Re: 16 bits = 15 bits in Photoshop?
Re: 16 bits = 15 bits in Photoshop?
- Subject: Re: 16 bits = 15 bits in Photoshop?
- From: Jim Rich <email@hidden>
- Date: Fri, 22 Apr 2005 09:10:22 -0400
Jeff,
As working in 16 bits to avoid all of these Urband Legend pitfalls such as:
The color being day and night different from 8 and 16 bit images.
That 8 bit files are fragile in terms of color reproduction.
Or that you will get artifacts like banding in gradients after a lot of
image editing.
That 10% percent of images require 16 bits so they don't break.
Or that you need to work in 16 bit because of device responses.
Let me say again on those points, I am more than skeptical that you require
16 bits. My experiences with RGB photos, CMYK print and Inkjet printing do
not indicate that one should jump to those conclusion. And we know that
mileage will vary.
And until I see a test or some other type of hard evidence that all of these
problems really exist and are as wide spread, as reported I cant buy into
the notion that there is an advantage to going to a full 16 bit workflow
for a few renegade images.
It would be interesting if some one would please show me a suite of images
where the benefits of 16 bit images jumps off the sheet and it is clear
what is an 8 bits and what is 16 bit file. Then I can really buy into the
16 bit way of life. There are a few expections, but they are not al that
compelling of an arugement to change a complete workflow.
However, your comments about masking and selections are the only ones so far
that make sense as a reason to consider working in 16 bits, except in a few
cases. So, on the virtual score board chalk one up for the 16 bit team.
I am not on board for the 16 bit workflow for the above stated reasons,
but if I had clients who's work involved a fair about of soft-edged
selections I would give 16 bits for all images in that workflow definite
consideration.
Good going Jeff, you moved me slightly off the mark.
Gotta go to work now.
Jim Rich
On 4/22/05 2:29 AM, "Jeff Schewe" <email@hidden> wrote:
> Jim Rich said:
>> It makes sense to capture everything as high bit images.Everyone seems to
>> agree on this.
>
>> Save the high bit parent file in your archive.
>
>> Create derivative 8 bit files from the parent file for production.
>
>> Use Adjustment layers.
>
>> If the 8 bit file breaks ( as they can in rare cases), then go back to
>> the parent 16 bit file and use the previous Adjustment Layers.
>
> While it sounds like a nice middle of the road solution, I would argue a
> different slant.
>
> I agree with the capture in high bit.
>
> But I would argue that it critical than ALL MAJOR tone and color moves be
> done in 16 bit. Ideally with Adjustment Layers for the simple reason that
> setting black & white points (unless you do it accurately in say Camera Raw)
> are the tip of the spear so to speak. Major gamma adjustments are second,
> such as when you stretch one area and compress another area of the image's
> histogram.
>
> I would also argue that depending on the color space you may be in while in
> 16 bit, it would be a good idea, if at all possible, to do any major color
> transforms while in 16 bit.
>
> The aim I try to do is to get the file to the "perfect 8 bit" file, while
> still in 16 bit. Then and only then will I drop it down to 8 bit.
>
> I agree that for most purposes, an 8 bit/channel file is all you really need
> to produce good gradations from black to white.
>
> The big problem I've personally have over the years when working from
> scratch in 8 bit, is there's just no telling what operation or what little
> tweek will be the one that is the tipping point for the 8 bit failure.
>
> Granted, as a photographer, it's VERY routine and using to do a lot of soft
> edged selections and gradient based adjustments. At lot of the problems
> people have with banding is NOT caused with the RGB image banding, it's
> caused by creating a soft edged selection as a channel and then really
> working on that channel. While an 8 bit/channel RGB does hold up remarkably
> well, it's the darn channels in 8 bit that can completely fall apart. Then
> the channel, turned into a selection will itself be a primary source of
> banding introduced into the RGB file. The banding may NOT be the result of
> the actual image adjustment, but the selection with banding, that the
> adjustment was made from.
>
> The point that various people decide to drop from high bit to 8 bit will
> depend largely on what they are doing and how they are doing it. Personally,
> I try to keep it 16 bit as long as possible, but if I'm doing an extensive
> retouching job with a ton of layers, it'll get dropped into 8 bit/channel
> pretty darn quick. Particularly when I've already made all my major tone&
> color most while in 16 bit!
>
> Regards
> Jeff Schewe
>
>
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