Re: compile XV?

[William Mattison]

Good afternoon,
> I know its not been updated in years, but this is still a must have

for me. I just upgraded > to fedora 24 (64bit)
> and Im trying to compile it from source because the rpms Ive found

are either broke or > dont work right.
[... snip ...]
> any ideas?

I like "xv" also, especially for colorizing weather satellite imagery. 
When I wanted to add it to my Fedora system in July 2013 (F-18 at that 
time), Ed Greshko pointed me to this rpm:
> > xv is in the rpmfusion repositories.
> >
> > xv-3.10a.jumbopatch.20070520-18.fc18.1.x86_64 : Visualisateur sous

X pour
> >                                          : quasiment tous les 

types d'images
> > Repo        : rpmfusion-nonfree-updates
> > Matched from:
> > Filename    : /usr/bin/xv

I don't recall having any problems with it.  I'm at F-23 now, and it 
still works.  My only suggestion is to try the rpm that Ed pointed me 
to.  The full Fedora users group discussion on this starts here:
https://lists.fedoraproject.org/pipermail/users/2013-July/437341.html

Two more general notes on "xv"...
1. I personally would like to see this tool supported again.
2. A new color standard "Rec. 2020" has been adopted.  Eventually, 
monitors will become available that can display the full range of colors 
that this new standard encodes.  That range of colors is substantially 
larger than the sRGB that most of today's monitors can display.  xv, the 
gimp, and everything else that involves color will need updating to 
properly handle and display colors encoded according the new standard. 
I suspect the same is true of Fedora itself, and quite possibly the 
Linux kernel.  I hope the appropriate people are on top of this!

Bill.

compile XV?

[Tim]

Allegedly, on or about 25 June 2016, William sent:
> A new color standard "Rec. 2020" has been adopted.  Eventually,
>
> monitors will become available that can display the full range of
> colors that this new standard encodes.  That range of colors is
> substantially larger than the sRGB that most of today's monitors can
> display.  xv, the gimp, and everything else that involves color will
> need updating to properly handle and display colors encoded according
> the new standard. I suspect the same is true of Fedora itself, and
> quite possibly the Linux kernel.  I hope the appropriate people are on
> top of this!

Really, the main thing that causes lack of good colour rendition in
monitors is the particular colour phosphors used (whatever the type of
display).  If you don't use pure red, green, and blue, but un-pure/pale
imitations, as many monitors to, you can never get accurate colours.
For example, any attempt to show red gets displayed as orange/red or
pale pinky/red, and since red is a primary colour (of additive mixing),
there's no other way to get red than to have the single red phosphor be
accurate, to begin with.  Likewise with blue and green, they're the
other primary colours of light.  All other colours are made by mixing.

It always gets me how some display manufacture likes to say that their
display shows a wider gamut for some bogus reason, such as having a
brighter display.  All a brighter display lets you have is the potential
for more different steps between fully black and fully white, you can't
get a more red, or more blue, or more yellow, or more anything, than the
actual colours the phosphors radiate at.

Way back when (years ago) I used some screen to printer matching
technology, so that printouts turned out as you expected them, it really
annoyed me that it worked by further messing up the printout, rather
than modifying the display to emulate the printout, so you could really
see what you were going to get.

But, until you get manufacturers producing monitors on spec, supplying
those specs, you're not going to get true displays.  Nearly every
monitor has different gamma (the trueness of the greyscale), and nearly
everybody adjusts the contrast and brightness too much.  Monitors need a
light sensor, and something to compute ambient light offset against your
settings, to get true readings.  It's no good trying to colour-grade
photos or printing, when your monitor is displaying black as a
washed-out grey, the monitor gamma is different from your printed media,
and the monitor has a different white tint than your paper and the
ambient light that you're going to look at it under.

compile XV?

[George N. White III]

On Sat, Jun 25, 2016 at 7:24 PM, Tim  wrote:

[...]

But, until you get manufacturers producing monitors on spec, supplying
> those specs, you're not going to get true displays.  Nearly every
> monitor has different gamma (the trueness of the greyscale), and nearly
> everybody adjusts the contrast and brightness too much.  Monitors need a
> light sensor, and something to compute ambient light offset against your
> settings, to get true readings.  It's no good trying to colour-grade
> photos or printing, when your monitor is displaying black as a
> washed-out grey, the monitor gamma is different from your printed media,
> and the monitor has a different white tint than your paper and the
> ambient light that you're going to look at it under.

Back when SGI was producing workstations with Trinitron monitors we had
complaints from PC users (probably running Windows for Workgroups) that
colors in images we produced were bad.  In fact, every PC was different.
We invested in inexpensive Pantone Huey colorimeters and could show
that our PC's matched the colors on the SGI workstations.  The Huey had
the ability to compensate for changes in ambient light.

There don't appear to be Windows 7 drivers for the Huey, but there are linux
drivers and associated utilities that seemed to work on a older laptop
running
Scientific Linux 7.   In practice it wasn't able to get the laptop display
to
resemble the Apple displays we use these days, but I'd certainly try it if
I relied on linux and had a decent display to work with.

--
users mailing list
[e-mail]
To unsubscribe or change subscription options:
https://lists.fedoraproject.org/admin/lists/[e-mail]
Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct
Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Have a question? Ask away: http://ask.fedoraproject.org

compile XV?

[Tim]

Allegedly, on or about 25 June 2016, George N. White III sent:
> Back when SGI was producing workstations with Trinitron monitors we
> had complaints from PC users (probably running Windows for Workgroups)
> that colors in images we produced were bad.  In fact, every PC was
> different.

I'm not surprised.  PCs had wierd pictures because their monitors were
different from everything else that had gone before it, likewise with
Macs.  They have a different gamma than TV monitors, so people editing
video on a computer had a different-looking picture than the end-user.
And you had the same issue with printed media (ink or photo).

I'd forever be seeing video with the black level pushed up to about 30%,
as they'd maladjusted a normal signal to suit their monitor, instead of
calibrating their monitor, and adjusting their video using a scope.  To
be fair, we'd see the same thing with non-computer edited material, for
the same reasons.  Edited on uncalibrated monitors, and the editor had
no real idea about what they should be doing.

Real video (TV/DVD) on the LCD computer monitors looks awful, for same
reasons (gamma, pale phosphor, mal-adjustment, a different video 0 to
100% range than PCs used, different resolutions with awful scaling, and
a different frame rate).  Trying to do the wrong with with the wrong
monitor just looks bad, and using it as your reference messes it up
further for everything else.