Blurring a small portion of the video

levifiction wrote on 6/19/2012, 3:01 PM

I'm recording some videos for how to take the Math and English placement tests at our college.  

Camtasia is nice for this, but I can't afford it and I can't get the school to buy it so I'm looking to simulate one of their effects.

Blurring a single portion of the image.   During the tutorial it actually shows questions for the tests.  I want to blur these out.  Normally I'd just duplicate the video, use the section effect and apply a simple artistic blur to this second area.

Sadly it's not static, the area changes as I scroll through the screen.

So for now I've resorted to putting up an image over this area and moving it around to match up and cover the questions.  Which of course looks very tacky. 

Does anyone have a good process for making a blurred area that moves?  I suppose I could use effect masks but I don't think I quite understand how to use them correctly, or the default ones are simply terrible because I can't get those to resize and animate over the area on my video at all.  

Thank you for any advice you have. 

Comments

cpc000cpc wrote on 6/20/2012, 2:27 AM

levifiction,

I'd suggest using three tracks (ignoring any audio) with your normal video, a copy with the blur effect throughout,   and in between a suitable black and white imge that gives you the shape you need for masking. Apply the 'Alpha' chroma key to the mask and move and resize it as needed with key frame animation. This should give you a result better than just moving a section which would presumably always be a rectangle. Note when I said black and white you can have a soft grey edge to your mask to enhance the effect. This is often the technique for masking face of people filmed going to court etc.

Have a look around Alwyn's site (he used to be very active on the old forum): http://www.aaproductions.net/mep/

http://vimeo.com/9515252 is a direct link to his 'Masking a moving face'

Also check the 'Tutorial' section at the top of the page here. Many are not in English but often the screen shots can get you pointed inthe right direction.

Regards,

Carl