There's a theory that it's better to compress than stretch as it's
less 'lossy - requires less interpolation of 'new' pixels. Don't know
if it's true or merely plausible.
Andrew Fildes
afildes@xxxxxxxxxxxxx
On 10/04/2009, at 10:28 PM, Chuck Norcutt wrote:
> Since you've asked on-list as well as off I'm posting the same
> response
> here below that I sent you privately.
>
> Chuck Norcut
> ---------------------------------------------
>
> Use Edit => Transform => Perspective (or Distort). Pull the sides of
> the image window out away from the image about 25% on each side so you
> have some room to work outside the bounds of the image.
>
> You will see that there is a bounding box drawn around the image.
> Change the perspective by pulling or pushing the corners of the box
> outside of or inside of the image. If you are using the "Perspective"
> transform both sides of the box will move together and apply equal
> correction on both sides. If you are using the "Distort" transform
> each
> side will move independently. In a recent post Moose commented
> that he
> preferred the Distort transform because sometimes it helps to be
> able to
> apply slightly different transforms on either side. I agree. But I
> would suggest you try the Perspective transform first. Then, after
> you
> see what it does when you pull the top right corner straight out,
> cancel
> out and switch to Distort and adjust each side individually to... what
> just looks right.
>
> Vertical perspective is altered by pushing the corners at top or
> bottom
> horizontally in or out. Horizontal perspective is altered by pushing
> the corners up or down. Rarely an image may require both. But we
> expect to see horizontal perspective as the image recedes to the
> "vanishing point". So use horizontal perspective control sparingly if
> at all.
>
> When you took this shot the camera was pointing upward causing the top
> to angle in. To correct it pull the top corners outward. Had you been
> at a high vantage point and were pointing the camera down the image
> would angle in at the bottom rather than the top. In that case
> pull the
> bottom corners outward. You can also make corrections in the opposite
> direction by pushing the corners inside of the image. But if you do
> that you will be overlaying the original image area and will need to
> crop the final output. Finally, note that both the Perspective and
> Distort transforms have a center "handle" at the sides of the bounding
> box. The Perspective transform doesn't allow you to do anything with
> that. The Distort transform will allow you to evenly squeeze or
> expand
> the width or height of the image by pushing or pulling the center
> handle.
>
> To avoid vertical perspective distortion when shooting the camera must
> be level. To avoid horizontal perspective distortion the image plane
> must be square to the subject. Generally, watch the vertical but
> don't
> sweat the horizontal.
>
> Hope that helps. If it's not clear ask away.
>
> Chuck Norcutt
>
>
>
> Nathan Wajsman wrote:
>> Hi Chuck,
>>
>> As I said on the Oly list, I agree with you and really like your
>> correction. I must admit that my Photoshop skills are not
>> sufficient to
>> make such a fix--so if you can tell me how you did it, I would
>> appreciate it.
>>
>> Cheers,
>> Nathan
>>
>> Nathan Wajsman
>> Alicante, Spain
>> http://www.frozenlight.eu
>> http://www.greatpix.eu
>> http://www.nathanfoto.com
>>
>> Books: http://www.blurb.com/bookstore/search?search=wajsman&x=0&y=0
>> PICTURE OF THE WEEK: http://www.fotocycle.dk/paws
>> Blog: http://www.fotocycle.dk/blog
>>
>>
>>
>> On Apr 9, 2009, at 12:53 PM, Chuck Norcutt wrote:
>>
>>> I very much like "pews" but it's calling out to be corrected.
>>>
>>> Chuck Norcutt
>>>
>>> Nathan Wajsman wrote:
>>>> Last weekend I took the family skiing in Sierra Nevada. Since I
>>>> don't
>>>> ski, I used Saturday to drive to nearby Granada and have a walk
>>>> around
>>>> that city, my first visit there. As usual, a small gallery of
>>>> somewhat
>>>> eclectic images is the result:
>>>>
>>>> http://www.frozenlight.eu/granada0409/
>>>>
>>>> I did not get to the Alhambra, the queue was too long. That will
>>>> have
>>>> to wait for the next visit, and there will certainly be one--I
>>>> found
>>>> Granada to be an extremely interesting city.
>>>>
>>>> As always, comments and critique are welcome and appreciated.
>>>>
>>>> Nathan
>>>>
>>>> Nathan Wajsman
>>>> Alicante, Spain
>>>> http://www.frozenlight.eu
>>>> http://www.greatpix.eu
>>>> http://www.nathanfoto.com
>>>>
>>>> Books: http://www.blurb.com/bookstore/search?search=wajsman&x=0&y=0
>>>> PICTURE OF THE WEEK: http://www.fotocycle.dk/paws
>>>> Blog: http://www.fotocycle.dk/blog
>>>>
>>>>
>>>>
>>> --
>>> _________________________________________________________________
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>>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>>
>>
>>
>>
>
> --
> _________________________________________________________________
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>
>
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