Doug Kerr
Well-known member
If I ever used Photoshop, I would already know part of the answer to this, but I don't, so I don't.
I sometimes have to correct for perspective effects in post-processing when dopng something like taking a photgraph of a quilt design when I can't shoot it head on (and don't have a tilt/shift lens either) but want a rectilinear mapping of the object in the image.
My image editor has what is described as a perspective correction facility, but it turns out that it really isn't. What it allows is to take an oblect containing the original image and stretch it along one axis and "make it trapezoidal" as well.
This gives me a representation of the rectanguar object that is rectangular, all right, and with the right overall aspect ratio, but not rectilinear. The reason of course is that the geometry of the shot results in a non-linear stretching of the object features from "top to bottom" of the shot.
So, for example, if I was shooting a quilt made up of square blocks, when I am done the blocks at the original "far side" will not be square in the image, although those at the near side are square.
Another way to say this is that I can fix the image so the vertical edges of buildings are straight lines in the image, but diagonal lines on the face of the building (as on the "Dos Equis" building in Dallas) are not.
Will Photoshop let me actually deal with this? I haven't played yet, and the discussion in the help system isn't encouraging.
If not, are there other tools to do this in postprocessing?
Thanks.
I sometimes have to correct for perspective effects in post-processing when dopng something like taking a photgraph of a quilt design when I can't shoot it head on (and don't have a tilt/shift lens either) but want a rectilinear mapping of the object in the image.
My image editor has what is described as a perspective correction facility, but it turns out that it really isn't. What it allows is to take an oblect containing the original image and stretch it along one axis and "make it trapezoidal" as well.
This gives me a representation of the rectanguar object that is rectangular, all right, and with the right overall aspect ratio, but not rectilinear. The reason of course is that the geometry of the shot results in a non-linear stretching of the object features from "top to bottom" of the shot.
So, for example, if I was shooting a quilt made up of square blocks, when I am done the blocks at the original "far side" will not be square in the image, although those at the near side are square.
Another way to say this is that I can fix the image so the vertical edges of buildings are straight lines in the image, but diagonal lines on the face of the building (as on the "Dos Equis" building in Dallas) are not.
Will Photoshop let me actually deal with this? I haven't played yet, and the discussion in the help system isn't encouraging.
If not, are there other tools to do this in postprocessing?
Thanks.