Lightroom Develop Preview Quality is Low Below 100% Zoom

[paytonfrost]

The preview quality of the develop module is poor until zoomed past 100%. At "fit" view this isn't much of an issue, the preview quality looks okay, but at 70% zoom it looks like that "fit" preview was just scaled up. At 99.6% zoom it's the same story, but at 100.5%, the image immediately clears up, looks great.

I put screenshots of the issue here: https://imgur.com/a/M9umgcw

I'm using Ryzen 5900HS, 3070-8gb, 40gb RAM, 1tb nvme. Windows 10, Lightroom CC12.3, nvidia studio driver 531.61. Tried disabling GPU, didn't work, Camera Raw Cache at 12gb, couldn't find many other tweaks. 

Seems like a bug since I don't remember this being an issue on previous versions of Lightroom.

[TheDigitalDog]

How (and why) are you setting the zoom to 99.6%?

[paytonfrost]

Hold shift and click and drag with right mouse for scrubby zoom to allow for fine control of zoom level.

The point is that I'm getting a low quality preview at any level less than 100% zoom. This is an issue because if I'm editing a portrait, I might zoom into a face to see it better and have it fill the screen. That zoom level might be at 40%, 70%, or at 95%. Each of those zoom levels I'm going to see a bad preview that doesn't allow me to work accurately. I have to zoom past 100% each time, and then zoom back out to my preferred zoom level.

[TheDigitalDog]

Still no answer: why are you setting the zoom to 99.6%?

100% (1:1) or greater zoom in any such product* is the only way to avoid preview subsampling. There is nothing wrong here other than user (zoom setting) error.

*https://community.adobe.com/t5/photoshop-ecosystem-discussions/photos-look-pixelated-when-zoomed-in-...

https://www.quora.com/Why-are-images-in-Photoshop-rendered-badly-when-viewed-at-33-33-or-66-67-zoom

[Jao vdL]

Hmm. I tried this on my M1 Max Macbook Pro and the image stays very crisp and sharp at sub 100% zoom in develop like 99.x%. Didn't realize that Adobe improved the algorithms here this much because it used to not be a good idea. Looks just fine. It's slightly blurry while you are actively zooming around with shift-right click but when you stop moving the pointer it crisps up in a few milliseconds to a perfectly sharp image. Really impressive. Don't know why it doesn't work like this on your machine. 

[paytonfrost]

Exactly. Thanks for the confifirmation that this is an odd issue on my machine. I wish it worked like you're describing, where perhaps it's slightly blurry when zooming but as soon as I stop, it resamples the preview from the full resolution and creates a reasonably sharp/quality image from whatever screen resolution I'm at.

[TheDigitalDog]

Ditto, on my MacBook Pro, even with GPU off, the image stays crisp at 99.6% (I had to enable the zoom slider in the toolbar to do so).

I would still suggest not zooming out past 1:1 if viewing the image is critical, even with the crisp preview, as color and tone can be affected. Examine this in a photo with a strong moiré. 

[Jao vdL]

You really only want to use powers of two zoom in Develop. The others are done by scaling up or down those powers of two. Especially close to 100% it is a real issue just due to the scaling algorithms. There you really only want to use 100% or higher.

[paytonfrost]

It didn't used to be like this. It used to be that whenever I zoomed in a bit, the preview would update so that at the screen resolution I still had a high quality preview. 

And the workaround to this is to zoom past 100%, then zoom back out to my preferred level because then the preview is high quality. Yes it's not perfect 1:1, but it's way better than the low quality I showed in the example images. 

[D Fosse]

There's one thing you don't seem to realize: At 100%, one image pixel is represented by exactly one physical screen pixel. So 100% is a significant number, unlike any other. It's the only zoom ratio that displays the exact pixel structure of the image. Any other zoom ratio means resampling of the screen image, with inevitable softening and artifacts.

[paytonfrost]

I do realize this. I use 100% view for checking certain parts of the image at the pixel level. But what I'm trying to figure out is why it's not resampling the image to create a high quality diplay of the image at the screen resolution that I currently have the zoom level at.

Because you are right, any zoom level other than 100% is a resample. However, what seems to be happening is that the resampled preview at the "fit" view of the image is adequatley resampled so that it's high quality, but any zoom level from "fit" to 100% does not engage in any resampling. Instead, it seems to simply zoom in on the "fit" preview quality and it's only at 100% that the quality jumps to 1:1. If I were to zoom out from 100%, then the image displays a high quality preview, it doesn't suddenly go back to displaying a zoomed in view of the "fit" preview that I had from "fit" to 100% zoom.

[RomasBudras · Accepted solution]

Do you have "Use Smart Previews for editing" enabled (in Preferences > Performance)? Smart Previews are low-quality downscaled images used for faster editing, and only at 100% the original raw image is used.

[paytonfrost]

Ohhhh I'm an idiot!

This was the correct answer. I had "Smart Previews" enabled, unchecking it fixed everything, and my sanity is restored. You're a saint, thank you.

I used to use Smart Previews when I had an underpowered laptop years ago, so I'm familiar with their usefulness. My current laptop is relatively new and when I set up lightroom again I thought it was an issue with the graphics driver or a deep performance setting or a buggy update or something else. Didn't realize that when setting up lightroom the option had either been checked by default, or I had checked it not knowing the consequences and forgotten about it.