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

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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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derin korman

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  • frustrated

Posted 4 years ago

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Chris Cox

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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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derin korman

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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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Chris Cox

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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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derin korman

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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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Chris Cox

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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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derin korman

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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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Tim Parkin

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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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Chris Cox

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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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Stefan Klein

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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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Tim Parkin

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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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Tim Parkin

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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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christoph pfaffenbichler, Champion

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

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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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christoph pfaffenbichler, Champion

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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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david

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This reply was created from a merged topic originally titled Photoshop: Why don't I see 16 bit quality previews when zoomed out?.

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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Golden Crop

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This reply was created from a merged topic originally titled Photoshop 2015.0.1: 16-bit image with adjustment layers banding on some zoom leve....

There is a problem with rendering 16-bit images on different zoom levels. See the picture for example:



Can someone confirm the problem?

Steps to reproduce:

  1. Create an empty RGB image in 16-bit color mode.
  2. Add any gradient layer
  3. Add a curve layer. Set the right point to Input 255, Output 4
  4. Add another curve layer. Set the right point to Input 4, Output 255
  5. Change zoom level - zoom in. The gradient should look fine.
  6. Now zoom out - at some point the 8-bit banding wil appear.


Configuration:

Adobe Photoshop Version: 2015.0.1 20150722.r.168 2015/07/22:23:59:59 CL 1032107 x64
Operating System: Windows 7 64-bit
Version: 7 SP1System architecture: Intel CPU Family:6, Model:10, Stepping:9 with MMX, SSE Integer, SSE FP, SSE2, SSE3, SSE4.1, SSE4.2, AVX, HyperThreading
OpenGL Drawing: Enabled.
OpenGL Allow Old GPUs: Not Detected.
OpenGL Drawing Mode: Advanced
OpenGL Allow Normal Mode: True.
OpenGL Allow Advanced Mode: True.
NumGLGPUs=1
NumCLGPUs=1
glgpu[0].GLVersion="3.0"
glgpu[0].GLMemoryMB=2304
glgpu[0].GLName="Intel(R) HD Graphics 4000"
glgpu[0].GLVendor="Intel"
glgpu[0].GLVendorID=32902
glgpu[0].GLDriverVersion="10.18.10.3958"
glgpu[0].GLRectTextureSize=16384
glgpu[0].GLRenderer="Intel(R) HD Graphics 4000"
glgpu[0].GLRendererID=354
glgpu[0].HasGLNPOTSupport=1
glgpu[0].GLDriver="igdumdim64.dll,igd10iumd64.dll,igd10iumd64.dll,igdumdim32,igd10iumd32,igd10iumd32"
glgpu[0].GLDriverDate="20140930000000.000000-000"
glgpu[0].CanCompileProgramGLSL=1
glgpu[0].GLFrameBufferOK=1
glgpu[0].glGetString[GL_SHADING_LANGUAGE_VERSION]="1.30 - Build 10.18.10.3958"
glgpu[0].glGetProgramivARB[GL_FRAGMENT_PROGRAM_ARB][GL_MAX_PROGRAM_INSTRUCTIONS_ARB]=[1447]
glgpu[0].glGetIntegerv[GL_MAX_TEXTURE_UNITS]=[8]
glgpu[0].glGetIntegerv[GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS]=[96]
glgpu[0].glGetIntegerv[GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS]=[16]
glgpu[0].glGetIntegerv[GL_MAX_TEXTURE_IMAGE_UNITS]=[16]
glgpu[0].glGetIntegerv[GL_MAX_DRAW_BUFFERS]=[8]
glgpu[0].glGetIntegerv[GL_MAX_VERTEX_UNIFORM_COMPONENTS]=[4096]
glgpu[0].glGetIntegerv[GL_MAX_FRAGMENT_UNIFORM_COMPONENTS]=[4096]
glgpu[0].glGetIntegerv[GL_MAX_VARYING_FLOATS]=[64]
glgpu[0].glGetIntegerv[GL_MAX_VERTEX_ATTRIBS]=[16]
glgpu[0].extension[AIF::OGL::GL_ARB_VERTEX_PROGRAM]=1
glgpu[0].extension[AIF::OGL::GL_ARB_FRAGMENT_PROGRAM]=1
glgpu[0].extension[AIF::OGL::GL_ARB_VERTEX_SHADER]=1
glgpu[0].extension[AIF::OGL::GL_ARB_FRAGMENT_SHADER]=1
glgpu[0].extension[AIF::OGL::GL_EXT_FRAMEBUFFER_OBJECT]=1
glgpu[0].extension[AIF::OGL::GL_ARB_TEXTURE_RECTANGLE]=1
glgpu[0].extension[AIF::OGL::GL_ARB_TEXTURE_FLOAT]=1
glgpu[0].extension[AIF::OGL::GL_ARB_OCCLUSION_QUERY]=1
glgpu[0].extension[AIF::OGL::GL_ARB_VERTEX_BUFFER_OBJECT]=1
glgpu[0].extension[AIF::OGL::GL_ARB_SHADER_TEXTURE_LOD]=0
clgpu[0].CLPlatformVersion="1.2 "
clgpu[0].CLDeviceVersion="1.2 "
clgpu[0].CLMemoryMB=1195
clgpu[0].CLName="Intel(R) HD Graphics 4000"
clgpu[0].CLVendor="Intel(R) Corporation"
clgpu[0].CLVendorID=32902
clgpu[0].CLDriverVersion="10.18.10.3958"
clgpu[0].CUDASupported=0
clgpu[0].CLBandwidth=1.80273e+010
clgpu[0].CLCompute=126.832
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Aric Guité

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This is also an issue with some of the tools, such as the healing brush, you'll get artifacting if you're working on a smooth gradient. Goes away when you zoom in past 66.7%.
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Charles Lanteigne

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Are there workarounds for this?! I'd be willing to take a hit in performance or practicality, because the alternative is that I can't rely on what I'm seeing.

I am dismayed that this would be considered merely a "feature request", when in fact it's the most basic core feature: showing me my image properly! At the very least this should be clearly indicated so the user knows he is looking at an approximation.