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16 bit files

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  #11  
Old 11-16-2014, 05:49 PM
klev klev is offline
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Re: 16 bit files

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Originally Posted by skoobey View Post
Or even simpler...

It's all number of combinations 8bit has 256 different lightness values for R, G and B.

16 bit has 65536.

32bit has 16777216.

Just an example, I know it's not real thing that you can see, and that it depends on the actual color profile blah blah.
That's not exactly it. One is stored as integer values. The other is stored in a linear floating point encoding, so no they are not comparable. In photoshop 16 bits stores the same range with more steps. 32 bits stores a wider range. They're stored in gamma 1.0, which is independent of their being floating point values.
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  #12  
Old 11-17-2014, 01:09 AM
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Repairman Repairman is offline
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Re: 16 bit files

Sometimes the conversion from 32 to 16 does zap the image creating the blown out effect. PS HDR Toning set to Exposure and Gamma (at default setting) seems to restore the image to normal - is that the best way to resolve the issue (in real world scenario rather than theoretically).
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  #13  
Old 11-17-2014, 01:28 AM
klev klev is offline
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Re: 16 bit files

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Originally Posted by Repairman View Post
PS HDR Toning set to Exposure and Gamma (at default setting) seems to restore the image to normal - is that the best way to resolve the issue (in real world scenario rather than theoretically).
Well that is basically what it shows you on screen when you're working in 32 bit mode. It doesn't display a linear file on screen. The display response is highly non-linear. Exposure/gamma is what I would use. It's just that if you have any totally blown areas prior to that point, you can use masking while in 32 bit mode to bring them back as long as the renderer wasn't set to clamp too tightly. 32 bpc does give you some incredible latitude. Try some of the color adjustment tools at that bit depth, especially channel mixer. You'll see what I mean.
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  #14  
Old 11-17-2014, 05:46 PM
skoobey skoobey is offline
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Re: 16 bit files

Oh, they are very much comparable when you're trying to explaining why we do something. Just like pen and paper are comparable with phtoshop.

Anyway, it's a bout what 32bit can do for us, nothing more or less.
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  #15  
Old 11-18-2014, 12:40 PM
shoreboy shoreboy is offline
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Re: 16 bit files

My brain hurts....but thanks for all the highly detailed discussion. Think I'll stick to 8 bit which should be fine for my purposes.
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  #16  
Old 11-19-2014, 02:55 PM
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andrewrodney andrewrodney is offline
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Re: 16 bit files

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Think I'll stick to 8 bit which should be fine for my purposes.
Perhaps work with the native bit depth of whatever the capture device handed off to you? You can always end up 8-bit per color for the times that bit depth is warranted.
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  #17  
Old 11-19-2014, 05:18 PM
Caravaggio Caravaggio is offline
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Re: 16 bit files

How does a smart object layer that is converted to 16 bits and then has a gradient drawn on it appear when that smart object is a layer in an 8 bit file? Will that 16 bit gradient smart object layer appear the same as a gradient drawn on an ordinary layer in an 8 bit file and exhibit the same banding issues?

Sorry if this question seems kind of dumb.

Last edited by Caravaggio; 11-19-2014 at 07:25 PM. Reason: clarity
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  #18  
Old 11-19-2014, 06:54 PM
klev klev is offline
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Re: 16 bit files

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Originally Posted by Caravaggio View Post
How does a smart object layer that is converted to 16 bits and then has a gradient drawn on it appear when that smart object is a layer in an 8 bit file? Does that 16 bit gradient smart object layer appear the same as a gradient drawn on an ordinary layer in an 8 bit file with the same banding issues?

Sorry if this question seems kind of dumb.
Drawing at 16 bits would be less likely to show banding, assuming the error resides with your image file and not your display. If you see banding at some odd zoom level, it's likely due to the way its redrawn, but anyway no algorithm is perfect. There's always some rounding, but any compounded rounding at 16 bits of precision is likely to remain small relative to the precision afforded by 8 bits of information. In that sense you may achieve better results, but in practice you have to try it out. If you convert down to 8 bits and maintain it as a smart object rather than rasterizing it, you may lose that. I'm not entirely sure, because I don't know how that smart object is stored. If it's stored as an exact value rather than just a set of instructions that are re-run when the image is loaded, you wouldn't gain anything from it. Smart objects aren't really an ideal solution to anything. I suspect that Adobe used that strategy to maintain compliance with older code.

I don't really care for my answer, so I'll try again. The distance between two equivalent colors in 8 or 16 bpc is basically the same, but at 16 bits we can describe more intermediate values. Say we count from 2 to 20 in steps of 2. If you count in steps of 1, the distance between steps is less, yet the total distance between 2 and 20 remains the same. That's basically it. Doing that at 16bpc is only meaningful if you commit to those changes at 16 bpc rather than exporting instructions to 8 bits. This is because while there's always a rounding error of some sort in these operations due to finite precision, the compounded effect of rounding may be less at 16 bpc in terms of absolute error, and the end result at 8 bits is what counts. Just be aware that once you look at either raw files or 32 bpc mode in photoshop, the rules are a bit different. I've demonstrated the differences in certain filters and color adjustments and why they aren't just due to gamut.

Last edited by klev; 11-20-2014 at 02:33 AM.
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