Return of Interesting article on DxO about 5D III and D800...

Started Apr 10, 2013 | Discussions
Mako2011
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In reply to aftab, Apr 11, 2013

aftab wrote:

How about resolution?

Scenario B

Does anyone really think that some people don't know that A has more resolution than B? Yeah, it shows so many line pairs/so much area.. yaada yaada and one can talk about how Fourier transform or that nyquist frequency can explain them. But everybody knows what they see, Resolution = Detail.

Same..in A and B above you can count and discern the same number of lines. The resolution of A and B is the same.

Now, we must talk about real world, because that is the norm in this forum (as if we can ever capture something that doesn't belong to this world:P).

Scenario C

A has more resolution than B, because we can count 1753 hair in A vs 1248 hair in B.

Now, let us look at scenario B and scenario C again. In both cases A looks sharper than B. What does that mean? More resolution = more sharpness. That is resolution = sharpness in this two scenarios. And almost all scenarios are like this. So, we can actually use the terms resolution and sharpness interchangeably.

Not the case at all. In scenario B...the resolution of the two images is equal. Sharpness though differs.

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John Sheehy
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Re: not sharpness
In reply to Dave Luttmann, Apr 11, 2013

Dave Luttmann wrote:

John Sheehy wrote:

Mako2011 wrote:

You seem to be mixing terms and describing sharpness but calling it resolution.  Resolution only describes how much detail a camera/lens is capable of capturing — and not necessarily the quality of the detail that is captured. The problem, in these types of discussions, is that folks keep mixing related terms an using them to describe inaccurately a concept

Did you actually read my post?  It seems very unlikely, given your response.

It seems he read it perfectly.  The second you try to discuss "both types of resolution".... Your discussion was over.  There is only one type of resolution.  And one type of acutance.  You seem to miss that simple distinction.

Perhaps you both need to go back and read it again.  The two types of resolution were "per mm of sensor area", and "per sensor".  I introduced the post by referring to disagreements in the previous thread about which of these "resolution" refers to.  My point is that they are both measures of resolution.

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schmegg
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Re: not sharpness
In reply to John Sheehy, Apr 11, 2013

John Sheehy wrote:

Dave Luttmann wrote:

John Sheehy wrote:

Mako2011 wrote:

You seem to be mixing terms and describing sharpness but calling it resolution.  Resolution only describes how much detail a camera/lens is capable of capturing — and not necessarily the quality of the detail that is captured. The problem, in these types of discussions, is that folks keep mixing related terms an using them to describe inaccurately a concept

Did you actually read my post?  It seems very unlikely, given your response.

It seems he read it perfectly.  The second you try to discuss "both types of resolution".... Your discussion was over.  There is only one type of resolution.  And one type of acutance.  You seem to miss that simple distinction.

Perhaps you both need to go back and read it again.  The two types of resolution were "per mm of sensor area", and "per sensor".  I introduced the post by referring to disagreements in the previous thread about which of these "resolution" refers to.  My point is that they are both measures of resolution.

Yeah - I agree with that myself.

In fact it's pretty much what I was alluding to back in the last thread ...

http://www.dpreview.com/forums/post/51244145

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Mako2011
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not res
In reply to John Sheehy, Apr 11, 2013

John Sheehy wrote:

Dave Luttmann wrote:

John Sheehy wrote:

Mako2011 wrote:

You seem to be mixing terms and describing sharpness but calling it resolution.  Resolution only describes how much detail a camera/lens is capable of capturing — and not necessarily the quality of the detail that is captured. The problem, in these types of discussions, is that folks keep mixing related terms an using them to describe inaccurately a concept

Did you actually read my post?  It seems very unlikely, given your response.

It seems he read it perfectly.  The second you try to discuss "both types of resolution".... Your discussion was over.  There is only one type of resolution.  And one type of acutance.  You seem to miss that simple distinction.

Perhaps you both need to go back and read it again.  The two types of resolution were "per mm of sensor area", and "per sensor".  I introduced the post by referring to disagreements in the previous thread about which of these "resolution" refers to.  My point is that they are both measures of resolution.

Image resolution can be measured in various ways. Basically, resolution quantifies how close lines can be to each other and still be visibly resolved. Resolution units can be tied to physical sizes (e.g. lines per mm, lines per inch), to the overall size of a picture (lines per picture height, also known simply as lines, TV lines, or TVL), or to angular subtenant. Line pairs are often used instead of lines; a line pair comprises a dark line and an adjacent light line.

The two types of "resolution" you're speaking of...are are more related to the concept of sharpness and not resolution.  I've not seen any resolution measurements in units of per sensor or pmmsa (per mom sensor area)

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Steen Bay
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Re: not res
In reply to Mako2011, Apr 11, 2013

Mako2011 wrote:

John Sheehy wrote:

Dave Luttmann wrote:

John Sheehy wrote:

Mako2011 wrote:

You seem to be mixing terms and describing sharpness but calling it resolution.  Resolution only describes how much detail a camera/lens is capable of capturing — and not necessarily the quality of the detail that is captured. The problem, in these types of discussions, is that folks keep mixing related terms an using them to describe inaccurately a concept

Did you actually read my post?  It seems very unlikely, given your response.

It seems he read it perfectly.  The second you try to discuss "both types of resolution".... Your discussion was over.  There is only one type of resolution.  And one type of acutance.  You seem to miss that simple distinction.

Perhaps you both need to go back and read it again.  The two types of resolution were "per mm of sensor area", and "per sensor".  I introduced the post by referring to disagreements in the previous thread about which of these "resolution" refers to.  My point is that they are both measures of resolution.

Image resolution can be measured in various ways. Basically, resolution quantifies how close lines can be to each other and still be visibly resolved. Resolution units can be tied to physical sizes (e.g. lines per mm, lines per inch), to the overall size of a picture (lines per picture height, also known simply as lines, TV lines, or TVL), or to angular subtenant. Line pairs are often used instead of lines; a line pair comprises a dark line and an adjacent light line.

The two types of "resolution" you're speaking of...are are more related to the concept of sharpness and not resolution.  I've not seen any resolution measurements in units of per sensor or pmmsa (per mom sensor area)

DxO's P-Mpix is an area measure, not a linear measure like lp/mm or lp/ph.

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Mako2011
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In reply to schmegg, Apr 11, 2013

schmegg wrote:

Yeah - I agree with that myself.

In fact it's pretty much what I was alluding to back in the last thread ...

http://www.dpreview.com/forums/post/51244145

Ah,...I can see that as a way to describe what sensor resolves more. A nuance I may have missed.

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Mako2011
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In reply to Steen Bay, Apr 11, 2013

Steen Bay wrote:

DxO's P-Mpix is an area measure, not a linear measure like lp/mm or lp/ph.

Not sure what it actually measures in any quantifiable way. They have not told us. We do know though that it is certainly not a measurement of actual resolution.

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Mikael Risedal
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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to qianp2k, Apr 11, 2013

qianp2k wrote:

Steen Bay wrote:

qianp2k wrote:

Steen Bay wrote:

qianp2k wrote:

Steen Bay wrote:

aftab wrote:

Now, let us look at scenario B and scenario C again. In both cases A looks sharper than B. What does that mean? More resolution = more sharpness. That is resolution = sharpness in this two scenarios. And almost all scenarios are like this. So, we can actually use the terms resolution and sharpness interchangeably.

But if comparing for example the 12.7mp 5D vs. the 18mp 7D, then things get a bit more complicated, because it seems that 5D (most often, with most lenses) has the best sharpness (MTF-50?),

true.

while the 7D has the highest resolution (MTF-10 or MTF-5?).

Not necessarily. Actually with most  EF lenses 5D outresolves 7D if you frame them in the same AOV (as tested by DXOMark in either old MTF or new P-MPix unit that are two different expressing units but with the same result). Only very few lenses such as with 300L/2.8 IS II 7D/60D outresolves 5D.

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But what if we could compare the MTF-10 er MTF-5 values (which we unfortunately can't anymore)? Then I think that the 7D would win, because it has quite a bit more MPs.

In theory maybe.  But it's a matter of our eyes can resolve or not that's all DXOMark test about, a paper resolution vs real resolution after deducting noise/grain, pixel magnification...  It’s a matter of perceptual sharpness (resolution) human eyes can perceive.

http://www.cambridgeincolour.com/tutorials/lens-quality-mtf-resolution.htm

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Yes, it's a matter of what the human eye can perceive, so how about comparing the resolution test chart shots in DPR's 5D and 7D reviews? (available for download). Haven't checked, but as far as I remember, then the 7D wins.

I don't think so with most EF lenses, 5D gains more with inferior lenses if you test by framing them in the same AOV.  I did such test other day (and will do again) that show 5D has resolution advantage except with the best lens 24-70L II in very close distance (macro mode) against a dollar bill but that is a very small center area (and 5D wins in edges/corners).  In real world outdoor test, 5D wins clearly.  I think DXOMark uses average frame resolution to calculate its DXOMark number.

http://www.dpreview.com/forums/thread/3447852

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off course, a APS camera as 7d needs 1,5 - 1,6 better lenses if you compare to 18Mp at 24x36 surface , it means the 7d demands  better contrast and resolution

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Steen Bay
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Re: unknown
In reply to Mako2011, Apr 11, 2013

Mako2011 wrote:

Steen Bay wrote:

DxO's P-Mpix is an area measure, not a linear measure like lp/mm or lp/ph.

Not sure what it actually measures in any quantifiable way. They have not told us. We do know though that it is certainly not a measurement of actual resolution.

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Yes, would be nice if they told us a bit more about how the P-Mpix score is derived, but it's easy enough to translate P-Mpix to a linear measure. If a 3:2 sensor + a lens 'resolves' for example 6 P-Mpix, then that's the same as saying that it resolves 2000 lines vertically (lw/ph) and 3000 lines horizontally (lw/pw).

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Mako2011
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Re: unknown
In reply to Steen Bay, Apr 11, 2013

I disagree as we no longer have any specifics as to what resolution number/measurement actually was used in the score. To many assumptions
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John Sheehy
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Re: not res
In reply to Mako2011, Apr 12, 2013

Mako2011 wrote:

The two types of "resolution" you're speaking of...are are more related to the concept of sharpness and not resolution.

Nonsense.  Did becoming a moderator give you a license to alter reality?

There are very few people more aware of the difference between resolution and sharpness (or acuity) than I.  I rail about the difference all the time.  I did not conflate them in my post.  It is all your doing.

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qianp2k
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Re: not res
In reply to John Sheehy, Apr 12, 2013

John Sheehy wrote:

Mako2011 wrote:

The two types of "resolution" you're speaking of...are are more related to the concept of sharpness and not resolution.

Nonsense.  Did becoming a moderator give you a license to alter reality?

LOL.  That's what I saw also he thinks himself an authority to decide who is right and who is wrong.  My puzzle on him is that why he keeps changing post subject line (title) then keeps suggesting someone off-topic

There are very few people more aware of the difference between resolution and sharpness (or acuity) than I.  I rail about the difference all the time.  I did not conflate them in my post.  It is all your doing.

He keeps downplaying sharpness (as something really not important to him) and emphasizing his "resolution".  I thought he knew what he meant until I saw this photo that closes to 100% cropped size (click 'original size' link to see in full size).  Even at reduced size, I don't see much textual details on the building and the photo is soft and mushy, and becomes total cr*b viewed at full size.  So to him 18mp is 18mp regardless if the lens can resolve or not, regardless if his eyes (or anyone's eyes) actually can resolve or not  No mention I have no idea why he shoot at ISO 250 at 1/320 from 17-55/2.8 on his 7D (from a bridge not on a moving vessel.  I know this place exactly as I was there last year).  I am sure about if I took 5Dc on the same scene with 24-105L the combo will resolve lots more fine details than his one, hehe.

http://www.dpreview.com/forums/post/51021107

Anyway I don't believe he knows what he is talking about, LOL.

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bgbs
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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to aftab, Apr 12, 2013

Back in the days when I bought my first digital camera, it was 6mp and at 100% it producer sharper images than anything else I saw from higher MP cameras and that is because the smaller the sensor resolution the sharper the images look at 100%.  Even though the increase of MP does increase resolution, but 100% crop reveals slight loss of detail and sharpness because of resolving issues, smaller pixel sizes and other minor things. What does that mean?  It means that if you are comparing a 36mp image with 22mp image at 100% the 22mp image will show slight more detail and sharpness due to the smaller sensor resolution.  However the 36mp will still maintain resolution advantage, and as I said before, that resolution advantage is clearly visibly on most distant objects such as tree branches and wires.

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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to John Sheehy, Apr 12, 2013

John Sheehy wrote:

When the original thread hit 150, what was being debated seemed to be what about what resolution is a measure of.  I don't think that there is a single meaning of resolution at all.  There are different kinds of resolution, one relevant more for one need than another.

Many people tend to shoot at medium and wide FOVs, and to those people, the resolution potential of the entire sensor and/or the system resolution with a lens is important.  Other people are almost always working with lenses that have too little magnification for their needs.  For example, only dead birds let you fill the frame the way you want all the time, and a photographer in the stands can't get the kinds of shots that they could get standing in the field, interfering with the game.  Jupiter only gets infinitesimally larger on the sensor if you drive towards it.  For such needs, higher pixel density is worth more, most of the time, than full sensor performance.

B

If that were absolute, the Pentax Q would be the most important wildlife/astrocamera extant.

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Mako2011
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In reply to John Sheehy, Apr 12, 2013

Mako2011 wrote:

The two types of "resolution" you're speaking of...are are more related to the concept of sharpness and not resolution.

Nonsense.  Did becoming a moderator give you a license to alter reality?

There are very few people more aware of the difference between resolution and sharpness (or acuity) than I.  I rail about the difference all the time.  I did not conflate them in my post.  It is all your doing.

perhaps then you should define resolution as I did above. That might help put everyone at a common point. Currently it appears you're interchanging the terms.
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aftab
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Re: Same
In reply to Mako2011, Apr 12, 2013

Mako2011 wrote:

aftab wrote:

How about resolution?

Scenario B

Does anyone really think that some people don't know that A has more resolution than B? Yeah, it shows so many line pairs/so much area.. yaada yaada and one can talk about how Fourier transform or that nyquist frequency can explain them. But everybody knows what they see, Resolution = Detail.

Same..in A and B above you can count and discern the same number of lines. The resolution of A and B is the same.

Now, we must talk about real world, because that is the norm in this forum (as if we can ever capture something that doesn't belong to this world:P).

Scenario C

A has more resolution than B, because we can count 1753 hair in A vs 1248 hair in B.

Now, let us look at scenario B and scenario C again. In both cases A looks sharper than B. What does that mean? More resolution = more sharpness. That is resolution = sharpness in this two scenarios. And almost all scenarios are like this. So, we can actually use the terms resolution and sharpness interchangeably.

Not the case at all. In scenario B...the resolution of the two images is equal. Sharpness though differs.

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)

I don't know if my line of thinking is right, but I invite you (and others) to it and give your opinion.

There is definition of sharpness and resolution and there is perception of them when we view a picture.

When we perceive a picture being sharp two conditions are fulfilled.

A. The picture has the details that we expect to see, either because of our past experience with the subject or because we are comparing more than one picture of the same subject side by side.

B. The details are seen clearly.

By definition these two conditions are separate entities. One is quantity. One is quality. One is resolution. One is sharpness.

Let's take a hypothetical but real world scenario. Two pictures of a piece of fabric. One taken with a FF 24 MP camera. The other with a FF 12 MP camera. Everything else including the lens used is same. 24 MP camera captured all the threads of the fabric distinctly. 12 MP camera captured 70% of the threads distinctly, rest 30% is not distinct or blurred. Now if we view these two pictures from same distance in same display size, the picture that shows 100% of the fabric threads distinctly will appears sharper than the one that shows 70% of the threads. You can extend this scenario to almost any other real life scenario, a face, a cat, a flower... almost anything that has any detail of significance. So, a picture with higher detail that matches our expectations/knowledge or better detail than another picture of the same subject in comparison will appear sharper. Simply put, we perceive higher resolution pictures as sharper than lower resolution pictures of the same subject when viewed in the same size to show the difference in detail and from the same distance. This is 'A' and this probably accounts for more than 90% of our perception of sharpness when we view see an image.

The contribution of 'B' to our perception of sharpness is minuscule compared to 'A'. After all, an information can't be seen clearly (or sharpened) if it can't be seen at all in the first place.

The condition 'A' can be emulated in many other ways we shoot. Using best aperture vs other apertures, using better lens vs poor lens etc.

I think in real life scenarios, 'detail' is the most important contributor to our perception of sharpness irrespective of how we achieve it. Yeah, we can manipulate an image and make clearer distinction between two adjacent threads, but detail remains at the heart of out perception of sharpness, the quality of detail contributing just a little.

So, from the perspective of our perception, resolution = sharpness.

So far we have looked at resolution from the perspective of sharpness. We can also do the opposite. Look at sharpness from the perspective of resolution. Any detail will be perceived as detail by a viewer if they are clear (or sharp) enough. So, if we look at the scenario A of my original post, by definition we will say A and B has the same resolution. But for a viewer B shows no detail at all (and hence no resolution), it is just a combination blurry stuffs. So, for a line pair to be a line pair (or detail to be a detail) some critical sharpness is essential. Sharpness contributes to our perception of of detail which in turn contributes to our perception of sharpness. They are inseparable.

Does my thinking make any sense, or it is all Penfold's fault?

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aftab
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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to Slideshow Bob, Apr 12, 2013

Slideshow Bob wrote:

Red wine definitely results in a loss of sharpness, and for that, there is no resolution.

SB

Ha ha. That is deep.

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schmegg
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Re: Same
In reply to aftab, Apr 12, 2013

aftab wrote:

Mako2011 wrote:

aftab wrote:

How about resolution?

Scenario B

Does anyone really think that some people don't know that A has more resolution than B? Yeah, it shows so many line pairs/so much area.. yaada yaada and one can talk about how Fourier transform or that nyquist frequency can explain them. But everybody knows what they see, Resolution = Detail.

Same..in A and B above you can count and discern the same number of lines. The resolution of A and B is the same.

Now, we must talk about real world, because that is the norm in this forum (as if we can ever capture something that doesn't belong to this world:P).

Scenario C

A has more resolution than B, because we can count 1753 hair in A vs 1248 hair in B.

Now, let us look at scenario B and scenario C again. In both cases A looks sharper than B. What does that mean? More resolution = more sharpness. That is resolution = sharpness in this two scenarios. And almost all scenarios are like this. So, we can actually use the terms resolution and sharpness interchangeably.

Not the case at all. In scenario B...the resolution of the two images is equal. Sharpness though differs.

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My opinions are my own and not those of DPR or its administration. They carry no 'special' value (except to me and Lacie of course)

I don't know if my line of thinking is right, but I invite you (and others) to it and give your opinion.

There is definition of sharpness and resolution and there is perception of them when we view a picture.

When we perceive a picture being sharp two conditions are fulfilled.

A. The picture has the details that we expect to see, either because of our past experience with the subject or because we are comparing more than one picture of the same subject side by side.

B. The details are seen clearly.

By definition these two conditions are separate entities. One is quantity. One is quality. One is resolution. One is sharpness.

Let's take a hypothetical but real world scenario. Two pictures of a piece of fabric. One taken with a FF 24 MP camera. The other with a FF 12 MP camera. Everything else including the lens used is same. 24 MP camera captured all the threads of the fabric distinctly. 12 MP camera captured 70% of the threads distinctly, rest 30% is not distinct or blurred. Now if we view these two pictures from same distance in same display size, the picture that shows 100% of the fabric threads distinctly will appears sharper than the one that shows 70% of the threads. You can extend this scenario to almost any other real life scenario, a face, a cat, a flower... almost anything that has any detail of significance. So, a picture with higher detail that matches our expectations/knowledge or better detail than another picture of the same subject in comparison will appear sharper. Simply put, we perceive higher resolution pictures as sharper than lower resolution pictures of the same subject when viewed in the same size to show the difference in detail and from the same distance. This is 'A' and this probably accounts for more than 90% of our perception of sharpness when we view see an image.

The contribution of 'B' to our perception of sharpness is minuscule compared to 'A'. After all, an information can't be seen clearly (or sharpened) if it can't be seen at all in the first place.

The condition 'A' can be emulated in many other ways we shoot. Using best aperture vs other apertures, using better lens vs poor lens etc.

I think in real life scenarios, 'detail' is the most important contributor to our perception of sharpness irrespective of how we achieve it. Yeah, we can manipulate an image and make clearer distinction between two adjacent threads, but detail remains at the heart of out perception of sharpness, the quality of detail contributing just a little.

So, from the perspective of our perception, resolution = sharpness.

So far we have looked at resolution from the perspective of sharpness. We can also do the opposite. Look at sharpness from the perspective of resolution. Any detail will be perceived as detail by a viewer if they are clear (or sharp) enough. So, if we look at the scenario A of my original post, by definition we will say A and B has the same resolution. But for a viewer B shows no detail at all (and hence no resolution), it is just a combination blurry stuffs. So, for a line pair to be a line pair (or detail to be a detail) some critical sharpness is essential. Sharpness contributes to our perception of of detail which in turn contributes to our perception of sharpness. They are inseparable.

Does my thinking make any sense, or it is all Penfold's fault?

I appreciate your posts - and I don't really disagree with most of what you say from a pragmatic standpoint.

However - I'm really not sure that it is helpful, conceptually, to attempt to espouse that resolution and sharpness are the same thing.

They are not.

Sharpness is the combination of resolution and acutance. Sharpness can vary independently of resolution. An image can be quite sharp but have low resolution (and high acutance). An image can also be soft but have high resolution (and low acutance). The best looking images have high resolution and high acutance - they appear sharp and detailed.

My personal opinion on this (as you've probably gathered as I've been pretty vocal on it - sorry) is that mixing these terms only leads to confusion down the track. You see comments like "a 5Dc out-resolves an 18MP crop" etc. These comments are made by people who are confused about these different imaging parameters - and probably because they simply have not conceptually separated and identified each for what it is (and what it is not).

I really think it's more useful to think of sharpness as what it is. And likewise resolution and acutance.

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Just another Canon shooter
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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to cpkuntz, Apr 12, 2013

cpkuntz wrote:

This isn't a half-bad introduction to the concept.

From Wikipedia:

http://en.wikipedia.org/wiki/Optical_resolution

Some optical sensors are designed to detect spatial differences in electromagnetic energy. These include photographic film, solid-state devices (CCD, CMOS detectors, and infrared detectors like PtSi and InSb), tube detectors (vidicon, plumbicon, and photomultiplier tubes used in night-vision devices), scanning detectors (mainly used for IR), pyroelectric detectors, and microbolometer detectors. The ability of such a detector to resolve those differences depends mostly on the size of the detecting elements.

Spatial resolution is typically expressed in line pairs per millimeter (lppmm), lines (of resolution, mostly for analog video), contrast vs. cycles/mm, or MTF (the modulus of OTF)). The MTF may be found by taking the two-dimensional Fourier transform of the spatial sampling function. Smaller pixels result in wider MTF curves and thus better detection of higher frequency energy.

I am not sure why my comment to this has disappeared.

This article explains how to measure resolution but not what it is. In an analog setting, things are clear - you measure the whole MTF curve, which determines the FT of the PSF, and then the PSF itself. Resolution is a function, not a number. On a sensor, this changes, which is the point John makes. You are pretending that you are measuring an analog signal but you are not. The discretization changes the nature of what you measure and even change of the angle of the slanted edge will change the result.

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schmegg
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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to Just another Canon shooter, Apr 12, 2013

Just another Canon shooter wrote:

cpkuntz wrote:

This isn't a half-bad introduction to the concept.

From Wikipedia:

http://en.wikipedia.org/wiki/Optical_resolution

Some optical sensors are designed to detect spatial differences in electromagnetic energy. These include photographic film, solid-state devices (CCD, CMOS detectors, and infrared detectors like PtSi and InSb), tube detectors (vidicon, plumbicon, and photomultiplier tubes used in night-vision devices), scanning detectors (mainly used for IR), pyroelectric detectors, and microbolometer detectors. The ability of such a detector to resolve those differences depends mostly on the size of the detecting elements.

Spatial resolution is typically expressed in line pairs per millimeter (lppmm), lines (of resolution, mostly for analog video), contrast vs. cycles/mm, or MTF (the modulus of OTF)). The MTF may be found by taking the two-dimensional Fourier transform of the spatial sampling function. Smaller pixels result in wider MTF curves and thus better detection of higher frequency energy.

I am not sure why my comment to this has disappeared.

No posts have been removed from this thread. You must be mistaken, or there is a gremlin. When did you post?

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