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8 bit vs 16 bit files

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8 bit vs 16 bit files

Postby momoffduty » Fri Apr 26, 2013 7:56 pm

I've been exporting raw files as 16 bit psd files to continue working in photoshop. It takes a lot longer to save a file when it is 16 bit. I changed my scratch discs to the 2nd Raid drive thinking it would make a difference with the memory, but it didn't. Is is normal for a 16 bit to take a long time to save? The 8 bit is done in a split second.

And in After Effects I had my scratch disc set to the SSD which is too small so I just changed it to the D drive. It is set at 50 and wonder if allocating more space will help AE since I run out of memory?
Also, what is the Conformed Media Cache? Should I change those folders too?...the Database & Cache Folders. Should I clean the Database & Cache? I periodically empty the disc cache.

By cleaning the AE Disc Cache I went from 22GB free space to 64GB on the C drive.
aka Cheryl
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Re: 8 bit vs 16 bit files

Postby Bob » Sat Apr 27, 2013 4:10 pm

Is is normal for a 16 bit to take a long time to save?


Not in my experience. A 16-bit file will be about twice as big as an 8-bit file, but on my system I don't notice any significant difference in time to save. They're both fast. How big are the saved files?

And in After Effects I had my scratch disc set to the SSD which is too small so I just changed it to the D drive. It is set at 50 and wonder if allocating more space will help AE since I run out of memory?
Also, what is the Conformed Media Cache? Should I change those folders too?...the Database & Cache Folders. Should I clean the Database & Cache? I periodically empty the disc cache.


I would not put either of those on the SSD system drive. The default location is in your user data (which is on the system disk), but that's not ideal. Adobe recommends putting the Disk Cache on a disk that is not the system drive or the drive where the source files reside. If you can't, don't worry about it. The disk cache is used heavily in AE CS6, that's where the global performance cache resides. The size will increase with use up to the maximum you set. 50GB is reasonable. Professionals working on many (or large) projects may want to increase it. I empty the disc cache whenever I finish a project.

The media cache database keeps track of the media cache files. These are the .cfa, .pek, etc. files. The media cache database is shared with Adobe Media Encoder, Premiere Pro, and Encore, so each of these applications can each read from and write to the same set of cached media files. Each application can use its own cache folder, the media cache database keeps track of them all. The Media Cache location is where AE will store the media cache files if they don't already exist. The space will continue to grow, so this is not a great candidate for an SSD. The clean database and cache button will only remove entries and cached files if the source that they correspond to is gone.
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Re: 8 bit vs 16 bit files

Postby momoffduty » Sun Apr 28, 2013 4:08 pm

Thanks Bob for the explanation. I'll change the Media Database & Cache folders in AE to the D drive. When working in AE, I usually have to Purge All after a sitting. If I don't when I open AE back up I get the warning about low on memory.

For the photos I shoot raw and save as PSD to continue working in PS. Ran a test on the same photo:

The 8 bit psd: 51.28 mb
The 16 bit psd: 102.54 mb
The 16 bit psd with about 10 layers: 698.19 mb

I see now that the last is HUGE! Do I really need to save in 16 bit for say color photos? I did watch a tut on black/white where you are using a lot of Curves adj layers and was recommended to work in 16 bit. But, say everyday color photos would 8 bit be okay?
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Re: 8 bit vs 16 bit files

Postby Bob » Sun Apr 28, 2013 7:56 pm

Do I really need to save in 16 bit for say color photos? I did watch a tut on black/white where you are using a lot of Curves adj layers and was recommended to work in 16 bit. But, say everyday color photos would 8 bit be okay?


Doesn't matter whether you're working in B&W or color. Manipulation of tonal values with curves and adj layers can benefit from the use of 16-bit. 16-bit is much less prone to banding/posterization and you'll get smoother gradients and transitions. Do you always need to go to 16-bit? No. It depends on the amount of manipulation and the nature of the image. Some images are more prone to banding than others. Especially the ones with large areas of nearly uniform area like skys. If you do use 16-bit, after the work on the image is complete, you can flatten the image or create a new merged layer and convert to 8-bit. You don't need to keep it 16-bit unless you plan on working with it some more. You seldom need to use 16-bit for casual or snapshot photos. I'll always use 16-bit if I'm trying for a high quality image that I intend to print in a larger size, or if I'm doing retouching or restoration.
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Re: 8 bit vs 16 bit files

Postby momoffduty » Mon Apr 29, 2013 8:02 pm

Thanks Bob for the detailed explanation. I am not doing any large prints so good to know on the bit size. I can see what you are saying about the tonal banding. It would be beneficial in black & white conversions.
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