2 Replies Latest reply on Oct 31, 2011 10:56 AM by Noel Carboni

    Opening a 16-bit as a 12 or 8-bit?

    mediafred Level 1

      Why would you open a 16-bit photo in ACR or Photoshop as a 12-or 8-bit photo?  What is the point of doing that and what is it doing to the image?



        • 1. Re: Opening a 16-bit as a 12 or 8-bit?
          ssprengel Adobe Community Professional & MVP

          Opening a photo as 8-bits out of ACR chops off the lower resolution bits.   Either you should open the file out of ACR as 16-bit ProPhotoRGB (large colorspace) if you have more processing to do in Photoshop, or as 8-bit sRGB (small colorspace) if you are done toning it in ACR and just need a file to display after doing a few more non-toning-related things in PS. 




          In short, 16-bit ProPhotoRGB keeps the most color resolution so there is the least degradation when toning the photo, but it cannot be saved as a JPG, so a conversion to 8-bit sRGB usually needs to occur before saving as a JPG.




          Some people convert to Adobe RGB instead of sRGB but only if the image will only be viewed on a color-managed system.

          • 2. Re: Opening a 16-bit as a 12 or 8-bit?
            Noel Carboni Level 8

            I know of no way to open an image in a "12-bit" mode.  Can you clarify what you mean by that?


            Regarding "8-bit"...  You might choose to open a photo as 8 bit if you don't plan on doing a lot of image editing steps and/or your intended use is strictly for an 8 bit purpose such as saving a JPEG.  Doing so simply uses fewer Computer Resources and will be faster. 


            There are also a fair number of features that will only work on 8 bit data - for example all the Filters in the Filter Gallery and a number of others.  If you're using these effects you have to be working on 8 bit data.


            People edited 8 bit images for years before the CS series made layers work with deep formats.  People with Photoshop Elements still do have to use 8 bits/channel if they want to use layers.


            I personally now always open raw files into 16 bits per channel, and convert only to 8 bits if I really need to.  If your computer is up to the added stress of working on the larger datasets 16 bits/channel probably the best default to choose.