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Canon xc10 c-log resolution


nikos

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Reading EBU xc10 tests found that according to Alan Roberts measurements c-log has less resolution than look1 (standard look)

Trying to test it in my xc10 I found that there is a loss in resolution going from standard profiles to c-log but also I found a weird "noise" in look1. 

c-log grab from davinci resolve 4k timeline (crop).

pnx3qHMYp

 

 

look1 (standard) grab from davinci resolve 4k timeline (crop).

 

pl33OkDhp

resolution is better in look1 but is this "noise" acceptable?

4k 305mbp 500iso f5,6 25p(Pal) exposure a bit to the right. 

 

4kclog_1.1.1.bmp

Did a test with a bit more light.

c-log 500iso f4

pmq2Mygtp

 

look1 500iso f4

pm7zOu2Pp

Resolution is better in look1 but there is still "noise"...

Any thoughts? 

 

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It's just sharpening. C-log turns it off (and it looks better to me). The sharpening is applied during debayering so it seems like it affects resolution but it really shouldn't. Here's the c-log jpeg file sharpened with a simple unsharp mask, quality isn't as good as I sharpened an already compressed file but anyways. People really underestimate how much sharpening is applied to cameras (hint: a shit ton!) 

 

 

sharpened.jpg

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5 minutes ago, hmcindie said:

It's just sharpening. C-log turns it off (and it looks better to me). The sharpening is applied during debayering so it seems like it affects resolution but it really shouldn't. Here's the c-log jpeg file sharpened with a simple unsharp mask, quality isn't as good as I sharpened an already compressed file but anyways. People really underestimate how much sharpening is applied to cameras (hint: a shit ton!) 

 

 

sharpened.jpg

"Sharpening" that happens during debeyering isn't real sharpening, it is just how the algorithm applies the surrounding information that is used to reconstitute the pixel color. You can have luma priority ("sharpened") or chroma priority ("unsharpened").

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Yes hmcindie, you are absolutely correct.

The standard setting in look1 is sharpness +3.

I  changed it to 0 and the noise gone.

Here is a new grab in Look1 with sharpness in 0.

 

4knoiseoff_zpszxhwu1nr.png

So now the real question.

Why there is less resolution in c-log?

Is this only in xc10? (haven't seen any comment  about c100)

 

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Guest Ebrahim Saadawi

Try applying a sharpening filter in post-production to the original XF-AVC C-LOG files until they give the same ''resolution'' as Standard and you'll see how it works. 

Even with 0 sharpening at Standard profile there's still some compared to Canon LOG, which completely, removes any kind of any digital sharpening. Magic Lantern has a ''Zero Digital Sharpening'' menu item that has the same effect (lower sharpness than turning it to zero on the Standard profiles, so Canon do give a tiny bit even at zero, but not in C-Log). 

Resolution: How much information there is in the image
Sharpness: How emphasized the edges of that information are

While they are technically un-related, perceptually, higher sharpness gives the illusion of higher resolution, and in some cases it does an amazing job at that.

Just find the look you prefer and shoot with that.

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4 minutes ago, Ebrahim Saadawi said:

Try applying a sharpening filter in post-production to the original XF-AVC C-LOG files until they give the same ''resolution'' as Standard and you'll see how it works. 

Even with 0 sharpening at Standard profile there's still some compared to Canon LOG, which completely, removes any kind of any digital sharpening. Magic Lantern has a ''Zero Digital Sharpening'' menu item that has the same effect (lower sharpness than turning it to zero on the Standard profiles, so Canon do give a tiny bit even at zero, but not in C-Log). 

Resolution: How much information there is in the image
Sharpness: How emphasized the edges of that information are

While they are technically un-related, perceptually, higher sharpness gives the illusion of higher resolution, and in some cases it does an amazing job at that.

Just find the look you prefer and shoot with that.

Got it!

thank you very much, I will try it.

(although In ebu document says that there is less resolution in c-log)

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  • 8 months later...

 

On 28/02/2016 at 4:22 PM, nikos said:

Ok, I did some more testing....

Xc10 c-log has less resolution than the standard (look1) profile.

Is this normal in c100 c300 c-log?

ar you ok with that?

 

 

On 21/11/2016 at 11:34 AM, hyalinejim said:

@Lintelfilm has a CXXX series camera I think. He might be able to take a look.

Resolution in C-Log on all Canon cameras (C100, XC10, whatever) is EXACTLY the same as it is in the other profiles.

Sharpening is turned off in C-Log by default, so that can be one explanation for the perceived difference in detail.

However - and much more crucially here and on the other XC10 thread I think - higher contrast is read by the human eye as "more detail". This is just a fact. It's an optical illusion if you like.

That's what this is about - perceived detail - not resolution. The resolution is the same.

If you want a "punchy" image with well defined lines/detail, you may be better capturing it in camera than trying to get it back in post from footage shot with a log profile on an 8-bit camera. 

Log footage is low contrast by nature, and therefore perceived resolution will always be lower unless you put all the contrast back in (and probably in the process sacrifice some dynamic range). You can't have it both ways  - particularly not with an 8-bit codec.

I always used to marvel at how much "punchier" graded HD images from my BMPCC were compared to my 4K GH4. This was because I would be able to put loads of contrast back into the 13-stop prores image without dropping down to an 8-stop result. Whereas I'd always try and coax as much dynamic range as I could from the GH4 and always end up with mushy detail. Of course the GH4 had far more resolution than the BMPCC, but stretching the lower dynamic range resulted in images that were less contrasty. Add the BMPCC's higher bit rate and colour depth to its superior dynamic range and you have what is arguably a more detailed image - certainly a richer one.

While I really do love 4K on my XC10, I think there is a real danger on forums like this of pixel peeping in such an analytical way that you forget to look at the image as a whole. Nobody watches films at 300% inches from their screen. 4K is largely a marketing thing pushed by TV manufacturers (yes I'm talking about you Panasonic, Sony, Samsung). It's an easily understandable number that can be stuck on a camera or a TV to sell them as "better". For high-end cinema 4K is certainly becoming an almost-necessity, but we independent filmmakers would be wise to remember most of our favourite films from the past several years were shot on the 14-stop dynamic range, RAW/prores, high colour-depth shooting Arri Alexa in HD/2K. None of us left the cinema saying "I'm going to watch a David Fincher film next time because he uses RED cameras so I can see more details in the actor's shirt."

Sorry, I'm having a ranty day. x

 

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7 hours ago, Lintelfilm said:

 

 

Resolution in C-Log on all Canon cameras (C100, XC10, whatever) is EXACTLY the same as it is in the other profiles.

Sharpening is turned off in C-Log by default, so that can be one explanation for the perceived difference in detail.

However - and much more crucially here and on the other XC10 thread I think - higher contrast is read by the human eye as "more detail". This is just a fact. It's an optical illusion if you like.

That's what this is about - perceived detail - not resolution. The resolution is the same.

If you want a "punchy" image with well defined lines/detail, you may be better capturing it in camera than trying to get it back in post from footage shot with a log profile on an 8-bit camera. 

Log footage is low contrast by nature, and therefore perceived resolution will always be lower unless you put all the contrast back in (and probably in the process sacrifice some dynamic range). You can't have it both ways  - particularly not with an 8-bit codec.

I always used to marvel at how much "punchier" graded HD images from my BMPCC were compared to my 4K GH4. This was because I would be able to put loads of contrast back into the 13-stop prores image without dropping down to an 8-stop result. Whereas I'd always try and coax as much dynamic range as I could from the GH4 and always end up with mushy detail. Of course the GH4 had far more resolution than the BMPCC, but stretching the lower dynamic range resulted in images that were less contrasty. Add the BMPCC's higher bit rate and colour depth to its superior dynamic range and you have what is arguably a more detailed image - certainly a richer one.

While I really do love 4K on my XC10, I think there is a real danger on forums like this of pixel peeping in such an analytical way that you forget to look at the image as a whole. Nobody watches films at 300% inches from their screen. 4K is largely a marketing thing pushed by TV manufacturers (yes I'm talking about you Panasonic, Sony, Samsung). It's an easily understandable number that can be stuck on a camera or a TV to sell them as "better". For high-end cinema 4K is certainly becoming an almost-necessity, but we independent filmmakers would be wise to remember most of our favourite films from the past several years were shot on the 14-stop dynamic range, RAW/prores, high colour-depth shooting Arri Alexa in HD/2K. None of us left the cinema saying "I'm going to watch a David Fincher film next time because he uses RED cameras so I can see more details in the actor's shirt."

Sorry, I'm having a ranty day. x

 

Not if you are debeyering off a sensor like that on the XC10, because the image is reconstituted from multiple pixels. The effective resolution will be determined during debeyering depending on whether it is luma weighted or chroma weighted. After debeyering and the limitations of the lens, the effective resolution from a XC10 is really 2K.

In order to get relatively unaffected optimal resolution you need an oversampled sensor, preferably one that images at 6K (which should give a good approximation of 4K after debeyering). This is why cameras like the NX1 and A6500 have much better resolution.

The only real 4K cameras out there are those that do a full sensor read off a 6K image.

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