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Photo Retouching "Improving" photos, post-production, correction, etc.

8 bit and 16 bit post processing

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  #11  
Old 02-10-2012, 08:22 AM
John Wheeler's Avatar
John Wheeler John Wheeler is offline
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Re: 8 bit and 16 bit post processing

Hi Chain
I liked that spatter technique as well (credit to Shift Studio). To get around the 8 bit limit I did somthing similar yet kept it in the same document.

- create stamped copy of image
- turn stamped copy into Smart Object
- click on Smart Object thumbnail to open Smart Object
- Convert to 8 bit
- add Spatter as a Smart Filter (works because Smart Object is in 8 bits)
- Save and close Smart Object, then go back to original image (which auto converts the Smart Object back to 16 bits)
- Use mask on Smart Object to limit to areas with banding (same as your steps)

Same trick, just keeps everything in one document, you can go back and edit the Spatter parameters, and no extra file nor pasting.
FYI
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  #12  
Old 02-10-2012, 08:46 AM
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Chain Chain is offline
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Re: 8 bit and 16 bit post processing

Smart Object is a good idea. Then you can keep the two documents as one. Better if you need to go back and tweak it more (I know I did).

I also ran Spatter several times with lower opacity to make it a smoother blend (helped in some areas). Had a heavy curves adjustment on top to exaggerate so I could see it.
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  #13  
Old 12-31-2015, 03:24 PM
Keano12 Keano12 is offline
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Re: 8 bit and 16 bit post processing

Curious. I exported from Capture One in sRGB and Adobe RGB as 16 bit tiff and can't see a different between them. I think the most important part is the 16bit. Most printers are even sRGB.
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  #14  
Old 12-31-2015, 03:34 PM
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andrewrodney andrewrodney is offline
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Re: 8 bit and 16 bit post processing

There is no such thing as an sRGB printer. It's based on an emissive display circa 1993 or so.
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  #15  
Old 01-01-2016, 04:59 AM
klev klev is offline
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Re: 8 bit and 16 bit post processing

Quote:
Originally Posted by Keano12 View Post
Curious. I exported from Capture One in sRGB and Adobe RGB as 16 bit tiff and can't see a different between them. I think the most important part is the 16bit. Most printers are even sRGB.
I did promise to look up my own reference for perceptual lookup tables, so I'm sure I'll hear about that. Photoshop seems to still just use relative colorimetric.

Andrew is saying that you cannot directly compare a function mapping light intensities to numeric values with one that maps ink density to numeric values.


Gamut Comparisons
To get around the issue, we can compare them in terns of their relation to some reference space. The ink values are usually interpreted by assuming a specific light source and estimating the expected intensity of light returned by that combination of ink and paper. That way you can describe everything with respect to a color model based on either light or cone response to light.


Bit Depth
8 and 16 bits per channel don't determine range. They determine the number of intermediate values that can be stored. Depending on how the data is processed, 16 bits may provide a less noisy result or one with less banding.

You could actually approximate the same gamut with 1 bit per channel. You would just have a much much much lower level of detail, because you would only have 8 colors rather than whatever 3.52e13 (I think Adobe's engine uses approximately 2^15 values per channel so I'm going with that).


Printer Output
Getting back to your printer, under a light source that approximates the reference viewing conditions, your printer should be able to approximate most colors that could be produced by a monitor which closely matches sRGB.

Much of the time you won't see any difference in output between sRGB and Adobe RGB. If you have some highly saturated colors that would clip in 1-2 channels (not 3) in sRGB but not in Adobe RGB or whatever is sent to the printer, then you may see a benefit.

I hope that is clear.
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