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winny
Joined: 09 Oct 2013 Posts: 403 Location: Sweden
TV/Projector: BD808s, BG1209/2
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Link Posted: Sun Apr 29, 2018 3:46 pm Post subject: Poor mans CMS on BG808s? |
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Thought I would come around to posting a full theater build, but that have to come later.
Long story short, new theater and took parts from two broken 808s and made a working one. Black is freakishly awesome and the white is more than enough, but I’m struggling with that dark gray shades disappear into black so for example Stranger Things or Dark City becomes a bit hard to watch.
Using Linux PC with kodi -> DVI -> DVI to port 3 adapter. 16-235 color space.
The s-models seem to have far more settings than my normal 1209/2, so I’m a bit lost here. Corse convergence will be a future endeavor too, but is there a standard procedure with a test image, gain and offset for each color in the projector to “lift” the dark gray from black?
Thanks in advance!
EDIT: Terrible cell phone photo added.
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Melifluonze wrote: | Digital is easy. This is torture, but far more interesting... |
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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winny
Joined: 09 Oct 2013 Posts: 403 Location: Sweden
TV/Projector: BD808s, BG1209/2
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Link Posted: Sun Apr 29, 2018 4:47 pm Post subject: |
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Long term plan in calibration and 3D LUT in kodi, but is there a “cheat” in the meantime to get started?
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Melifluonze wrote: | Digital is easy. This is torture, but far more interesting... |
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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winny
Joined: 09 Oct 2013 Posts: 403 Location: Sweden
TV/Projector: BD808s, BG1209/2
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Link Posted: Sun Apr 29, 2018 5:12 pm Post subject: |
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Cheat in this regard is tweeting the brightness, contrast, gain and offset (and possibly G2) to get the dark gray visible. Think someone who wants cruise control for his car but only has a brick on the gas pedal. It’s not what you want, but it gets you more cruise control than with no brick.
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Melifluonze wrote: | Digital is easy. This is torture, but far more interesting... |
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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winny
Joined: 09 Oct 2013 Posts: 403 Location: Sweden
TV/Projector: BD808s, BG1209/2
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Link Posted: Sun Apr 29, 2018 5:22 pm Post subject: |
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Let me flip the question around. Suppose you do have perfect gamma, what test image do you display and calibrate to for setting brightness, contrast, gain and offset to their correct values?
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Melifluonze wrote: | Digital is easy. This is torture, but far more interesting... |
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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winny
Joined: 09 Oct 2013 Posts: 403 Location: Sweden
TV/Projector: BD808s, BG1209/2
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Link Posted: Sun Apr 29, 2018 7:27 pm Post subject: |
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Of course not, but being the authority on calibration, is there any one you would recommend for calibration by eye? Gradient steps?
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Melifluonze wrote: | Digital is easy. This is torture, but far more interesting... |
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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winny
Joined: 09 Oct 2013 Posts: 403 Location: Sweden
TV/Projector: BD808s, BG1209/2
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Link Posted: Mon Apr 30, 2018 10:48 pm Post subject: |
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Five hours spent on the theater today. Swapped out the neck boards for Decibels 120 MHz ones and reset everything. Paid more attention to the analog centering and V size (is there an Hsize for R&B somewhere?) and got much better picture.
Spent some time with the gain and offset for each channel and made a compromise to lower color temperature, followed by overall brightness and contrast. Dark gray got better, but still far from perfect. I need to get a sensor and read up on 3D LUTs.
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Melifluonze wrote: | Digital is easy. This is torture, but far more interesting... |
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
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gjaky
Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary
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Link Posted: Tue May 01, 2018 5:50 am Post subject: |
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Old video standards were made to suit to the characteristics to the CRT displays, so they need very little tayloring actually. This is not like with the modern digital displays, which have to meet the CRT-like characteristics which they don't have.
I'd say the less digital manipulations to the signal the merrier.
As for gamma, there are several specially-breed test pattern to imulate the gamma behavior. As they are, all depending to some extent on display focus and/or bandwidth, the two weak points of CRT, so the results can be very misleading...
Nontheless, here is one such pattern:
_________________ projectors in the past : NEC 6-9PG xtra, Electrohome Marquee 6-7500, NEC XG 1351 LC ( with super modified Electrohome VNB neckboard !!!)
current: VDC Marquee 9500LC
The MOD: VNB-DB, VIM-DB
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