#Setting r3 gamma
37 messages in this thread
I've got a question about setting the Framebuffer gamma with r3.
I've get a Targa+64 with an NTSC type monitor (a TV with composite video
input), and the TConfig batch files I use have been set with gamma at 1.0.
I run the little "Set" framebuffer gamma calibration in 3DS, but the
two areas look NOTHING like one another, no matter where I put the
slider. Am I just not standing back and squinting far enough, or
does it have something to do with the
picture/color/black_level/contrast/tint settings on the monitor? I
have tried displaying a little test pattern image with red, blue,
green, greyscale, etc) and setting the monitor to make those colors
look acceptable first, but I have no other resource as to what they
should look like than my eyes.
Do I just set it at 2.0 and leave it?
gamma certainly adds a knew level of confusion. I just faithfully use
2.2 for all my NTSC work, regardless of the matching thing on my TV.
Martin's right on two counts: gamma adds confusion and, when in doubt,
set it for 2 or 2.2 for NTSC. (1.8 usually works for most other
applications.)
OH! I see, Jack & Martin!!!!!! This whole gamma thing is just
something that old-timers (video-wise) use to confuse us neophytes
(kinda like a high-tech snipe hunt!).<g> You sit back and laugh
while we squat out there in the bushes all night, waiting to catch
the elusive Gamma Correction!
"Elusive" is definitely the word to describe gamma. But once you get
it adjusted, you don't have to bother with it again (unless you
change monitors), and the results are fantastic.
YG: "Elusive" is definitely the word to describe gamma. But once you get it
adjusted, you don't have to bother with it again (unless you change monitors),
and the results are fantastic.
I'd like to change the subject line to read "Trouble in Paradise!"
I just spent a marathon 1.5 hours on the phone with Truevision to find out why
Gamma correction in 3DSr3 isn't helping me at all. The gamma adjustment slider
in 3DS always winds up darn close to 1.0 for my composite NTSC signal.
According to Truevision, here's why: The Targa + boards are "optimized" for
NTSC video, utilizing look-up tables to put the correct information on the
screen. To me, this translates to "pre-corrected" gamma. The techies there (I
had 3 of them on speaker phone) asked that the Yost Group contact them
regarding my question. They were able to reproduce my results exactly. I will
Email you the phone number.
Please check into this as many of us would like to take advantage of your gamma
correction instead. Thanks.
– David J. Marks
There are definitely ways to inhibit the Targa+ boards from doing any
gamma correction. I'll call the guy at Truevision you mentioned in
your email and see what he says.
Re: Disabling Targa Gamma correction
Thanks for looking into it. I had three of their guys on the phone
trying to figure this one out. We did find that their TCONFIG
program has a gamma slider. It is set to a value of 1.0 as a
default, and can be set to values below 1 if necessary. Backing into
things, I set 3DS Gamma to 2.2 (your number from somewhere), shelled
out to TCONFIG and dropped their gamma to 0.5 to make the grey boxes
match. However, this was just a test, and I'd guess that this
correction/decorrection combo must trash the adjustment.
Now I just have to hope that my Sony EVO-9650's don't have built in
Gamma correction! Argh.
Wow! 3 guys, 1.5 hours? And someone say that there are no Truevision
support. <g>
ana /krazy images
Is it uncommon to see a gamma level of 1.35? Our final renderings
will be displayed on computer monitors only, so using the pattern
setup, that's the number it came up with. I imagine the number will
vary from monitor to monitor and likewise for graphics cards…
A gamma of 1.35 isn't that unusual for certain computer monitors. If
that's the number that the pattern came up with, use it!
I also have a Targa 64+. When I adjusting Gamma, I got results
similar to yours. I discovered that contrast and brightness controls
make a difference, the Tconfig program for the Targa allows gamma
correction, and some VTR's have built in Gamma. So…
Try to run from the framebuffer directly to the NTSC monitor, thus
eliminating any VTR gamma correction. Then check TCONFIG to make
certain it is NOT gamma correcting. Then try to adjust 3DS gamma to
get the grey squares to match up. Play with brightness and contrast
on the monitor and you may detect a little difference too.
Let the forum know how you make out. I'm not completely satisfied
that I've got gamma working, and I'm sure more people will run into
the same problems.
It sounds like your Targa board might be trying to do some gamma
correction on its own. Are you setting tconfig to make the gamma 1.0
(which would be gamma-correcting to make it linear on a video device)
or are you making sure that the gamma board is booting up in 1.0 mode
(with no gamma correction at all)? It's critical, if you want to use
3DS gamma correction that absolutely nothing else in the video chain
attempts to do gamma correction. DavidM's note re playing with the
brightness/contrast on your monitor is important… plus, some
monitors actually do their own built-in form of gamma correction.
First, absolutely make sure that the targa is not gamma correcting at
all, and then plug a plain vanilla NTSC monitor (preferably
composite) into the targa. I'm assuming that you're going out to
video. Is that right?
I seem to be having the same problem setting the gamma on my
Targa+. I'm running through a T+ 16/32 straight to an NTSC monitor
via S-video. The Targa Gamma is set to 1.0 via "tconfig". I couldn't
get the color swatches to come even close. The outer box was much
darker than the inside, and it also gives off an annoying moire
pattern. After reading the notes here, I tried adjusting the
brightness and contrast controls to get the grays to match, (they
still don't, but they're closer) with the gamma set to 2.1. I did this
in the Mat editor and left the display at 1.8 (a perfect gray match!)
and rendered some materials on both the display and the Targa. The
samples appear dark and kind of muddy on both displays, but they do
match, however… I loaded several JPEGs off the CD (view image) and
they ALL apear much to dark.
I've reverted to what I was doing, which is seting the Targa
gamma to 2.1 in 3ds and then setting the monitor's bright/contrast so
that the cd sample images look their best.
My display gamma is still set to 1.8, which seems to be the
best by matching the gray squares, but sample materials rendered on
the display still seem much to dark.
Althouigh I haven't gotten this far with installation of r3 I've been
following this gamma problem on the targa+. It seems to me that one
would be advised to not adjust the monitor to get the gamma to work.
The monitor is your primary measuring device and as such should be
calibrated using a standard NTSC color bar from a standard source and
using blue gun set the color/tint/brightness/ and contrast for
perfect bars. The bars should be from a standard source like a
signal generator or camera, or, in a pinch recorded from broadcast TV.
Once the monitor is calibrated leave those controls alone! Then go
in and attempt to use the gamma adjusting setup in r3. You see, if
you're constantly adjusting your monitor to match what ever the
targa+/3DSr3 is putting out you won't be calibrating anything. It's
like trying to get your car to go faster so in tinkering with the
speedometer you're able to accomplish this, right? <g>
Don, you're ABSOLUTELY correct.
Actually, I spit out several images onto the Targa and
adjusted the monitor controls so that I got the best image on all the
stills with a single monitor setting, so now that they're set, I
don't need to touch them again. I certainly didn't mean to imply that
I was adjusting the monitor each time a different image was
displayed. That would be rather pointless. Regarding the NTSC color
bar pattern, that is something I should check into. I think there's
one in one of the libraries here, if I remember right. I think it
would be helpful if a color bar targa file was included on the 3ds cd
for just this kind of thing. (maybe next release, Gary?)
I uploaded an NTSC colorbar from a test generator and grabbed as a
targa file. It would be ok to use to adjust your targa gamma but not
for monitor adjustment. You really need a standard CB source.
Actually, to adjust the targa you really need the match gray panels
test that you have been using. Your adjusting the monitor with
unknown source targa files would still be guess work in my book.
I'm currently trying to match gamma between TOPAS output and 3DS.
The strategy I'm using is to match each to a standard monitor and
hope for the best. However, I might have to use TOPAS as the
standard since 3DS has more user control over this setting,
especially r3. I'm using both packages to lay tga's in sequence
using effects from each for the project.
>>to adjust the targa you really need the match gray panels test that you have
been using. Your adjusting the monitor with unknown source targa files would
still be guess work in my book.<<
Unfortunately, the gray panels test simply won't work. If the
brightness/contrast controls are close to centered, the grays can't
even come close, and if the monitor's controls are adjusted to let
the grays kinda match, then the images displayed are much too dark.
Everthing seems to look good now, so I'll try rendering some of the
sample scenes on the cd, and if they look good without adjustment, I
should be set.
I havn't spent much time this past week with 3DSr3 due to three
projects finishing up on r2.01 and evaluating Topas. I did look at
the Targa+ output gamma test and it matched perfectly at 1.0. I have
the gamma adjustment in tconfig at 1.0 if I recall. My monitor is
calibrated with NTSC CB from a signal generator. I'll play with it
some more this weekend when I finish these projects. No work for the
next two weeks so I should have some time to play and update my
resume tape.
There is a color-bar .GIF (which, considering toff he colors
used, is just fine) included on the 3D Studio R3 CD.
Could you tell me where and under what name? I looked but couldn't
find anything.
Where what & under what name what? It figures – just when you
want people to cut down on extensive quoting of previous messages…
Lost in an impenetrable forest.
>> Where what & under what name what? It figures – just when you want people
to cut down on extensive quoting of previous messages…<<
I was asking about….
>> There is a color-bar .GIF (which, considering the colors used, is just
fine) included on the 3D Studio R3 CD.<<
Thanks.
>>Lost in an impenetrable forest.<<
Have you tried leaving a trail of bread crumbs? Or does that
only work in caves?<g>
David,
The file you want is actually distributed on the R3 diskettes. In your
3DS3\IMAGES directory, look for TESTPAT.GIF. It is a low-res version, though –
I guess 320×200. It includes RGB, CMYB and grey-scale.
Kevin Krell – Computer Support Associates
Found it. Thanks.
David
You should always have your brightness and contrast controls set at
their normal (centered) position when you adjust gamma values. It
sounds like your Targa board is still doing gamma correction, if the
outer box is always darker than the inner box. You can try running
to the monitor via the NTSC signal instead of the S-video signal…
that might give you a better idea of what's going on. Since you say
that you're setting your display gamma to 1.8 and your samples are
"much too dark", it sounds like you're either setting your brightness
and/or contrast too low (off the center position) or that something's
wrong with your monitor.
Are you going out to videotape with this setup? If you aren't, you
might want to try turning gamma off and seeing if that makes life
easier for you.
All the controls on both monitors were pretty much centered
when setting the gamma (and still are). If the Targa is doing
correction on its own, I don't know, But a tconfig batch set to 1.0
is run before starting 3ds. I'll try to use the composite out of the
Targa and see if that has a different effect. I do plan on sending a
bunch of stuff out to be laid to tape in the next few months, so I
would like to keep the 3ds gamma on, rather than not dealing with it.
The controls are also centered on the NEC 5FGe, and everything
looks fine in Windows and other programs, including the 3ds modules,
with the single exception of the rendered spheres in the mat editor,
which don't look nearly as vibrant as the screenshot of the mat
editor on the 3ds box. However, since I'm rendering those to the
Targa, I'm not that concerned with that.
This whole gamma thing brings up another question. When a shot
is rendered in 3ds and brought in to another program such as
Photoshop for touchup, what Photoshop gamma setting is ideal, none,
1.0, (same?) 1.8, or simply whatever looks best (1.8)? A whole book
can probably be written on the subject, if it already hasn't! Well, I
think I'll go read the gamma section in the advanced users guide
again.
Based on my experience with PhotoStyler, which is very close to
Photoshop, you would adjust their monitor calibration in much the
same way as in 3dsR3, and then just leave it alone. They also have a
method of applying gamma curves to the bitmap image, which you should
avoid since they work in 24-bit color space.
As Jack said, you want to get the gamma right in 3DS, and then leave
it linear in Photoshop.
Gamma in Photoshop is set at the default of 1.8, and stuff looks fine,
so I don't think I'll mess with it.
I'd agree with you that if everything looks fine, leave it.
Yes, I checked the batch files that TConfig had created, and they were
made with Gamma set to 1.0. My monitor is a little 13" Panasonic TV
set that has a composite video in. I will try the following: I will
run the gamma config from 3DS and set it to 2.0. Then, using the
black level control on the Panasonic, I'll try and get the greys
close. I'll let you know.
Yes, I'm trying to set this for video. When I'm doing something for
print (dye-sub) and film (slide/4×5), should I use a 1.0 setting, and
then let PhotoStyler or whatever I'm using to print from correct the
gamma?
If you look at the 4-color section in the 3DSr3 reference manual, on
the top of the 3rd page of that section you'll see gamma tests for
print output. We've found that a gamma value of 1.8 provides the
best balance of contrast for print. You definitely want to get as
close as possible in 3DSr3 instead of doing all the gamma correction
in PhotoStyler. Why? Because once the 24-bit image is in a paint
program, you'll be quantizing the colors when you do gamma correction
to it (since it's out of the 3DS 48-bit color domain). That's BAD.
Thanks Gary! Yeah, I forgot about the little gamma illustrations. I
appreciate it, and await the results of your conversation with the
Truevision techs.
I also have a Targa 64+. When I adjusting Gamma, I got results
similar to yours. I discovered that contrast and brightness controls
make a difference, the Tconfig program for the Targa allows gamma
correction, and some VTR's have built in Gamma. So…
Try to run from the framebuffer directly to the NTSC monitor, thus
eliminating any VTR gamma correction. Then check TCONFIG to make
certain it is NOT gamma correcting. Then try to adjust 3DS gamma to
get the grey squares to match up. Play with brightness and contrast
on the monitor and you may detect a little difference too.
Let the forum know how you make out. I'm not completely satisfied
that I've got gamma working, and I'm sure more people will run into
the same problems.
Okay, I'll play around. See my reply to Gary.