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

[freshsisyphus]

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.

[Golden_Crop]

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. 
   
2. Create an empty RGB image in 16-bit color mode.
   
3. Add any gradient layer
   
4. Add a curve layer. Set the right point to Input 255, Output 4
   
5. Add another curve layer. Set the right point to Input 4, Output 255
   
6. Change zoom level - zoom in. The gradient should look fine.
   
7. 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

[FeedbackCommunityMember]

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%.

[Charles Lanteigne]

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.

[Lee James]

I recently began using 16-bit mode and just couldn't work out why the quality of my images was so poor.

After a lot of confusion and testing, I finally figured out that Photoshop doesn't display the image properly UNLESS you zoom in close on a photo!

I find it simply INCREDIBLE that this is not considered a bug! How can photographers work in 16-bit mode when we can't even see what we're doing? THIS NEEDS FIXING IMMEDIATELY!

Please see my screen grab of the problem:

[J453]

I'm not seeing the kind of banding you're seeing. Here's a 16-bit image shown at 50% and I'm not seeing the kind of banding you're seeing:



I'd suspect there's something else wrong like a bad color profile or a bad graphics driver. It may help if we could see your Photoshop System Info. Launch Photoshop, and select Help > System Info... and copy/paste the text in a reply.

[Lee James]

Sorry, I should clarify that the banding only appears as a result of adjustment layers.

In my example, I used two simple curves layers as shown below. This is perhaps an extreme example in order to make the banding very obvious, but I've noticed banding in my regular projects and found it totally confusing.



I agree with the poster above who noted that most people who work in 16-bit mode would settle for a performance reduction in order to see the image in full quality. If nothing else, I think there should be an option in the prefs to enable "true 16-bit view mode" or something.

To me, the point of using 16-bit mode is that it lets you "go crazy" with adjustment layers without having to worry about banding. Though I will add that the problem of banding wouldn't exist in 8-bit mode if Photoshop didn't round down its calculations to 8-bit for every layer. It would be nice to have that option too: "16-bit calculations in 8-bit mode, to reduce banding"

[J453]

OK. Gotcha. Correct. 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.

[Lumigraphics]

I have a couple of images that look TOTALLY different at 50% and 100%. I mean, major content changes. I was tearing my hair out over it last night, in fact. I'll post samples on this thread when I get home tonight.

Add my vote for this being a problem, as I always work in 16-bit.

[Lee James]

Thanks for your reply, Mr Tranberry.

[Lumigraphics]

This is the same file- 16 bit on the left, converted to 8 bit on the right. No other changes. This is consistent with what I get zooming in and out on the (much larger) original between 50% and 66.7%. I've seen this before with multiple layers set to Difference blending.

Is this behavior expected? Doesn't seem right to me.

[J453]

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 a lot more compute power.

If you want accurate 16-bit previews at all levels of the zoom pyramid, you can go to Preferences > Performance... and set the "Cache Levels" to 1 (close all docs and reopen them). You can see how 16-bit at all zoom levels affects performance and why this decision was made.

(Christoph pointed this out earlier in the thread but I wanted to capture it in an official answer)

[Lumigraphics]

What about my post above where there is actually a big change when converting a file from 16 to 8 bit? IOW, its not just a cosmetic difference but different actual pixels. I've seen this happen one other time with layers and Difference blend mode.

[J453]

I'd need to get your sample file that reproduces the problem so I can get it in front of engineering.

[Charles Lanteigne]

Changing the Cache Levels to 1 does not fix the issue for me, there's still a shift in color when I zoom in/out. (I also notice no difference in performance.)

To be clear, I use adjustment layers when I see the issue. "Flattening" the image (or placing a composite of the stack at the top) makes the difference go away (regardless of the cache levels), but obviously this is not convenient.

[pinktank]

You have to restart Photoshop after doing that but it will also slow photoshop down to a crawl for general use.

To Adobe: What would be useful perhaps is a toggle on a panel that can switch to 16bit rendering without restarting photoshop so that we can enable it as needed for a task and disable it afterwards, not dissimilar to 'high quality previews' found in some tools.

On a similar note, what would be great is to have a 16 Bit curve adjustment option, the current one is rather limiting in precision for setting the black point in common color spaces.

[Lumigraphics]

I can send you that file, let me know how to get it to you. Thank you!

[pinktank]

A suggestion: put a toggle on a panel that can switch to 16bit rendering for all levels without restarting Photoshop so that we can enable it as needed for a task and disable it afterwards, not dissimilar to 'high quality previews' found in some modal tools.

[Charles Lanteigne]

I did restart Photoshop, no dice.

[J453]

David, will send you an email to get the file. Thanks.

[SebSchGer]

This still bugs me. Please Adobe! Computational power gets better and better. Please find a way to make use of 16 bit everywhere, not just in 100% crop (66%+) ...

[FeedbackCommunityMember]

Proper 16-bit preview would be great. Hope this issue will be solved soon.

[FeedbackCommunityMember]

Hi Guys, I was just wondering if there is any update or a fix to this issue? Im so glad i found this thread as Ive wasted so much time searching for an answer to this. It has also affected the way I work as i have not been pushing my edits to their fullest potential because i didn't want to introduce even more banding and artefact's. Still cant believe how much stress this has caused me, just because i wanted to view my image as a whole! Cheers

[pinktank]

Hey Dean, nope, Adobe has yet to provide a solution. (I'll be surprised the day they do)

[benj_v]

thread written in December 23 2014.
It's hard to expect anything.
Even with 10-bits display and graphic cards, Photoshop doesn't care.

[pinktank]

To be clear: The issue is not related to 10bit displays, it's about the image processing that happens before it is sent to the display, you would see the effect even if your display and graphics card were from 10 years ago.