Inverted (Negative) Images and Uniformity

**mechman** · **10-06-07, 08:53 AM**

I'm going to try this again as the previous thread got way off track!

If you've been here awhile I'm sure you've seen either Bill or myself post a screen shot of an inverted image. Such as this:

But I don't think we've ever explained the thought process behind it. In the DIY screen community it's been accepted practice that to take a flash photograph of your screen will help to determine whether or not the screen will hot spot. If you don't know what hot spotting is please read this post. Bill has since shown that you can see this much easier if you create an inverted or negative image. The negative darkens the whites and lightens the blacks. Up until recently the only thing we've ever done this with is DIY screens. Well... I expanded a bit!

I inverted a screen shot of the HoloVega:

And here's one of Silver Matte:

Now take a good look at those shots and then compare them to these:

And for comparison this is what hot spots look like with a flash shot:

So what I've noticed is that the inverted images of the hot spot samples clearly show a lack of uniformity. And the professionally manufactured screens all clearly show uniformity. From the dictionary:

Quote:

The state or quality of being uniform; overall sameness, homogeneity, or regularity: uniformity of style.

I think that should be a goal when attempting to create a screen. And it is yet another failure identified in past mixes which attempt to claim "as good as a professional screen". Now don't get me wrong! I'm not saying it cannot be done! I'm just saying that everything out there so far that I've sampled is no where near that plateau and that claims being made in the past and present are unfounded.

So what does a DIY'er do? Well that's easy! Look for uniformity as well as the other attributes discussed here at the Shack! Every flat paint image that I have inverted has come up as uniform as the pro screens. And that's good! And then there's the elusive screen being worked on in the depths of the Shack labs! The other than base pigment - Pigment Free Gray. Can we call it PFG Bill? Or maybe TSPFG (The Shack's Pigment Free Gray)? I like TSPFG!

Initial testing has shown a very uniform image! This extremely simple mix shows much potential in that it has characteristics of a gray screen and what appears to be a little bit of gain. While some folks are thinking "Tell us!" Bill has decided not to do so as he doesn't want this to head down the path of previous endeavours - 'all talk no data'. Personally I'm hoping we can get it done by the end of the month.

But this strays off topic. Let's limit the TSPFG talk to the 'Teaser' thread.

In summary, I believe that uniformity is another facet of screen building. And an excellent yet easy way to determine uniformity has been theorized.

mech

**mechman** · **10-06-07, 08:54 AM**

This reply would be from Bill...

The PFG (for lack of any better short reference right now) as we know is made from Aluminum and just a white paint, in this case Kilz2. The panel above does have some roller imperfection marks and I am working on getting it to roll better and more uniformly.

As far as inverting images, I jokingly called this 'Predator vision' in one of the PM's with mech discussing it. When we see an image with colors our eyes and brain can easily get distracted.

Where this came into play and ended up identifying the problem within seconds was a member that was having wave issues with his laminate screen. The inverted image showed exactly what was happening.

Once the image was inverted it was very clear that the support braces that the laminate was glued to was pulling it and causing the 'waves', which in turn were wreaking havoc with hot spotting in the high and low areas. The laminated was separated from the support braces and the waves went away as did the dark areas due to the non-uniform screen surface.

What we found was this method also made hot spotting very visible (or as some call the beginning stage of hot spotting- 'warm spotting').

It really does work and shows us what's going on much better than what we can see with a normal image.

**mechman** · **10-06-07, 09:25 AM**

There was also talk of doctoring photos. I just shrugged it off as this process is so extremely easy for anyone to do (with photo editing software), that the thought of 'doctoring' never entered my head. I mean how could one doctor what many could easily notice. I mean all one needs to do is download the same photo I did and invert or create a negative image of it.

Well I'm going to spin a bit off topic here but I'm going to continue down this road for a bit and I may spin it off as a new thread.

A little history lesson...

I think what brought it about was AVS. There were two folks there that were consistent at posting 'doctored' photos. They even went so far as to post a picture of a rear projection TV on their business webpage and try to pawn it off as one of their front projection screens! They're gone now - well one of them still runs around pm'ing as 'the ghost'. And the sad part of it all was there was never any proof to back up statements made. Silver Fire and S-I-L-V-E-R have been the main acts over there for awhile and I'm on the verge of dotting all my i's and t's debunking them. And the creators are not happy!

Well... tough! This isn't about "I say it's so so it is!" This about what's right and what's wrong. It's wrong to run around at the mouth utilizing a second hand thesaurus every fourth word in order to confuse the masses. It's also wrong to tempt the masses into spending their hard earned money on a solution that's so ridiculously difficult, that they're bound to fail! It's also wrong to consistently bump old threads under the 'guise' of history. If that's their history I want no part of it!

The former main (and one currently still there) players there thrived themselves on outlandish claims with the rest of us asking "Where's the beef?" I went back last night and counted how many times the loudest mouthpiece said he was going to do a shootout. I counted 5 times since I had joined AVS and there was never one done. I can say now, after mixing up some Silver Fire, that I can see why! And yet it was always the best and 'heads and tails' above my FG laminate. Well my initial tests have shown this false, as well as the ridiculous claims of 'gains around 2.5'. I do have to wait for my measurement gear to come back from X-Rite and I have to either attempt to flatten my current panels or repaint them on something that won't curve before I start that thread though.

So where do I go from here? My plan was to publish everything here and then do a mini version at AVS. But here's the kicker, if I do this I can guarantee you that there will be folks coming out of the wood work saying that "you mixed it wrong", "your photos are doctored", etc. the seeds have already been planted over there. Lately my thoughts have been why bother.

There are no hidden agendas here. No one's trying to make a buck off you. The only thing we're guilty of at this point is trying to steer folks down the proper path to a great screen - be it DIY or a professionally made one. There will be no sales pm's from Bill and I nor will they be tolerated. Speak your mind, be nice and respectful, stay on topic, and enjoy yourself. If you want to argue, be condescending, resentful, or downright difficult, find someplace else!

mech

**mechman** · **10-06-07, 10:44 AM**

Back on topic now!

So again, you take the image that someone has posted and using your photo software you either invert or create a negative image of it. It's very simple and it seems to be an excellent way to judge uniformity of the screen surface as well as notice any hot spotting. Believe it or not it was one of the folks talked about in the post above who showed me this way of determining hot spots in a pm well over a year ago.

mech

**cynical2** · **10-07-07, 01:56 AM**

Well...I had to try this with my screen. All I can say is that ignorance is (was) bliss.

I posted some pics a week or so ago of my screen and Todd sent me a PM asking about what looked like some vertical lines on my screen. I was convinced that it was related to the unevenness of my wall...the studs are definitely not in a nice straight line, and I wasn't about to float the whole wall in drywall mud to make it perfect. Well, the inverted image tells the full story. It doesn't appear to be the wall after all. Instead, the lines appear to be due to my rolled paint job. So, I don't know what I didn't do correctly...I thought I followed the directions to a "T", but nonetheless something is amiss (there's also a bit of non-uniformity from the center of the screen moving to the edges, but that doesn't seem to bad). In person, the vertical lines aren't noticeable on the screen (even in a lit room with no movie playing), and definitely don't show up while viewing. But, now I know they exist, and will probably dwell on it (cause that's how I am).

Anyway, below are both a "normal" pic and an "inverted" pic of the screen.

As Bill and mech stated, the inverted image definitely makes it much, much easier to see issues with screen uniformity (which is a good thing, even if it does lead to occasional disappointment). In my mind, it's great to have a more "sensitive" way to check the screen application than just looking at the uniformity across a grey/white surface.

BTW, mech...to prove I actually read your posts in this thread, I wanted to let you know that in Post #1 there isn't a definition following, "And the professionally manufactured screens all clearly show uniformity. From the dictionary:".

I assume an excerpt was supposed to go there?

**wbassett** · **10-07-07, 03:39 AM**

Jim how does it look with an image? No screenies or anything like that, how does it look in person to you? Can you see any anomalies?

Never mind! I missed it in your post. As long as you can't see them when the projector is on it shouldn't be a big deal, but I know what you mean about dwelling on something you know isn't perfect. I do the same thing.

**cynical2** · **10-07-07, 06:56 AM**

Quote:

wbassett wrote:

Jim how does it look with an image? No screenies or anything like that, how does it look in person to you? Can you see any anomalies?

I don't see any issues with the image...it looks pretty good. So, seeing the vertical lines doesn't drive me to change anything with my screen...but, now I'm aware that I have some work to do on my painting technique.

The main thing that I wanted to do is reinforce you and mech's comments about how much more sensitive the inverted image is (how it's much easier to see issues with uniformity by inverting the colors). I never would've seen it without the negative image.

**mechman** · **10-07-07, 08:24 AM**

Quote:

cynical2 wrote:

BTW, mech...to prove I actually read your posts in this thread, I wanted to let you know that in Post #1 there isn't a definition following, "And the professionally manufactured screens all clearly show uniformity. From the dictionary:".

I assume an excerpt was supposed to go there?

That'll teach me to cut and paste without checking!

mech

**mechman** · **10-07-07, 08:33 AM**

Quote:

cynical2 wrote:

I don't see any issues with the image...it looks pretty good. So, seeing the vertical lines doesn't drive me to change anything with my screen...but, now I'm aware that I have some work to do on my painting technique.

The main thing that I wanted to do is reinforce you and mech's comments about how much more sensitive the inverted image is (how it's much easier to see issues with uniformity by inverting the colors). I never would've seen it without the negative image.

Correct me if I'm wrong but the vertical lines are your wall studs right? Other than that I see very little wrong with your screen. It would be nice to get a pre and post pearl/poly shot. Do you have a pre pearl/poly shot Jim? My hunch is that flat paint alone will give you much better uniformity. ***This is not to say that pearl poly has no merit! If anything, Jim's shot shows that it retains some uniformity.***

Keep in mind this is theory on our part and I'm trying to build up a bit of a 'database', if you will, of shots for comparisons.

**cynical2** · **10-07-07, 08:44 AM**

Quote:

mechman wrote:

Correct me if I'm wrong but the vertical lines are your wall studs right? Other than that I see very little wrong with your screen. It would be nice to get a pre and post pearl/poly shot. Do you have a pre pearl/poly shot Jim? My hunch is that flat paint alone will give you much better uniformity. ***This is not to say that pearl poly has no merit! If anything, Jim's shot shows that it retains some uniformity.***

Keep in mind this is theory on our part and I'm trying to build up a bit of a 'database', if you will, of shots for comparisons.

Mech, I thought it was the studs until I studied the inverted image. For perspective, the tiles on the ceiling are 24" wide. Some of what you see (like in the center of the image) could be studs on 16" centers. But, some parts of the screen (like the left 1/3 or so) clearly have vertical lines on a dimension that's less than 16"...more like the width of a roller. My conclusion from that is that I need to practice my rolling technique.

As far as the "global" uniformity of the screen, I think it looks pretty good. So, I don't think the poly introduced any significant issues as far as screen uniformity is concerned.

One other thought...on my second-to-last coat of paint, I know I put a lousy coat on...it was late, I was tired, and I dry-rolled some of the screen. The next day, I put on a very nice final coat of paint, followed by the poly topcoat. Is it possible that the texture from the second-to-last coat of paint (that I know I screwed up) is what's showing through? That would actually make sense to me, because I thought that my last coat of paint and my topcoat were good applications.

**mechman** · **10-07-07, 09:42 AM**

That's a good question. I'm not sure what could be causing the lines. Because they're fairly straight up and down it'd more than likely be associated with rollering technique. But I'm no painter! You should see the panel of SS I rolled! Turned out awful! Lots of texture and then I sprayed the Silver concoction on it.

mech

**cynical2** · **10-07-07, 10:05 AM**

Quote:

mechman wrote:

That's a good question. I'm not sure what could be causing the lines. Because they're fairly straight up and down it'd more than likely be associated with rollering technique. But I'm no painter! You should see the panel of SS I rolled! Turned out awful! Lots of texture and then I sprayed the Silver concoction on it.

mech

Yep, I agree it's the rolling technique...I'm just wondering if poor rolling technique in the 2nd to last coat of paint could be what's showing through, or if it has to be my rolling technique in the topcoat.

**mechman** · **10-07-07, 01:47 PM**

Quote:

cynical2 wrote:

Yep, I agree it's the rolling technique...I'm just wondering if poor rolling technique in the 2nd to last coat of paint could be what's showing through, or if it has to be my rolling technique in the topcoat.

That's tough to say without seeing it firsthand. I say if it works don't fix it!

Can you see the mica up close in the particular areas? It'd be interesting to note if it has something to do with either less mica near the edges of the roller or if the mica is not aligning or laying flat properly near the edges of the roller. I have no idea how we could determine any of this right now with your screen though. I do have a secret weapon for this when I do my testing though -

. I've used it before and it looks like it may come in handy again!

mech

PS Click the winking smilie!

**cynical2** · **10-07-07, 02:08 PM**

Quote:

mechman wrote:

That's tough to say without seeing it firsthand. I say if it works don't fix it!

Can you see the mica up close in the particular areas? It'd be interesting to note if it has something to do with either less mica near the edges of the roller or if the mica is not aligning or laying flat properly near the edges of the roller. I have no idea how we could determine any of this right now with your screen though. I do have a secret weapon for this when I do my testing though -

. I've used it before and it looks like it may come in handy again!

mech

PS Click the winking smilie!

Hmmm...I'll check it out when I go down later today to do some more work. Right now, I'm watching my beloved Redskins.

I'll let you know.

BTW, how are you going to use that microscope on my screen?

**mechman** · **02-29-08, 02:26 PM**

A shameless bump back to the first page! And a bit of trivia!

Did you know that the majority of DIY screens are ones that have been developed, nurtured and proliferated by Shack folks? Well they have!

And we're getting closer to a couple more to add to the list!

Laminates
Off the Shelf Neutral Grays
Black Widow

Thank you Bill!

mech

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