different fused results depending upon crop size

[kevin]

I just noticed something tonight while doing some test stitches. I
have a very large stitch that I'm doing test stitches of various crops
from that large stitch to see the results so I can adjust control
points, settings for enfuse/enblend, etc. I'm getting different
results from "Fused and blended panorama" based upon the crop size.
Here's the same section from a stitch that's using the same input
images and the same pto file, only difference is the crop size:

http://www.bluelavalamp.net/hugin/large_crop.jpg
http://www.bluelavalamp.net/hugin/small_crop.jpg

As you can see the large crop is darker then the small crop.

Here's the output of diff on the two pto files:

diff test-large_crop.pto test-small_crop.pto
3c3
< p f13 w30576 h21630 v62 E-0.266483 R0 S9484,15985,6919,11887
n"TIFF_m c:LZW"
---
> p f13 w30576 h21630 v62 E-0.266483 R0 S11724,13994,10005,11066 n"TIFF_m c:LZW"

Is this normal behavior? Would enfuse output a different result for a
section of an image based upon the crop of the image?

[bruno.postle]

On Dec 18, 4:00 am, kevin <ke...@bluelavalamp.net> wrote:

> Is this normal behavior?  Would enfuse output a different result for a
> section of an image based upon the crop of the image?

This could be a bug, but I would expect a crop to be different in some
way to the same region of a larger stitch:

When you stitch a 'cropped' view, Hugin decides which photos are
relevant and ignores the rest, but for the larger stitch all images
are used.

Any output pixel produced by enblend/enfuse can be a combination of
all input pixels from all photos if the maximum number of blending
levels is chosen. If you have just 8 blending levels then photos 2^8
pixels (256 pixels) beyond any frame will influence content in the
frame.

[I've been considering creating a gigapixel stitcher 'wrapper': It
would generate the grid tiles directly rather than stitching the whole
thing at once, but the tiles would each need to be oversized by the
number of blending levels and this border would have to be discarded
after stitching]

--
Bruno

[kevin]

Yup, that was it, the blending levels for enfuse. Thanks for taking a
look at it and explaining it. Now I just need to try different
settings to get the correct look.

Thanks