DIY video test patterns

[Mr.D]

After a bit of fiddling about I'm confident I can create and encode mpeg2 test patterns with accurate levels. I can probably also generate 1080i/1080p ones ( or any other res for that matter).

I often find the test patterns on DVE and others a little coarse with regards to the levels they represent. I've made my own pluge that delineates 0 , 16 , 18 for setting black point correctly (clips on 16 but 18 still visible).

I'll probably bang one out that delineates 235 to 255 for white point ( although I set for visibility right up to 254 for white ref anyway but a pattern with clearly marked levels close to 254 could be useful , : the belle-nuit one pretty much does this anyway).

So does anyone think this will be useful or do you have everything you need on DVE and the others?

I'm looking into interlacing so should be able to create some common cadence situations : 2:2 pulldown , 3:2 pulldown , 50i , 60i . Mixed cadence on same image etc.

Strangely enough the trickiest part of all this is making sure the encoding behaves itself but tmpgenc seems to be persuadable.

HD-DVD type test patterns may also be a possibility if I can get the time to investigate the issues involved.

I was also thinking it would be nice to host these on the forum if possible ?? Figure the AV forums might as well have its own test patterns. I could also post only the single image file as a tiff and leave the encoding up to you lot individually if that's easier. Obviously won't work for the animated ones though.

Any thoughts?

[Neil Davidson]

Get Grey does what I need for test patterns (but often you never know you need something until you try it) but a 50Hz DVD for evaluation of the displays processing is very much something I would be interested in seeing.

Luciano Mehringhi (sp?) posted an interesting DVD working towards this a while ago. Might be worth looking at that for an idea on what he had acheived. Plus a look at some of the items in the Peter Finkel DVD.

Looking forward to seeing what you can come up with.

Neil

[Mr.D]

Just done some tests and yes I can render out examples of 2:2 , 3:2 pulldown , 50i and 60i.

[eviljohn2]

I'm very interested in whatever you can come up with Keith.

[merifon]

Originally Posted by ceenhad

Luciano Mehringhi (sp?) posted an interesting DVD working towards this a while ago. Might be worth looking at that for an idea on what he had acheived. Plus a look at some of the items in the Peter Finkel DVD.

Looking forward to seeing what you can come up with.

Neil

The correct spelling is: Luciano Merighi. Don't worry, even italian people sometimes make a mistake...

Anyway, if anyone wants to take a look to home brew TestDVD, I repost the link:
http://digilander.libero.it/merifon

[Mr.D]

Thanks for that

Having had a look at the available options. I'm wondering if there is any real necessity for anything other than some different cadence examples. However if anyone wants something not covered in any of the other options then I'm happy to knock up a test mpeg for you.

[Alaric]

Hi There,

On a slightly different side, i've been looking for a decent focus patern for my CRT. The best i've found so far is the double box with 9 tripple rings on the Philips test patern generator (v3). However this only has a 5 boxes, one in the centre and one in each corner, which is fine for optical focus (centre & Edges) however the electromagnetic focus is Centre, Top, Bottom, Left & Right....which only the centre one is useful for !!!

I guess i'm going to have to mimic the Nokia one in Photoshop or something....However then its resolution dependant and is not actualy part of the DVD chain (not that the nokia one is either) !

A set of DVD based looped focus patern may be useful.

Oh and maybe the + style intermitant green & magenta crosses for convergance

I wouldn't mind looking at those brightness/contrast paterns as to be honest DVE/Avia are great but the navigation is always a pain.

cya,
Lee

[Mr.D]

All seems easy enough. The convergence pattern : when you say alternating how fast would you want? Every couple of frames so its strobing or just alternating every 5 secs or so?

The focus one seems easy enough .Its reminded me of one final test I need to make on my image pipeline to see if the encoder is handling non square pixel 720x576 and 720x480 correctly.

[Alaric]

Hi There,

*Laugh*

I meant alternating in colour. Convergance is used to match (normaly) red and blue (hence magenta) to green. The typical patern is a set of horizontal and vertical lines that create a grid of boxes. This is a good patern for initial convergance, but should the red or blue be a different width (sharper focus) to the green then as soon as they aline you loose any sense of acuracy.

By having a patern of +++ that alternate in colour between green and magenta, aligning them edge to edge you never actualy overlap and hence can effectivly see how the colours actualy relate to each other without one effectivly canceling the other out.

Thanks,
Lee

[Neil Davidson]

Just a heads up that there is similar discussion going on in the VP forum - perhaps a joint project brewing?

Neil

[clarky78]

I dont even understand what you said, but it sounds interesting!

[Mr.D]

Originally Posted by Alaric

By having a patern of +++ that alternate in colour between green and magenta, aligning them edge to edge you never actualy overlap and hence can effectivly see how the colours actualy relate to each other without one effectivly canceling the other out.

Thanks,
Lee

Yes I know the pattern you mean how quickley would you want it to alternate is what I'm asking.

[Mr.D]

Originally Posted by ceenhad

Just a heads up that there is similar discussion going on in the VP forum - perhaps a joint project brewing?

Neil

Can't see it neil what one is it?

[Miniholic]

Originally Posted by Mr.D

Yes I know the pattern you mean how quickley would you want it to alternate is what I'm asking.

Keith, IIRC the colour of the individual crosses remains static, something like this.

+++++++++
+++++++++
+++++++++

Then, when perfectly converged the crosses will line up horizontally, and vertically.

[Mr.D]

Ah gotcha , even easier .