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I was on a Zoom video call with a coworker today, and I had my background image set to this photo.

She asked me about it, and I told her that I took the photo. Then she started making some really confusing comments, such as "Is that a photo of a painting?" She said everything looked like brushstrokes, and she finally shared this screenshot of how Zoom was showing my background image to her. As you can see, it looks like my photo was converted into a painting.

I looked at my Zoom settings and I didn't see anything that would "painting-ify" a background image. I have my Video Filters, Avatars, and Studio Effects all set to "None".

Why did Zoom show her a "painting-ified" version of my background image?

Additional information: I sent my coworker a copy of the original photo through Slack, and it did look like an actual photo to her, so it must be a problem specific to Zoom.

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    have you tried joining your own meeting on another device to perhaps eliminate your co-worker's hardware from consideration? This looks like a denoise filter run amok, perhaps an AI filter that trained on faces. And yes, it looks radically different than the original image you posted, especially when opened in a new tab at their native sizes. Is your face affected by this as well (even if not as pronounced) Commented Jan 11, 2024 at 19:28
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    Looks like typical video compression stuff + some beauty filters that are supposed to make humans look good. Commented Jan 11, 2024 at 19:43
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    I wouldn't have described it as a painting, it just looks like lossy compression so lots of fine detail is gone. (From a video codec that blurs instead of getting blocky like JPEG, which is normal since modern codecs like h.264 and later have deblocking filters in the loop; the reference picture for the next P-frame has filtering applied.) Commented Jan 12, 2024 at 3:33
  • On 2nd look, there's probably some filtering to account for that amount of smearing. ffmpeg -i xbHKw.jpg -vf scale=-2:480 -c:v libx264 -crf 30 foo.mkv to downscale (bicubic) and make one h.264 I-frame (about 10.6KiB vs. 402KiB JPEG) with x264 has blurring, but also some blocking, unlike this. Maybe a blurrier downscale like bilinear instead of bicubic could also be a factor. (Without downscaling, but with -crf 45 to get a similar file size, there's much worse blocking. With crf 40 for a 21K file, its less blocky, more like your "painting". But Zoom wouldn't use such low-quality hi-rez) Commented Jan 13, 2024 at 18:43

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  1. For free Zoom plans the max resolution is 360p, for pro plans it can go up to 720p for Pro or 1080p for business (source)(official source), but the HD and FHD options depend on (A) the user has selected HD under Video settings, (B) the number of callers and (C) whether the account admin has explicitly requested HD Group calling through Zoom Support. HD was standard for PRO accounts in 2020, but the Zoom infrastructure had to grow so fast during the pandemic, that they did a 'silent downgrade' for everyone. (This is documented somewhere, but I can't find the link right now - I speak of my own experience, though).

  2. Moreover, on Standard HD, the Bandwidth for a 1-on-1 Zoom call is indicated as 1.2Mbps (up/down).

    To this end, any sent image will be heavily compressed. Also, for sure the compression algorithm will be optimized for movement rather than for details, and will privilege the face of persons, as that's the principle element that is of interest. So that algorithm just isn't optimized for such a detailed image as yours.

  1. Then again, on the receiver's end the image will be upscaled again to the screen resolution, and depending on the GPU power this might be handled differently from system to system.

    That second Image of yours looks like either 360p or 480p upscaled.

What you are seeing is the combined effect of these three factors.

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I guess as a supplement to @1NN’s answer I made a trial image (below) using your original posted image: reduced to 720px wide; one pass with a denoise filter with "max denoise" and "min preserve detail"; upscaled to 1198px wide (same as your "painterly" image).

Not exactly what happens to the video as described by @1NN’s answer, but illustrative. I am not that familiar with zoom settings, but the denoiser may be a default setting not exposed to the user.

enter image description here

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  • Nice. Note though that 720p resolution is 1280 x 720, so it's 720 pixels high, not wide. Commented Jan 12, 2024 at 11:07
  • I just used 720 as a round number since I was thinking of it. What I was actually doing was downsizing it by decent amount, about a third. Commented Jan 12, 2024 at 15:46
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As you can see, it looks like my photo was converted into a painting.

No it doesn't.

The second image looks like it has been put through lossy image compression (most likely JPEG) and very heavily compressed. The "streaks" which I guess you think look like brush strokes are fairly characteristic of the effects that you get along boundaries wherever the colours change.

Load the picture into any image editor, and save it as a JPEG file with successively lower quality. (Almost all image editors should let you change image quality.) You'll find that the file gets smaller and smaller, whilst the image gets more and more blurred, and edges get strange "halo" effects along them. At some point, you'll see it look like your second picture, at which point you know what level of compression/quality Zoom uses.

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    it's pretty clear that something other than just jpeg-esque compression on its own is happening here. for example, probably denoising, like the top answer suggests. Commented Jan 12, 2024 at 14:44
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    This is what the original image looks like after resaving it several times as a JPG at 10% quality: i.imgur.com/AxW2ZHv.jpg. The "painting" image looks nothing like this and doesn't have the typical blockiness/pixelation of JPG compression. Commented Jan 12, 2024 at 15:05
  • @pacoverflow: Yup, JPEG gets blocky and has "ringing" artifacts (en.wikipedia.org/wiki/Ringing_artifacts#JPEG) at low bits/pixel because it doesn't do filtering, it just does a DCT and rounds off (quantizes) and discards near-zero coefficients (en.wikipedia.org/wiki/Discrete_cosine_transform#Example_of_IDCT) (and then compresses those losslessly, like zip). Modern video codecs (like h264, especially h265) often get blurry at low bitrate (blog.biamp.com/understanding-video-compression-artifacts). And Zoom is probably using separate filters as well as downscaling. Commented Jan 13, 2024 at 11:28

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