to drive 100 times as far as the distance down the road, so you multiply 100 by 100 and get 10000, but since the real value was 95 feet then 100 times that should be 9500, a difference of 500 feet from the true value, which is now very significant!.

This is roughly similar to what happens when you're editing your photos because every time you run a filter on your picture or add an adjustment layer you begin to compound the error of the original round off, eventually the error drift can become significant enough to impact your results. This is why it is best to use as high precision as you can when making active edits to data, even if you're working in a precision that is much higher than you need for the final result...

Comment #11

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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