Chroma keying with DVX interlaced or progressive?
- Thread starter mattdj
- Start date
MovieSwede
Well-known member
Its better to shot progressive. Interlace is much more complicated to key.
avoid shadows on the screen and avoid that the screen itself light the subject.
The problem i have with the thing i shot saturday is the 4:2:0. The edges wont go away.
avoid shadows on the screen and avoid that the screen itself light the subject.
The problem i have with the thing i shot saturday is the 4:2:0. The edges wont go away.
MovieSwede
Well-known member
No blue egdes. But DV is sampled 720*576 but the chroma res is just 360*288 that creates block with color 2X2 pixels. And when those blocks are on the edge between the subject and the screen, it much harder to key it out.
Thats why they shoot SWIII with 4:4:4. (well sort of)
Thats why they shoot SWIII with 4:4:4. (well sort of)
I dont really understand what you mean "that creates block with color 2x2 pixels". I will do some more reading and ask a mate who may be able to shed some light on it. There seems to be a lot to it from what i'm reading on the net, but I guess if you light the blue screen evenly and place your subject as far from the screen as you can and light your subject for whatever the background is supposed to be and the exposure is set correctly for both subject and screen then things will be a lot easier. Thanks again MS, will check for more post tommorrow. Funnily enough I just finished painting a blue screen for a studio tonight!
mihnea de vries
Member
Definitely progresive!!! interlaced footage is very hard to pull out a good matte. Also use 1/100 ore higher shuter speed if there are dancing chicks or anithing moving fast on the scene.. becouse the motion blur will give you a hard time when keyng if you will use shuter speed under 1/100 . Try to light well the screen. Use Priamatte to key in Shake or Combustion.
here is a trick for pulling out a nice matte from dv footage. (i'm qoting some unknown suspect, i use this trick on my latest music video and i works perfect)
Because the Chroma channels in DV footage are sampled at a lower rate than the luminance, a good way to improve your DV keys outa site is o blur the chroma channels only. Because Combustion doesnt have a YUV chanel blur, you have to use some fancy giggery-pokery to do this.
First of all blur your footage. I tend to use an unconstrained box blur for this, generally either 2 px or 4 px depending on whether you are keying NTSC or PAL DV.
Now apply a Compound HSV operator, set the V operator to 'set', choose the footage of your layer (before it hits the blur operator) as the 'V Layer' & set the 'V input' to value. This will bring back the unblurred luminance of the footage, effectivly acheiving the same thing as blurring the chroma channels.
Now place a keyer operator after this, you can play around with the blur values to see what values work best once the keyer is operational.
Mihnea de Vries
here is a trick for pulling out a nice matte from dv footage. (i'm qoting some unknown suspect, i use this trick on my latest music video and i works perfect)
Because the Chroma channels in DV footage are sampled at a lower rate than the luminance, a good way to improve your DV keys outa site is o blur the chroma channels only. Because Combustion doesnt have a YUV chanel blur, you have to use some fancy giggery-pokery to do this.
First of all blur your footage. I tend to use an unconstrained box blur for this, generally either 2 px or 4 px depending on whether you are keying NTSC or PAL DV.
Now apply a Compound HSV operator, set the V operator to 'set', choose the footage of your layer (before it hits the blur operator) as the 'V Layer' & set the 'V input' to value. This will bring back the unblurred luminance of the footage, effectivly acheiving the same thing as blurring the chroma channels.
Now place a keyer operator after this, you can play around with the blur values to see what values work best once the keyer is operational.
Mihnea de Vries
Thanks heaps for your help on this topic. I read all about blue screen lighting (use daylight or super blue tubes in the kino banks to light the blue screen and tungsten lights to light the talent) for the shoot and was provided with a green screen instead of blue!
The talent was wearing yellow, so hopfully all is going to be ok for the post guys?!
So this brings the question of what lights you would use for a green screen, daylight or tungsten?
The talent was wearing yellow, so hopfully all is going to be ok for the post guys?!
So this brings the question of what lights you would use for a green screen, daylight or tungsten?