Stairstepping at DVinfo.net

Dave Largent · June 2nd, 2004, 02:51 AM

I processed some footage in Vegas and noticed more
stairstepping than usual. It was around/over
peoples' faces and clothing, and around their eyes.
Even on the front of a bride's white dress, and along the edges of her arms. The footage received color correction and sharpening.
Any ideas? Could it be because I put the sharpen
filter first in the chain? This was followed by color corrector,
brightness and contrast, levels, and color curves.
It wasn't the cameras seeing as two different
cameras were used. And it happened indoors
and out. I deinterlaced the footage and that
only made it worse.
What increases stairstepping and what
decreases it?
If it would help, I could email out a couple
jpegs to anyone showing the problem.

Edward Troxel · June 2nd, 2004, 08:09 AM

I noticed this problem once when rendering to MPEG2 and the "quality" slider was not at 31 (all the way up). Can you give more details about how you were rendering?

Dave Largent · June 2nd, 2004, 06:09 PM

Hi Edward.
I was at the "best" setting. I guess I can't say for sure
that I didn't switch something different from what
I usually do. Made DV AVIs.
Here's the interesting thing. It wasn't like the
usual stairstepping. Along the edge of her arm, for example,
there were the diagonal lines, but then they were
crossed by diagonal lines going crossing at
about 90 degrees. So the resultant effect was
like tic-tac-toe lines up and down her arm edge.

\ / \ / \ / \ / \ /
\ / \ / \ / \ / \ /
\ / \ / \ / \ / \ /
\ / \ / \ / \ / \ /
\ / \ / \ / \ / \ /

And there were patches like this below on some faces and on a
white dress and a black suit coat.

_ l _ l _ l _ l _ l _ l
_ l _ l _ l _ l _ l _ l
_ l _ l _ l _ l _ l _ l
_ l _ l _ l _ l _ l _ l

Aaron Koolen · June 2nd, 2004, 08:03 PM

Dave, can you post a screen shot for us to look at?

Cheers
Aaron

John Cline · June 4th, 2004, 09:13 PM

NTSC DV is based on 4:1:1 color sampling. While the luminance (black and white) information is sampled at the full 720x480 pixels, the chroma (color) information is sampled at a resolution of only 180x120. The sharpening filter may also be revealing the color filter stripes used on the imaging chip on a single chip camcorder (assuming it was shot on one.) Either way, I would suggest not applying the sharpening filter.

John

Dave Largent · June 8th, 2004, 09:26 PM

I don't have somewhere to post. Are there any persons
I could mail a few JPGs to? In one the bride's entire dress
is covered with these squares. It's from the AVI. Shot
with a 3CCD Sony. It's not on the original imported
footage. It appeared after I did some color correction.
Just wondering if anyone has seen anything like this.
The color correction was done at the "best" setting.

Dave Largent · June 8th, 2004, 10:03 PM

I found this link. This is what the patchy areas look
like. On people's faces, arms, clothes. But just patches:
not all over. Take a look at this Shure mic PDF. It's the
blue picture I'm referring to.

http://www.shure.com/pdf/userguides/...pg_mics_en.pdf

Dave Largent · June 10th, 2004, 01:58 AM

I know that, for making *stills*, the preview window
should be set at "best full". Does the preview window
setting (e.g. "good", "best", etc.) affect in any
way the quality of *video*. I am under the impression
it does not, but I just want to make sure.

Graham Bernard · June 10th, 2004, 03:18 AM

Where are you previewing the footage? On your pc? On your external monitor? Or as a final product OUT to . . . what DVD. . VHS tape . . or what?

Dave your comments on the function of the various options for Preview woke me up . . . I know I have to have the Preview window "relax" to its naturl size. I do this by carefully placing the cursor of ne of the corners of the Preview window and and carefully double clicking the mouse. This gets the Preview Window in what I call its"Relaxed" state - meaning it will expand OR contract to what it wants. Pulling it manually to a size, I can get lucky, and i'll convince myself that it is "okay". Now, with it in this "proper" size I've noticed a whole load of Previewing issues just melt away .. or should that be vanish! Or Dissolve or fade . . .

Yes the correct relaxed size for capturing stills is a must . ..

Try it . . It might work . .works for me ..

Grazie

Dave Largent · June 10th, 2004, 04:16 AM

I'm referring here to Vegas' preview window on the
PC when rendering video. The setting here, being
"Draft", "Best" or whatever, this does not affect the
results, does it?

Graham Bernard · June 10th, 2004, 05:31 AM

No, it doesn't effect the finished product/render . .I wanted to asscertain if you were making a comment on the Final product/render OR that which you are seeing in the Preview.

If your finished product/render looks good, then you are okay. It will be the way you could be "viewing" your work, hence my attempt to explain the options around Previewing.

So, please tell us if the final render .. do a small piece . . is good or not. View this on something "other" than Vegas or anything PC - yeah?

Lets start there.

Grazie

June 2nd, 2004, 02:51 AM	#1
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Stairstepping I processed some footage in Vegas and noticed more stairstepping than usual. It was around/over peoples' faces and clothing, and around their eyes. Even on the front of a bride's white dress, and along the edges of her arms. The footage received color correction and sharpening. Any ideas? Could it be because I put the sharpen filter first in the chain? This was followed by color corrector, brightness and contrast, levels, and color curves. It wasn't the cameras seeing as two different cameras were used. And it happened indoors and out. I deinterlaced the footage and that only made it worse. What increases stairstepping and what decreases it? If it would help, I could email out a couple jpegs to anyone showing the problem.

June 2nd, 2004, 08:03 PM	#4
Aaron Koolen Trustee Join Date: Apr 2002 Location: Auckland, New Zealand Posts: 1,727	Dave, can you post a screen shot for us to look at? Cheers Aaron __________________ My Website Meat Free Media

June 2nd, 2004, 08:09 AM	#2
Edward Troxel Sponsor: JET DV Join Date: Dec 2001 Location: Southern Illinois Posts: 7,953	I noticed this problem once when rendering to MPEG2 and the "quality" slider was not at 31 (all the way up). Can you give more details about how you were rendering?

June 2nd, 2004, 06:09 PM	#3
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	Hi Edward. I was at the "best" setting. I guess I can't say for sure that I didn't switch something different from what I usually do. Made DV AVIs. Here's the interesting thing. It wasn't like the usual stairstepping. Along the edge of her arm, for example, there were the diagonal lines, but then they were crossed by diagonal lines going crossing at about 90 degrees. So the resultant effect was like tic-tac-toe lines up and down her arm edge. \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / And there were patches like this below on some faces and on a white dress and a black suit coat. _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l _ l

June 4th, 2004, 09:13 PM	#5
John Cline Major Player Join Date: Oct 2002 Location: Albuquerque, New Mexico USA Posts: 333	NTSC DV is based on 4:1:1 color sampling. While the luminance (black and white) information is sampled at the full 720x480 pixels, the chroma (color) information is sampled at a resolution of only 180x120. The sharpening filter may also be revealing the color filter stripes used on the imaging chip on a single chip camcorder (assuming it was shot on one.) Either way, I would suggest not applying the sharpening filter. John

June 8th, 2004, 09:26 PM	#6
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	I don't have somewhere to post. Are there any persons I could mail a few JPGs to? In one the bride's entire dress is covered with these squares. It's from the AVI. Shot with a 3CCD Sony. It's not on the original imported footage. It appeared after I did some color correction. Just wondering if anyone has seen anything like this. The color correction was done at the "best" setting.

June 8th, 2004, 10:03 PM	#7
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	I found this link. This is what the patchy areas look like. On people's faces, arms, clothes. But just patches: not all over. Take a look at this Shure mic PDF. It's the blue picture I'm referring to. http://www.shure.com/pdf/userguides/...pg_mics_en.pdf

June 10th, 2004, 01:58 AM	#8
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	I know that, for making stills, the preview window should be set at "best full". Does the preview window setting (e.g. "good", "best", etc.) affect in any way the quality of video. I am under the impression it does not, but I just want to make sure.

June 10th, 2004, 03:18 AM	#9
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	Where are you previewing the footage? On your pc? On your external monitor? Or as a final product OUT to . . . what DVD. . VHS tape . . or what? Dave your comments on the function of the various options for Preview woke me up . . . I know I have to have the Preview window "relax" to its naturl size. I do this by carefully placing the cursor of ne of the corners of the Preview window and and carefully double clicking the mouse. This gets the Preview Window in what I call its"Relaxed" state - meaning it will expand OR contract to what it wants. Pulling it manually to a size, I can get lucky, and i'll convince myself that it is "okay". Now, with it in this "proper" size I've noticed a whole load of Previewing issues just melt away .. or should that be vanish! Or Dissolve or fade . . . Yes the correct relaxed size for capturing stills is a must . .. Try it . . It might work . .works for me .. Grazie

June 10th, 2004, 04:16 AM	#10
Dave Largent Trustee Join Date: Aug 2003 Posts: 1,483	I'm referring here to Vegas' preview window on the PC when rendering video. The setting here, being "Draft", "Best" or whatever, this does not affect the results, does it?

June 10th, 2004, 05:31 AM	#11
Graham Bernard Old Boot Join Date: Aug 2002 Location: London UK Posts: 3,633	No, it doesn't effect the finished product/render . .I wanted to asscertain if you were making a comment on the Final product/render OR that which you are seeing in the Preview. If your finished product/render looks good, then you are okay. It will be the way you could be "viewing" your work, hence my attempt to explain the options around Previewing. So, please tell us if the final render .. do a small piece . . is good or not. View this on something "other" than Vegas or anything PC - yeah? Lets start there. Grazie