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REPOST: Calibrating DILA Tracking/Phase for Pixel Perfection  

post #1 of 5
Thread Starter 
SUBJECT: Calibrate your DILA with HTPC to get Pixel Perfection!
FORUM: DLP, LCD, D-ILA Projectors
DATE: 10-05-2000
STATUS: Originally posted on old UBBS system.

___________________


If you're a HTPC user of DILA projectors, you're interested in this! This improves picture quality of a DILA from a HTPC!

I used DisplayMate to calibrate Alan's DILA projector. However, I have created a new custom DILA test pattern from scratch so you do not need DisplayMate! You can get your DILA projector perfectly and sparkingly "PIXELLY SHARP<tm>".

Remember, setting a HTPC to do 1360x1024 does NOT necessarily get the best picture quality. You're not there yet! You need to adjust the "PIXEL CLOCK" on your DILA projector to get optimal results! That means TRACKING and PHASE adjustments in the "PIXEL CLOCK" adjustment setting of your DILA projector?

What is TRACKING and PHASE, you say? Good question. Allow me to explain - all digital projectors, including DILA, use digital electronics for displaying images. However, VGA input is analog! In a digital projector, the VGA is converted to digital. This means the PIXEL CLOCK in the projector must be exactly the same as the dot clock of the computer's video card (i.e. GeForce). Otherwise, you will get jittering and flickering if you walk up closely to your screen. TRACKING allows you to increase/decrease the PIXEL CLOCK of the projector relative to the computer's dot clock. PHASE allows you to adjust the synchronization of the clocks - on the exact pixel and not half-a-pixel out of alignment.

Fortunately, it is easy to adjust TRACKING and PHASE - using my new DILA test pattern! First, you should already have a 1360-pixel-wide computer resolution already configured on your HTPC computer, and you switch to the SXGA3 input. Doublecheck that you're already on the SXGA3 input of your DILA. To do this, use your DILA remote control, hit the MENU button, then select VIDEO SOURCE, then select SXGA3. You must be using SXGA3 to use the full 1360-pixel-wide resolution, unless the other inputs are modified to use 1360 pixels wide.

Use SXGA3 Input. If you cannot do 1360-pixel-wide or you do not want to bother with custom computer resolutions, simply select 1280x1024 instead and use SXGA1 or SXGA2. Remember, 1280x1024 looks better than 1360x1024 on SXGA1 and SXGA2. Use 1360x1024 ONLY on SXGA3.

Do not use a HTPC with the HDTV input on the DILA. This is not recommended due to vertical scaling artifacts (720p->768p or 540p->768p). Switch to one of the SXGA inputs depending on the above.

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MY DILA TEST PATTERN

http://www.marky.com/misc/testpatter...ern_ByMark.gif

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STEP BY STEP:
HOW TO ACTIVATE TEST PATTERN

  1. Right click this link and select "Save As":
    Digital_TestPattern_ByMark.bmp
  2. If your PC is your HTPC, save to your WINDOWS subdirectory (C:\\WINDOWS).
    If your PC is not, save to a floppy disk. Then bring the floppy disk to your HTPC and then copy the file to your WINDOWS subdirectory.
  3. On your HTPC, bring up Control Panel:
    Start Menu -> Settings -> Control Panel
  4. Doubleclick Display icon
  5. Click Background Tab
  6. Select "Digital_TestPattern_ByMark" as the background wallpaper.
  7. Important! Select "Tile" (instead of "Center" or "Stretch")
  8. Click OK
  9. You will now see multiple copies of the test pattern tiled horizontally and vertically in the background.
  10. Close or minimize all windows, so you only see your Windows Desktop. You do not need to move or remove your icons, as long as at least half of your screen is empty.

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STEP BY STEP:
HOW TO ADJUST YOUR DILA USING TEST PATTERN


I made a few simulations of the artifacts that you will see on your DILA projector.

While making the below adjustments, feel free to run up to the scren and watch from 2-3 feet away from the screen while you adjust your DILA. It makes the adjustment easier! Also, while adjusting the patterns, watch all 3 test pattern bands, and also the sharpness of the tiny text in my test pattern. All of these items will assist in adjustment.

Important! The following simulated images are meant to be viewed on a desktop computer monitor. This is because the below simulations will be messed up if you're trying to view the below on an uncalibrated DILA projector. If so, please view this post on another computer that is using an ordinary desktop computer monitor, so you can see the true look of these images.

Important! Remember, you need to TILE the test pattern on your background, not stretch the test pattern to have one test pattern fill the whole screen. Do not right click on any images above or below and "Set as Wallpaper" - don't do that - because it does not tile the test pattern.
  1. This is probably the pattern you will see on your DILA:
    http://www.marky.com/misc/testpatter...UST-NEEDED.gif

    These vertical bands can be any thickness, from a few pixels thick to almost full screen width. If you see vertical bands like the above, you need to adjust your TRACKING adjustment.

    To adjust TRACKING, use your DILA remote and hit MENU button, then select PIXEL CLOCK. Now adjust TRACKING upwards and downwards. Don't adjust PHASE yet. As you adjust TRACKING, you will notice that the number of bands will go up and down. Try to decrease the number of bands to zero.
  2. If you succeed in the above, you will see the following:
    http://www.marky.com/misc/testpatter...ern_ByMark.gif

    Important! If you're unable to get the above, don't worry. Try to adjust until the whole picture is noisy - with no bands. You want a picture that's either *uniformly* perfect or *uniformly* noisy. What you want to do is eliminate ALL bands - even bands that are half a screen wide! Go to next step.
  3. HOWEVER, if you failed to get the picture clear on the first try and your image looks like either of the following:
    http://www.marky.com/misc/testpatter...UST-NEEDED.gif OR http://www.marky.com/misc/testpatter...T-NEEDED-2.gif
    If you see either of the above, you simply need to adjust your PHASE adjustment.

    Notice that the first image looks very muddy, including the text. You might not even be able to tell the difference between the 1st and 2nd of the 3 test pattern bars. Other times, you will see a noisy image, much like the second image.

    Adjust your PHASE adjustment upwards and downwards. Notice how you start to make the image sharper? Try to find the PHASE adjustment that produces the sharpest image without noise.
  4. Finally, if you succeed, you will see the following image:
    http://www.marky.com/misc/testpatter...ern_ByMark.gif

You now have DILA PIXEL PERFECTION!
post #2 of 5
Thread Starter 
Featured in December 2001 issue of
Stereophile Guide to Home Theater
in Pat Megenity's PCinema column! (Page 32)


This pattern also works with most digital projectors and most plasma displays too.

Alternate QUICKER method of installing test pattern, using Internet Explorer, if you are already on the computer that you want to install the test pattern on:
  1. Right-click on the DILA test pattern image (first image in my post above) and then select "Set As Wallpaper"
  2. On your HTPC, bring up Control Panel:
    Start Menu -> Settings -> Control Panel
  3. Doubleclick Display icon
  4. Click Background Tab
  5. At the bottom, select "Tile" (instead of "Center" or "Stretch")
  6. Click OK
You will now see multiple copies of the test pattern tiled horizontally and vertically in the background. This is a quick way of checking Tracking and Phase of nearly any digital display!
post #3 of 5
Hey Mark,

Any comments about phase drift? I use your testpattern as wallpaper on the desktop of my HTPC > G15. I notice that it is difficult to achieve perfect phase adjustment, and that the optimal phase adjustment varies significantly over time.
post #4 of 5
Thread Starter 
Phase drift can occur. To minimize this, warm up your projector AND your HTPC for 20 minutes before calibrating Tracking/Phase. Temperature tends to be the primary culprit for phase drift (both in the HTPC and in the projector).

Seasonal environment changes, interference affecting behaviour of video card or projector, electrical wear factors, etc. may apply over longer time periods, but generally the primary enemy is temperature changes.

[Edit: Remedies to Phase Drift can be found here.]
post #5 of 5
Thread Starter 
Note: This test pattern CAN be used on any digital display technology including LCD, DLP, LCOS, DILA, Plasma, or any other pixel-addressable display to verify pixel perfection (ala 1:1 mapping).

The instructions are usually identical. Some displays may have different terminology in place of "tracking" and "phase", such as "clock".
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