Image resolution when using "Montage"

Discussions related to the 1.36.x series of ZoneMinder
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User6677
Posts: 20
Joined: Sat Dec 24, 2022 9:32 am

Image resolution when using "Montage"

Post by User6677 »

I'm on 1.36.33. I often use the Montage feature with 4 cameras in a zone which I have open in firefox fullscreen mode on a small 1280x600 touchscreen, next to my main monitor (that switches between PCs with a KVM switch).

The reason I'm starting this thread is that if I maximise firefox on my tiny 1280x600 screen and I go to Montage the picture quality is very bad. It looks like it was downscaled to half size and upscaled from that. However, if I move firefox window to the big 4K screen, I refresh the site, then I move it back to the tiny screen it looks great...

Here is a comparison:
Opened on a 1280x600 screen:
Screenshot from 2024-08-26 11-38-49.png
Screenshot from 2024-08-26 11-38-49.png (477.81 KiB) Viewed 1247 times
Same view after being refreshed on a 4K screen and placed on the small screen again:
Screenshot from 2024-08-26 11-39-26.png
Screenshot from 2024-08-26 11-39-26.png (585.93 KiB) Viewed 1247 times
In both cases I have Low quality set. Why does it happen? And more importantly, is there anything I can do to be able to load the website on the tiny screen and get good quality from the start? I'd love to be able to start that browser automatically without having to move it every time.
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iconnor
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Re: Image resolution when using "Montage"

Post by iconnor »

We attempt to optimised bandwidth use by requesting an image scaled to the actual dimensions displayed. When you then resize the window it isn't updating the requested size.

We have fixed this in 1.37 series along with a million other improvements.
User6677
Posts: 20
Joined: Sat Dec 24, 2022 9:32 am

Re: Image resolution when using "Montage"

Post by User6677 »

iconnor wrote: Mon Aug 26, 2024 4:33 pm We attempt to optimised bandwidth use by requesting an image scaled to the actual dimensions displayed. When you then resize the window it isn't updating the requested size.
I'm not sure not updating is a problem. I'm very happy it is not updating to the tiny size of the screen I move it to. The problem seems to be it is somehow underestimating the size and resolution of the screen. It is capable of displaying a pretty good picture when scaled down from 4K by firefox - I'm guessing this is what is happening. But when ZM tries to do the scaling the result is worse.
iconnor wrote: Mon Aug 26, 2024 4:33 pm We have fixed this in 1.37 series along with a million other improvements.
When you say you have fixed it in 1.37 I suppose you mean the not updating part (that I'm not bothered about at all).

Are there some improvements in the quality of how scaling down is done?

To add some more information to this let me say I've also tried to see what happens if I move the window to the 4K screen but I leave it the small size and refresh. This results in a very bad image, same as on the tiny screen.

So the problem seems to be the type/quality of scaling that is being done by ZM. I tried upping the bandwidth to High, this made no noticeable difference.

Can you point me towards where is the scaling happening? (filename etc?)
User6677
Posts: 20
Joined: Sat Dec 24, 2022 9:32 am

Re: Image resolution when using "Montage"

Post by User6677 »

I found a kind of workaround. If I set zoom level to 30% the images look great on the small screen and there is no need to drag the window and refresh on the big screen.

That is good enough for me. I'm posting in case anyone else encounters this. Having a tiny screen showing Montage next while you're switching the main screen between PCs has been quite handy for me.
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