Damien Symonds

Ok, thanks. And may I see an actual photo you've taken (with a subject in it), before and after your wall fix?

Ok, I understand more now. If you just sharpen up the masking (use a smaller brush) around the rug behind the baby's butt, I think it'll be fine.

May I see the whole photo as well, for context?

May I see the separate photos which you combined?

Yeah, that's just ok.

I wonder why it changed? That's a funny ol' glitch, all right.

Hooray!

That's right. Because mine is set to Bicubic.

This is well short of the 1/3rd free space that Brian recommends, but it's not dangerously small either, particularly since you restart regularly. I see no particular problem here. Bingo!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! It must be on Bicubic (best for smooth gradients).

Can you check something for me? Under Edit>Preferences>General, what is your "Image Interpolation" set to?

Just to be safe, can you do this for me?

What about if you have a smart object layer, and use Ctrl T to resize it bigger or smaller (no rotation). Does that end up with any blockiness?

Now it's saying 21 minutes

I'm presently uploading my version of the file to email back to you. You should get it in ten minutes or so. I'll be very interested to know if it looks smooth, or jagged, to you.

This is SO weird! Yes, when I open your file, I can see the jaggedness too. I can see that you've rotated the photo to 2.76 degrees. So, I tried re-rotating it. No matter what rotation I tried, it always resulted in a perfectly smooth result, exactly like it should. I tried 1 degree, 3 degrees, 3.76 degrees, even 2.77 degrees - a change of only 0.01 degree! No matter what I did, it always ended up beautifully smooth. Not only that, when I put it back to 2.76 degrees ... perfectly smooth!!!! Something is screwy with your Photoshop.

With the rotated smart object layer, of course. But nothing else needs to be done, no.

Wait, can you please send me that PSD?

Good.

Try these: https://www.damiensymonds.net/2015/09/black-boxes-and-other-weird-behaviour.html

That is very weird. I've never seen it before.

103%

Screenshot please.

Only while the transform handles are active. As soon as you hit Enter, they go away, yes?

Oh shit, duh! Never straighten with the crop tool. https://www.damiensymonds.net/2010/01/straightening-horizons.html

Also, with Content Aware turned off? Also, with no values at all in the options bar?