On Thu, 19 May 2005, Dik Takken wrote:
> On Thu, 19 May 2005, E.Chalaron wrote:
>
> > http://forum.doom9.org/showthread.php?s=&threadid=93571
>
> Wow, that looks good. Might be very useful for improving DV camcorder
> recordings. The screencaps on this site show the typical consumer
> camcorder problems due to sub-optimal lighting conditions. The improved
I have several reservations/concerns...
First - the work is being done in RGB so there's the (lossy) conversion
from Y'CbCr to RGB. Then the data has to be converted back and while
that's not lossy there is the problem of accumulated (roundoff) error
creeping in.
Second - the luma and chroma are being "punched up" to look
good on a COMPUTER display. What looks vivid and colorful on a
computer screen is going to end up being way out of bounds for
TV/broadcast/DVD. NTSC ("PAL" too I suppose) video when viewed on a
computer _should_ look a bit dim and unsaturated (don't worry - it looks
fine on a TV).
I've seen that type of enhancement done in scanning and image
manipulation software - for example:
http://www.silverfast.com/show/silverfast-hdr/en.html
Problem is video isn't still imagery ;)
> Other than that: Time to introduce 'y4mautogain' I'd say.. :)
There's the problem of applying a filter like that over the entire
video instead of scene by scene - and then matching the scenes so
you don't have wild fluctuations (which are quite jarring to the eye).
Ideally what you'd want is to have something like that inside your
editor that has a visual display so you can get adjacent scenes to
have similar contrast/exposure/color-balance.
Looks interesting but be careful with the levels - perhaps run y4mhist
afterwards to see if things are too far out of range.
Cheers,
Steven Schultz
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