I dunno if I've gone too far down the rabbit hole or something, but I've noticed that my copy of avidemux seems to have swapped the definitions of U and V around in its "Remove Plane" filter.
See, it's supposed to go Y, U, V. More properly, it should be Y', Cb, Cr. Luma, chroma blue, and chroma red. I'll demonstrate with this 341x256 image of a parrot.
Photo by
Mari Gimenez on
UnsplashIf you tell avidemux to filter out the U and V planes, you get this. Perfectly normal; it's just a grayscale image.
The wackiness begins once you start removing just one of U or V.
Here's the original with only Y and "U":
Hold up, why is "U" red; isn't it supposed to be blueish? I think avidemux's drunk.
Here's Y and "V":
So avidemux has indeed swapped U and V in its filter.
How it manages to still work at all with this flaw in here, I don't know.
Here's what happens if you swap U and V:
This isn't a hue shift or anything; it's not possible to recover the original photo with yet another hue shift. Try it yourself, you're not gonna get the colors right. The best you can do here is a +120 degree hue shift, but now the leaves in the background are blue.
Yes, I installed the newest version of avidemux (2.7.6) for Windows, so this is an actual issue.
I think I need to stop. There's only so much knowledge I can snort at a time, and I'm really hitting my limit.