...so what's with the color RED?

Phantasmagoriat · Post by **Phantasmagoriat** » Wed May 31, 2006 12:04 am

I'm encountering overly apparent pixelation when the color red is used [especially against a black background! ...which is what I'm trying to achieve...]

...so...what's up with that?

...can it be fixed?

my snazzy new intro in 'The_Human_Equation'
http://www.animemusicvideos.org/members ... p?v=118410
just doesn't look right, and even in NetTroop's 'Another Half' this can be observed...

Qyot27 · Post by **Qyot27** » Wed May 31, 2006 6:39 am

Yeah, red often has trouble when it comes time to compress the video. Either you can get something like dot crawl, or worse, bleeding. I'm not quite sure how to fix it either than allotting as much bitrate as you can or possibly seeing if using AVC (instead of XviD) fixes it, but then the general audience will probably avoid it because they'll scream about not being able to play it back.

Zarxrax · Post by **Zarxrax** » Wed May 31, 2006 10:37 am

Use less saturated color.

Zero1 · Post by **Zero1** » Thu Jun 01, 2006 1:23 pm

More bitrate won't fix it.

Less saturation won't fix it (it will be a bit less noticable though).

So what's the problem?
YV12 is the "problem". YV12 is a colourspace that allocates 1 chroma sample per 4 luma samples (for every 4 "brightness" pixels, you get 1 "colour" pixel). In effect the chroma has quarter of the resolution of luma, and this is why it looks blocky (since it's being stretched to a larger size). YV12 is referred to as 4:2:0, your alternative would be to use 4:2:2 or 4:4:4. 4:2:2 would be less blocky, but still have a lower resolution than the luma. 4:4:4 gives the chroma the same amount of samples as luma, therefore should not appear blocky. Obviously though, the higher colourspaces you use, the more bits they require to encode, so you will need a larger filesize, or if the filesize is the same, it will look slightly worse.

Do be aware though, that DVD uses YV12, so if you are complaining that your original source is blocky, well that's just how it is and you can't fix that save for interpolating the chroma (which ought to happen when you change the colourspace anyway).

Check out the guides for more information on colourspaces.

Phantasmagoriat · Post by **Phantasmagoriat** » Fri Jun 02, 2006 11:10 am

Thanks for the explaination

...okay, so I know its not my source because its not a video source ...it's just a .jpg ...in fact this is it:
http://www3.telus.net/public/chris211/pics/project2.htm

-see the red moon

[if anything, its more blured than pixelated]

...so now that you've told me what I should try to do, where should I look; is it an adjustment I can make under codec options [I didn't see anything ...unless I have a different version of XviD]

...or is it something I must look for in my encoding software; I'm using Magix movie edit pro10 [...if anyone is familiar]

Zarxrax · Post by **Zarxrax** » Fri Jun 02, 2006 11:39 am

Well, its not something you can configure in the codec, because Xvid only does yv12. While Zero1 had a very correct technical answer, it is a useless practical answer :p

I suggest you take my suggestion of lowering the saturation or brightness on the image a bit.

Phantasmagoriat · Post by **Phantasmagoriat** » Fri Jun 02, 2006 2:45 pm

hmmmm............... a less intense red would make it a more gorey blood-colored moon.
.................which might not be bad

TaranT · Post by **TaranT** » Sat Jun 03, 2006 3:50 am

I had this same problem with my last project. Most shades of red were fine, but the red in Kiki's headband was a constant problem when set against her black hair or just the black border lines.

Desaturation helps, but it seems like overkill to affect an entire clip that way. Selective masking could limit the effect to the red area.

With Vegas, the color correctors can also be used. (Premiere may have this tool, as well). The "Boost Mids" preset in the Secondary Color Corrector, or the "Red Midtones" preset in the main Color Corrector - both will smooth the problem area at the risk of adding some red tone to the entire image.