Author Topic: mlv_dump on steroids  (Read 11919 times)

Kharak

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Re: mlv_dump on steroids
« Reply #125 on: August 18, 2017, 01:42:36 PM »
Okey, luckily not an isuue I come across on the 5d3. Perhaps the 3x3 bayer helps get rid of it, as it has 8 other pixels to draw on in the case of a cold pixel?
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Danne

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Re: mlv_dump on steroids
« Reply #126 on: August 18, 2017, 01:47:58 PM »
On the 5D mark III there is seldom any use of cold pixel fix. If you use darkframes they take care of them anyway. As well as the hot pixels if any.

a1ex

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Re: mlv_dump on steroids
« Reply #127 on: August 18, 2017, 07:01:52 PM »
Cold pixels used to be a problem before this PR; see also this analysis. I think most of them were actually pixels marked as bad by Canon firmware (they mark them as 0, so they are very easy to detect by our "cold pixel" heuristic). Some of them were not 0; they were only below the black level, although I don't remember the specific conditions one would get such artifact.

Need to double-check whether there are still cold pixels on other models (60D and 600D were troublesome, possibly also 550D and 500D, not sure about others). One has to compare a MLV (or a DNG developed with all processing turned off) from any recent build, vs any 2016 build.

Some of the "cold pixels" used to appear near very strong highlights (there were some bug reports about this for 5D3, with green artifacts: this one or this one or this one). These are dynamic and won't be fixed with default processing settings (they require scanning every frame for bad pixels, which is very slow: option --fixcp2).

Kharak

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Re: mlv_dump on steroids
« Reply #128 on: August 18, 2017, 10:06:41 PM »
Those examples all seem to derive from bad post-processing software of the mlv/raw. No?

The only thing i see as a consistent issue with the 5D3 is with red channel in high contast to other colours, be it black or blue or green etc. there is an example on the forum from maybe 2 years ago or more where a guy showed an example from some red flowers in the foreground with a blue sky behind (red and blue channel interacting) and he had grey pixels howering over the red colours (in the blue sky) some few pixels away. I cant find it, but remember it as later I myself have seen this a lot. It comes mostly from "really" red sources.

I spend so much time on fishing vessels shooting for clients and for personal use. Here the issue comes up a lot, the bright red/orange Oil Clothes that is the typical colour of any fishermans outfit, in contrast to basically any other darker colour will exerborate this behaviour. Gray pixels hovering over the edge of the Red/orange.

I also recall back in the day shooting on boats, pre dslr, shooting with Panasonic and sony, crappy bit depths, they could not reproduce the true colours of the Outfits, they would turn in to a red blob/mess or orange mess, very difficult to work with.

Dont have my computer, so no examples to show from.

The colour is very intense, its made to be as visible as possible in case of MOB or Blackouts.

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DeafEyeJedi

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Re: mlv_dump on steroids
« Reply #129 on: August 19, 2017, 01:56:54 AM »
On the 5D mark III there is seldom any use of cold pixel fix. If you use darkframes they take care of them anyway. As well as the hot pixels if any.

+1  8)
5D3.113 • 5D3.123 • EOSM.203 • 7D.203 • 70D.112 • 100D.101

bouncyball

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Re: mlv_dump on steroids
« Reply #130 on: August 19, 2017, 12:08:25 PM »
I also recall back in the day shooting on boats, pre dslr, shooting with Panasonic and sony, crappy bit depths, they could not reproduce the true colours of the Outfits, they would turn in to a red blob/mess or orange mess, very difficult to work with.
Yeah I remember that mess of deep saturated colors with my SONY and JVC analog and early DV cameras. :) That JVC had 25p progressive scan mode and it hooked me, funny the DR was about 5-6 stops I guess :P

If you'll find the time, post gray pixel artifact examples please.

bb

Kharak

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Re: mlv_dump on steroids
« Reply #131 on: August 19, 2017, 12:24:50 PM »
I will find you some examples.
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mothaibaphoto

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Re: mlv_dump on steroids
« Reply #132 on: August 20, 2017, 04:56:52 AM »
I guess if dark/flat frame is used there is no need to fix badpixels or stripes after that.
bb
If only that was true, but not :(
I've processed file with --no-stripes --no-fixcp twice - one time with black frame, one - without and than pixel peep the difference.
Hot pixels(bright ones) are really gone with black frame, cold/bad - no sure, i dont see any on both shots,
BUT, vertical stripes are the same on both!!! keep investigating, though...

Kharak

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Re: mlv_dump on steroids
« Reply #133 on: September 03, 2017, 06:46:10 PM »
Here is an example with the Red Channel having difficulties with the high contrast edges.

Like in this example, look at the Boots of the guy closest to camera, the Red Oil Pants are outlining the boots around the edges. The edges get  This is pretty much consistent from 5D3.

It makes the Boot look "cut out" of the picture or placed there. The Gray pixels appear all over the edges.

When Sharpening the image which I always do, this effect becomes very obvious.

DNG:
https://mega.nz/#!1MoRjCKZ!yU7zbQFKMEpEi4VxCqYIqOdkfVLzDvfnKgOf3JKt-aQ
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bouncyball

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Re: mlv_dump on steroids
« Reply #134 on: Today at 04:57:44 PM »
@Kharak

Sorry about very late answer :)

It makes the Boot look "cut out" of the picture or placed there. The Gray pixels appear all over the edges.
When Sharpening the image which I always do, this effect becomes very obvious.
Yeah you are right, now I understand what did you mean.

bb