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Discussion Starter · #1 ·
I'm trying to improve my color balance by "eyeing it" so bare with me. This is for a NEC 9PG+.



Part 1) Could someone provide me a detail definition of "Blooming". I am trying to sort out a few things with my black/color/white balance and need some basic definitions from which to work.



Part 2) With images that have some dark and some bright areas (say like an indoor shot with light coming through the window) I seem to be getting horizontal bleeding/streaking/banding from these bright areas. What's going on?



Part 3) When I put up a grey scale 0 - 100% with 5% increments (using Philips Monitor Test) I notice that my blue is flat at the bottom (not enough difference between 5% 10% 15% AND at the top 80% and above all look pretty much the same. Green and Red look better. What, if anything, should I do to improve blue?



I did search on this, but failed to find any good stuff. If you know where the answers exist, please post a link no sense in duplicating effort!



Thanks,

shoot
 

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In general, 'blooming' is defined as a degredation of the image, usually due to lack of focus because the tubes in a projector are driven too hard.


This can take numerous forms however.


1) Too much brightness and contrast, which overdrives the tubes


2) Because of (1) above, the power supply or HV section may drop in voltage, aggravating poor focus as well.


3) If the CRT emission is weak due to age, tubes can bloom even under normal brightness and contrast levels.


4) Ditto for problems in the focus, HV or LV power supplies.


Blooming can also be a label for an increase in height and width, usually accompanied by a lack of focus due to any of the reasons above. This was mainly an issue with older tube consumer TV's that had weak tubes in the HV section, causing blooming to occur due to HV or focus voltage instability.


Curt
 

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Discussion Starter · #3 ·
BUMP for 2 & 3


and Curt,


Thanks for all the info, does "blooming" degrade the image in a particular way that can be indentified just by looking at the screen?




shoot
 

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I tried to run my 6PG Xtra with high contrast and bumping up the white balance settings as well. The picture looked very very contrasty BUT I could only tell that it was blooming in certain scenes. I was watching a clip of the Barry Manilow concert one night and noticed his face was blotchy. I lowered all my contrast settings down to defaults and the blotchy look went away. I then paused the screen to his face shot (I can do that with my sony receiver) and increased the contrast again until I started seeing blotchyness.


It is easy to see blooming on a htpc or dvd because you can look for things by pausing the dvd. The contrast settings with the HD receiver however is another story because of the inability to always find a good program to test it with. I note the difference between the two sources because the brightness and contrast settings are different between the two to give the best picture on each.


To sum it up my method has always been to look at peoples faces but I am no expert.
 

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There are a few posts here that cover the subject. Obiously the best way is to use test equipment but this will get you close. Get a Video essentials or Avia DVD test disk. Set all color, brightness and contrast information in the scaler or HTPC to default settings. Go into white balance and set all w and b settings to 50% or mid scale. Set the brightness to 50% and contrast to 75%. Put up the 10 step grayscale test pattern. Shut off or block the red and blue. The W adjusts 50-100 and the B adjusts 0-50. the idea is to have ten equal steps. We are looking at the green now but this is the same for red and blue. Start by changing the B adjustment until the 0 IRE and 10 IRE steps just match then increase it by 5%. Go to the w adjustment and adjust up or down until you see even steps from 50-100. Go back and forth to double check because these are slightly interactive. Aahhh ten even steps but you've still not told me about blooming. Walk up to the screen and look in the area of 50 IRE and see if you can detect scan lines. Follow those scan lines from 50 to 100. Do they look the same all the way up or did you lose them at about 90 IRE. If you lost or are loosing them, your blooming so reduce the w adjustment. Now double check the b adjustment and your done with the green. Do the red and blue the same way. Now project all three and observe the scale. It should be close to neutral gray the intire scale from black to white. If your upper and or lower end of the scale exibits any color (red or blue) you can adjust them down to remove them or you can just call a ISF guy.


Chip S.
 
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