Coring Question RE: Setting

[Lou Bruno]

I recently visited the XL-H1 forum where the writer stated that CORING should be set in the negative or -4. This resulted in smaller grain.

I always thought that the PLUS setting in coring reduces the grain.

Any input would be appreciated.

Thank you.

[Tony Tremble]

Lou

-ve values reduce coring therefore there is an increase in fine noise (some people call it grain!!) but fine "real" detail is not removed.
+ve value increase coring reducing noise and fine detail.

I prefer -5. I came to that conclusion by hooking up the XH-A1 to a monitor pointing it at a grassy field and played with the slider to get a balance between noise and detail. High coring settings will make a grassy field look like a tarpaulin!

TT

[Tom Roper]

Interesting observation Tony. I'd like to follow up on that this weekend and see if it will yield an MTF50 resolution improvement at the minus 5 coring setting.

[Tony Tremble]

Originally Posted by Tom Roper

Interesting observation Tony. I'd like to follow up on that this weekend and see if it will yield an MTF50 resolution improvement at the minus 5 coring setting.

That would be interesting.

I haven't done extensive tests to see what effect it has on the quality of encoding. As with all things there is a trade off less coring means more high frequency detail and noise thus stressing the MPEG encoder more.

So your test might show something interesting.

Cheers

TT

[Lou Bruno]

Me too!!!! :-)

Originally Posted by Tony Tremble

That would be interesting.

I haven't done extensive tests to see what effect it has on the quality of encoding. As with all things there is a trade off less coring means more high frequency detail and noise thus stressing the MPEG encoder more.

So your test might show something interesting.

Cheers

TT

[Tom Roper]

I did the MTF50 resolution tests using Tony's -5 setting for Coring.

Result:

Horizontal = 889.8 line widths per picture height
Vertical = 696.4 line widths per picture height

I have previously recorded results of about 858 horizontal and 684 vertical.

While an improvement, and the horizontal number is eye popping, I would still discount the gain as negligible to non-existent. I'm not sure whether it's real, or I'm just getting more precise each time I repeat the tests and improve with practice. What matters more is Tony's subjective impression of the grassy field versus tarpaulin look, since that is viewed overall across the whole of the frame, not just a measurement point at the center.

I only obtained resolution at the center. In previous testing, f3.7 yielded the best result and that is still true. The resolution falls off significantly toward the borders as you would expect. Again, these measurements are just reference points. They are valid since I repeat the test exactly the same each time I perform them, but there are so many variables. People see a number and latch onto it. But different focal lengths, camera to subject distance, differences from center to corner, and different ways to interpret the same data all affect the numbers. By interpreting the above data using edge profile data instead of MTF50, the horizontal stays about the same but the vertical shoots up to 832 lines. The conservative thing to do is to accept the MTF50 normalized to a standard 2 pixel sharpening radius, which is what I reported at the top. As stated previously, for 24F the vertical resolution drops 10-12% from the above numbers.

My subjective opinion of the -5 coring setting is not favorable, in as much that where it works well for Tony on grassy fields, I think I am observing line twitter or crawling ants on architectural geometric shapes like buildings and neighborhoods.

The rule is, you always change one thing at a time, and I will confess to breaking that rule. All previous resolution testing on the A1 I did with HDF (horizontal detail frequency) set to "high" in the belief I would improve resolution. But I think now that "high" may be applying a filter on high frequency horizontal patterns which would have the effect of reducing horizontal resolution. For the above tests, I used HDF = "mid" and and coring -5.

So draw your own conclusions, (and feel free to advise me on just what the HDF actually does), but my subjective observation is a preference for HDF= "high" and Coring = 0, due to a more clean, artifact free presentation.

For what it's worth, I also have the HV10, and while the MTF50 numbers are about the same as the A1 at the center, I think the HV10 actually resolves more fine detail at the borders, and with slightly less CA. But it's no free lunch because it's horrid in low light. I have the color and contrast set low on the HV10 to reduce the neon luminescence on colors and blown highlights. But the HV10's imagery in the sunny outdoors more than rivals the A1 overall. I think I prefer it. It's kind of a shame that one camera can't be the best at both tasks.

I think the HV10's low light performance is overrated and the A1's underrated, but that's just my opinion. I shot some really excellent indoor/low light footage last weekend at a Rollerball Tourney at Barney's Pub with the A1. The key is to not try to elevate the blacks with gain. I never used more than +6db, and usually tried to work in the 0 to +3db range, master pedastal = mid, setup level 0, cine 1. It was plenty. The dark corners of the pub stayed dark as they should, minus any grain, looked exactly right, highlight detail was retained.

[Tony Tremble]

Originally Posted by Tom Roper

I did the MTF50 resolution tests using Tony's -5 setting for Coring.

Result:

Horizontal = 889.8 line widths per picture height
Vertical = 696.4 line widths per picture height

I have previously recorded results of about 858 horizontal and 684 vertical.

While an improvement, and the horizontal number is eye popping, I would still discount the gain as negligible to non-existent. I'm not sure whether it's real, or I'm just getting more precise each time I repeat the tests and improve with practice. What matters more is Tony's subjective impression of the grassy field versus tarpaulin look, since that is viewed overall across the whole of the frame, not just a measurement point at the center.

I only obtained resolution at the center. In previous testing, f3.7 yielded the best result and that is still true. The resolution falls off significantly toward the borders as you would expect. Again, these measurements are just reference points. They are valid since I repeat the test exactly the same each time I perform them, but there are so many variables. People see a number and latch onto it. But different focal lengths, camera to subject distance, differences from center to corner, and different ways to interpret the same data all affect the numbers. By interpreting the above data using edge profile data instead of MTF50, the horizontal stays about the same but the vertical shoots up to 832 lines. The conservative thing to do is to accept the MTF50 normalized to a standard 2 pixel sharpening radius, which is what I reported at the top. As stated previously, for 24F the vertical resolution drops 10-12% from the above numbers.

My subjective opinion of the -5 coring setting is not favorable, in as much that where it works well for Tony on grassy fields, I think I am observing line twitter or crawling ants on architectural geometric shapes like buildings and neighborhoods.

The rule is, you always change one thing at a time, and I will confess to breaking that rule. All previous resolution testing on the A1 I did with HDF (horizontal detail frequency) set to "high" in the belief I would improve resolution. But I think now that "high" may be applying a filter on high frequency horizontal patterns which would have the effect of reducing horizontal resolution. For the above tests, I used HDF = "mid" and and coring -5.

So draw your own conclusions, (and feel free to advise me on just what the HDF actually does), but my subjective observation is a preference for HDF= "high" and Coring = 0, due to a more clean, artifact free presentation.

For what it's worth, I also have the HV10, and while the MTF50 numbers are about the same as the A1 at the center, I think the HV10 actually resolves more fine detail at the borders, and with slightly less CA. But it's no free lunch because it's horrid in low light. I have the color and contrast set low on the HV10 to reduce the neon luminescence on colors and blown highlights. But the HV10's imagery in the sunny outdoors more than rivals the A1 overall. I think I prefer it. It's kind of a shame that one camera can't be the best at both tasks.

I think the HV10's low light performance is overrated and the A1's underrated, but that's just my opinion. I shot some really excellent indoor/low light footage last weekend at a Rollerball Tourney at Barney's Pub with the A1. The key is to not try to elevate the blacks with gain. I never used more than +6db, and usually tried to work in the 0 to +3db range, master pedastal = mid, setup level 0, cine 1. It was plenty. The dark corners of the pub stayed dark as they should, minus any grain, looked exactly right, highlight detail was retained.

Excellent post Tom. Thanks for taking a look.

I hadn't noticed any twitter but will take a closer look. Thanks for pointing this out.

TT

[Tom Roper]

Tony,

I am very much interested in your observations on the line twitter or crawling ants at -5 coring and HDF mid, and also whether you are seeing it on either or both 60i and or 24f.

I realize across the pond you may have upgraded the A1 for 50i/25f, so just report on what you see or don't.

It's possible I'm imagining this but if so why have adjustments so subtle they can't be noticed?

Regards

[Tony Tremble]

Originally Posted by Tom Roper

Tony,

I am very much interested in your observations on the line twitter or crawling ants at -5 coring and HDF mid, and also whether you are seeing it on either or both 60i and or 24f.

I realize across the pond you may have upgraded the A1 for 50i/25f, so just report on what you see or don't.

It's possible I'm imagining this but if so why have adjustments so subtle they can't be noticed?

Regards

I looked in more detail for signs of twitter and indeed there was in very fine lines just off the vertical. I'll alter coring and HDF values and see what I come up with.

TT

P.S. I haven't noticed any change with the HDF setting. It is indeed very subtle or useless!!! :)