P: Support more accurate 16 bit/channel display even when zoomed out below 66.67% magnification

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Community Beginner ,
Dec 22, 2014 Dec 22, 2014

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It is rather abysmal that photoshop still has this critical bug, given that is has been reported for years now. It is a software for professional imaging yet you cannot work on an image at print resolution and have accurate color displayed on the screen.



Steps to reproduce:
-For full effect, open an image with dark shadows you would like to lighten
-Again, to dramatize, we are going to add two curve adjusment layers
--Make one curve to set your black and white points and your gray balance
--Make another curve to open up the dark shadows
-You should see that at 66.67 magnification you will get the true colors while at 50% below colors suddenly change, meaning you cannot look at the image as a whole and make color adjustments. This applies to any image that is more than 4/3 your screens total resolution, which, for a 1080p monitor that is beyond the average, would be 3MP. Yes, that is three megapixels as in DSLRs of 14 years ago.

Perhaps you could have an option to 'render proxy at this magnification' which would render a 16bit cache level at a specified magnification at which curves et al could be calculated from there on.

Shame on you for not having addressed this despite pleas from multiple professional fields for so long.

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Adobe Employee , Jan 17, 2019 Jan 17, 2019
As Chris pointed out earlier, the current implementation, where pyramid levels above the base (that is, the 50%, 25%, levels) of a 16 bit document are in 8 bit. The thinking at the time was that zoomed out representations are previews (inaccurate for a number of reasons including interpolation, etc) and  speed/performance was more important than accuracy. It might be something we can revisit as compute power increases and we refactor and improve our drawing code - but it's not 'free' - it takes...

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LEGEND ,
Dec 22, 2014 Dec 22, 2014

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That is because 50% you are seeing an 8 bit/channel preview instead of 16 bit/channel.

Would you like to change this to a request to support more accurate 16 bit/channel display even when zoomed out?

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Community Beginner ,
Dec 23, 2014 Dec 23, 2014

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Hello Chris,
Thank you for taking the time to recognise this and saying hi 🙂 I know the underlying reason for the problem, and yes, to support more accurate display while zoomed out is essentially my request, but I think to call it a 'feature request' is a bit problematic.

I say that because it is currently an implicit default without a warning as it has great consequences for the unknowing user. If anything, it should be the compromise in accuracy for performance that should be optional, given that Photoshop caters to users in professional imaging.

The performance tab could have a checkbox that reads 'Render 8bit previews below 66.67 magnification', even if it comes checked, this would be an explicit feature.

cheers,
d

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New Here ,
Dec 23, 2014 Dec 23, 2014

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The proposed solution to allow 16bit previews would be fantastic.

This is a particular problem when inverting colour negative scans too. The colours are extremely screwed when applying the massive curve adjustments needed to provide a decent inversion.

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LEGEND ,
Dec 23, 2014 Dec 23, 2014

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Performance and memory usage are also important - and using 8 bit upper pyramid levels improve performance and reduce memory usage.

What you describe is not a bug or mistake. It can only be changed through pretty extensive code changes and testing. Yes, that makes it a feature request.

As a bug report, this isn't going to go anywhere.
But as a feature request, it has a much better chance to make some changes.

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LEGEND ,
Dec 23, 2014 Dec 23, 2014

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Yes, any adjustment with an extreme change will show more banding in 8 bit/channel, which is what you get when zoomed out.

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Community Beginner ,
Dec 23, 2014 Dec 23, 2014

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Of course I understand that 8bit upper pyramid levels improve performance, what I meant to say that since there is no notice anywhere that tells you what you see is not exactly what you get, this is a bit of a problem for general use.

I guess we can make it a feature request then, do you need me to edit the original post?

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LEGEND ,
Dec 23, 2014 Dec 23, 2014

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Hmm, the behavior of the pyramid levels used to be in the manual/help files.

Nope, Jeff already changed it to a request. (and now we have something we can present to our product management :-).

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Community Beginner ,
Dec 24, 2014 Dec 24, 2014

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Thank you. Feel free to contact me if I can be of any help in the future in regards to this. I can forward a draft of the changes, if you need feedback, to the global museum imaging community.

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Participant ,
Dec 29, 2014 Dec 29, 2014

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Chris,
if a 16bit image is only displayed with 8bit/channel, AT LEAST some kind of information/warning should be displayed! And, of course, 16bit/channel should be supported in all zoom levels.

BTW. (and this may be off-topic), there should be a more realistic display of layer-styles at zoom levels below 100%. Depending on the style, the difference to 100% view can be rather extreme.

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LEGEND ,
Dec 29, 2014 Dec 29, 2014

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We're already doing the best we can with downsampled layer styles. Anything more would require compositing at 100% and downsampling after (which would be really slow if you have more than a few layers).

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New Here ,
May 04, 2015 May 04, 2015

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Yes - however this is exaclty what i have to do when adjusting files. Copy to a new file, flatten stack, resize to monitor size, zoom to 100% and then make my curve adjustment and copy back to the main file. get's tiring pretty quickly

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LEGEND ,
May 04, 2015 May 04, 2015

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You don't need to copy to a new file. Just zoom in to 100%, or open another window for the document and change the zoom on it.

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New Here ,
May 04, 2015 May 04, 2015

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But i then need to get the curve adjustment i make back to the full size document',,.

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LEGEND ,
May 04, 2015 May 04, 2015

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There is no "full size document" - just use ONE document, and different views of it.

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New Here ,
May 05, 2015 May 05, 2015

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Yes but I can't make the adjustments i need at 100% and hence i have to resize the document to do so. I cant resize the original document as i then cant get back to the fulll size document. Hence i dupe the document, flatten, resize to fit screen at 100%, make curve adjustments and then copy curve adjjustments to original document. Long winded but the only way to do what i need

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LEGEND ,
May 05, 2015 May 05, 2015

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Don't duplicate the document. Just make another window for the document, and set it's zoom to 100% to judge the results.

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Adobe Community Professional ,
May 05, 2015 May 05, 2015

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Tim Parkin, did you get that Mr.Cox is referring to Window > Arrange > New Window for ...?

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New Here ,
May 05, 2015 May 05, 2015

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Yes - the fundamental problem is I that I need to make global adjustments whilst seeing the whole frame which means 16% zoom. At this zoom level the preview is 8 bit and so I can't trust my edits. The only way to trust edits is at 100% and hence I need to resize my original document to apply to appropriate curves. Then I can't get the curves back to my full size document. Make sense?

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Adobe Community Professional ,
May 05, 2015 May 05, 2015

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Not exactly.
Adjustment Layers on a downsampled copy do not necessarily produce results that appear identical when applied on the original image so your »trust« seems to be misplaced.

What kind of Adjustments, Masks, Styles, ... are you talking about anyway?
Could you post an example?

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New Here ,
May 05, 2015 May 05, 2015

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Yes, i have to flatten them too. I'll change tack as I dont seem to be getting my problem across. How do i accurately colour correct a large image with multiple adjustment layers whilst viewing the whole image (e.g. Not at 100%)

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New Here ,
May 05, 2015 May 05, 2015

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P.s. At the minimum all i want to so is make a basic curve adjustment but if i duplicate the original document (with a simple 1 point tweak on the green curve) and resize the duplicate to fit the screen and zoom out on the original to fit the screen they look different!

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Adobe Community Professional ,
May 05, 2015 May 05, 2015

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You can try setting Preferences > Performance > Cache Levels to 1 and restart Photoshop.

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Community Beginner ,
May 05, 2015 May 05, 2015

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Christoph, that slows photoshop to a crawl for large documents, and therefore not a solution. The problem is well outlined and exemplified above, and acknowledged. Are you playing Socrates for any reason?

As Tim also pointed out, the fundamental task of color correcting photographs using adjustment layers, especially in working with film scans and negatives that require dramatic change, cannot be performed with Photoshop as it stands. You cannot correct overall color balance while looking at your photograph through a loupe.

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Adobe Community Professional ,
May 05, 2015 May 05, 2015

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I just got involved because I got the impression (possibly mistakenly) one of the posters did not understand the multiple view option or employ a work-around that would not actually produce reliable results.

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Community Beginner ,
Sep 19, 2015 Sep 19, 2015

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why aren't 16-bit previews possible? i use layer adjustments and i end up seeing a lot of color banding mainly in the sky that is gone when i flatten the file. the problem is it sometimes appears that there is a color cast when there really isn't. it makes color correcting very tedious. i would think that PS could display what the file will look like when flattened, but keep the layers, no?

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