Q: motion 4 - removing background on video

Hi Tokun1,

The general mac users group might not have an answer for this or some might come along and be able to field this one.

In the mean time try asking you question to this group or see if the resources are available from here.

http://www.applemotion.net

NO magic bullet to automatically remove the background of a regular video clip.

WE professionals shoot our actors and needed objects on a green screen.  Then in post-production, apply a Keyer filter to remove that color.   At this point we can lay any background we wish behind (bellow) it.

http://help.apple.com/motion/mac/5.2/#/motn14b9a0be

tokun1 wrote:

... how to remove the background of a video clip ... I imagine it is not that complicated, I've seen many an effect where they take a video clip and changed the background,....

Any of your examples online avail (YouTube)?

to 'cut out' a foreground could be highly complex, ever 'shopped' a photo?

Now do it 30 times a second

There are several techniqués:

• plain black (or white) background could be replaced using a Luma-key

• Differential-matte - rarelly seen in the wild (Apple Photobooth), asks for a clean-plate (bg without foreground), asks for static bg, … for video avail as Phyx Keyer (200$) ....

• Color-key, green/blue/any solid color (for the movie Predator they used pink…) gets transparent

• Rotoscoping - drawing the matte by hand, frame per frame, painstaking, but probably your only solution

• auto- or tracked Rotoscoping, commercial products like SliceX from coremelt follow automatically a highlightes subject in the clip ...

for details on each process, google/wiki yourself ... each method has its dis- and advantages ...

Thanks for posting the pic - much better to give advice...

originally shot this person with a black drape behind her.

then, I would suggest a luma-key, ... a bit tricky - the table is close-to-black too, and you notice in your example that ugly 'black border'  around her... a luma-key is never as precise as a color-key.

but you can fix that with the Magic Key filter... oops, you're in Motion4 (four)? Sorry, no idea, if M4 offers a MagicKey filter either... in M5 it allows to adjust the mask, like that:

for the table I applied a second, 'dirt' mask...

But sorry, haven't seen you're in M4 ....

tokun1 wrote:

… I do need to buy motion 5 to get up to date soon.  Would you mind listing the steps, …

Hi Tony,

sorry for forcing you into purchasing M5 (hey, Apple, 30% comission!!)

But my start with Motion isn't too long ago, so vers4 is just hearsay for me ...

OK, cooking recipe Luma-key:

('cause I hadn't have your original source with the black background, I erased the jungle in Pixelmator...that is a bit cheating, 'cause my bg is 100%black… yours probably not…)

Step#1

Create a new project with your clip, two groups, Source and BG (as an example: a gradient)

Under Filters/Keying you should find Luma-key.

Apply that to your source and you get this…

Step#2

whooo, spooky!! LOL

out-of-the-box, the Luma-keyer is set to some sort of 50/50… we have to adjust that:

move the Whites-slider to the left …

Step#3

Now, the filters threashold is much steeper, your talent isn't a ghost anymore.

But - at the borders we notice ugly artifacts... esp. when you don't have a 100% perfect (=black) bg, you can tweak the settings for hours  - will not work. Hm…?

Magic Keyer to the rescue!

Step#4

Now, we can adjust the key/matte, make it smoother, blurring it ... try the various settings...

Last step, the table: it is always nonsense to have the same color in foreground as the key-color (green obkjects in a green screen), here: the table. So, for cosmetics, I double the source and apply manually a drawn mask:

Step#5

... finally, <drumroll> aaaand done:

ok, I botchered and cheated with creating my source-file… but basically that is is the workflow.

Next time use a green screen; in the school project I'm supporting, we do have the worst green screens of movie making history - and they work like charme! Using some fleece-cloth from the pennystore and just available (day)light we a get an acceptable key. ok, not broadcast quality but … nice.

If you have more question, Tony, just ask ...

tokun1 wrote:

 

I used a black backdrop but it was very wrinkled and looked terrible ...

you can color-correct your clip first, crushing the blacks to get a more solid background... but that affects the whole screen => that's why a use a dirt-mask = handdrawn to keep the table and don't make it transparent.-

A pleasure to help... learned from the community. give back to community.

simple deal…