Luminous Landscape Forum

Raw & Post Processing, Printing => Colour Management => Topic started by: Redcrown on September 19, 2020, 11:53:36 am

Title: Wide Gamut monitor confusion.
Post by: Redcrown on September 19, 2020, 11:53:36 am
I got a new monitor yesterday, a BenQ SW270C, which is a 2.5K (2560x1440) wide gamut model with 99% Adobe98 coverage. I have not calibrated it yet, but it claims to be factory calibrated. I'm baffled by several things, but here is the first.

The unit has a hockey puck controller that shifts between sRGB and Adobe98 modes, and I'm confused what that means.

If I view an image in Photoshop and toggle that monitor control, the image on screen clearly changes. In Adobe98 mode the image is more saturated. This is regardless of the internal colorspace of the image (sRGB, Adobe98, or ProPhoto).

The sat difference is obvious, however it is much less than what appears if I "assign" the wrong profile in Photoshop. Example: If I take an Adobe98 image and assign sRGB, I see a decrease in saturation that is far greater than if I toggle the monitor control between Adobe98 and sRGB.

In another test, I did screen captures in both monitor modes and pasted them into a Photoshop document. There, they are identical. No difference, in spite of the obvious difference on screen.

This is my first experience with a wide gamut monitor, so help me with the learning curve. What the heck is toggling the monitor control between sRGB and Adobe98 actually doing?
Title: Re: Wide Gamut monitor confusion.
Post by: Doug Gray on September 19, 2020, 08:44:36 pm
I got a new monitor yesterday, a BenQ SW270C, which is a 2.5K (2560x1440) wide gamut model with 99% Adobe98 coverage. I have not calibrated it yet, but it claims to be factory calibrated. I'm baffled by several things, but here is the first.

The unit has a hockey puck controller that shifts between sRGB and Adobe98 modes, and I'm confused what that means.

If I view an image in Photoshop and toggle that monitor control, the image on screen clearly changes. In Adobe98 mode the image is more saturated. This is regardless of the internal colorspace of the image (sRGB, Adobe98, or ProPhoto).

The sat difference is obvious, however it is much less than what appears if I "assign" the wrong profile in Photoshop. Example: If I take an Adobe98 image and assign sRGB, I see a decrease in saturation that is far greater than if I toggle the monitor control between Adobe98 and sRGB.

In another test, I did screen captures in both monitor modes and pasted them into a Photoshop document. There, they are identical. No difference, in spite of the obvious difference on screen.

This is my first experience with a wide gamut monitor, so help me with the learning curve. What the heck is toggling the monitor control between sRGB and Adobe98 actually doing?

This is normal behavior Edit: with the exception of the difference re assigning profiles. I don't see that with the Eizo.

If you are in Photoshop, it will react to a change in the monitor colorspace so long as the associated profile is assigned to the monitor. Photoshop, however, will not redraw displayed images until you also touch the image with a mouse click. At that point Photoshop will pick up the monitor profile change and redraw the image correctly.

That's how it works in Eizo monitors when you change colorspaces. BenQ may not work that way but I don't have a BenQ to test. Looking at BenQ stuff on the web is seems unlikely the BenQ doesn't automatically report the colorspace.

However, if I remove the USB connection to my Eizo and change the colorspace between sRGB and Adobe RGB the computer is not notified of the change so the image is displayed unnaturally saturated.


Thus, if, when you touch an image in Photoshop after changing the monitor's colorspace, there is no correction and it continues to show increased saturation after shifting from sRGB to Adobe RGB, then the computer's OS is not aware the change took place and is continuing to treat the display as if it was still in sRGB. In that case you need to go to the OS settings and tell the OS that your monitor is in Adobe RGB. Then the image will be displayed correctly.
Title: Re: Wide Gamut monitor confusion.
Post by: Redcrown on September 25, 2020, 04:06:20 pm
Thanks for the response, Doug, and sorry for the late acknowledgement. A bunch of other issues came up regarding this monitor and I've been going back and forth with vendors for days trying to understand and solve problems.

The POST/BIOS screens refuse to appear on this BenQ monitor, so I can't get into BIOS. But when I add the old monitor as a secondary display and boot, the POST/BIOS screens appear there. Turns out there is some issue between the newer UFEI boot control and the old BIOS boot control. Looks like I will have to convert my older "MBR" system disk to UEFI, which looks like a complicated process.

But to your comment, the saturation shift when I toggle the monitor between Adobe98 and sRGB is static. If does not change when I "touch" the image inside Photoshop. In Windows Color Management I started with only 1 profile, the "BenQ SW270C Color Profile,D6500". So I added sRGB and Adobe98 profiles and set them as defaults to test. Neither one made any difference.

Another issue is that the "Factory Calibrated" BenQ is supposed to include a printed calibration report. Mine had none. Nothing in the box but a quick start guide showing how to assemble. I queried BenQ support, and several days later I received an e-mail with a PDF calibration report. Even though the report shows my serial number, I'm a little suspicious. In the meantime, I challenged B&H about this. They quickly offered to replace the monitor, but refused to open boxes to see if calibration reports are included in any. I asked them to just loan me a profiler, but they said no can do. Finally, their rep said just order one, use it, and return it. So that's what I've done.
Title: Re: Wide Gamut monitor confusion.
Post by: digitaldog on September 25, 2020, 04:34:26 pm
There should be no Saturation (color) shift, there should be visible desaturation of colors outside sRGB when viewed as followed:
Open an image in Adobe RGB (1998) that has colors outside sRGB color gamut while the display is in a wide gamut behavior.
Convert to sRGB.
Colors that fall outside sRGB should change color appearance in terms of just saturation. I'd use the following test image:
http://www.digitaldog.net/files/2014PrinterTestFileFlat.tif.zip
Factory calibration is rather meaningless. But the above test does require the calibration be such the full gamut of the display is being used.
Title: Re: Wide Gamut monitor confusion.
Post by: simon.garrett@iee.org on September 25, 2020, 06:05:21 pm
Thanks for the response, Doug, and sorry for the late acknowledgement. A bunch of other issues came up regarding this monitor and I've been going back and forth with vendors for days trying to understand and solve problems.

The POST/BIOS screens refuse to appear on this BenQ monitor, so I can't get into BIOS. But when I add the old monitor as a secondary display and boot, the POST/BIOS screens appear there. Turns out there is some issue between the newer UFEI boot control and the old BIOS boot control. Looks like I will have to convert my older "MBR" system disk to UEFI, which looks like a complicated process.

I've had this problem with a Benq monitor, and it wasn't an MBR/GPT issue.  There's something slightly different about the way the BIOS detects a monitor and the normal way Windows does, or maybe it's just a bug in some motherboards.  I got the problem only on an Asus X570 (AMD) motherboard.  When I recently installed that motherboard, with my Benq connected by Displayport and another monitor by HDMI I got the problem you describe (which hadn't previously occured on a system with a different mb but otherwise identical).  When I swapped the two monitor connectors on the video card: no problem.  More recently, both monitors are connected by Displayport and again, no problem.  Try swapping monitors and video card ports and see if that helps.  Remember: you can specify which is monitor 1 and 2 in Windows irrespective of which physical port you use. 

But to your comment, the saturation shift when I toggle the monitor between Adobe98 and sRGB is static. If does not change when I "touch" the image inside Photoshop. In Windows Color Management I started with only 1 profile, the "BenQ SW270C Color Profile,D6500". So I added sRGB and Adobe98 profiles and set them as defaults to test. Neither one made any difference.

The Benq puck doesn't actually do much.  It changes the monitor from one colour mode to another, but it doesn't change the Windows profile (which the equivalent Eizo utility does as well).  When you change the monitor colour space, you must also change the Windows profile.  I don't know what colour space the Benq profile you mentioned corresponds to, but when the monitor is in sRGB mode, you must set the profile in Windows to sRGB, similarly for Adobe RGB.  However, most Windows programs (except Photoshop) won't notice the change of profile, as Doug says (you have to exit and restart most programs) and even with Photoshop you have to touch the image with a mouse. 

When you display an image on the Benq with a profile matching the current colour space, then provided you change both monitor colour space and profile (and click the image to make Photoshop notice) then the image should look unchanged.  No saturation change.

Another issue is that the "Factory Calibrated" BenQ is supposed to include a printed calibration report. Mine had none. Nothing in the box but a quick start guide showing how to assemble. I queried BenQ support, and several days later I received an e-mail with a PDF calibration report. Even though the report shows my serial number, I'm a little suspicious. In the meantime, I challenged B&H about this. They quickly offered to replace the monitor, but refused to open boxes to see if calibration reports are included in any. I asked them to just loan me a profiler, but they said no can do. Finally, their rep said just order one, use it, and return it. So that's what I've done.