I'm finally caught up on this thread and thought that I would propose the idea to everyone that we hold off for a short time on the detailed technical discussions related to DI characterization and focus on some procedural issues that are needed to clarify the direction of the project. I think it's important that we try to summarize:
- The goals of the project (again).
- Review the work that has been achieved so far in the first two stages.
- Discuss how to improve our working relationship.
- Discuss the next step.
Please think of these points as a platform that we need for taking the next step. As the thread starter, what I would like people to do is take a few moments and read through this post and then comment on what has been posted. I'd like to get all of those who have been contributing recently to discuss these steps and when everyone is in agreement we can then move forward. If you don't agree with this platform or the need for it or don't want to go along with it then voice that opinion but be willing to defend your position while also providing an alternative platform.
Let's also agree to use the term static contrast to mean instantaneous contrast that does not involve dynamic gamma adjustments. This term applies to native projectors, fixed iris projectors and can also apply (in the correct situations) to dynamic iris projectors. Let's use the term dynamic contrast to refer to contrast that changes due to the combination of dynamic gamma and dynamic iris (typical DI behavior such as Sony's). Let's also use the term instantaneous contrast to mean mixed contrast that is available at one time (unlike sequential). I think with the possible exception of instantaneous contrast that this is Darin's terminology and it seems to describe things well so let's try and be consistent and use it from here on out.The Goals of the Project
I think everyone is in agreement that this project is not attempting to replace the ANSI and sequential contrast standards. Rather than replacing these standards what we are attempting to do is to supplement these standards with additional tools that help to quantify contrast and hopefully also allow people to better visualize and understand these metrics. I'm going to change the thread title to better capture this title.Review of the Work So far
There has been discussions that the work achieved so far is essentially meaningless because contrast vs 0-100% luminance is something that can be calculated from on/off and ANSI metrics. I beg to differ on this point for the following reasons:
- As stranger89 correctly stated, static contrast with a DI isn't something that falls out of sequential on/off. Interestingly enough, it has worked out that this value that can be closely approximated with the work done so far (using the contrast at 0% APL definition). I think this alone is of value and it's also something that I didn't anticipate when going through this process and it's an example where going through a process can yield benefits that aren't initially seen.
- This work has also provided some metrics for the relative change in white level vs luminance as well as relative change in black level vs luminance.
- It has also provided metrics on the static contrast benefits of reducing the iris aperture.
- Finally as Chris Wiggles pointed out early on there is always the chance that reality doesn't mesh with theory. Performing these measurements has given us a chance to compare theory with reality and it also allows us to identify and avoid problems in the future when we try to apply these techniques to other technologies.
- A very good point was raised that this stage of the project unfairly depicted DI projectors because it doesn't account for dynamic contrast. Even though this phase of the project was not intended to capture dynamic contrast, I think that this is fair criticism and it's something that I'm in the process of correcting by adding a section defining static contrast and also changing the names of the graphs so that it's clear what is and is not being measured. I want to caution though that just because one part of the project is unclear, mistaken or completely wrong (not that it was in this case) does not invalidate the whole project and people should try to keep their criticism focused on the part that is wrong versus the whole.
There was also the issue raised on why we should use these particular test patterns generated by Wm and not a traditional 4x4 test pattern that achieves APL by varying luminance % by using grey whites rather than different sized boxes with full whites. Here are my thoughts on this:
Discuss how to improve our working relationship.
- The current test patterns do a fine job of characterizing static contrast which was their original purpose.
- A lot of work has gone into these designs so far and some of the measurements, spreadhseets, data collection and methodology gets dumped if we move to new test patterns. If the current work done so far keeps us from achieving our goals them we must do what we need to (including abandoning work), but I think we should only do this if there is very compelling reasons to do so.
- One of the initial goals of this project was to involve the AVS community in getting them to submit data on their projectors. As such keeping them as easy to use and requiring as little HW as possible is a goal. These inital test patterns require nothing more than either a PC or a HD-DVD/BD player and a light meter.
- As pointed out it does not allow for characterization of dynamic gamma and therefore dynamic contrast with DI's, so if we decide to make DI characterization a goal then this is something we should (and have been) debating.
- If we decide the next step is to characterize DI performance then it's clear that these 0-100% test patterns will not test dynamic gamma so they can't be used.
- If we decide to come up with a different set of test patterns and methodology for testing dynamic contrast then it isn't clear that the initial set of test patterns need to be replaced, but rather supplemented.
I want to reinforce jsaliga's comments about the need to not let attacks get personal. One way to achieve this is by avoiding sarcasm completely as this doesn't come off well in posts and it reduces the readers resolve in trying to see a persons point of view.
Another thing I would caution against is shooting down a persons complete argument when part of it is either incomplete or flawed. I saw this a few times in analogies being bandied around and it's important for people to try and not dismiss an idea because of a flaw, but to see past the flaw and try to understand the argument.
The other thing I noticed is that we could better use e-mail in some of the discussions. Hopefully people are okay with pm'ing others with their e-mail address. E-mail is a good mechanism for discussions that don't need to involve everyone and it helps to keep the forum focused on key issues. It has the potential on the otherhand of keeping people out of the loop on important issues and discussions so I wouldn't use it if something has benefit the group only if it's mostly beneficial to one (or a few).The Next Step
There has been much discussion recently on methods for measuring DI performance even though this wasn't the initial goal of the project. If it ends up that we decide against measuring DI performance then a lot of this discussion was for naught. I for one think however that all of this discussion is uncovering a desire in everyone to measure DI performance and hopefully make this the goal in the next step of the project. So I would like to propose that we all agree to conclude the static contrast results of the first stage of the project (assuming that people see no issues with what has been done so far) and then to agree that the third step of the project is to tackle dynamic contrast.
Whatever people collectively decide to do for the next phase, I would urge people to try and stay focused on this phase and not let small issues sidetrack the discussion. Divide and conquer!