Stiching Photos In PS CS3 (Exposure Difference)

Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts Load Files
Into Stack (Automatically Align Source Images), there are slight exposure
differences between the images (I.E. you can see the square edges of the
individual photos where there are exposure differences).

The shots were all taken using manual exposure so the aperture, shutter
speed, ISO, etc were identical, and also identical RAW settings were used
for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between shots
when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg

Glen wrote:
Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts Load
Files Into Stack (Automatically Align Source Images), there are slight
exposure differences between the images (I.E. you can see the square
edges of the individual photos where there are exposure differences).

The shots were all taken using manual exposure so the aperture, shutter
speed, ISO, etc were identical, and also identical RAW settings were
used for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between shots
when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg

Probably vignetting (dark corners). Running them through a vignetting
correction first should improve things.

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Glen wrote:
Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts Load
Files Into Stack (Automatically Align Source Images), there are slight
exposure differences between the images (I.E. you can see the square
edges of the individual photos where there are exposure differences).

The shots were all taken using manual exposure so the aperture, shutter
speed, ISO, etc were identical, and also identical RAW settings were
used for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between shots
when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg

You don't say what camera you're using and strangely enough the EXIF
data is cleared.

You say that it was all a single exposure setting. Are you sure? Did
the light change between shots?

The 'upper band' is a bit darker suggesting that either the light
changed or the metering did.

This is not, btw, "stacking" but mosaic/panoramic. Stacking refers to
two other processes (one for DOF deepening and one for noise reduction
in (mainly) astrophotography).

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Paul Furman wrote:
Glen wrote:
Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts Load
Files Into Stack (Automatically Align Source Images), there are slight
exposure differences between the images (I.E. you can see the square
edges of the individual photos where there are exposure differences).

The shots were all taken using manual exposure so the aperture,
shutter speed, ISO, etc were identical, and also identical RAW
settings were used for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between
shots when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg

Probably vignetting (dark corners). Running them through a vignetting
correction first should improve things.


No, it's not vignetting there, not by a long shot. The bottom row is
differently exposed. Why is speculation.

--
John McWilliams

John McWilliams wrote:
Paul Furman wrote:
Glen wrote:
Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts
Load Files Into Stack (Automatically Align Source Images), there are
slight exposure differences between the images (I.E. you can see the
square edges of the individual photos where there are exposure
differences).

The shots were all taken using manual exposure so the aperture,
shutter speed, ISO, etc were identical, and also identical RAW
settings were used for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between
shots when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg

Probably vignetting (dark corners). Running them through a vignetting
correction first should improve things.

No, it's not vignetting there, not by a long shot. The bottom row is
differently exposed. Why is speculation.

Increased contrast shows that possibility:
http://edgehill.net/1/temp/2mi5i4z.jpg
Overlap could mask out the vignetting on the bottom row.

--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

"Glen" wrote in message
...

Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts Load
Files Into Stack (Automatically Align Source Images), there are slight
exposure differences between the images (I.E. you can see the square edges
of the individual photos where there are exposure differences).

The shots were all taken using manual exposure so the aperture, shutter
speed, ISO, etc were identical, and also identical RAW settings were used
for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between shots
when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg


Thanks for the replies.

I must admit, the first thing that came to my mind too was that it could
have been due to lens light fall off at the edges, but I had the benefit of
seeing the whole picture/the individual photos and as John mentioned, this
was not the cause.

Well, I am still not sure why it is doing it, however I think that I was
maybe using the wrong tool for the job. If I use 'Automate Photomerge',
instead of 'Scripts Load Files Into Stack (Automatically Align Source
Images)', there's no problem. For some strange reason, I thought that
loading them into a stack was a better technique than using Photomerge, but
it turns out this is not the case.

Here's a comparison (Photomerge is the bottom one):
http://i39.tinypic.com/2a0gbw7.jpg

Paul Furman wrote:
John McWilliams wrote:
Paul Furman wrote:
Glen wrote:
Anyone come across this before?

In PS CS3, if you stitch multiple exposures by going to Scripts
Load Files Into Stack (Automatically Align Source Images), there are
slight exposure differences between the images (I.E. you can see the
square edges of the individual photos where there are exposure
differences).

The shots were all taken using manual exposure so the aperture,
shutter speed, ISO, etc were identical, and also identical RAW
settings were used for all shots in ACR before stacking them.

I can't think why there should be any exposure differences between
shots when it stitches them together.

http://i42.tinypic.com/2mi5i4z.jpg

Probably vignetting (dark corners). Running them through a vignetting
correction first should improve things.

No, it's not vignetting there, not by a long shot. The bottom row is
differently exposed. Why is speculation.

Increased contrast shows that possibility:
http://edgehill.net/1/temp/2mi5i4z.jpg
Overlap could mask out the vignetting on the bottom row.

I phrased that poorly. While vignetting may well be there, the problem
is overshadowed (pun intended) by the absolute differences in exposure.

--
John McWilliams