can i replace background part of the video (still frame) with the picture (matte)?

hofno wrote on 1/23/2012, 10:43 AM

Hi!

i´ve been filming a scene shown below on the picture where the picture on the wall and the lamp cover are overxposed. as the scene is never changing (it´s filmed with tripod and i never touched the camera during the recording), i wold like to replace the overexposed picture (the one on the left top corner) with its photo or with its video (it is kind of animated), which would be exposed correctly. the same goes with the lamp cover. it doesn´t move except when the light is turned on and off at the begening and at the end of the scene..

is it possible to do that? is there any plugin or whatever i could get to make it work? like matte stuff? or is there any software you would suggest?

thanks

Comments

cpc000cpc wrote on 1/23/2012, 4:07 PM

hofno,

The picture in the top left is relatively easy. Simply place a properly exposed version (still or video) on a timeline track below (higher number) your scene where it will preview in front. Then adjust its size and position using that option under 'Effects' >> 'Video effects' so that it exactly covers the overexposed version.

The table and the lamp present a different problem -- as they are not properly exposed in the original there is nothing that can add information to the blank white of the lamp or near pure black of the table. If you can record some video with these area exposed to your satisfaction you can combine them with your original using an alpha channel mask thus:

Track 1 -- your original & assuming audio is on track 2

Track 3 -- a black and white mask with its chroma set to 'Alpha' 

Track 4 -- a properly exposed lamp and/or table

The alpha channel lets you see track 1 or track 4 depending on where the mask is black or white. For best effect you would probably soften the edges with shades of gray so the transition is smooth.

That said, why not think away from effects, plugins and programs and adjust the lighting before you shoot? Eg just get a small, out of sight, fill-in light to shine on the table area (from an angle that matches the lamp in the scene if possible) and use a lower wattage bulb in the lamp? Or even darken some of the lampshade with a layer or two of tissue paper inside?

Hope this helps,

Carl

hofno wrote on 1/25/2012, 7:27 AM

hey!

thanks for your answer. just wanted to add some details that might matter...

there will be a person walking in front of the picture, table and lamp. if i apply your first suggestion (to add track with the picture exposed correctly) is the person going to be visible just as if she was visible on the unedited video?

if so, can i do the same thing with the table and with the lamp cover insteda of trying your alfa suggestion?

Thanks again

hofno,

The picture in the top left is relatively easy. Simply place a properly exposed version (still or video) on a timeline track below (higher number) your scene where it will preview in front. Then adjust its size and position using that option under 'Effects' >> 'Video effects' so that it exactly covers the overexposed version.

The table and the lamp present a different problem -- as they are not properly exposed in the original there is nothing that can add information to the blank white of the lamp or near pure black of the table. If you can record some video with these area exposed to your satisfaction you can combine them with your original using an alpha channel mask thus:

Track 1 -- your original & assuming audio is on track 2

Track 3 -- a black and white mask with its chroma set to 'Alpha' 

Track 4 -- a properly exposed lamp and/or table

The alpha channel lets you see track 1 or track 4 depending on where the mask is black or white. For best effect you would probably soften the edges with shades of gray so the transition is smooth.

That said, why not think away from effects, plugins and programs and adjust the lighting before you shoot? Eg just get a small, out of sight, fill-in light to shine on the table area (from an angle that matches the lamp in the scene if possible) and use a lower wattage bulb in the lamp? Or even darken some of the lampshade with a layer or two of tissue paper inside?

Hope this helps,

Carl

 

hofno,

The picture in the top left is relatively easy. Simply place a properly exposed version (still or video) on a timeline track below (higher number) your scene where it will preview in front. Then adjust its size and position using that option under 'Effects' >> 'Video effects' so that it exactly covers the overexposed version.

The table and the lamp present a different problem -- as they are not properly exposed in the original there is nothing that can add information to the blank white of the lamp or near pure black of the table. If you can record some video with these area exposed to your satisfaction you can combine them with your original using an alpha channel mask thus:

Track 1 -- your original & assuming audio is on track 2

Track 3 -- a black and white mask with its chroma set to 'Alpha' 

Track 4 -- a properly exposed lamp and/or table

The alpha channel lets you see track 1 or track 4 depending on where the mask is black or white. For best effect you would probably soften the edges with shades of gray so the transition is smooth.

That said, why not think away from effects, plugins and programs and adjust the lighting before you shoot? Eg just get a small, out of sight, fill-in light to shine on the table area (from an angle that matches the lamp in the scene if possible) and use a lower wattage bulb in the lamp? Or even darken some of the lampshade with a layer or two of tissue paper inside?

Hope this helps,

Carl