Author Topic: best saving settings for image quality  (Read 611 times)

patrickrebstock

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best saving settings for image quality
« on: January 30, 2018, 11:28:12 AM »
does anyone have sugestions for saving setting for best IQ?
usually 1500fps or around there

tesla500

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Re: best saving settings for image quality
« Reply #1 on: January 31, 2018, 07:34:41 AM »
You can get a slight improvement over default settings by turning up the bitrate limit in the save settings window. Default is 40Mbps, you can set it up to 60. Also make sure the bits per pixel is set high enough to take advantage of that bitrate limit you set, 2.0 is a good setting. Won't matter much at 720p but at low resolutions it will help.

patrickrebstock

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Re: best saving settings for image quality
« Reply #2 on: January 31, 2018, 10:06:27 AM »
thanks so much,
do you notice a big drop in quality if you pick your own resulution, i have a fisheye that doesnt fully cover the corners and so i slightly drop the res, but it seems like it makes way more of a diffrence in quality than the small change would seem?

tesla500

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Re: best saving settings for image quality
« Reply #3 on: January 31, 2018, 09:47:13 PM »
Yes, as soon as you go below 1280 pixels width at maximum frame rate for your resolution, there is a drop in quality, as the sensor is configured for a mode that supports down to 640 pixels width. For best quality, run full horizontal resolution and crop your video in post, or alternately, set the resolution to any lower resolution you want, but reduce the frame rate to the value you would get if you were to set 1280 pixels horizontal.

For example, if you want 1024x720 at maximum quality, set the camera to 1280x720, observe the maximum frame rate (1502), set the camera to 1024x720 and set the frame rate to 1502 or lower.

This limitation will be fixed in a future software update, there is a way to configure the sensor optimally for any selected resolution but we need time to implement this change.


John DeLonghi

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Re: best saving settings for image quality
« Reply #4 on: February 03, 2018, 03:22:23 AM »
Ah this is interesting. What sort of quality loss is to be expected and is it a linear effect?

i.e. If I am using max. frame rate at every resolution, will the quality be noticeably worse if I change from 1280 x 480 to say 1279 x 480 or will it get steadily worse as I decrease horizontal resolution?

If it's currently in a mode supporting 640 width, does that mean I'll get the same quality if I shoot at 1280 x 480 and crop it to 640 x 480 as i would if I shot it at 640 x 480?

I'm going to do some testing to see how this all works, but will I be able to see the difference in quality if I shoot a static test card or do I need to have a fast moving subject? 

John DeLonghi

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Re: best saving settings for image quality
« Reply #5 on: February 04, 2018, 11:54:34 AM »
I've done some tests with static targets and I'm struggling to see a difference between 1280x1024, 1280x800 and 640x386 in terms of image quality when I crop everything to the same centre portion of the frame, so I'm assuming there's going to be a difference when shooting moving subjects?

tesla500

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Re: best saving settings for image quality
« Reply #6 on: February 04, 2018, 12:56:45 PM »
No, the difference is visible in static images. It is quite minor, only really well trained eyes will spot it. There are three main diferences:

  • Slightly reduced dynamic range (only by about 1dB)
  • Very slightly flickery column band line, 640 pixels from the right side of the image (will be corrected once we have dynamic wavetable generation working)
  • Horizontal shutter artifact line is more pronounced (corrected by Black cal)

As you reduce horizontal resolution, the this quality reduction occurs as you go below each of the following resolutions (applies to software versions up to an indluding v0.2.5)
1280
640
496
416

For example, going from 640 down to 624 reduces the quality slightly, and going from 496 down to 480 reduces it another step. It's really not very noticeable, except at very low resolutions in cases where you don't have sufficient light (which is quite common at those frame rates!)

John DeLonghi

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Re: best saving settings for image quality
« Reply #7 on: February 04, 2018, 01:53:47 PM »
So probably not worth worrying about? What does 1db of DR equate to roughly in stops?

BiduleOhm

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Re: best saving settings for image quality
« Reply #8 on: February 04, 2018, 02:18:19 PM »
Should be 1/3 stop.

patrickrebstock

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Re: best saving settings for image quality
« Reply #9 on: February 04, 2018, 02:29:33 PM »
Yes, as soon as you go below 1280 pixels width at maximum frame rate for your resolution, there is a drop in quality, as the sensor is configured for a mode that supports down to 640 pixels width. For best quality, run full horizontal resolution and crop your video in post, or alternately, set the resolution to any lower resolution you want, but reduce the frame rate to the value you would get if you were to set 1280 pixels horizontal.

For example, if you want 1024x720 at maximum quality, set the camera to 1280x720, observe the maximum frame rate (1502), set the camera to 1024x720 and set the frame rate to 1502 or lower.

This limitation will be fixed in a future software update, there is a way to configure the sensor optimally for any selected resolution but we need time to implement this change.

great to know! sounds good i will do that,
thanks
patrick

John DeLonghi

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Re: best saving settings for image quality
« Reply #10 on: February 05, 2018, 03:52:13 AM »
I've taken a look at some test shots and it's very difficult to see what you've described so I'm not going to let it bother me for now.

Hopefully I've now got enough light that the small resolution/high frame rate shots I'm planning will look pretty good...

Owens

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Re: best saving settings for image quality
« Reply #11 on: February 10, 2018, 09:32:33 AM »
That's my logic too. It's just not worth spending a lot of time to get marginal improvements like that.