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Old April 23rd 18, 04:40 AM posted to rec.photo.digital
Savageduck[_3_]
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Default The Photoshop "Straighten Tool"?

On Apr 22, 2018, Peter Jason wrote
(in ):

On Sun, 22 Apr 2018 18:17:39 -0700, Savageduck
wrote:

On Apr 22, 2018, Peter Jason wrote
(in ):

On Sun, 22 Apr 2018 17:00:40 -0700, Savageduck
wrote:

On Apr 22, 2018, Savageduck wrote
(in iganews.com):

On Apr 22, 2018, Peter Jason wrote
(in ):

Wide-angle photos have a confusing number of lines.

Which one should be used for straightening the image?

One in the very center perhaps?

Which edition of Photoshop are you using?
Not all editions have all the correction tools that later editions have.

Are you working with RAW or JPEG files?
Some corrections are better made with RAW files, and some tools might not
be available to JPEGs.

There are several methods of correcting wide-angle lens distortion with
Photoshop and/or Lightroom.

Sometimes, if you are lucky, just having a correct lens profile can
correct non-extreme distortion provided the FL is not too extreme.

If you are processing RAW files then you would start with ACR or
Lightroom, and use the Lens Correction tools, Transition with guided correction.
This is probably the most effective correction for wide-angle lens distortion.

There is the Adaptive Wide Angle Filter which can Auto correct if there
is a matching lens profile, or the manual Perspective correction which
requires some understanding how the filter is used. You also have options for Fish
Eye lens correction, or full Spherical correction.

Using the Adaptive Wide Angle filter, manual Perspective correction you
can use any number of distorted lines which should be straight for
correction.
Understand that with an Ultra Wide Angle lens the greatest distortion is
going to be away from the center line, and over correction can induce
unwanted distortion of straight lines in the center of the image.

Good Luck.

BTW: What WA lens and camera combination are you using?

Thank you.

I have PhotoShop 6


Is that PS6 (very old), or PS CS6?

I have just installed Photoshop CC 2015 on the other computer.


PS CC 2015?? PS CC is currently PS CC 2018. Are you subscribing to Adobe CC
which will give you the current editions of PS CC 2018 and LR CCC 2018?

(These two have the RAW processors)


So does PS CS6 if that was what you were talking about.

I use several cameras:
Olympus E500 (Usually the kit Lens)
Olympus E5 (Wide Angle Zuiko lenses)
Smart phone
A Panasonic Lumix (fixed lens with zoom)


OK, but how wide, what focal lengths?


The kit lenses of Olympus do rather well for me. For small rooms I
use the Zuiko 7 - 14 F4. All 2/3 of course.


OK, that is a fairly nice WA.


I use jpegs normally, but RAW for contrasty group shots)


Then you are wasting all that RAW can provide.

The straighten tool is faster to use than the others,


The straighten tool does nothing to correct wide angle lens distortion, it
will only straighten undistorted vertical or horizontal lines. To correct WA
distorted lines you will need to use either the Guided Transform tool found
in the lens correction panel in ACR or Lightroom, or the Adaptive Wide Angle
Filter in Photoshop.


One loses a fair amount of the edges with distortion correction. But
I have used these.


So? Do you want to straighten a vertical, or horizon in the image, or are you
trying to fix diverging/converging lineds due to WA lens distortion?

If all you are trying to do is fix a horizon, or straighten a vertical, then
use the straighten tool on a horizontal line, or a vertical line closest to
the center. Just understand that none of the WA lens distortion is going to
be corrected. Also with either straightening, or distortion correction there
can be data loss at corners, and/or edges, which can be fixed if you check
the “Constrain to Crop” box, or use auto fill.

The Transform tool (in ACR lens correction/Lightroom Transform) will actually
do a much better job of straightening.

I would suggest that you check on some of the video tutorials which are
available on this subject.

--

Regards,
Savageduck