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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Half Res. Good vs. Full Res. Premium

Andrae Palmer

Andrae Palmer

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Can someone familiar with the debayer process explain why Half Res. Good looks so much sharper than Full Res. Premium?
 
I think you need to set OLPF compensation up high to make FRP really shine.

Graeme
 
As far as I remember yes. Rocket always does full demosaic BTW, so there's no concept of "half" on it.

Graeme
 
Graeme,

If one can attain Half. Res Premium realtime playback on a 12 core Mac Pro as in Davinci Resolve and Premiere Pro via CPUs alone. What are the advantages of doing a Full Res. Premium in those software or in genral having a RED Rocket Card? I was expecting Full Res. Premium to look sharper.
 
David, it's a setting under the look control settings called "sharpness" - set it to full if you're doing Half Premium.

Andrae - are you able to try it again with the sharpness on and see how it looks?

Graeme
 
I'm running into a workflow issue here Graeme. The pic in the original post was done in Davinci Resolve. If grading R3D's in Davinci Resolve how would I go about turning sharpness on? Also perhaps someone from Davinci can chime in on how 1/2 Res. Good in Davinci compares to 1/2 Resolution in REDcine-X. To my eyes 1/2 res in redcine-x looks more like 1/2 res premium in Resolve.
 
Andrae, I don't know resolve, so we'll need Davinci help there. All apps go through the SDK so maybe they just need help on settings and what and where to expose to the end users.

Graeme
 
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What I just don't understand is how comes there is such a big sharpness difference going from 1/16, 1/8, 1/4, 1/2.... but when you get to "Full" the image could look worse than at 1/2 res? Is there a laymans way to explain this.
 
Something doesn't seem right there Andae - can you email me that frame as an R3D snapshot please?

Graeme (@red.com)
 
Just sent it Graeme... thanks for looking into this... hope I'm doing something wrong on my end. :-)
 
I was told by RED (cant remember who, maybe Jim mentioned it)

half good WILL look sharper than half premium and that is perfectly normal.

Full and Premium will benefit from a "sharpen" if you want it to appear sharper.

After testing this numerous times, It is also my conclusion.

ofcourse which "down sample algorithm" you use also determines how sharp it will appear. - catmul being sharpest if I remember correctly.

you can set which algorithm you use in REDcineX.
 
Half good is sharper only through allowing more aliasing and noise. If you're not seeing aliasing or noise on half good - take it and it's inherent sharpness and enjoy.

Graeme
 
click on image for original 5760x1080 image:


click on image for larger 5760x1080 image:


Resolutions in order are: 1/4 Res. Good, 1/2 Res. Good and Full Res. Premium

I'm observing that Half Res. Good appears sharper and that the image appears brighter as resolution is increased (look at the green branches in the background and the face).
 
Graeme Nattress said:
Half good is sharper only through allowing more aliasing and noise. If you're not seeing aliasing or noise on half good - take it and it's inherent sharpness and enjoy.

Graeme
Click to expand...

ok that makes sense. I seem to remember Jim also stated that you "throw away" 70% of the resolution doing a half- debayer compared to a full. Is this the case? that must be very apparent on a big screen?

- what about the algorithms? - don't they also affect sharpness? - and if so at what "price"...?
 
Sidney L. Plaut said:
I seem to remember Jim also stated that you "throw away" 70% of the resolution doing a half- debayer compared to a full.
Click to expand...

It seems very noticeable to me in the luminance channel.
 
With half, you're throwing away a good chunk of the data, your measured resolution drops and you may see aliasing. With full, you'll always get the best resolution performance and scaling down from full will give you great noise performance too.

Graeme
 
So, again, why does the half good deBayer look so much better? At least it certainly does to my eyes.

Stephen
 
Stephen, that's not what I see here. I just ran Andrae's test shot through the three options and half-good looked worst, with Full (post reduced 50%) and half-high looking best. Half high looked a bit sharper, Full (50%) looked more natural to my eyes, a bit smoother.

Half-high is very much like doing a full demosaic then a 50% scale reduction in one step, so no wonder it looks similar to doing full.

Graeme
 
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