> Hello,

> Could please someone explain how multiblend works in details? I am not
> interested in the seaming but in the actual blending steps. This is what I
> know.

>    1. Given source images with alpha channels (mask-000.tit,mask-001.tif)
>    crop to alpha bounding-box and in-paint empty regions. Hence image masks
>    will have a rectangular shape.
>    2. Compute NTF transform on the full  resolution final-image
>    (resolution of the panorama).
>    3. Compute 2 gaussian pyramids (inverted) on the image obtained in
>    step 2
>    4. Compute Laplacian pyramid on each individual cropped image (0-level
>    have the resolution of the initial mask bounding-box)

> Then?

> I have been looking into the source-code but it's quite difficult to
> understand at low-level. I know the Burt algorithm but I can't really
> figure out, the right way to make it work correctly with alpha-channels (I
> get bleeding colors in the zero-alpha regions)

> Thanks

> Each image's Laplacian pyramid is mutiplied by its mask pyramid and this
> result is placed into a full size (and to begin with, blank) Laplacian
> pyramid. Shortcuts are taken where the mask is pure white or black (masks
> are stored and processed in a compressed format so the code is a little
> more complex than usual). Once all images have been processed the big
> Laplacian pyramid is collapsed and the result is the output image.

> I'm not sure from your final sentence whether the colour bleeding is a
> problem you are having with multiblend (in which case can you provide a
> screenshot) or are you trying to implement something multiblend does in
> your own way? Multiblend's final output is blacked out where in those areas
> where all images have 0 alpha. You can disable this with --nomask but then
> all you should see on the outside are the inpainted parts of the source
> images.

> Some other points:

> > Given source images with alpha channels (mask-000.tit,mask-001.tif) crop
> to alpha bounding-box and in-paint empty regions. Hence image masks will
> have a rectangular shape.

> I may be misunderstanding you, but this is not quite true. Only RGB in
> inpainted - masks retain their shape, within the image's rectangular
> bounding box.

>    1. Compute NTF transform on the full  resolution final-image
>    (resolution of the panorama).
>    2. Compute 2 gaussian pyramids (inverted) on the image obtained in
>    step 2

> The NFT (nearest feature transform?) is performed on a map made up of
> those regions where only one image's mask is present. All other regions are
> left black to be filled by the NFT.

> multiblend computes *n* gaussian pyramids for *n* images. They are only
> the inverse of each other when there are only two source images.

> David

> Friday, 5 October 2012 14:53:21 UTC+1, memecs wrote:

>> Hello,

>> Could please someone explain how multiblend works in details? I am not
>> interested in the seaming but in the actual blending steps. This is what I
>> know.

>>    1. Given source images with alpha channels
>>    (mask-000.tit,mask-001.tif) crop to alpha bounding-box and in-paint empty
>>    regions. Hence image masks will have a rectangular shape.
>>    2. Compute NTF transform on the full  resolution final-image
>>    (resolution of the panorama).
>>    3. Compute 2 gaussian pyramids (inverted) on the image obtained in
>>    step 2
>>    4. Compute Laplacian pyramid on each individual cropped image
>>    (0-level have the resolution of the initial mask bounding-box)

>> Then?

>> I have been looking into the source-code but it's quite difficult to
>> understand at low-level. I know the Burt algorithm but I can't really
>> figure out, the right way to make it work correctly with alpha-channels (I
>> get bleeding colors in the zero-alpha regions)

>> Thanks

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> Hi David thanks for your explanation. I am implemented the blender myself
> because I will need to do some adjustments in the future.

> However here I am still missing something.

> Each image's Laplacian pyramid is mutiplied by its mask pyramid and this
>> result is placed into a full size (and to begin with, blank) Laplacian
>> pyramid.

> Thus most likely at each level of the pyramid the laplacian images will be
> immersed into a big-black image (see attachment). So when collapsing the
> pyramid (leading to the final stitching), image colors wiil be blurred with
> the black background. Is there any way you are handling this situation?

> Thanks again,
> Federico

> On Mon, Oct 8, 2012 at 5:40 PM, Monkey <davidh...@gmail.com <javascript:>>wrote:

>> Then...

>> Each image's Laplacian pyramid is mutiplied by its mask pyramid and this
>> result is placed into a full size (and to begin with, blank) Laplacian
>> pyramid. Shortcuts are taken where the mask is pure white or black (masks
>> are stored and processed in a compressed format so the code is a little
>> more complex than usual). Once all images have been processed the big
>> Laplacian pyramid is collapsed and the result is the output image.

>> I'm not sure from your final sentence whether the colour bleeding is a
>> problem you are having with multiblend (in which case can you provide a
>> screenshot) or are you trying to implement something multiblend does in
>> your own way? Multiblend's final output is blacked out where in those areas
>> where all images have 0 alpha. You can disable this with --nomask but then
>> all you should see on the outside are the inpainted parts of the source
>> images.

>> Some other points:

>> > Given source images with alpha channels (mask-000.tit,mask-001.tif)
>> crop to alpha bounding-box and in-paint empty regions. Hence image masks
>> will have a rectangular shape.

>> I may be misunderstanding you, but this is not quite true. Only RGB in
>> inpainted - masks retain their shape, within the image's rectangular
>> bounding box.

>>    1. Compute NTF transform on the full  resolution final-image
>>    (resolution of the panorama).
>>    2. Compute 2 gaussian pyramids (inverted) on the image obtained in
>>    step 2

>> The NFT (nearest feature transform?) is performed on a map made up of
>> those regions where only one image's mask is present. All other regions are
>> left black to be filled by the NFT.

>> multiblend computes *n* gaussian pyramids for *n* images. They are only
>> the inverse of each other when there are only two source images.

>> David

>> Friday, 5 October 2012 14:53:21 UTC+1, memecs wrote:

>>> Hello,

>>> Could please someone explain how multiblend works in details? I am not
>>> interested in the seaming but in the actual blending steps. This is what I
>>> know.

>>>    1. Given source images with alpha channels
>>>    (mask-000.tit,mask-001.tif) crop to alpha bounding-box and in-paint empty
>>>    regions. Hence image masks will have a rectangular shape.
>>>    2. Compute NTF transform on the full  resolution final-image
>>>    (resolution of the panorama).
>>>    3. Compute 2 gaussian pyramids (inverted) on the image obtained in
>>>    step 2
>>>    4. Compute Laplacian pyramid on each individual cropped image
>>>    (0-level have the resolution of the initial mask bounding-box)

>>> Then?

>>> I have been looking into the source-code but it's quite difficult to
>>> understand at low-level. I know the Burt algorithm but I can't really
>>> figure out, the right way to make it work correctly with alpha-channels (I
>>> get bleeding colors in the zero-alpha regions)

>>> Thanks

>>  --
>> You received this message because you are subscribed to the Google Groups
>> "Hugin and other free panoramic software" group.
>> A list of frequently asked questions is available at:
>> http://wiki.panotools.org/Hugin_FAQ
>> To post to this group, send email to hugi...@googlegroups.com<javascript:>
>> To unsubscribe from this group, send email to
>> hugin-ptx+...@googlegroups.com <javascript:>
>> For more options, visit this group at
>> http://groups.google.com/group/hugin-ptx