To Perspective Crop or not to Crop

[JohnRostron]

I recently posted an image of the Aysgarth Falls as an illustration of the problem of horizontal alignment of waterfalls. My wife likes waterfalls, so we tend to find ourselves at a number of waterfalls. In 2014 we went to the famous Ingleton Waterfalls in Yorkshire.

Below I post two images of Thornton Force ('Force' is a dialect word for waterfall) at the head of the Ingleton waterfall walk. The first is cropped but otherwise SOOC. The second has had a perspective crop applied to align the top and bottom of the waterfall to the horizontal.
#1 Without perspective crop:

#2 With perspective crop:


Given that there is going to be some loss of quality in the perspective transform, is #2 any real improvement on #1?

John

[Manfred M]

In photography, there are a lot of generalizations and of course there are always exceptions to those "rules". The general direction in any landscape shot is that the scene should look level and whenever possible I use a level to ensure that my shots are close; whether I use a tripod, a hot shoe bubble level or the electronic level in my camera. Even with all that measurement, sometimes the shot can be perfectly level, but the optics of the particular scene make things look off a bit, so I will then tweak the image in PP to make it "look level".

Is there a loss of quality? Yes, in theory, but unless you are printing the image, it's not something to consider as images are downsampled when you view on a computer screen or post to the internet. The theoretical loss in quality is more than compensated for by an image that looks "right". With the two images you posted, I find the second one "looks right" whereas the first one looks visually "wrong".

If you are worried about cropping too much, shot a bit wider and allow yourself some space all around that you don't mind losing during cropping.

[george013]

I recently posted an image of the Aysgarth Falls as an illustration of the problem of horizontal alignment of waterfalls. My wife likes waterfalls, so we tend to find ourselves at a number of waterfalls. In 2014 we went to the famous Ingleton Waterfalls in Yorkshire.

Below I post two images of Thornton Force ('Force' is a dialect word for waterfall) at the head of the Ingleton waterfall walk. The first is cropped but otherwise SOOC. The second has had a perspective crop applied to align the top and bottom of the waterfall to the horizontal.
#1 Without perspective crop:

#2 With perspective crop:


Given that there is going to be some loss of quality in the perspective transform, is #2 any real improvement on #1?

John

Be careful to level on horizontal lines. Unless those lines, the waterfall, are parallel to your sensor, it's never parallel to the image boarders. Use vertical lines, but you don't have them in your image.

I think the original is better.

George

[Wavelength]

I feel the perspective correction was necessary because looking at the first image i feel the whole water would now fall my lap

[AlwaysOnAuto]

I say the first is more 'correct' looking because you don't have the camera square in front of the falls. If you did then you could line up the top edge of the falls horizontally. Doing so in the second shot has distorted the perspective of the near side of the fall edge being closer to the camera than the far side, thus it looks wrong, to me anyways.

[Wavelength]

I remember one experience of mine; when i travel in train rainy season, water pools are seen formed at the base very small hills close to the track and the water pools appear to remain slanted towards the viewer. So i think the original view itself can be deceiving; again if we look upwards amidst surrounding tall building we see them tapering to the centre. So which is right, to keep the same in photograph or apply distortion correction? i am not sure

[bnnrcn]

Hi John I find the original better as it looks better with the environment. Your correction could have looked better though if you hadn't lost most of the environment when cropping. I think which one looks better depends on the scene you shoot , some scenes might look very nice even if you don't apply perspective correction and some scenes might not

[dje]

Hi John

In general, I think that perspective correction is more important for cityscapes with buildings than for more natural scenes. That's not to say it shouldn't be used for natural scenes though. In this case, an alternative to perspective cropping would be to simply rotate the image so that the bottom area of the falls looks about horizontal.



Incidentally when I use the Perspective crop tool, I usually do my sharpening for the image after the perspective correction, That way, sharpening can be used to compensate for an extra small loss in sharpness caused by the transform

Dave

[MrB]

I agree with Nandakumar, that the pool is the key here - in the first image it appears to be tipping over, as though the water would flow out of the image to the left.

I also agree with Dave, that a simple clockwise rotation is needed. However, not quite so much is needed to level the pool.

As Alan points out, the camera is not square in front of the falls - the 'face' of the falls is going away from us. An additional point is that the camera is positioned some distance above the surface of the pool but way below the top of the falls. These factors together will produce a perspective view that converges the top and bottom edges of the falls:



Cheers.
Philip

[dje]

These factors together will produce a perspective view that converges the top and bottom edges of the falls:
Cheers.
Philip

Yes I think that's the point here - it is a perspective view and it's not necessary (or even desirable probably) to have everything either horizontal or vertical for a scene like this.

Dave

[Jimr1961]

What looks "straight" to me is right smack dab between the original and the adjusted. What Manfred (and I'm sure others alluded to, but I won't re-read them all) said speaks to me. I've had many shots that needed to be adjusted by my eye and my gut so it just "feels" straight. I'm sure the mind interprets this based on various converging lines, whether we can articulate it or not.

[JohnRostron]

Thanks to all for commenting. I agree with most of what people have said. There is no 'right' answer. What looks OK to some looks somehow wrong to others.This particular shot was unusual (for me) in that the upper edge of the waterfall is above my eye-line and the lower edge is below it. My conclusion is that it is best to leave the perspective as it is unless there is some very good reason not to.

John

[george013]

Thanks to all for commenting. I agree with most of what people have said. There is no 'right' answer. What looks OK to some looks somehow wrong to others.This particular shot was unusual (for me) in that the upper edge of the waterfall is above my eye-line and the lower edge is below it. My conclusion is that it is best to leave the perspective as it is unless there is some very good reason not to.

John

One remark. You call it perspective but it's leveling what you mean.

George

[JohnRostron]

One remark. You call it perspective but it's leveling what you mean.

George

No, the perspective is what is present in the original image. Levelling is what you might do to it, which actually destroys the original perspective.

John

[AlwaysOnAuto]

I think the original shot stands best as is. The line of the falls at the top is going away from the camera. The line of the falls at the bottom isn't parallel with the top, it is actually coming out from the wall the water is falling down as well as going away from the camera. This coming out starts at about where the tree limb crosses the falls.
I think you did a nice job of capturing the falls John.

[William W]

. . . Given that there is going to be some loss of quality in the perspective transform, is #2 any real improvement on #1?

Initially, disregarding any loss of Image Quality, I think the process to answer your question is this:

A. What is the Subject?
B. What is the Purpose of the Image?

If the Subject is something akin to "Landscape", then #2 is no improvement upon #1 because the (natural) Perspective of the Scene is integral

If the Subject is something akin to "Waterfall" then move to question (B)

If the Purpose is something akin to "Show waterfall in situ", then #2 is no improvement upon #1 because the (natural) Perspective of the Waterfall is integral to showing it, in situ

If the purpose is something akin to "Artist's rendition of Waterfall" or "Geometry of Waterfall" then #2 is an an improvement upon #1 because the oddment of the skewed perspective ascribes value and attention to it (The Waterfall).

***

On the loss of Image Quality, the original (as much as one cane tell) is in pretty good shape technically and if you use a reasonable quality PP program (like Photoshop as one example) for the slight Perspective Correction necessary, there would be not much loss for a 10 x 8 print, you might see at 20 x 16 or larger.


***

I don't necessarily agree with the line of thinking that the pool is tipping over: I think that often once "an issue" is raised, then that "issue" is all that is seen.

Though we can't have the time over, I wonder if the original mage were simply place up for C&C, what "issues" would be discussed.

Although: It appears to my eye that a ROTATION was also applied (i.e. using PS nomenclature - "Rotation" was applied in addition to "Perspective Correction") and if that is the case then my comments above doe NOT refer to the "Rotation".

What I mean is - it appears the camera was NOT parallel to the Ground Line, (i.e was not "level") and I think that should be corrected, even if it is only to render the "correctness" of the Waterfall as it appears within the Landscape Scene.

WW

Addendum:

Re-reading the whole conversation - my last four paragraphs are exactly what Dave Ellis wrote: sorry I didn't notice that earlier.