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Thread: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

  1. #1

    Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    Friends, I have an Eversmart Pro II which I use to scan 6x6cm and 4x5 chromes. The Oxygen software scans in 8 bit, though there is, I understand, a plugin that converts to 16 bit. My question is whether an 8 bit scan that is converted to 16 bit in CS2 responds to color management in the same way as a file originally scanned in 16 bit. FWIW, I do most all the color adjustments prescan with very modest adjustments in CS2. Since I am scanning 4x5 chromes, the 16 bit scans would be twice the size of already processor choking files in 8 bit.
    Much obliged.

    David

    PS If someone is familiar with the Oxygen v1 software, can you tell me how to rotate the image in the preview window (if it is possible).

  2. #2

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    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    ...responds to color management in the same way as a file originally scanned in 16 bit.

    The file will respond the same way, but you will be starting out with a fraction of the quality. Capturing in high definition is important. Performing adjustments in high definition is also important. You should only downgrade to low definition at the end.

    You might find this short article to be helpful: 16-Bits-per-Channel: Goodbye "Banding", Hello Smooth Tones

  3. #3

    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    Quote Originally Posted by Deliberate1 View Post
    ...My question is whether an 8 bit scan that is converted to 16 bit in CS2 responds to color management in the same way as a file originally scanned in 16 bit....
    Is your question with regard to profile conversions? Or by color management do you mean color adjustments, corrections, etc...?
    Any kind of edit has loss, how much matters is the question. Of course there will be more potentially problematic loss in 8 bit than 16 bit, but the likelihood is less in color, which you are doing, than B&W as the loss is never equal in all channels and tends to mask. Since your major moves are in the scanner software (so actually native scanner bit depth, higher than 8) you are most probably fine.
    With regard to assigning a scanner input profile, then converting to a working space (what one might assume is meant by "color managed"), the issue gets more complex due to the relevance of a scanner profile when using software controls that are not locked down to those used when creating the profile itself...
    Sorry if I've confused matters, hard stuff to simplify.
    Tyler

  4. #4
    Resident Heretic Bruce Watson's Avatar
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    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    Quote Originally Posted by Deliberate1 View Post
    My question is whether an 8 bit scan that is converted to 16 bit in CS2 responds to color management in the same way as a file originally scanned in 16 bit.
    No. Converting it to 16 bits doesn't mean you have 16 bits of information. You still have 8 bits worth, you just put it in a bigger jar.

    However, if done carefully this can still get you acceptable results.

    Bruce Watson

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    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    First of, if you start with an 8-bit image and youre going to edit, you should be working in 16-bit mode anyway to avoid crushing your histogram.

    Of course it's always good to have a higher bit depth source originally, which is even better.

    If the plugin is converting to 16-bit, yes it's the same thing as doing it in photoshop, if it enables 16-bit scanning, then no its not, check the wording, or look up the hardware specs to see if the hardware is at all capable of higher bit depth scanning.

    8-bit source (A good quality 8-bit source ie: as long as your histogram doesn't need stretching out, ie: makes full use of the space) is perfectly fine for editing (always edit in a 16-bit space though).

    But 8-bit scanning is not, typically if you have no adjustments in the scan software, you can see the histogram is only a small portion of the space, thus 16-bit is needed to capture the optimal range of steps between each tone that's displayable.

    Even if your histogram is 1/8th the size of a full histogram in a scan (before levels adjustment), in 16-bit, that's still 32x the amount of steps as 8-bit (that would be 13-bit... it's logarithmic not linear)

    Explanation:
    8-bit has 256 possible steps from darkest (pure black, or minimum intensity of the colour channel) to lightest (pure white, or maximum intensity of that colour channel).

    16-bit has 65536 possible steps.

    If you're only making use of half the histogram shown, that's 32768 steps between all the tones (thus half a 16-bit histogram isnt 8-bit like expected, but 15-bit), which means either your darkest scanned tone or lightest wont be the possible lightest or darkest in display - levels adjustment corrects this.

    With any kind of film profile or adjustments enabled during scanning, you generally wont see that.


    Edit:
    Also why it's important to edit a 8-bit source in 16-bit, if you perform something that crushes the histogram down, to say half, you'll lose 1-bit, thus editing in an 8-bit space will reduce your number of steps between everything to 7-bits (128 steps), where as in 16-bit space, that'll be 15-bits and you will have lost nothing (essentially), and will be able to stretch it back out with another adjustment for whatever kind of editing you're intending.

  6. #6

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    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    David, I am not sure that oXYgen v1.x functions the same on the Pro II as it does on the Supreme, but with the Supreme you have the option to set up the scan as a DT file which is 16 bit. There is also a plug in for Photoshop that enables opening of the raw 16 bit file in Photoshop. Again, I do not know if oXYgen on the Pro II has 16 bit DT file capability but if it does you may want to consider making a 16 bit master file from your scans.

    Ben

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    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    Quote Originally Posted by Deliberate1 View Post
    Friends, I have an Eversmart Pro II which I use to scan 6x6cm and 4x5 chromes. The Oxygen software scans in 8 bit, though there is, I understand, a plugin that converts to 16 bit. My question is whether an 8 bit scan that is converted to 16 bit in CS2 responds to color management in the same way as a file originally scanned in 16 bit. FWIW, I do most all the color adjustments prescan with very modest adjustments in CS2. Since I am scanning 4x5 chromes, the 16 bit scans would be twice the size of already processor choking files in 8 bit.
    Much obliged.

    David

    PS If someone is familiar with the Oxygen v1 software, can you tell me how to rotate the image in the preview window (if it is possible).
    You might want to read this thread listed on Photo.net.

    http://photo.net/digital-darkroom-forum/00TjSz

    Don Bryant

  8. #8

    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    Quote Originally Posted by Ben Hopson View Post
    David, I am not sure that oXYgen v1.x functions the same on the Pro II as it does on the Supreme, but with the Supreme you have the option to set up the scan as a DT file which is 16 bit. There is also a plug in for Photoshop that enables opening of the raw 16 bit file in Photoshop. Again, I do not know if oXYgen on the Pro II has 16 bit DT file capability but if it does you may want to consider making a 16 bit master file from your scans.

    Ben
    Be, I will ceheck this out. My understanding is that the DT is a Photoshop plug-in. The version of Oxygen I am working with is way old and perhaps was written before a Photoshop version that permitted the 16 bit conversion. I am quite sure that the DT function is applied after the scan.
    Am I off on this? Just read that Pro II makes 14 bit native files?????

  9. #9

    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    i think try after updating cs2 , i have seen somewhere that it can be convert. hope you will do it. best luck

  10. #10

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    Re: Are 16 bit scans = 8 bit scans converted to 16 bit in CS2?

    Quote Originally Posted by Deliberate1 View Post
    Be, I will ceheck this out. My understanding is that the DT is a Photoshop plug-in. The version of Oxygen I am working with is way old and perhaps was written before a Photoshop version that permitted the 16 bit conversion. I am quite sure that the DT function is applied after the scan.
    Am I off on this? Just read that Pro II makes 14 bit native files?????
    That is correct. The analog to digital conversion with the Eversmart Pro II is done in 14 bit. You should be able tl save this as a 16 bit file with the Oxygen software, even the earliest version, without a Photoshop plug-in.

    Sandy King

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