#Gamma question ??
8 messages in this thread
I'm experiencing something that I hope somebody on the forum can explain.
– Here's my scenario…I have a scene that I'm rendering and it's being saved
as a JPEG (or whatever – dosn't really matter). After the rendering is
complete the image is displayed on my screen – I'm happy with the image. Then
I go to Render / View / Image and pull up the saved image and it now looks
washed out – like the lights were over-luminated.
I'm thinking this is a funky gamma effect – but, since I have little experience
with and/or a fuzzy understanding of gamma and what it really affects ….?? I
have done the gamma set up for my monitor….
Explanations, ideas, and suggestions are greatly appreciated !!
T.I.A.
Gary 🙂
Gary,
unless you are rendering for film (or possibly print) it's probably best to set
all the gamma settings at 1.8 (gamma ON) which are the defaults when r3/r4 are
installed. If doing film work just have gamma OFF.
Martin –
>> unless you are rendering for film (or possibly print) <<
When you say "film"…do you mean video or movie or just any type of output
other than on-screen viewing ? 80% of what I do, at this point anyway, are
still-images. Typically, I send them off as TIFs to our MACs where we use
Photoshop and Quark, etc., convert them to CMYK and incorporate them into
brochures that _do_ go out to service bureaus. So they do get re-touched before
they go out.
The only reason that I brought it up is that it was such a drastic difference.
On one PC the image looked fine and on the other it looked like garbage. I
don't know if it's because of gamma….or if it's just a difference in the
monitors. I'll take your advice, try putting both systems back to 1.8 gamma.
But what about that setup thing for gamma ? – the one where you sort of squint
and try to get the grey square to blend with the Pantone-ish dots ? I thought
that was supposed to equal out your monitor ?
Thanx for the response –
BTW – I hear there's another "Special Effects" book in the works -are you
involved with this one ?
Gary 🙂
Gary,
>> When you say "film"…do you mean video or movie or just any type of output
other than on-screen viewing ? <<
film means film: 35mm movie or slide generally, or possibly 70mm.
print output should probably be linear gamma (1.0) but a lot of people like 1.8
aesthetically. It's all greek to me.
>> I hear there's another "Special Effects" book in the works -are you involved
with this one? <<
no sir. I think they tried to contact me some time ago, but work commitments
have been overwhelming. Plus, the pay is pretty poor unless you get into a
royalty situation which is generally only true when 1 or 2 authors are
involved.
<<On one PC the image looked fine and on the other it looked like garbage. I
don't know if it's because of gamma….or if it's just a difference in the
monitors. I'll take your advice, try putting both systems back to 1.8 gamma.
But what about that setup thing for gamma ? – the one where you sort of squint
and try to get the grey square to blend with the Pantone-ish dots ? I thought
that was supposed to equal out your monitor ?>>
Try saving the images as Targa since this file format encodes the gamma used to
create the image. So when 3DS loads the image file it can "degamma" the image
precisely whereas the JPEG file format doesn't encode this information so the
standard 1.8, the setting in Input Gamma, will be used. If you have alot of
different gamma settings for different monitors Targa files are the way to go
when combined with 3DS.
DaviD "targa is right on target" GouID
>> I'm thinking this is a funky gamma effect…
Could be. It sounds as if the file-output gamma and file-input gamma are set
differently. Under normal circumstances you will keep them set to the same
value.
– Dave
Dave –
>>… sounds as if the file-output gamma and file-input gamma are set
differently…<<
This was part of the problem, I found out through some experimentation. But
there is still a big difference between the image quality on my two systems.
So I don't know if the problem lies within the "gamma" concept or just the
monitors themselves ? I'm gonna try Martin Foster's suggestion to just set the
gamma back to system default of 1.8. As I questioned him… why then does the
manual and Inside 3DS book suggest setting gamma by going through that little
"squint and match the grey squares" routine?
Appreciate your response
C.U.
Gary 🙂
>> "squint and match the grey squares"
To somewhat simplify the concept, gamma makes up for the non-linear response of
certain video devices. RGB computer monitors are fairly linear, ie. 50,50,50
is half the intensity of 100,100,100. OTOH, on NTSC video displays, this
isn't necessarily true. Gamma adjustments allow you to get an equal response
from both.
In theory, if you match the grey squares on each of your systems, any image
will look very close from system to system. Each system's FrameBuffer and
Display gammas will be different, but make sure that all machines have equal
settings for File In/out gamma (ie. 1.8 or whatever works best for you).
Hope this helps. There are others here who can give you a FAR more detailed
response. Hopefully, they will jump in.
– Dave