ISO, ISO...

[Rob Ruffo]

I totally agree, I know well the benefit of resolution downsampling for acutance. As a photographer, I practice downsampling all the time.

But I have the impression that the noise level and type play a part in what is better to do. Perhaps is noise is an atomized tempest, a little downsampling may just cut the trouble away, and than it may even be worthwhile to up-res again. Or a good noise reduction may solve it.

Anyway this is still not the case witha a super clean image, where there is no noise.
Some say that 4k with bayer is not real 4k. I partially agree, since technically it's not.
But, if the image is clean, it's so easy to make bayer 4k look as sharp as downsampled 4k or monocrome-type 4k cameras, that I'm pretty comfortable at calling it 4k.
Of corse I think the same for 3k.

That said, I think a clean 3k can be up-ressed to 4k succesfully - well at least in photoshop; I don't know what it will be like with Red Scarlet and Red One.
If there is no noise to be increased, it will not increase.

I think a given acuity, which is ALWAYS related to it's optimized image size - that's why when I up-res, the RELATED acuity decrease (the new image has less acuity), is less and and less important as the original resolution was high.
I can distinguish a person from another in a group of ten or one hundred (low resolution)
I will never be able to distinguish a person looking at a square full with a million people (high resolution).
I certainly agree with most of your theory as well as with most established theory,
but not to your conclusion:
I think for a prject that was shot 90% at 4k and 10% at 3k, I'd prefer to stay with 4k and up-ress only that little bit.
It's not like up-ressing a 10% from, say, 1 megapixel to 1,3 megapixel: even if the jump is proportionally the same, at this low spatial frequency it is much easier to notice a difference in resolution or acuity - we may just consider acuity as ratio between resolution and image size.

Also, a more trivial reason could be uniformity in the worklow and the process.
Usually, Super 16mm features were, and still are, blown up to 35 for theatrical release.
The importance of acuity, especially if not bounded to resolution, has a lot of limits, otherwise all movies shot on 35mm would be reduced to Super 16mm to gain some acuity. There is always a point where, running behind acuity, we start to loose real bits of information. That's why to me resolution is more important than acuity. You can alsways make the resolution more visible with some tricks which enphasize acuity, but you cannot gain real bits of information from acuity alone.
Yes, in a certain way I let resolution seduce me, spoil me, because if I have enough abundance of data for my eyes to be mega happy, I can do whatever I want.
To me, 3k is minimum for theatrical release, and I mean 3k videoprojection.
I can see the pixel matrix of 2k if I watch from front sits. When I saw Blade Runner remastered in high definition this happened.
But the world will skip 3k projection and will go for 4k, and this can't be bad at all.

For similar reason, I may not be able to see beyond 3k even from the front sits.
If that's the case, uprezzed 3k to 4k will be absolutely the same as native 4k for my eyes. Of course, if there was no noise is the 3k, otherwise - you're right - noise will increase.

I think it's a lot about quantity, or to be more precise, we are at a point where, quantity not only can make contingent problems dissolve in the mass, but quality now really sort of depends on quantity, is triggered by quantity.


Every time a make an enlargement of a picture, if the original file was at very high resolution and was not degraded, I can afford not to care about resolution, no matter what size I will print it at. If resolution is high, it is high.

if it was alredy fine for 2 meters high, should I enlarge a print to skyscraper size, resolution would be fine too.
If resolution was poor for an medium size print, I will be poor for everything exept for the smallersizes. Hey, acuity is highest there: but this doesn't mean they are the richest. Quite the opposite. They are poorer than the original file, because they even cut away part of the already low resolution.

If acutance is less than 100%, it doesn't matter at all, since what is perceived as rich image, richer than what we can see, it doesn't have to be optimized.
I mean: it would be worse if a size reduction cut away sothing, and anything above 100% acuity is just lost data.

Thankfully, we are past the point where big screen projection was a problem and acuity would play a dominant role, being impossibly to go over 100% as there was no high resolution to reduce.

I'm not sure hwo you are using 'acuity' here? Please define... A few people have eagle-eyes. I can sometimes see grain in daylight-shot Imax filsm (REAL IMAX, liek what you see in science centers). But... Most people cannot resolve more detail than 1080p watched at a comfortable (read-non-nauseating) distance from teh screen. It is a matter of the resolution of your eyes. This 1080p-safe distance account for roughly 65% - 70% of the seats in any cinema.

A larger or smaller screen makes no differences (unless you are near or far sighted, and not wearing your glasses) as you will (within reason) sit closer to a smaller screen. It's not size, it's fill-factor of yoru eyes' "pixels".

Of course, a family watching an SD Television cannot all sit with their heads right in front of what used to be an average screen size (20 inches) If all screens were still 20 inches, we would not really need HD. There are also limits in other ways, like your eyes have trouble operating in macro-mode, so a 1 inch photo would be hard to look at in proper focus.... But....

Watching video 2 feet away from a "24 monitor, and 12 feet away from a 100 inch screen, and so on - these lead to identical resolutions being resolved by your eyes, and the max that most people can resolve is around 1080p. That said, 4 K DOES downsample to 1080p/2K better, (much better) and it stands to reason that 5K 10K any K would do so even better. But this is not the neatest thing about it. The neatest thing is the ability to re-frame in post. Once you start realizing the creative latitude post-created reframes allow, you get very, very excited about them.

 

[C_Skaff]

Not sure the point of beating a dead horse. As stated and seemingly not read...camera firmware in the middle of development, hacked together prototype, wrong OLPF, and I'm getting yelled at by the team for getting excited and posting these images because they insist people will pick them apart. I said "no they won't." Please stop. You're making me look stupid and I don't like it.

Jim

Oups, sorry if I affended you. my post was ment to the guy that told another guy to re-cal his monitor cus he saw blue in the black.
I fully understand that you are in the middle of development, but is sure looks amazing what you have done so far

 

[Adrian T.]

the max that most people can resolve is around 1080p.

Where did you learn this from? That's not true.

The human eye resolves around 0.35 arcmin. If you look at a 16:9 picture from a distance that is equal to its width, you resolve over 5000 lines.

References:
http://www.clarkvision.com/imagedetail/eye-resolution.html
http://en.wikipedia.org/wiki/Eye#Acuity

 

[jbeale]

The human eye resolves around 0.35 arcmin. If you look at a 16:9 picture from a distance that is equal to its width, you resolve over 5000 lines.

References:
http://www.clarkvision.com/imagedetail/eye-resolution.html
http://en.wikipedia.org/wiki/Eye#Acuity

Maybe the right question to ask is, how close can you comfortably sit to your display? Personally, at a distance equal to the display width, I feel a bit too uncomfortably close to my computer screen for normal viewing, and I sit much farther than that from my TV.

 

[Craig Parkes]

Where did you learn this from? That's not true.

The human eye resolves around 0.35 arcmin. If you look at a 16:9 picture from a distance that is equal to its width, you resolve over 5000 lines.

References:
http://www.clarkvision.com/imagedetail/eye-resolution.html
http://en.wikipedia.org/wiki/Eye#Acuity

Thanks a lot for this Adrian. Based on the clarkvision sites maths I just did a calculation for a 32 inch tv viewed at 7 feet, which is about what I view in my bedroom.

To reach a resolution at which I'd no longer be able to resolve any difference I'd need an image about pixels 2140h x 3780w.

Which pretty much proves that you'd be able to tell the difference between a 4K and HD display, but wouldn't quite need all of that 4K (in fact Reds 4KHD setting is remarkably close to this.)

This calculation proves incredibly useful I think and is a good one to know. In fact I wonder if someone a little bit better at math than me could do up some graphs that shows visual acuity for particular common screen sizes at a range of distances.

 

[Alan Fletcher]

In fact I wonder if someone a little bit better at math than me could do up some graphs that shows visual acuity for particular common screen sizes at a range of distances.

I've posted elsewhere (alanf at dpreview.com -- c 2004) a 'viewing distance' formula, based on the resolving power of the eye:

Viewing distance = 3500/DPI

(Distance in inches)

If you're any further than that your eye can't resolve line pairs.

Half that distance and you may be able to see the dots.

This approximates very closely to the rule of thumb "300 DPI for an
8x10 inch print" : the uncompensated eye can't focus much closer than 10 inches, and beyond that you can't resolve line pairs.

 

[David Mullen ASC]

I find the conversion from DPI or PPI to the terms we use in filmmaking for scanning (4K, 2K, etc.) a bit confusing.

I mean, a 35mm frame is almost an inch wide (1" = 25.4mm, a Super-35 frame is about 24.8mm wide) but when I hear terms like 600PPI for scanning film, that makes it sound like the scan is only 600 pixels wide for a 35mm frame, which can't be right.

 

[D Fuller]

I find the conversion from DPI or PPI to the terms we use in filmmaking for scanning (4K, 2K, etc.) a bit confusing.

I mean, a 35mm frame is almost an inch wide (1" = 25.4mm, a Super-35 frame is about 24.8mm wide) but when I hear terms like 600PPI for scanning film, that makes it sound like the scan is only 600 pixels wide for a 35mm frame, which can't be right.

A 600 ppi scan would be a very low-rez scan for film of any kind. It is OK for scanning flat art or prints, which you are presumably not going to enlarge, but it's a poor choice for scanning film. A nikon film scanner, for example, scans at 4000 ppi for either 35mm or 120/220 film.

 

[JD Holloway]

Not sure the point of beating a dead horse. As stated and seemingly not read...camera firmware in the middle of development, hacked together prototype, wrong OLPF, and I'm getting yelled at by the team for getting excited and posting these images because they insist people will pick them apart. I said "no they won't." Please stop. You're making me look stupid and I don't like it.Jim

This sort of analysis also makes RedUsers feel like their part of the development program. Obviously there is a cost/benefit to this open-handed approach. That sense of "inclusiveness" attaches us to the product. I for one, love it. It must be tough, though. Having to listen to people critique your children, even before their born.

The blue cast looks a lot like soft lens flareing from the candle IMO. Not surpirsing at these (relative) iso's.

 

[Craig Parkes]

I find the conversion from DPI or PPI to the terms we use in filmmaking for scanning (4K, 2K, etc.) a bit confusing.

I mean, a 35mm frame is almost an inch wide (1" = 25.4mm, a Super-35 frame is about 24.8mm wide) but when I hear terms like 600PPI for scanning film, that makes it sound like the scan is only 600 pixels wide for a 35mm frame, which can't be right.

Hence why I think graphs for particular frame sizes at various distances in the video world would be very useful. DPI/PPI is a completely inaccurate measurement for video because printer dots simply do not equal pixels - the limitations of a printer 'dot' because of the ink is very different to that of a 'pixel'...

Ok, I did some graphs of my own, in Excel, they aren't anything to write home about so I am not going to post them, but I basically figure you need to be viewing at a distance of about 0.4 feet for every inch of diagonal screen size for greater than HD resolution to not matter.

E.g For a 32 inch tv, you've got to be about 14 feet away, a 42inch tv about 18 feet away and a 60 inch tv about 24 feet away.

Viewing conditions will change depending on the size of the tv, but I'd imagine the average room allows somewhere between 9 and 12 feet between yourself and the tv.

Double the horizontal resolution (e.g RED's 4KHD) and you can half the distance. So with 32 inch tv you can sit 7 feet away, 42inch TV 9 feet away, and a 60 inch tv and you can sit 12 feet away and not benefit from any increased resolution.

For home viewing, this does indeed seem like the sweet spot for resolution for home viewing for me given normal viewing conditions.

 

[Steven Caesare]

Thanks a lot for this Adrian.

...

This calculation proves incredibly useful I think and is a good one to know. In fact I wonder if someone a little bit better at math than me could do up some graphs that shows visual acuity for particular common screen sizes at a range of distances.

I've used this one a number of times, but doesn't go beyond 1440P as a VERTCIAL resolution, which would be 2560 HORIZONTAL pixels.

EDIT to correct: Interestingliy it suggests that at a viewing distance equal to display diagonal that grater than 2560H would be needed. A 133" diag is about 120" in width... so the chart is indicating that you are definitiely in the realm of needing 1440V (2650H) or better at 1 screen width seating distance.

I wonder how that relates to the 5000 "lines" mentioned by Adrian, as I know that "line pairs" and pixels don't always equate.

-sc

 

[Craig Parkes]

I've used this one a number of times, but doesn't go beyond 1440P as a VERTCIAL resolution, which would be 2560 HORIZONTAL pixels.

Interestingliy it suggests that at a viewing distance equal to display width, that grater than 2560H would be needed.

I wonder how that relates to the 5000 "lines" mentioned by Adrian, as I know that "line pairs" and pixels don't always equate.

-sc

Interesting... It is a little conservative compared to the calcs I did based on an acuity of 0.3, as my graph would show an increase in resolution as an noticeable out to 14 feet rather than about 12 on that chart for a 32inch size screen. I would have thought though there should be some curve going in on the higher resolutions, because I would have thought that once you get within say 2 to 3 feet of a hi res object you would notice changes in resolution much more, so I take issue with the distances and size at which 1440p would start to become noticeable.

 

[David Mullen ASC]

So basically you'd have to sit closer than 5' to a 50" TV screen before you'd appreciate/see any more resolution than 1080P?

 

[Craig Parkes]

So basically you'd have to sit closer than 5' to a 50" TV screen before you'd appreciate/see any more resolution than 1080P?

I think it was designed around home theatre projectors so is focusing much more on the larger sizes and further distances and what is actually available. I am sure those lines should not be straight when you get towards the shorter distances (for the same screen size the difference between 5' and 10' my calcs show about double the resolution visible, so that a 50 inch screen would need to be more than 7k horizontally (4K vertically, so I guess 4320P) to reach the limit of human vision.

EDIT
As a comparison I just looked at what you would need for your average IMAX screen at the back row and it looks like (assuming my maths is correct...) That you could resolve something about 11K horizontally...

 

[Steven Caesare]

So basically you'd have to sit closer than 5' to a 50" TV screen before you'd appreciate/see any more resolution than 1080P?

To be fair, the "beginning" of the "Benefit of 1440 becomes noticable" range seems to start at at somewhere at the 7' mark if I'm reading correctly.

Assuming that we aren't talking about the inter-pixel spacing mask becing evident (aka the "screen door effect"), and are indeed tallking about the actual pxiel visibility itself, I'd suggest that's proabably pretty accurate.

After all, 50" diagonal display is only 44" wide... which means that at the 7' mark, you are sitting almost 2 screen widths away (~1.9).

-sc

 

[Rob Ruffo]

Thanks a lot for this Adrian. Based on the clarkvision sites maths I just did a calculation for a 32 inch tv viewed at 7 feet, which is about what I view in my bedroom.

To reach a resolution at which I'd no longer be able to resolve any difference I'd need an image about pixels 2140h x 3780w.

Which pretty much proves that you'd be able to tell the difference between a 4K and HD display, but wouldn't quite need all of that 4K (in fact Reds 4KHD setting is remarkably close to this.)

This calculation proves incredibly useful I think and is a good one to know. In fact I wonder if someone a little bit better at math than me could do up some graphs that shows visual acuity for particular common screen sizes at a range of distances.

This is simply not true. Check your math.

 

[Rob Ruffo]

So basically you'd have to sit closer than 5' to a 50" TV screen before you'd appreciate/see any more resolution than 1080P?

You can test this at home with your friends and family - it bears out as truth.

 

[Stephen Williams]

You can test this at home with your friends and family - it bears out as truth.

Hi,

Normally when I look at other peoples TV's they are badly set up often with the incorrect aspect ratio. Most people notice very little unless it's pointed out to them, they probably don't care one way or another.

Stephen

 

[Aiden K.]

Hi,

Normally when I look at other peoples TV's they are badly set up often with the incorrect aspect ratio. Most people notice very little unless it's pointed out to them, they probably don't care one way or another.

Stephen

This is a perfectly inconvenient truth.

 

[nigelsmith]

You can test this at home with your friends and family - it bears out as truth.

???
You looked at a 50 inch TV capable of displaying resolutions greater than 1920 x 1080?
I didn't realise my friends and family were so poor ....