Ad
Ad
Ad
Pages: « 1 [2] 3 4 ... 10 »   Bottom of Page
Print
Author Topic: removing the AA filter  (Read 68865 times)
Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #20 on: October 18, 2007, 08:32:41 PM »
ReplyReply

Resolution is meaningless if it's corrupted by aliases.

Graeme
Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
spotmeter
Sr. Member
****
Offline Offline

Posts: 310


WWW
« Reply #21 on: October 18, 2007, 08:45:22 PM »
ReplyReply

LEPING,

Where did you go to have your AA filter removed?
Logged

Ray
Sr. Member
****
Offline Offline

Posts: 8939


« Reply #22 on: October 18, 2007, 09:07:37 PM »
ReplyReply

Quote
Resolution is meaningless if it's corrupted by aliases.

Graeme
[a href=\"index.php?act=findpost&pid=147072\"][{POST_SNAPBACK}][/a]

Note that LEPING wrote that the D2X provides about 30% more resolution than his 5D both with AA filter.
Logged
John Sheehy
Sr. Member
****
Offline Offline

Posts: 838


« Reply #23 on: October 18, 2007, 09:20:51 PM »
ReplyReply

Quote
Resolution is meaningless if it's corrupted by aliases.
[a href=\"index.php?act=findpost&pid=147072\"][{POST_SNAPBACK}][/a]

The standard for measuring resolution, like lines per mm, comes from film which does not alias in a regular pattern.  Therefore, no one ever safeguarded the term "resolution" against aliasing in grid-like captures.  I think the definition of photographic resolution needs to be upgraded to "that which can be reproduced consistently with any random chance alignment of subject and photosites".

An aliased capture can capture alternating black and white lines on every line, but shift the alignment 1/2 the pixel pitch, and nothing is captured at all, except solid grey.  This former is not "resolution".
Logged
Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #24 on: October 18, 2007, 09:30:26 PM »
ReplyReply

That's why I use a nice linear sinusoidal zone plate to measure resolution and test demosaic algorithms.... It makes all this clear and plainly visible.

Graeme
Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #25 on: October 18, 2007, 09:34:39 PM »
ReplyReply

That's a perfect image to show how the aliases fold back to a lower spatial frequency, and hence cannot now be removed by a blur, other than a blur so large that ruins the image and removes all the detail in it. There's no way known to repair an image like that and remove it's aliases.

Graeme

Quote
No software can do a good job of removing this moire (GNU Licensed Image, usage allowed):


[a href=\"index.php?act=findpost&pid=147070\"][{POST_SNAPBACK}][/a]
Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
jing q
Sr. Member
****
Offline Offline

Posts: 594


WWW
« Reply #26 on: October 18, 2007, 09:37:49 PM »
ReplyReply

Quote
Resolution is meaningless if it's corrupted by aliases.

Graeme
[a href=\"index.php?act=findpost&pid=147072\"][{POST_SNAPBACK}][/a]

blahblahblahblah
Let's wait to see more people upgrade their cameras and hopefully post
I've been in touch with Dan Llewellyn who's also planning to upgrade his MkII, so a MkII upgrade seems possible. will keep updated on his progress to see whether it's a good bet to upgrade mine

I'm sure everyone loves hearing theory but somehow I find practical experience with my eyes more trustworthy.
To tell you the truth I am not that bothered by aliasing. In fact it's quite simple to minimize the effect in photoshop with abit of clone stamping.Sure it's not the best thing in the world but frankly it's a tradeoff you'll have to decide if you're willing to live with.
if you've scanned a 4x5 piece of film at high rez before you'll also see aliasing in certain textures.
« Last Edit: October 18, 2007, 09:39:21 PM by jing q » Logged
Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #27 on: October 18, 2007, 09:48:32 PM »
ReplyReply

I think "Upgrade" should be in quotes. I'd call it a "downgrade" :-)

As for selective cloning or blurring - yes on mild cases. However, if you get chroma fringes, that'd be a nightmare to remove. And quite frankly, I enjoy taking photos, and I enjoy creative stuff in Photoshop or whatever, but I could not stand for one minute to slave away with my Wacom to remove aliases when a properly designed camera with OLPF minimises or eliminates them. Life's too short..... Is the quest for resolution "that" important. Resolution is part of the image, and quite frankly a small part, well below contrast and below composition and lighting.

Graeme

Quote
blahblahblahblah
Let's wait to see more people upgrade their cameras and hopefully post
I've been in touch with Dan Llewellyn who's also planning to upgrade his MkII, so a MkII upgrade seems possible. will keep updated on his progress to see whether it's a good bet to upgrade mine

I'm sure everyone loves hearing theory but somehow I find practical experience with my eyes more trustworthy.
To tell you the truth I am not that bothered by aliasing. In fact it's quite simple to minimize the effect in photoshop with abit of clone stamping.Sure it's not the best thing in the world but frankly it's a tradeoff you'll have to decide if you're willing to live with.
if you've scanned a 4x5 piece of film at high rez before you'll also see aliasing in certain textures.
[a href=\"index.php?act=findpost&pid=147089\"][{POST_SNAPBACK}][/a]
Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
jing q
Sr. Member
****
Offline Offline

Posts: 594


WWW
« Reply #28 on: October 18, 2007, 10:05:35 PM »
ReplyReply

Quote
I think "Upgrade" should be in quotes. I'd call it a "downgrade" :-)

As for selective cloning or blurring - yes on mild cases. However, if you get chroma fringes, that'd be a nightmare to remove. And quite frankly, I enjoy taking photos, and I enjoy creative stuff in Photoshop or whatever, but I could not stand for one minute to slave away with my Wacom to remove aliases when a properly designed camera with OLPF minimises or eliminates them. Life's too short..... Is the quest for resolution "that" important. Resolution is part of the image, and quite frankly a small part, well below contrast and below composition and lighting.

Graeme
[a href=\"index.php?act=findpost&pid=147094\"][{POST_SNAPBACK}][/a]

Well Graeme I got my composition and lighting and contrast down. so I'm all game for something that can improve the image.
it bugs me when I'm working on my images to see that bloody softness and flatness from my canon files.
I'm sure you understand that the quality of the image can make you feel like working on it all night or just looking at it once and chucking it aside.
Logged
madmanchan
Sr. Member
****
Offline Offline

Posts: 2110


« Reply #29 on: October 19, 2007, 08:29:44 AM »
ReplyReply

That's what capture sharpening is for ...
Logged

Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #30 on: October 19, 2007, 09:04:28 AM »
ReplyReply

Quote
Well Graeme I got my composition and lighting and contrast down. so I'm all game for something that can improve the image.
it bugs me when I'm working on my images to see that bloody softness and flatness from my canon files.
I'm sure you understand that the quality of the image can make you feel like working on it all night or just looking at it once and chucking it aside.
[a href=\"index.php?act=findpost&pid=147096\"][{POST_SNAPBACK}][/a]

I'm sure, but that softness is absolutely correct. The alternative is unnatural artifacts and bayer colour fringes on edges. Both, to me, are totally unnaceptable. If it looks soft to you, then sharpen it! And there are sharpening tools now that don't do halos, so you don't have to make it look like a cartoon sketch either.

Or maybe you're staring at the image pixel for pixel and of course it's going to be a tad soft. You're looking at it way too close. You need to get back and take in the entire image. You need to learn to love the OLPF, not fight it. Or, downsample. No other way is completely harmonious with the integrity of the image.

Graeme
Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
jing q
Sr. Member
****
Offline Offline

Posts: 594


WWW
« Reply #31 on: October 19, 2007, 09:22:50 AM »
ReplyReply

Quote
I'm sure, but that softness is absolutely correct. The alternative is unnatural artifacts and bayer colour fringes on edges. Both, to me, are totally unnaceptable. If it looks soft to you, then sharpen it! And there are sharpening tools now that don't do halos, so you don't have to make it look like a cartoon sketch either.

Or maybe you're staring at the image pixel for pixel and of course it's going to be a tad soft. You're looking at it way too close. You need to get back and take in the entire image. You need to learn to love the OLPF, not fight it. Or, downsample. No other way is completely harmonious with the integrity of the image.

Graeme
[a href=\"index.php?act=findpost&pid=147172\"][{POST_SNAPBACK}][/a]

Graeme, have you ever seen a file from a medium format back enlarged beyond 4ft x 5ft, no AA filter, with bayer colour fringes?
Have you seen a clean AA filtered file enlarged beyond 4ft by 6ft?

Are you saying that if I put an AA filtered image next to a non-AA filtered image, side by side, enlarged to 4 ft, both being equal, I would get an equally detailed image from the AA filtered image than from the non-AA filtered image?
Are you saying there's no loss of detail from an AA filter?

Because from my experience this is not the case, and sharpening past a certain point can make pixels stand out but the detail has turned into clumps already, and the interpolation doesn't create any new detail.

I'm not talking theoretically, I've spent too many hours trying out different methods on different files and ultimately come to the realisation that I prefer a more detail laden file to start with, and moire is an issue I can deal with.

Can we say that all things being equal, and disregarding the moire issue, if I remove the AA filter I am more likely to get an image that is sharper right from the start than an AA filtered one?

And the non-AA filtered image will require less sharpening than the AA filtered image when uprezzed?

How important moire is to each individual is their own issue then, to me it's really not a big problem. I think it's overhyped. I've shot many a textile with medium format backs and the moire issue pops up once in awhile but it's not such a big deal!
« Last Edit: October 19, 2007, 09:35:41 AM by jing q » Logged
Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #32 on: October 19, 2007, 09:38:07 AM »
ReplyReply

Sounds like you need to go shoot film and avoid all these issues :-) If you're shooting MF and taking a long time over getting your shot right with regards lighting / exposure and composition, it would be silly for you to spoil your effort by shooting digital if very large prints are what you desire....

Of course there a loss in resolution from the OLPF, but there's an equal loss in aliasing artifacts, moire and aliasing. You can't have one without the other.

But that's the point of having a sensor with an awfully high resolution - it means you can properly anti-alias the incoming light and still have bags of resolution left to spare. If you're shooting 1 or 2 mp, you need all the resolution you can get, and hell at that small count, what's an artifact or three among friends? But as you get beyond that, up past the current mainstream DSLR 10mp or so, and into the realm of 22mp or 39mp, you have a lot of wiggle room, and that means you can properly optically low pass filter your images, downsample them properly and still have a very high resolution image.

I think the problem is that if a camera says it's 10mp, they expect 10mp resolution and they don't get the maths of sampling theorm and understand that to attempt to do so would introduce a vast swathe of unnatural artifacts into the image.

The MF backs probably expect you stop stop way down into diffraction territory so you can stand a hope in hell of getting a decent amount of DOF, and at that point, the diffraction is your OLPF.....

Graeme
« Last Edit: October 19, 2007, 09:44:11 AM by Graeme Nattress » Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
jing q
Sr. Member
****
Offline Offline

Posts: 594


WWW
« Reply #33 on: October 19, 2007, 09:51:59 AM »
ReplyReply

Quote
Sounds like you need to go shoot film and avoid all these issues :-) If you're shooting MF and taking a long time over getting your shot right with regards lighting / exposure and composition, it would be silly for you to spoil your effort by shooting digital if very large prints are what you desire....

Graeme
[a href=\"index.php?act=findpost&pid=147182\"][{POST_SNAPBACK}][/a]

unfortunately I don't have the luxury of shooting film when I am dealing with a group of 20 people and only 5 minutes to get the shot. I have to get it and then finish the shoot in such circumstances, and digital's the only way. Abit of background on what I do so that perhaps you won't think I'm a raving lunatic.

I shoot large groups of people in outdoor environments using strobes. I started out shooting with my 1dsMkII, and then with a Rz67 and a Mamiya 7 once in awhile.
I started shooting 100G on 4x5 film for awhile but that didn't work out due to the lack of speed.
I scan my film on Imacon virtual drum scanners (funny...I prefer the Imacon to drum scans which seem to come out oversharpened and lacking grain usually for some reason)

I print my images up to 5ft for exhibition purposes so we're talking about putting your nose right in front of the print.

I exhibited two images, one shot with a 1DsMkII and one with a H39. now I know it's unfair to compare them since the resolution difference is astounding but one thing I noticed and have been noticing when uprezzing 1DsMkII files is that the interpolation causes edges to have a clumpy (for a lack of better word) look to them, after I sharpen the images.

The H39 file, which never seemed to look that great to me on the computer screen, suddenly popped out in print. everyone noticed it. The details were much finer, edge details especially.

The 1DsMkII file , which I absolutely adore and looks bloody good in my 13x19 portfolio, has a certain flatness to it. When I read on the Hot Rod page about how it looks like your image looks like there's a haze to it and it looks like a photo of a photo rather than a photo alone (does that make sense?), something went off in my head "Bingo!Exactly!"

The 1DsMkII files can look really great with careful processing, but frankly I've always felt that the files lacked a certain depth to them when printed. Editorially I could always tell that my file was a 1DsMkII file whereas it's pretty easy for me to point out when my peers have a film image.

This is just my personal opinion from all the work I've been doing.
Perhaps how the brain and eye perceives and digests visual information and ideas of depth and realism are more minute and diverse than just a simple theoretical explanation.
Logged
jing q
Sr. Member
****
Offline Offline

Posts: 594


WWW
« Reply #34 on: October 19, 2007, 10:00:12 AM »
ReplyReply

Quote
Sounds like you need to go shoot film and avoid all these issues :-) If you're shooting MF and taking a long time over getting your shot right with regards lighting / exposure and composition, it would be silly for you to spoil your effort by shooting digital if very large prints are what you desire....

Of course there a loss in resolution from the OLPF, but there's an equal loss in aliasing artifacts, moire and aliasing. You can't have one without the other.

But that's the point of having a sensor with an awfully high resolution - it means you can properly anti-alias the incoming light and still have bags of resolution left to spare. If you're shooting 1 or 2 mp, you need all the resolution you can get, and hell at that small count, what's an artifact or three among friends? But as you get beyond that, up past the current mainstream DSLR 10mp or so, and into the realm of 22mp or 39mp, you have a lot of wiggle room, and that means you can properly optically low pass filter your images, downsample them properly and still have a very high resolution image.

I think the problem is that if a camera says it's 10mp, they expect 10mp resolution and they don't get the maths of sampling theorm and understand that to attempt to do so would introduce a vast swathe of unnatural artifacts into the image.

The MF backs probably expect you stop stop way down into diffraction territory so you can stand a hope in hell of getting a decent amount of DOF, and at that point, the diffraction is your OLPF.....

Graeme
[a href=\"index.php?act=findpost&pid=147182\"][{POST_SNAPBACK}][/a]

I want to point out also that you'll be really surprised at how different images on screen and images in print turn out. You really can't tell much from a web image, and when you're going into enlargements, that's a whole new ball game. When I'm printing my enlargements I literally have to print strips to compare the contrast between edges to see what I feel is still within the realm of being "photographic", and not cartoonish.

Surprisingly with MF backs I've had situations where I've had to shoot at reaaaaally wide open apertures and they come out great.
This image is on a H39, 35mm F/4

This image is STUNNING when printed big. in my 13x19 portfolio it's pretty tame. Very strange. Anyway I only noticed abit of moire problems.


This is on a Mamiya 7, 65mm f/4


and this is on a Canon 1DsMkII, 35mm f/16


love love love this image but the problem arose in the small details.
Honestly I do not trust my 1dsMkII for ANY small details. like the faces in the background. They do not enlarge well at all. even when I was using a 16mp Kodak Pro Back the amount of detail you're starting off with when there's no AA filter is just so much finer than with a Canon. This really helps in enlargements.

Regarding bayer colour fringing, I totally agree. In fact when I'm putting my noise up to fashion advert posters I'm looking out for that to guess if the file's shot with a medium format digital back or some other device. Usually I will try to lessen the problem in my files in postproduction.

So I'm willing to live with the issues involved with having no AA filter, and I would like people to know that I think it's not as BAD as everyone seems to think!

btw I've read your recent post in the other forum. Very detailed, learnt abit from there. Thanks. I think the issue I face is the removal of detail by the filter. Would love to see more samples from people who have modded their cameras to confirm what I'm seeing in my experience.
« Last Edit: October 19, 2007, 10:06:54 AM by jing q » Logged
Graeme Nattress
Sr. Member
****
Offline Offline

Posts: 582



WWW
« Reply #35 on: October 19, 2007, 10:05:42 AM »
ReplyReply

How did you shrink those images down for the web - the grass is aliassing very badly in the 2nd jpg (the grass now looks gritty and harsh).

Yes, if you have more detail, you'll be able to uprez better, but any adaptive / intelligent algorithm for uprezzing will get confused by any aliases it sees. Aliases are also bad for "sharpening" as false detail gets exaggerated along with real detail.

Graeme
Logged

www.nattress.com - Plugins for Final Cut Pro and Color
www.red.com - Digital Cinema Cameras
jing q
Sr. Member
****
Offline Offline

Posts: 594


WWW
« Reply #36 on: October 19, 2007, 10:14:23 AM »
ReplyReply

Quote
How did you shrink those images down for the web - the grass is aliassing very badly in the 2nd jpg (the grass now looks gritty and harsh).

Yes, if you have more detail, you'll be able to uprez better, but any adaptive / intelligent algorithm for uprezzing will get confused by any aliases it sees. Aliases are also bad for "sharpening" as false detail gets exaggerated along with real detail.

Graeme
[a href=\"index.php?act=findpost&pid=147192\"][{POST_SNAPBACK}][/a]

Hi Graeme, regarding the grass image I use bicubic sharper. I could have made it less gritty and harsh but that is exactly how I want it to look. I exaggerate it almost nearly as much in my other prints too.

I do two things with a file that has the problems of aliasing and bayer color fringing.
It's usually easier to deal with editting out the color fringing problems through careful clonestamping when the image is enlarged actually.
So far the color fringing has not been that big of a deal, occurs on edges which are not heavy with detail in the first place

Aliasing surprisingly has not been much of a problem. Just did a fashion shoot recently where that problem did occur and I clonestamped the hue to make the aliasing even in colour. Left it alone after that because the area affected was minimal.
Not the most optimal of situations I agree, but once again I am aware of the trade off and I find it easy enough to live with, as do alot of other people who deal with their medium format backs that lack AA filters.

Phase One actually mentioned how having more pixels on a sensor helps to reduce moire, which is one of their selling points for upgrading from a P25 (22mp) to P45(39mp)
I'm not sure how true this is, but if this is the case then the 1DsMkII should have less problems with moire using the same logic, even without an AA filter

I think that one has to put into perspective that the number of situations where aliasing comes into effect are not overwhelming. If you're shooting alot of textiles then perhaps that will come into play much more. But I've been shooting people in their clothing for quite awhile now on medium format digital backs and the issue of aliasing pops up so rarely and on such an insignificant scale that I've never felt strongly about it enough to type such tediously long posts on internet forums like this one....

Which leads me to state now that it's friday night here and the club is full of hot chicks waiting for me to pounce on them, so I won't go any further into this. I suggest you try some of the cameras that don't have AA filters to see the benefit, print out some of the images too. I hear the Leica M camera doesn't have one and people seem to like the different feeling the images have.
« Last Edit: October 19, 2007, 10:19:01 AM by jing q » Logged
Peter Gregg
Jr. Member
**
Offline Offline

Posts: 62


« Reply #37 on: October 19, 2007, 11:42:43 AM »
ReplyReply

I am in the process of selecting between a Canon 1Ds MK3 and the Nikon D3. The reason for those 2 cameras even being in the same mix is possibly because of this topic.

First, the 21mp appeals to me. But any pictures I can garnish from the internet all have what I call that "Canon Cloud" and I guess i neve realized that it was the AA filter causing it. I just gave that thought over to the possibility that Canon's just never get that "spot on" focus and was something to live with.

On the other hand, almost ALL the samples I am able to find from the Nikon D3 seem to be the opposite. And that caused me to think that the Nikon actually CAN focus spot on. The pictures don't have that cloud and have a clear look to them.

Now the explanation may be different. Maybe the D3 has a considerably weaker AA filter and that would in fact bear out the AA filter argument. So even though the D3 doesn't have the resolution that the sMK3 has, it seems to deliver a "clearer" picture.

Since I also use PK Sharpener, I tried that sharpening that was recomended and it seems to work better than I thought. I tried it on some of my 5D and even a couple of MK3 files and I like the outcome - and not in a small way.

So now the 1Ds MK3 is back on top of my list. I still need to see how much of a handicap it will be in the high ISO compared to what the D3 will deliver because I do a lot more wedding and social work than art or landscape work and low light has a very high place on my list.

Ultimately, I would very much contemplate having the AA filter removed if it became possible to do that. To me, these clinical argument for the AA filter do not go along with real life and remind me very much of my doctor than can only prescrible high priced chemical medicines and balks if i suggest any natural alternatives. For him, there is only one way, but I know that is not true.

So i need to decide between "power files" of the sMK3 or the cleaner higher ISO and clearer pictures of the D3. I lean towards the sMK3 and the luminous sharpening in PK may tip the balance.

Peter
Logged
John Sheehy
Sr. Member
****
Offline Offline

Posts: 838


« Reply #38 on: October 19, 2007, 04:54:33 PM »
ReplyReply

Quote
Ultimately, I would very much contemplate having the AA filter removed if it became possible to do that. To me, these clinical argument for the AA filter do not go along with real life and remind me very much of my doctor than can only prescrible high priced chemical medicines and balks if i suggest any natural alternatives. For him, there is only one way, but I know that is not true.[a href=\"index.php?act=findpost&pid=147222\"][{POST_SNAPBACK}][/a]

The problem with your analogy is that aliasing is not the natural choice; it is the synthetic one.  Things in the real optical world do not snap to grid, subsample, and alias.  They just run out of resolution.

I can't explain why so many people like the look of aliasing, and mistake it for subject detail.  At the risk of sounding condescending, I have to think that people who like the look of aliasing have a problem with spatial interpretation.  Aliasing loses the real center of points of light, of edges, etc, with it's snap-to-grid effect.  Everything is choppy and in the wrong place with aliasing, and it is so clearly obvious to my eyes and brain.  The images look shattered, in a fixed, repeating pattern.
Logged
Leping
Jr. Member
**
Offline Offline

Posts: 87



WWW
« Reply #39 on: October 19, 2007, 05:02:42 PM »
ReplyReply

Maxmax.com .

If you look at MF lens MTF curves and think about the MF digital back pixel size, you understand there are not much real resolution there for strong aliasing, or in other words the lens MTF attenuation acts as an AA filter by itself, which is probably a big part that they can go without one in general.

For 35mm DSLR non-landscape works I agree absolutely we need these filters, just as we saw from the Kodak 14n/c examples.  35mm lens can often produce high spacial frequencies over 100lpr/mm while most MF lenses reaches around 60lpr/mm.

The 30% resolution advantage I referred (D2x over 5D) is the amount of true details a careful de-convolution kind of sharpening (definitely not USM) can bring up, such as the Richard-Lucy filter in Raw Developer (the LightRoom came somehow close with the smallest radius but not quite there because of lacking the number of iteration parameter).  The R-L deconvolution filter was the one NASA used to fix the fuzzy Hubble Space Telescape images.  Again it does not work with all the images but to us "westcoast f64 school" "rock and tree photographers" it is the choice.  It is not the edge transition measurements you get from DxO, for example.
Quote
LEPING,

Where did you go to have your AA filter removed?
[a href=\"index.php?act=findpost&pid=147077\"][{POST_SNAPBACK}][/a]
« Last Edit: October 19, 2007, 05:12:46 PM by LEPING » Logged

Pages: « 1 [2] 3 4 ... 10 »   Top of Page
Print
Jump to:  

Ad
Ad
Ad