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Thread: brightness problem with LSX/ILD SOS

  1. #1
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    Sep 2013
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    Default brightness problem with LSX/ILD SOS

    EDIT: The way some of the members here have desperately tried to identify my location and nationality for whatever reason they believed was needed for by asking an admin to check my profile logs and researching me by the content of my posts has been very creepy and unnecessary. So bye.
    Last edited by dream; 04-28-2016 at 16:29.

  2. #2
    Join Date
    Feb 2007
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    Hey Dream!

    I posted almost this same question about 18 months ago when comparing frames generated in Medialas' MIII and then exporting them to LSX. Both tests were done using Medialas DACs. I was getting half the power out when using LSX running the frames at the same pps, although several of the laser modules tested didn't have a good linear power ramp-up and I didn't test the modulation voltage either to see what that difference was. (I have since most of my linearity issues through driver upgrades (frequently Flexmod P3s with a smattering of other drivers)).

    In the following week, I spent a good deal of time comparing MIII's default optimisation settings, what I had set them to in MIII and what the default optimization settings in LSX. It was an apples-to-oranges comparison to some degree as MIII had far fewer and sometimes different optimization settings as compared to LSX. Although I never went back and retested in MIII, I got significantly improved brightness and image reproduction quality after significant tweaks. I also learned to appreciate LSX's ability to create and save an unlimited number of optimization settings so that you could optimize each projector based on its own limitations. I was simultaneously adjusting the DZ Color board to get equivalent ramp-up and ramp-downs from each color. These modifications made significant differences as well. Since so many variables were changing simultaneously, it is difficult for me to say where the biggest difference was, but at some point, I no longer noticed relative power issues when switching between MIII and LSX. I should go back and retest with the same ILDA frames one of these days, but I've pretty much abandoned MIII after getting LSX.

    I'll be interested to hear if you are able to quantify your observations further.

    -David
    "Help, help, I'm being repressed!"

  3. #3
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    using a single point? either use a beam event or copy paste a point 200x before comparing brightness

  4. #4
    Join Date
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    Hey Dream,

    LSX's default optimization settings demonstrate that 'one size does not fit all'. For example, if you have a simple frame with one point (lets assume that single point was drawn as a blanking point repeated 6 times and a single 'on' point repeated 15 times, which I believe is the default way LSX quick-pic editor creates a point. Other editors vary how they draw points, circles, squares, etc.)

    This means that displaying that one point without any optimization (e.g. most optimization settings at zero), for every time you've activated your laser to draw that point, you are only letting it come one for 0.0001 seconds (at 18K) before turning it off again for about 0.00004 seconds and then repeating. So even if your laser was instantly responsive, you are only projecting 71% of the time, i.e. not close to what you would perceive as your lasers 'peak brightness'. In the "real world", your laser diodes and especially DPSS greens/blues are going to be slow to ramp up for that short period you have them on, then have them shut off for a period and turned back on. This will make your single point quite dim depending on the laser itself and its associated driver.

    Now all of this was with *no* optimization settings. Let's consider what happens if you project this same single point frame using the "default" LSX settings. For every time your frame (consisting of that single point) is displayed, you have 6 / 18000 to wait as "ToStartPoint" defaults to six. This drags down your "on time" for the point to 15/27 (56% of the time) before any considerations of laser 'ramp-up' time. Then you start considering the extra blanking points both on and off which the default settings net to slightly more off points being added to this frame than on points when using LSX's default settings. The bottom line is slightly dimmer still.

    So not to belabor the point (pardon the pun ), but optimization settings and proper frame design are critical to a nice beam, graphics, or abstract show. If I wanted to display a single hot beam, I would go into that frame and delete the first blanking point in that frame or reduce the repeats down to 1. In our example, the scanners aren't moving away from that one point so it doesn't makes much sense to allow for time for the scanners to get there except the first time the frame is displayed. I would duplicate the on-point as well - at least 6 times (6x15 repeats gets you to 90 on for every one off before optimization).

    My default settings at least on this PC are "ToStartPoint" set to 2, "ExtraPreBlankingOn points" set to 8, "Extra PostBlankingOFF" points set to 2, and Extra pre and post Blanking off/on points set to 1 each. This works well for the frames I'm creating combined with the laser I'm displaying them with, but 'your mileage may vary'.

    In the past, I've found myself trying to compensate for poorly drawn frames using optimization settings or compensating for inappropriate optimization settings by modifying frames. The real answer IMO is to create a few optimization settings for different types of content (beam, graphics, abstracts). If you have multiple projectors with different characteristics (e.g. DPSS in some and all-diode in others) or good scanners in some and junky 20K Chi scanners in others, you may want to create even more optimization settings to adapt to those projectors. Then when you've got that nailed down, make sure your frames are drawn with consideration of their intended display speed and some consideration given to your optimization settings when necessary. For example, if you want a nice large square, interpolate the lines and increase repeats on the corners enough to get sharp edges. I find that checking frames with a projector as you are making them very helpful in this regard.

    Apologies for the long post and any 'obvious points' I made.

    -David
    "Help, help, I'm being repressed!"

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