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| Computers Forum Index » Computer - Graphics - Applications (Photoshop) » How to stitch photo the hard way?... |
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| david... |
 Posted: Tue Sep 22, 2009 6:49 pm |
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Guest
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I have a photo larger than my scanner so I had to scan it as two separate
section with some overlapping.
The two sections are about 4000 x 3000 each.
Now I want to stitch them together. What I do is load each section into a
layer in photoshop and do a rough alignment. Now in order to align them
perfectly, I zoom in to pixel level at one side of the overlapped area, make
one layer 50% transparent and nudge until the pixels line up.
Then I zoom in to the other side of the overlapped area. Often, I need to
rotate one of the layer to line up everything. Ideally I would put the
center of rotation on the previously lined up area, and then drag the
rotation handle to line up the current side. But at the pixel level, the
rotation handle is not visible. If I zoom out until I can see the rotation
handle, I can no longer see enough detail to line up the two layers with
pixel accuracy.
How do you get around this problem?
I know there are stitching function in newer photoshop and standalone
stitching software. But just for the challenge, how can I do this the way I
want? |
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| mike... |
| Posted: Wed Sep 23, 2009 1:41 am |
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In article <h9ao4i$eu8$1 at (no spam) aioe.org>, nospam at (no spam) nospam.com says...
Quote: I have a photo larger than my scanner so I had to scan it as two separate
section with some overlapping.
The two sections are about 4000 x 3000 each.
Now I want to stitch them together. What I do is load each section into a
layer in photoshop and do a rough alignment. Now in order to align them
perfectly, I zoom in to pixel level at one side of the overlapped area, make
one layer 50% transparent and nudge until the pixels line up.
Then I zoom in to the other side of the overlapped area. Often, I need to
rotate one of the layer to line up everything. Ideally I would put the
center of rotation on the previously lined up area, and then drag the
rotation handle to line up the current side. But at the pixel level, the
rotation handle is not visible. If I zoom out until I can see the rotation
handle, I can no longer see enough detail to line up the two layers with
pixel accuracy.
How do you get around this problem?
I know there are stitching function in newer photoshop and standalone
stitching software. But just for the challenge, how can I do this the way I
want?
The following works for me on PS7.0 (which doesn't have fancy alignment
software) and assumes the two image halves overlap a little, and that
they are within a few degrees of rotational alignment.
1) Place them as two layers and align them approximately horizontally
and vertically by eye (without rotating!!!).
2) Now zoom in (to pixel view) to one side of the image (I am assuming
the images are upper and lower halves) at a point where the overlap
occurs and, assuming you have sufficient pixel contrast to do so, nudge
until you have the pixels as close to spot on at that side. You can use
transparency or whatever to help here.
3) Now zoom out and select one of the layers and hit Transform Rotate.
Before doing any rotation, drag the rotation centre point locator to the
approximate point where the pixels have been overlapped correctly (it is
the circle with the cross and dot in the centre - looks a bit like a
telescopic gun-sight). Zoom in using Ctrl + and the side sliders to
position the rotation point accurately on the exact point where you
achieved the pixel match.
4) Now use Ctrl - and the sliders and Ctrl + to get to the opposite side
of the image (at pixel view) where there is a visable 'wedge' where the
pixels don't match due to rotational inaccuracy. You can enter an angle
into the 'Control bar' at the top (the one that becomes visible when you
enter Transform - Rotate) - it is the box next to the little triangle
5th from the left or 3rd from the right. Start by making 1-2 degree
adjustments, and then by triual and error get down to tenth of a degree
(or less) till you have a good pixel match on this side.
5) Ctrl - out and check that you matched the pixels and not something
else - then accept the change. Bring the layers up to full opacity and
if you have sufficient overlap fade a mask in on the bottom edge of the
top layer. Merge layers etc, and you are done.
As long as the images are top the same scale, you should be able to get
near perfect match by tis technique. If they are out of scale, you can
add a scaling step the same way, although the pixels get a bit muddy and
it is a little more trial and error.
Mike |
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| Kingdom... |
| Posted: Tue Sep 29, 2009 4:01 am |
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"david" <nospam at (no spam) nospam.com> wrote in news:h9ao4i$eu8$1 at (no spam) aioe.org:
Quote: I have a photo larger than my scanner so I had to scan it as two
separate section with some overlapping.
The two sections are about 4000 x 3000 each.
Now I want to stitch them together. What I do is load each section
into a layer in photoshop and do a rough alignment. Now in order to
align them perfectly, I zoom in to pixel level at one side of the
overlapped area, make one layer 50% transparent and nudge until the
pixels line up.
Then I zoom in to the other side of the overlapped area. Often, I need
to rotate one of the layer to line up everything. Ideally I would put
the center of rotation on the previously lined up area, and then drag
the rotation handle to line up the current side. But at the pixel
level, the rotation handle is not visible. If I zoom out until I can
see the rotation handle, I can no longer see enough detail to line up
the two layers with pixel accuracy.
How do you get around this problem?
I know there are stitching function in newer photoshop and standalone
stitching software. But just for the challenge, how can I do this the
way I want?
Try using the "DIFFERENCE" screen mode (drop down in layers palete) I find
this invaluable when trying to line up pixel perfect joins
see Matching Oversized Scans
http://www.design-u.org/Photoshop/monroy/matching.html |
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| Joe... |
| Posted: Tue Sep 29, 2009 8:55 pm |
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Guest
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Kingdom <kingdom at (no spam) noaddy.com> wrote:
Quote: "david" <nospam at (no spam) nospam.com> wrote in news:h9ao4i$eu8$1 at (no spam) aioe.org:
I have a photo larger than my scanner so I had to scan it as two
separate section with some overlapping.
The two sections are about 4000 x 3000 each.
Now I want to stitch them together. What I do is load each section
into a layer in photoshop and do a rough alignment. Now in order to
align them perfectly, I zoom in to pixel level at one side of the
overlapped area, make one layer 50% transparent and nudge until the
pixels line up.
Then I zoom in to the other side of the overlapped area. Often, I need
to rotate one of the layer to line up everything. Ideally I would put
the center of rotation on the previously lined up area, and then drag
the rotation handle to line up the current side. But at the pixel
level, the rotation handle is not visible. If I zoom out until I can
see the rotation handle, I can no longer see enough detail to line up
the two layers with pixel accuracy.
How do you get around this problem?
I know there are stitching function in newer photoshop and standalone
stitching software. But just for the challenge, how can I do this the
way I want?
Try using the "DIFFERENCE" screen mode (drop down in layers palete) I find
this invaluable when trying to line up pixel perfect joins
That seems to be one of the easier way, and the OP wants to HARD WAY. My
guess would be doing it with the eyes CLOSED. Or hands behind ones back? |
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