overexposure? at DVinfo.net

Go Back   DV Info Net > Windows / PC Post Production Solutions > Non-Linear Editing on the PC

Non-Linear Editing on the PC
Discussing the editing of all formats with Matrox, Pinnacle and more.


Reply
 
Thread Tools Search this Thread
Old June 15th, 2004, 10:31 PM   #1
Regular Crew
 
Join Date: Jan 2004
Location: Edmonton, Alberta
Posts: 51
overexposure?

anyone know any good ways to tone down overexposure? thanks.
Lyndon Golanowski is offline   Reply With Quote
Old June 16th, 2004, 03:31 AM   #2
Wrangler
 
Join Date: Jan 2002
Location: Hampshire, England
Posts: 1,543
Hi Lyndon,

Generally, adjusting the brightness and contrast can tone down overexposure.

These are normally applied by filters in the NLE software.

If it is way overexposed then it will be hard to rectify.

- What software are you using?
- How over exposed is the image?

Cheers,
__________________
Ed Smith
Hampshire, UK

Good things come to those who wait

My Skiing web www.Frostytour.co.uk


For quick answers Search dvinfo.net | The best in the business: dvinfo.net Sponsors
Ed Smith is offline   Reply With Quote
Old June 16th, 2004, 07:05 AM   #3
Capt. Quirk
 
Join Date: Apr 2002
Location: Middle of the woods in Georgia
Posts: 3,596
If it is extremely over exposed, you can try this photoshop trick- Copy the clip, and paste it over top of the original. In the copy's properties, adjust the opacity to around 50%, and multiply it. This will help to bring out the details of the original. You may have to play with the opacity to taste.

On the other hand, it it is under exposed, do the same thing, but select screen. I do this in Premiere, and it does work.
__________________
www.SmokeWagonLeather.us
K. Forman is offline   Reply With Quote
Old June 16th, 2004, 11:38 PM   #4
Inner Circle
 
Join Date: Jun 2003
Location: Toronto, Canada
Posts: 4,750
1- If your highlights have clipped then there is not much you can do. DV values range from 0 to 255. Any values that go past 255 get knocked down to 255, which means there is no information for highlights above 255. There is no way to rescue information that does not exist.

There may be some smart ways to make up information for overblown highlights, but no filters exist to do this.

2- If your camera has a soft knee then you can rescue some detail out of highlights.

3- You can get artistic on your footage and make the overblown highlights into an 'intentional' effect. You can use color curves and push more of your footage overblown but with a soft knee for the highlights.

Depending on your NLE you can also add glow to the highlights.

4- If the sky is overblown, it is possible to create a matte and add a color gradient in the background. You probably want to use 2/3/4 tones of the color you are using. i.e. start from a dark saturated blue to a less saturated and warmer blue for the midtones to white.

5- If you are using a not-so-good camera, there will be weird coloration around overblown highlights. This is because some of the color values (RGB) clip while the others do not. If you use a secondary color corrector you may be able to bring this down.
Glenn Chan is offline   Reply With Quote
Old June 16th, 2004, 11:46 PM   #5
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
DV color space is not 256 colors, but more like 220 (I don't remember the exact number). An 8 bit color space like sRGB or Adobe RGB will have values of 0 to 255.
__________________
Jeff Donald
Carpe Diem




Search DVinfo.net for quick answers | Where to Buy? From the best in the business: DVinfo.net sponsors
Jeff Donald is offline   Reply With Quote
Old June 17th, 2004, 09:46 PM   #6
Inner Circle
 
Join Date: Jun 2003
Location: Toronto, Canada
Posts: 4,750
The legal NTSC values are between 16 and 235??? So in a way DV values range from 16 to 235?

Anyways, DV is recorded 8-bit so it's like 0-256 to begin with.
Glenn Chan is offline   Reply With Quote
Old June 17th, 2004, 10:19 PM   #7
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
Not all the 8 bits are used for color information. YUV and YIQ color space are used for broadcast (PAL and NTSC, respectively) and are almost identical. Y represents the luminance portion and UV, or IQ represent the chrominance , or color portion. These are known as kYUV219 (with values between 0 and 219, for 220 colors). FCP has two color spaces, kRGB219 and kRGB255 (known as Super White). kRGB255 is a standard RGB computer color space, the same as other color aware programs, such as Photoshop. kRGB219 is designed to match YUV and YIQ, the broadcast standards. You can create graphics etc. in RGB (256 colors per channel) but you're using colors that will have to be remapped to the YUV, YIQ color space. That is why Photoshop has an NTSC filter. The filter attempts to remap the colors to the more restrictive color space required for broadcast.
__________________
Jeff Donald
Carpe Diem




Search DVinfo.net for quick answers | Where to Buy? From the best in the business: DVinfo.net sponsors
Jeff Donald is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Windows / PC Post Production Solutions > Non-Linear Editing on the PC

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 02:52 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network