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Archive 2012 · Changing color bit depth during processing
  
 
altern3
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p.1 #1 · p.1 #1 · Changing color bit depth during processing


Some functions in photoshop take a very long time when working with 16bit files, is it a good idea to change for that particular task to 8bit and then change back to 16 bit?

For example surface blur takes 6min for a 10mg file using 16bit and on the other hand it takes seconds with 8bit version of the same file.



Aug 22, 2012 at 12:03 AM
Peter Figen
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p.1 #2 · p.1 #2 · Changing color bit depth during processing


Once you switch from 16 to 8, you've effectively thrown out your extra bit depth and switching back cannot miraculously restore what you threw away. Photoshop will tell you that you have a 16 bit file, but really you'll only have an 8 bit file with the extra bits "padded" to make it look like 16.


Aug 22, 2012 at 12:27 AM
Alan321
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p.1 #3 · p.1 #3 · Changing color bit depth during processing


Stay with 16 bit at least until you have finished all significant edits that affect the number of tonal levels or colour levels either overall or in a particular part of the image (exposure, contrast, WB, curves, etc.). If what you've then have fits nicely into 8-bit space then you should lose relatively little by converting to 8-bit before doing relatively subtle edits.

Is your 8bit file that takes only seconds to process a jpg, or tiff ? Compression on a converted jpg may be having an influence. Otherwise you should only have halved the amount of data to be processed and not see such a great change in processing time. [no experience with this - just supposition]

Also, is your "10mg" file 10 megapixels or 10 megabytes ? How big is it in Ps memory after raw conversion ? That will give you a better idea of what amount of data is being processed.

- Alan



Aug 22, 2012 at 11:28 AM
phil hawkins
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p.1 #4 · p.1 #4 · Changing color bit depth during processing


If you want to reduce the processing time for surface blur, which is usually on faces for skin, draw a selection around the specific area you want affected and then mask that part in.


Aug 22, 2012 at 04:24 PM
altern3
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p.1 #5 · p.1 #5 · Changing color bit depth during processing


Thanks for your input. I found out that the amount of surface blur also has an impact as well as using it on a smart filter. To save time I did not use a smart filter and only applied moderate levels and then copied that layer for more blur if I wanted.



Aug 22, 2012 at 07:16 PM





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