post-process photos of flat rectangular objects to removeperspective

Hi,

I am looking for a tool to post-process the following type of photo:

Given a series of photos of flat rectangular objects, such as book
covers, letters, magazines, posters, taken against an uniform
background.

One object per photo, slightly skewed and rotated due to perspective,
since the camera is usually not exactly aligned. (suppose a scanner is
not an option)

I am searching for a tool that allows quick post-processing to remove
the distortion introduced by the perspective, and to discard
unnecesary background. In the end the object should be aligned with
the picture borders and fill the whole picture

So either this tool should be able to recognize the rectangular shape
automatically and guess the correct transformation, or let me quickly
change the shear/rotation/cut manually until the object fits.
Optionally there would also be a filter to remove glare.

Most image manipualtion software can already do the manual part
somewhat, but at least with the Gimp is very cumbersome to do this for
a series of pictures and requires lots of adjustments and clicks.

Is there any tool good for this sort of task?

"Hugo Trebl" <singalong@dodgeit.com> wrote in message
news:4738c02f-8373-457c-9ca1-4f8190ecb17c@a70g2000hsh.googlegroups.com...
> Hi,
>
> I am looking for a tool to post-process the following type of photo:
>
> Given a series of photos of flat rectangular objects, such as book
> covers, letters, magazines, posters, taken against an uniform
> background.
>
> One object per photo, slightly skewed and rotated due to perspective,
> since the camera is usually not exactly aligned. (suppose a scanner is
> not an option)
>
> I am searching for a tool that allows quick post-processing to remove
> the distortion introduced by the perspective, and to discard
> unnecesary background. In the end the object should be aligned with
> the picture borders and fill the whole picture
>
> So either this tool should be able to recognize the rectangular shape
> automatically and guess the correct transformation, or let me quickly
> change the shear/rotation/cut manually until the object fits.
> Optionally there would also be a filter to remove glare.
>
> Most image manipualtion software can already do the manual part
> somewhat, but at least with the Gimp is very cumbersome to do this for
> a series of pictures and requires lots of adjustments and clicks.
>
> Is there any tool good for this sort of task?

I have no doubt that there are a number of software solutions.

But the very best solution requires almost no Post Processing, it is called
a Copy Stand and your camera fits onto it. You can use a suitable
background below the book, and if you arrange the lighting correctly there
should be no glare.

Roy G

On Fri, 18 Jul 2008 00:53:39 +0100, "Roy G" <roy.gibson1@virgin.net>
wrote:

>
>"Hugo Trebl" <singalong@dodgeit.com> wrote in message
>news:4738c02f-8373-457c-9ca1-4f8190ecb17c@a70g2000hsh.googlegroups.com...
>> Hi,
>>
>> I am looking for a tool to post-process the following type of photo:
>>
>> Given a series of photos of flat rectangular objects, such as book
>> covers, letters, magazines, posters, taken against an uniform
>> background.
>>
>> One object per photo, slightly skewed and rotated due to perspective,
>> since the camera is usually not exactly aligned. (suppose a scanner is
>> not an option)
>>
>> I am searching for a tool that allows quick post-processing to remove
>> the distortion introduced by the perspective, and to discard
>> unnecesary background. In the end the object should be aligned with
>> the picture borders and fill the whole picture
>>
>> So either this tool should be able to recognize the rectangular shape
>> automatically and guess the correct transformation, or let me quickly
>> change the shear/rotation/cut manually until the object fits.
>> Optionally there would also be a filter to remove glare.
>>
>> Most image manipualtion software can already do the manual part
>> somewhat, but at least with the Gimp is very cumbersome to do this for
>> a series of pictures and requires lots of adjustments and clicks.
>>
>> Is there any tool good for this sort of task?
>
>I have no doubt that there are a number of software solutions.
>
>But the very best solution requires almost no Post Processing, it is called
>a Copy Stand and your camera fits onto it. You can use a suitable
>background below the book, and if you arrange the lighting correctly there
>should be no glare.
>
I do a lot of tabletop photography shooting straight down on the
subject. I'd love to have a copy stand, but it's just another piece
of equipment to buy. I use a car window clamp with a ball head. The
clamp is attached to board c-clamped to a table. Ugly, but cheap and
utilizes a piece of equipment I already owned.

--
Tony Cooper - Orlando, Florida

On Thu, 17 Jul 2008 06:16:28 -0700 (PDT), Hugo Trebl <singalong@dodgeit.com>
wrote:

>Hi,
>
>I am looking for a tool to post-process the following type of photo:
>
>Given a series of photos of flat rectangular objects, such as book
>covers, letters, magazines, posters, taken against an uniform
>background.
>
>One object per photo, slightly skewed and rotated due to perspective,
>since the camera is usually not exactly aligned. (suppose a scanner is
>not an option)
>
>I am searching for a tool that allows quick post-processing to remove
>the distortion introduced by the perspective, and to discard
>unnecesary background. In the end the object should be aligned with
>the picture borders and fill the whole picture
>
>So either this tool should be able to recognize the rectangular shape
>automatically and guess the correct transformation, or let me quickly
>change the shear/rotation/cut manually until the object fits.
>Optionally there would also be a filter to remove glare.
>
>Most image manipualtion software can already do the manual part
>somewhat, but at least with the Gimp is very cumbersome to do this for
>a series of pictures and requires lots of adjustments and clicks.
>
>Is there any tool good for this sort of task?

I know of no automated systems that will do this but there is some editing
software that makes this completely painless, using just one tool in one step.

Photoline from www.pl32.com

This program does more and does it better than anything that Adobe has ever
sold. Unfortunately (or fortunately), Photoline is not for the stupid and inept,
those that need to be hand-held all the time with tutorials and hints from more
experienced people. You know who they are because they are mindless sheep
following the brainless Photoshop masses, the blind leading the blind. You must
know how to use an advanced editor to begin with before you can comprehend the
depths of Photoline. This program intimidates most people so they just claim how
lousy it must be. But in reality they are only revealing how inexperienced and
stupid they are. It's all quite amusing.

From some Photoline information online: "...select a crop area with the Lasso
Tool, rotate the Lasso while holding down CTRL, resize it proportionally or
freely with ALT or SHIFT keys, correct perspective with CTRL + ALT, select
"Straighten" in the Lasso's Tool Settings, input a Soft Edge number, and then
press "Crop Lasso". This will add a feathered border, remove any tilt, correct
distortion, and crop the image to your final Lasso/Mask all at once. (Hold down
SHIFT while pressing "Crop Lasso" puts your edits into a new window.) Seeing /
Doing this just once starts to make you appreciate why the authors didn't bother
following others' lame conventions."

Localized glare is a whole other matter. You will have to learn advanced editing
functions and how to work with contrast and curve brushes on different color
channels to bring those areas back to the same contrast, colors, and intensity
as the rest of the image. Simple to do in Photoline but you must have some
editing experience of this nature or you'll be lost. Or learn how to take your
photos properly to begin with so you don't have to deal with this seemingly
difficult editing problem.

On Jul 17, 9:16 am, Hugo Trebl <singal...@dodgeit.com> wrote:
> Hi,
>
> I am looking for a tool to post-process the following type of photo:
>
> Given a series of photos of flat rectangular objects, such as book
> covers, letters, magazines, posters, taken against an uniform
> background.
>
> One object per photo, slightly skewed and rotated due to perspective,
> since the camera is usually not exactly aligned. (suppose a scanner is
> not an option)
>
> I am searching for a tool that allows quick post-processing to remove
> the distortion introduced by the perspective, and to discard
> unnecesary background. In the end the object should be aligned with
> the picture borders and fill the whole picture
>
> So either this tool should be able to recognize the rectangular shape
> automatically and guess the correct transformation, or let me quickly
> change the shear/rotation/cut manually until the object fits.
> Optionally there would also be a filter to remove glare.
>
> Most image manipualtion software can already do the manual part
> somewhat, but at least with the Gimp is very cumbersome to do this for
> a series of pictures and requires lots of adjustments and clicks.
>
> Is there any tool good for this sort of task?


Copystand and a short macro lens, no perspective problems. Use a short
macro 35-50mm anyway will greatly reduce perspective problems,
providing you can align the images straight. Good use copy stands can
be found fairly cheaply. I received a Polaroid Mp3 free for taking it
away and it was set up for a standard camera.

Tom

On Jul 18, 2:41*pm, tomm42 <tmon...@wildblue.net> wrote:

> Copystand and a short macro lens, no perspective problems. Use a short
> macro 35-50mm anyway will greatly reduce perspective problems,
> providing you can align the images straight. Good use copy stands can
> be found fairly cheaply. I received a Polaroid *Mp3 free for taking it
> away and it was set up for a standard camera.

A copy stand would be nice, but my searches have so far only turned up
quite expensive ones.

Still, when I am not at home but for example in a library, some
automatic perspective correction tool would be cool.

Hugo Trebl wrote:
> On Jul 18, 2:41 pm, tomm42 <tmon...@wildblue.net> wrote:
>
>> Copystand and a short macro lens, no perspective problems. Use a short
>> macro 35-50mm anyway will greatly reduce perspective problems,
>> providing you can align the images straight. Good use copy stands can
>> be found fairly cheaply. I received a Polaroid Mp3 free for taking it
>> away and it was set up for a standard camera.
>
> A copy stand would be nice, but my searches have so far only turned up
> quite expensive ones.
>
> Still, when I am not at home but for example in a library, some
> automatic perspective correction tool would be cool.

Many tripods have threads on the bottom of the vertical shaft, and it
occurred to me that one could jury rig off that, or probably someone's
made a decent adaptor for that which would be much more adjustable than
a home made attachment.

--
john mcwilliams

Hugo Trebl wrote:
> Hi,
>
> I am looking for a tool to post-process the following type of photo:
>
> Given a series of photos of flat rectangular objects, such as book
> covers, letters, magazines, posters, taken against an uniform
> background.
>
> One object per photo, slightly skewed and rotated due to perspective,
> since the camera is usually not exactly aligned. (suppose a scanner is
> not an option)
>
> I am searching for a tool that allows quick post-processing to remove
> the distortion introduced by the perspective, and to discard
> unnecesary background. In the end the object should be aligned with
> the picture borders and fill the whole picture
>
> So either this tool should be able to recognize the rectangular shape
> automatically and guess the correct transformation, or let me quickly
> change the shear/rotation/cut manually until the object fits.
> Optionally there would also be a filter to remove glare.
>
> Most image manipualtion software can already do the manual part
> somewhat, but at least with the Gimp is very cumbersome to do this for
> a series of pictures and requires lots of adjustments and clicks.
>
> Is there any tool good for this sort of task?

You can do it manually using the free Windows app `PAINT.net`:

http://www.getpaint.net/doc/latest/en/RotateZoom.html

On Fri, 18 Jul 2008 16:08:03 -0700, John McWilliams
<jpmcw@comcast.net> wrote:

>Hugo Trebl wrote:
>> On Jul 18, 2:41 pm, tomm42 <tmon...@wildblue.net> wrote:
>>
>>> Copystand and a short macro lens, no perspective problems. Use a short
>>> macro 35-50mm anyway will greatly reduce perspective problems,
>>> providing you can align the images straight. Good use copy stands can
>>> be found fairly cheaply. I received a Polaroid Mp3 free for taking it
>>> away and it was set up for a standard camera.
>>
>> A copy stand would be nice, but my searches have so far only turned up
>> quite expensive ones.
>>
>> Still, when I am not at home but for example in a library, some
>> automatic perspective correction tool would be cool.
>
>Many tripods have threads on the bottom of the vertical shaft, and it
>occurred to me that one could jury rig off that, or probably someone's
>made a decent adaptor for that which would be much more adjustable than
>a home made attachment.

As the user of a "home made attachment", I have to come to the defense
of us cheapskate users of jury-rigged devices. Not much vertical
adjustment is required unless you routinely switch from posters to
books. If you use, say, an 18-55 lens, the adjustment is in the lens.

Vertical shooting with a tripod is an pain in the *** unless you have
one of those expensive tripod systems with a boom. The legs get in
your way, and the structure is easy to jiggle. If you pop for a
tripod with a boom, you'd be about the same if you had a standard
tripod and a copy stand.

The real issue is volume/frequency. If you shoot vertically with the
camera in a fixed position for the occasional project, the home-made
device wins. If you routinely shoot that type of shot, the copy stand
wins. It's the somewhere-in-between that gets awkward.




--
Tony Cooper - Orlando, Florida

Hugo Trebl <singalong@dodgeit.com> wrote:
> Hi,

> I am looking for a tool to post-process the following type of photo:

> Given a series of photos of flat rectangular objects, such as book
> covers, letters, magazines, posters, taken against an uniform
> background.

> One object per photo, slightly skewed and rotated due to perspective,
> since the camera is usually not exactly aligned. (suppose a scanner is
> not an option)

> I am searching for a tool that allows quick post-processing to remove
> the distortion introduced by the perspective, and to discard
> unnecesary background. In the end the object should be aligned with
> the picture borders and fill the whole picture

> So either this tool should be able to recognize the rectangular shape
> automatically and guess the correct transformation, or let me quickly
> change the shear/rotation/cut manually until the object fits.
> Optionally there would also be a filter to remove glare.

> Most image manipualtion software can already do the manual part
> somewhat, but at least with the Gimp is very cumbersome to do this for
> a series of pictures and requires lots of adjustments and clicks.

> Is there any tool good for this sort of task?

If the camera has a live view LCD which can have a rectangular grid
projected onto it you can use the grid to align a hand held shot of a
rectangular object so that this kind of post processing is
unnecessary. If the camera doesn't have a grid option I'd be tempted
to print a transparent foil with a grid and stick it over the LCD for
such shots.

In some cases, such as rectangular things hanging on walls, you can't
always get the height to stop a vertical convergence, but using a grid
to get exactly on the centre line stops horizontal convergence and
makes the post processing to fix the vertical much easier.

--
Chris Malcolm cam@infirmatics.ed.ac.uk DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]