Is perspective control allowed in...

09/08/2005 12:38:16 AM · #1

Is using the PS crop tool with perspective control allowed in basic challenge?

Pentax DA 18-55mm f/3.5-5.6 AF

09/08/2005 12:38:58 AM · #2

Nope. It's considered "moving pixels" or somesuch. There was a thread on this a ways back.

R.

faidoi

Pentax K10D

09/08/2005 12:48:19 AM · #3

What no shift lens? :P

AzCKelly

Nikon D70s

Nikon AF-S DX Zoom-Nikkor 55-200mm f/4.0-5.6G ED

09/08/2005 01:01:23 AM · #4

I am new here so don't laugh but what is "PS Crop Tool"? Is that part of a software feature?

Canon EF 70-300mm f/4.5-5.6 DO IS USM

09/08/2005 01:02:33 AM · #5

Originally posted by AzCKelly:

I am new here so don't laugh but what is "PS Crop Tool"? Is that part of a software feature?

Photoshop Crop Tool

cpanaioti

Canon EOS-40D

09/08/2005 01:02:35 AM · #6

Originally posted by AzCKelly:

I am new here so don't laugh but what is "PS Crop Tool"? Is that part of a software feature?

It's the crop tool in photoshop. You'll see a lot of references to PS in the forums as well as PSP (Paintshop Pro).

Nikon AF-S DX Zoom-Nikkor 55-200mm f/4.0-5.6G ED

09/08/2005 01:04:20 AM · #7

Originally posted by AzCKelly:

I am new here so don't laugh but what is "PS Crop Tool"? Is that part of a software feature?

Photoshop Crop Tool; it's how we crop images in Photoshop. He's also referring to a sophisitcated "perspective adjustment" feature in photoshop that allows you to make converging lines parallel (or parallel lines converging, for that matter).

*******

Nsbca,

Now that I've thought back, I seem to recall the baseline reason for disallowing perspective control in basic challenges was that it requires making a selection first, btw...

Robt.

AzCKelly

Nikon D70s

09/08/2005 01:13:52 AM · #8

Got it, Thanks.

09/08/2005 01:17:45 AM · #9

Originally posted by bear_music:

*******

Nsbca,

Now that I've thought back, I seem to recall the baseline reason for disallowing perspective control in basic challenges was that it requires making a selection first, btw...

Robt.

So does cropping.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/08/2005 01:37:18 AM · #10

Originally posted by nsbca7:

Originally posted by bear_music:

*******

Nsbca,

Now that I've thought back, I seem to recall the baseline reason for disallowing perspective control in basic challenges was that it requires making a selection first, btw...

Robt.

So does cropping.

Well, yeah, but that's the one, specific exception to the no-selections rule... But what do I know? I'm not SC...

R.

Tom_Robbrecht

09/08/2005 02:03:10 AM · #11

Originally posted by faidoi:

What no shift lens? :P

I believe using a shift lense would be legal because the perspective control is done in-camera.

Message edited by author 2005-09-08 02:03:50.

violeta

Sony DSC-P41

09/08/2005 02:07:23 AM · #12

all i know is that i entered two contests so far and i got disqualified for both. the first one i understand why but the branch one really pisses me off cuz i did nothing wrong...

GeneralE

Canon PowerShot S3 IS

09/08/2005 02:25:30 AM · #13

Originally posted by violeta:

all i know is that i entered two contests so far and i got disqualified for both. the first one i understand why but the branch one really pisses me off cuz i did nothing wrong...

Apparently, when requested, you did not submit an original file within the time allowed. There should have been both an email and a notice on your Home page at DPC informing you of the need to send in the original ... that's all I can tell you here.

And, no, you can't use any (software) perspective tools in Basic Rules challenges. If you do it physically with the camera/lens/etc. and capture the image directly it's OK.

Message edited by author 2005-09-08 02:27:14.

HBunch

HP PhotoSmart 315

09/08/2005 02:32:56 AM · #14

Originally posted by violeta:

all i know is that i entered two contests so far and i got disqualified for both. the first one i understand why but the branch one really pisses me off cuz i did nothing wrong...

violeta, I'm sending you a PM. We can discuss your DQ privately. Or you can IM me at hbunch7187 if you have instant messaging.

Chiqui

Olympus OM-D E-M1 Mark II

Olympus 12-40mm f/2.8 Pro

09/08/2005 03:43:42 AM · #15

If the whole point of the challenge is to use perspective to your advantage, why would you want to correct it? Just curious.

June

Rikki

Canon EOS-20D

Canon EF 17-40mm f/4L USM

09/08/2005 03:45:40 AM · #16

oxymoron?

09/08/2005 04:08:25 AM · #17

Originally posted by chiqui74:

If the whole point of the challenge is to use perspective to your advantage, why would you want to correct it? Just curious.

What??????? Do you know what the word perspective means?

I'm not trying to be rude here, but the callenge states "Use perspective to create a dramatic effect with your photograph".

I don't see anything in there that says anything about distorted or any other kind of perspective. And what makes you think I was going to do corrections in Perspective Control?

per·spec·tive
n.

1) A view or vista.
2) A mental view or outlook: �It is useful occasionally to look at the past to gain a perspective on the present� (Fabian Linden).
3) The appearance of objects in depth as perceived by normal binocular vision.

4) The relationship of aspects of a subject to each other and to a whole: a perspective of history; a need to view the problem in the proper perspective.
5) Subjective evaluation of relative significance; a point of view: the perspective of the displaced homemaker.
6) The ability to perceive things in their actual interrelations or comparative importance: tried to keep my perspective throughout the crisis.
7) The technique of representing three-dimensional objects and depth relationships on a two-dimensional surface.

And BTW, perspective has no more to do with a wide angle lens as it does with any other lens.

Message edited by author 2005-09-08 04:09:10.

Olympus OM-D E-M1 Mark II

09/08/2005 04:52:24 AM · #18

Originally posted by nsbca7:

And BTW, perspective has no more to do with a wide angle lens as it does with any other lens.

While this may be strictly true (the rendering of 3-dimensional shapes onto a 2-dimensional surface will involve perspective no matter what lens is used) it's nevertheless true that the wider-angle the lens, the more dramatic the perspective will be, all other things being equal.

Originally posted by chiqui74:

If the whole point of the challenge is to use perspective to your advantage, why would you want to correct it? Just curious.

Photoshop's perspective control can be used to exaggerate perspective as easily as it can correct it. It's a moot point for this challenge, though, since it's basic editing rules.

Robt.

Chiqui

Olympus 12-40mm f/2.8 Pro

09/08/2005 05:00:33 AM · #19

Originally posted by nsbca7:

Originally posted by chiqui74:
If the whole point of the challenge is to use perspective to your advantage, why would you want to correct it? Just curious.

What??????? Do you know what the word perspective means?

I'm not trying to be rude here, but the callenge states "Use perspective to create a dramatic effect with your photograph".

I don't see anything in there that says anything about distorted or any other kind of perspective. And what makes you think I was going to do corrections in Perspective Control?

per·spec·tive
n.

1) A view or vista.
2) A mental view or outlook: �It is useful occasionally to look at the past to gain a perspective on the present� (Fabian Linden).
3) The appearance of objects in depth as perceived by normal binocular vision.

4) The relationship of aspects of a subject to each other and to a whole: a perspective of history; a need to view the problem in the proper perspective.
5) Subjective evaluation of relative significance; a point of view: the perspective of the displaced homemaker.
6) The ability to perceive things in their actual interrelations or comparative importance: tried to keep my perspective throughout the crisis.
7) The technique of representing three-dimensional objects and depth relationships on a two-dimensional surface.

And BTW, perspective has no more to do with a wide angle lens as it does with any other lens.

My bad. You did ask about perspective control so I assumed correction.

June

taterbug

Nikon D300

Nikon AF Nikkor 50mm f/1.4D

09/08/2005 05:16:33 AM · #20

Originally posted by chiqui74:

If the whole point of the challenge is to use perspective to your advantage, why would you want to correct it? Just curious.

June

An example I can think of would be to correct for barrel distortion. A lot of digital cameras (especially the non dslr) due to small sensors, tend to have some barrel distortion that especially manifests when shooting tall things, like buildings. This will make them look like the leaning tower of Pisa (the tops will look like they're leaning over). You can use the perspective tool to straighten up those buildings or tall objects. I believe that is why it would be illegal in basic editing, because it does select and move certain pixels, it leaves the base, and un-tilts the tops. It's a cool tool, but takes a little playing around to use effectively.

So in other words, you might use a cool perspective in your shot, like for example from the base of a building looking up, but not want it skewed or to look like it is leaning over. The perspective is just the 'point of view' basically. It doesn't mean that it has to be distorted or skewed. Just using a cool point of view (perspective) to make the impact of your shot. For example, if you were to stand in front of a door, and take a shot, it probably wouldn't have a lot of interest to it, that's the point of view everyone always sees the door from. But if you were to say, get down on the ground and shoot up at the door, or climb up on a ladder and shoot down at it, those would be a point of view or perspective that people are not used to seeing the door from, thus adding drama, or dynamics, or interest to the shot.

Of course, that's just my line of thinking, I could be totally nuts, it has been known to happen :-)

09/08/2005 05:35:13 AM · #21

Originally posted by taterbug:

Barrel distortion is not affected by perspective alterations. There ARE tools that allow you to remove barrel distortion (the rendering of straight lines as curves) but the PS perspective control does not do this. I have a tool from Richard Rosenmann called "Lens Corrector Pro" that can be used to remove (or add, it can even create a fisheye effect) barrel and spherical distortion from images. I needed it with my Coolpix 5700, but none of my lenses on the 20D show any barrel or spherical distortion at all so it's gathering dust now.

What you're describing is a straight perspective effect, "converging verticals" and it's universal to any lens, regardless of its optical quality. Any time the given face of an object is not parallel to the imaging plane of the camera, there WILL be convergence (or divergence, if you're looking down from up high). Perspective control in PS allows you to manipulate that convergence, either by decreasing it or increasing it, as you choose. In fact, you can ADD convergence (create a vanishing point) even in images that show parallel lines out of the camera.

A related control is the "skew" control, which you would use if you wanted to keep the convergence but it seemed off-center (leaning to left or right rather than converging equally on both sides of the implied vertical), in which case you could skew the top of the image right or left to correct for this.

Robt.

Canon EF 300mm f/2.8L IS USM

09/08/2005 05:41:26 AM · #22

It's worth noting that all of this discussion (except nsbca's detailed definition) is ASSUMING that the "logical" interpretation of "perspective" in this challenge is limited to the presence of strong vanishing points and receding/converging lines. While it's possibly true that this is what the average voter will fixate on, there are other possible takes, including (for one example) the sort of perspective-of-size that comes when you combine near and far objects of visually recognizable size within the same image.

Here's a good example of the above by Neil Shapiro: note that there are no strongly-defined receding lines (not any straight ones anyway, though there are implied receding lines in the rock detail) but there's a dramatic near/far perspective effect between the pool and the lighthouse.

Robt.

Message edited by author 2005-09-08 05:42:20.

Skip

Canon EOS-1D X

09/08/2005 05:51:26 AM · #23

Originally posted by bear_music:

good point, bear. the photoinf article in this other thread identifies these types of perspective:

..Linear Perspective
..Rectilinear Perspective
..Vanishing Point Perspective
..Height Perspective
..Overlap Perspective
..Dwindling Size Perspective
..Volume Perspective
..Atmospheric Perspective

this article should be required reading for anyone VOTING on this challenge...

Message edited by author 2005-09-08 05:51:56.