ASD Not displaying images at correct size?

[choreo]

I just installed a new ASD on my 2019 Mac Pro yesterday. It replaces one of my (3) connected NEC 27" monitors - all connected to my w5700x GPU via Thunderbolt.

I just upgraded my OS today to the latest version of Monterrey to get full support for the ASD Presets, etc.

Something I first noticed last night was when opening any image in PhotosShop CC every thing was displaying on-screen at 1/4 the expected physical size. If I open say a 1600x1200 pixel image on the ASD, it opens about 1/4 the expected physical size on the screen. If I drag that image to one of my NEC screens it retains that small size. However, if I open the same image on one of the NEC screens FIRST, it opens at 4-times the physical size as on the ASD (what I am used to), and if I then drag that image to the ASD it retains that same larger size! Very weird. I thought I was losing my mind last night when I kept opening images of the same pixel dimensions on different monitors and they looked different with the same specs!

Apparently this is not an Adobe problem as when I open an image in Affinity Photo - same behavior - the display size of the image depends on which monitor I open it on?

The two NECs are set to native 2560x1440and the ASD is set to "Default" (should be the same I think). The Desktop Icons, MenuBar on the ASD and application palettes all look as expected, just scales images.

What would cause this?

 

[choreo]

After further testing, just to make things more complicated, if I open images in the PREVIEW app on the ASD, they are the full (larger) size at 100% (as expected)? Images opened in PREVIEW look the same on ALL my monitors?

All I can figure is that when opening an image in Photoshop or Affinity, is the ASD maybe displays an image at the TRUE 5K resolution "pixel per pixel", no matter what "scaling" is set in Preferences? But if an image is opened on another monitor, it does apply the scaling if "dragged" onto the ASD?

 

[Amethyst1]

All I can figure is that when opening an image in Photoshop or Affinity, is the ASD maybe displays an image at the TRUE 5K resolution "pixel per pixel", no matter what "scaling" is set in Preferences?

One might argue that this is the “correct” behaviour: the image is shown at actual size (100%) with full detail, and just the UI of the application is scaled to 200% to make it usable.

[...] if I open images in the PREVIEW app on the ASD, they are the full (larger) size at 100% (as expected)? Images opened in PREVIEW look the same on ALL my monitors?

Preview displays images at 200% — twice as wide and twice as tall as their actual size — on a screen that is using a HiDPI mode.

 

[choreo]

One might argue that this is the “correct” behaviour: the image is shown at actual size (100%) with full detail, and just the UI of the application is scaled to 200% to make it usable.


Preview displays images at 200% — twice as wide and twice as tall as their actual size — on a screen that is using a HiDPI mode.

Apparently the "Scaling" option on the ASD only applies to the UI, desktop icons/text, widows, etc., but "images" inside applications are NOT SCALED and are displayed at the TRUE 1:1 resolution. Therefore, a 1200 pixel wide image would show on-screen half as wide on a native 5K monitor as it would on a 2560x1440 monitor (like my NEC's). I did not know that the "scaling" option only affected the UI. If that is then case, then I understand that behavior now and can compensate. I have never had a large screen RETINA display, so this took me by surprise. I assumed that when I changed "scaling", that it applied to EVERYTHING.

I also understand that a 1200-pixel wide image on one of my NECs (with a native resolution of 2560x1440) will appear twice as large if my assumptions are correct.

What I cannot explain is why if I OPEN say a 1200-pixel-wide image on one of my NEC's and then drag that image to the ASD, the ASD automatically RETAINS the physical displayed size of that image from the NEC (and visa-versa). In other words the physical-size of the displayed images is not just dependent on the pixel resolution of the display, but also dependent on the native resolution of the display they are originally opened on? I would have expected that dragging a 1200-pixel wide image between displays with different resolutions would change the apparent size of the image, but it doesn't (going either direction) - the physical-size of the image is solely dependent on which screen the image is OPENED on first!

Now that (I think) I know what is going on, I can manage the situation, but it is curious. I would imagine most people with multiple monitors do not mix different monitor pixel densities, so they would never experience this. This behavior is actually more manageable - as once an image is opened it does not change magnification when dragged across all 3 monitors - so it is more fluid. It is also interesting that a high pixel image displayed at 1:1 on the ASD is automatically scaled down by 50% when dragging it to a 2560x1440 monitor.