Gradient tool not working as expected

[mal25]

Good Morning,

I am on a W 10, 64 bit system with the latest 2020 version 21.0.1 of PS.  I had recently noticed that I had a problem with my gradient tool when I made a black to white gradient I saw bands of color through the half tones.  This usually indcates I need to reprofile my monitor LOL  however this looked different, the eyedroper showed that there were fluctuations off the neutral by one or two points, I have never seen this before.  I am using the gradient today and I was wondering if I could laydown a gradient and then continue manipulating it after the fact, so I started watching videos on the gradient tool.  The tutorial started by demonstrating drag and drop a gradient from the Gradient Editor to a background layer, this does not work, not only to a background layer but any layer.  I can click and drag on the canvas and it works just fine (except for the bands of color).  Any Ideas on either problem would be appreciated.

Thanks

Chris   

[nikunj.m]

Hi Chris,

We are sorry about the bands that in the gradient in Photoshop while working with the Gradient tool. 

Please update Photoshop to the latest version (21.0.3) through the Creative Cloud desktop application and check if the issue persists. You can also check for updates for both Windows and the Graphics card drivers (from the manufacturers website) to ensure that the issue is not related to missing updates or faulty drivers.

Try calibrating your monitor to the sRGB 2.1 color profile and check if that helps. You can check: https://www.windowscentral.com/how-configure-correct-color-profile-your-monitor-windows-10

Regards,

Nikunj

[mal25]

Hi Nikunj,

Yest there were updates to be had, they made no difference.  I also updated the monitor profiles, but I make custom monitor profiles every 2 weeks using iProfiler and a colorimeter, I did this yesterday the profile is good.  As I said before, as the profile ages it wanders from the true colors, but the eyedropper usually confirms that the gradient is neutral and the problem is the monitor.  In this case the eyedropper is confirming what I am seeing, there are color shifts within the RGB Gradient, if I change the document profile to Grayscale it looks as it should, neutral, if I then return to the RGB profile the gradient remains the same, neutral.  The problem is that it is creating a corrupt gradient in RGB.

Thanks

[D Fosse]

What's the document profile?

Generally (excluding a corrupt document profile), as long as you're working in 16 bit depth, any banding you see is somewhere in your display system. It has to be. Remember that the display pipeline, from the video card to the panel, is 8 bit depth only! (unless you have a 10 bit capable video card and monitor).

It could be the monitor profile, but much more likely it's calibration tables in the video card. If these curves are a bit irregular, it will sit on top of, and add to, the normal 8-bit banding. Banding is cumulative and it quickly adds up.

It could also be a buggy video driver. Display color management is executed in the GPU these days, except when you set GPU to "basic" in preferences. Does that make any difference?

If it's a ProPhoto file, there's a well known problem with OpenGL code that gives cyanish color bands in the deep shadow values. This also goes away in Basic mode (and sRGB/Adobe RGB).

[D Fosse]

While there's nothing explicitly wrong in that link, using a calibrator will always give superior results over generic manufacturer profiles. In addition, these manufacturer profiles are surprisingly often defective, not written correctly to icc specification. One of the most frequent color management issues we see here is bad manufacturer profiles, usually distributed through Windows Update.

Another thing is that you don't calibrate a monitor "to sRGB". That makes no sense. You can use sRGB as a generic display profile if you don't have a calibrator, or as a diagnostic test.

[mal25]

D_Fosse,

Thanks for responding.  The document profile is assigned to the photo, you have just mentioned it ProPhoto, Adobe 1998 RGB, or sRGB.

"If these curves are a bit irregular, it will sit on top of, and add to, the normal 8-bit banding. Banding is cumulative and it quickly adds up."

This is interesting, also I do use the ProPhoto profile these days as it has a larger Gamut than Adobe 1998 RGB, I will look out for the banding problem you raised.  I have updated both Intel and Gforce drivers still no difference, I don't know how to set the GPU to Basic.  The document with the banding is only 8 bits and it has an sRGB profile.  

You do understand that the eyedropper is reading directly from the document and not measuring color from the screen, if you open a photo take a reading then change the monitor color using one of the RGB controls on the monitor and remeasure at the same spot the readings will match regardless how strong a color cast you have added to the monitor. I think I will start by deleting the video drivers and reload them but the other problem is that it doesn't react as it should in other ways like the drag and drop from the Gradient Editor.  I was thinking of a re-install of PS 2020 yesterday, as I was backing up settings and presets I came across some psp files and there were two for gradients, they seemed different to the presets for gradients, which I have none because I don't save them. Are these the files that control the gradients behavior, can they be replaced without a complete re-install?  Anyway thanks for your time.

Chris

[D Fosse]

"The document with the banding is only 8 bits"

The very first thing you need to do is stop working in 8 bit depth. Then there will be banding in the data - there are only 256 available values per channel, from black to white. You have to be in 16 bit depth where you have 32768 discrete values on the same scale. I'm sure you can see why it's so much more likely that banding happens in the 8 bit display pipeline, rather than the 16 bit data.

[mal25]

Yes I do see that it makes perfect sense, I always work @ 16 bit and then convert it to 8 bit and I do sometimes deliver @ 8bit.  I have never put 2 and 2 together to explain tonal banding in my airbrushed backgrounds.  So to test I have made a 16 bit Adobe 1998 RGB gradient and the eyedropper shows it is neutral, I save it, converted it to 8 bit and saved and closed it.   They are identicle when re-opened, I then made a 16 bit Prophoto and it looks identicle and the eyedropper confirms it is neutral darks and all no cyan.  I tried 8 bit canvases an there it is large as life both in Adobe RGB and sRGB.  Odd that a 16 bit converted to 8 bit saved and reopened as 8 bit remains neutral as the 16 bit original but gradients created in 8 bit are not as accurate. I'll be a little more carefull in what goes out the door at 8 bit now.  Well thanks you did solve this side of it but I still have the other side, the behavior of the Editor and my document, maybe I have a wrong setting somewhere, I have been working when I'm tired and getting frustrated that the eraser doesn't work only to find after trying everything else I toggled to the background eraser while working on a mask, LOL.

Do you have any ideas on why gradients would not drag and drop from the Gradient Editor?