Re: [Mjpeg-users] Contrast
Hello Steven / List > Computer screen or TV screen? There's a big difference. Well I do it on computer screen, but now I know what I'll get. If it looks Ok on a computer screen it will be far too dark on a TV. > What does the final MPEG-2 burned to a DVD look like on a TV set? Usually too dark if not using the gamma @ 1 on the camera. > I guess the next question I have is "how are you reducing to the PAL > standard"? Perhaps there's something about how that is being done > that is causing the range to be shifted to the dark side. find files | y4m422 | y4munsharp | y4mscaler -S option=cubic | yuvdenoise | yuvcorrect | mpeg2enc > Or are you going thru a YUV -> RGB -> YUV conversion step along the > way - that would account for some of the level shift. Ho no ... long gone ... thanks to y4m422 > Have you tried both settings? I wonder if the 0 means "none"/"disabled" > while 1 enables the gamma of whatever value is wired into the camera This is it the 1 enables the gamma correction wired to the camera. Results on TV are pretty god after but there is definitely a lost in the definition / sharpness, it tends to flatten a lot out... > -Y Y_0.95_16_235_24_235 > might be what you want. I've found, in my recent conversions of > old/dark tapes, that a gamma adjust of 0.95 works nicely to brighten > the data without overexposing/blowing-out the highlights. Ok will give it a go I think I can get rid of -Y CONFORM then.. > Problem with the current state of the tools is that there's no > immediate visual feedback. Well I choose a short scene and yuvplay, but then, yes, I need to go back to the script, modify etc I tried to install Cinepaint without much success... > You need to run an encoding session, > look at the results, change the script(s), repeat. I use FinalCutPro > to do all my editing and color correction - there you can adjust the > filters and see (on an external TV monitor) the effect. ->> Well What I can do is actually foward the acquisition to my TV card (eventually a use for it !) then a TV monitor, broadcast ones are too expensive yet for me.. > First lesson is to use a TV monitor and not a computer screen for > video editing (color correction). I will then use DV files and Kino option External monitor.. Get my parameters Ok, then go back to raw data directly to mpeg2enc > What does 'y4mhist' say about your data? Run a few frames thru > 'y4mhist' (which understands 4:2:2 so there's no need to convert > the chroma sampling). The Y' table will show the distribution of > luma samples (a waveform monitor would be Nice - but that's probably > outside your budget ;)). If there's a heavy concentration below 32 Ok will keep that in mind > or > so then the scene is quite dark. Run a histogram before and after > whatever processing is being done to reduce to PAL and see if the > levels are being shifted. Good point Should have done that already; the first step in fact... Will keep you posted. > Good Luck! Thanks a lot E --- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf ___ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
Re: [Mjpeg-users] Contrast
On Tue, 6 Sep 2005, E.Chalaron wrote:
> Well I do it on computer screen, but now I know what I'll get.
> If it looks Ok on a computer screen it will be far too dark on a TV.
That's the opposite of what happens to me - if it looks good on a
computer it'll be too bright on the TV. If it looks a bit dim/dark and
faded (unsaturated) on the computer screen it'll be fine on TV.
Common mistake is to create bright highly saturated colors that look
good on a computer - those will be out of bounds ("illegal") and not
look correct on a TV.
> > Or are you going thru a YUV -> RGB -> YUV conversion step along the...
> Ho no ... long gone ... thanks to y4m422
I think it was renamed to 'yuyvtoy4m' but yes, that's what I hoped
you were using.
> That is it. The 1 enables the gamma correction wired to the camera. Results on
Ah, I guessed correctly ;)
> > -Y Y_0.95_16_235_24_235
> > might be what you want. I've found, in my recent conversions of...
>
> Ok will give it a go I think I can get rid of -Y CONFORM then..
It won't hurt to leave that present. You probably could also write
a simple program to read the frames, add a value to the Y' array and
then write the data to stdout.
> Well I choose a short scene and yuvplay, but then, yes, I need to go back to
> the script, modify etc I tried to install Cinepaint without much success.
That's what I thought. It's not an ideal workflow - much more
time consuming and tedious than one would prefer.
> ->> Well What I can do is actually foward the acquisition to my TV card
> (eventually a use for it !) then a TV monitor, broadcast ones are too
Finally get to use that extra connector on your card, eh? :)
You'll want to check that the brightness/color adjustments on the TV
are more or less centered. The goal is to see what is actually present
and not to make it look good at the TV end (consumer TVs have
circuitry to "enhance" the picture rather than show the signal exactly).
The 'production/broadcast' monitors do not do that - which is why
they're used in studios ;)
> I will then use DV files and Kino option External monitor.. Get my parameters
> Ok, then go back to raw data directly to mpeg2enc
That sounds like an excellent idea and should work well (definitely
a big improvement over relying only on a computer monitor).
> > What does 'y4mhist' say about your data? Run a few frames thru...
> > Run a histogram before and after whatever processing is being done ...
>
> Good point Should have done that already; the first step in fact...
It's not a waveform monitor but it'll serve nicely to get an idea
where the levels are concentrated.
Have Fun!
Cheers,
Steven Schultz
---
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Re: [Mjpeg-users] Contrast
> > > I will then use DV files and Kino option External monitor.. Get my > > parameters Ok, then go back to raw data directly to mpeg2enc > > That sounds like an excellent idea and should work well (definitely > a big improvement over relying only on a computer monitor). Actually I have an option for a flat TV LCD 15 in, would it be better than a usual TV screen. Cheers E --- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf ___ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
Re: [Mjpeg-users] Contrast
On Tue, 6 Sep 2005, E.Chalaron wrote: > Actually I have an option for a flat TV LCD 15 in, would it be better than a > usual TV screen. It'll take up a lot less space on the table/desk. If you have the spacefor a 13 or 14" CRT TV (preferably one with a flat (Trinitron or similar) tube) that might be cheaper. I haven't compared the display quality of the two. My guess is the vendors would make the response curve of the LCD panel be the same as the CRT. Which is less expensive would probably be as good a criteria as any ;) Cheers, Steven --- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf ___ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
