Difference between revisions of "Hugin Crop tab"

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(reordered so that "What it is (not)" and HowTo info comes first, added my hints from recent list discussion)
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''Image cropping'' shouldn't be confused with a camera's [[Crop factor]], which is something else entirely. Use the '''Crop''' tab to indicate the areas of the input images that [[hugin]] should exclude from the stitching output. There are three situations where you might want to use crop parameters:
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Use the '''Crop''' tab to indicate the area of the panorama that should be used as output. This crop tab doesn't work on the individual images, but on the entire panorama.
* With a scanned input image, there are usually black edges or marks along the sides of the image.
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* With a circular [[Fisheye Projection]] image there are black unexposed areas outside the image circle.
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* Some lenses have a lot of flaring around the edges which you don't want to keep.
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Select the image to be cropped in the list to the left, you can adjust the position of the crop area by dragging the perimeter in the image preview on the right.  Multiple images can be selected by holding down the ''Shift'' or ''Ctrl'' keys while clicking in the image list.
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[[image:Hugin2013 crop tab.png|thumb|600px|left|Screenshot of the Crop tab; click for larger image]]
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{{clr}}
  
Note that unlike [[PTGui]], setting [[crop parameters]] in hugin doesn't change the [[Field of View]] or optical centre of your images, it simply indicates areas of the image to be masked out, so you can change the cropping for photos in your project at any stage of the stitching process.
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The "Autocrop" and "HDR Autocrop" buttons will adjust the crop rectangle so that it is entirely within the image area, i.e. there will be no 'black' borders in the final stitched image. It does this by maximising the area of the rectangle rather than the width or height. This is automatically done when running the [[Hugin Assistant tab]].
In detail, [[hugin]] uses the '''S''' 'selection' parameter in the '''i''' and '''o''' script lines instead of the '''C''' 'crop' parameter.
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Depending on the input image type, cropping has two different behaviours:
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To change the cropping at each edge, move the mouse towards that edge until a semi-transparant white box appears along it, then drag with the left mouse button until the edge is where you want it. The area outside the dragging rectangle represents the areas that will be cropped off the panorama. You can move two edges at once by moving the mouse towards the corner shared by the edges until both white boxes appear. If you wish to move the whole region at once, move the mouse into the middle so that all four edges have boxes along them and drag.  
* For circular fisheye photos the crop area is a circle.
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* For any other input image, the crop area is a rectangle.
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Change the input image type in the [[Hugin Camera and Lens tab]].
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The '''Crop''' tab features four text boxes for '''Left''', '''Top''', '''Right''' and '''Bottom''' where you can manually enter the positions of the four edges.  The origin is top-left and numbers indicate the distance in pixels from this origin.
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This [[Hugin Crop tab]] also has the option to display guides in the preview to help you crop the panorama until the composition applies to for example the "rule of thirds".
  
Note that numbers can be negative and can extend beyond the width and height of the photo, this is primarily useful for partial fisheye images where the full circle is not visible, in this case the crop circle extends beyond the picture frame.
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Note: ''cropping the panorama'' shouldn't be confused with a camera's [[Crop factor]], which is something else entirely.  
  
The default '''Always center Crop on d,e''' assumes that all cropping is symmetrical around the optical centre of the lens.  This is normal unless you are using the crop feature to remove lens flare, in which case the crop may need to be asymmetrical.
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Note 2: This [[Hugin Crop tab]] is neither to crop individual images, like you would do for e.g. [[fisheye Projection]] images having a circular area in the middle with a useless black area outside or scanned images that might have edges that need to
 
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be ''cropped'' away.
The '''d''' and '''e''' lens parameters setting the position of the optical centre are used by the [[Lens correction model]] and are set in the [[Hugin Camera and Lens tab]].
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== Save and apply crop values ==
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Usually crop values don't vary too much for each lens/camera combination. So instead of always creating an almost same crop for new projects these values can be saved using the 'Save lens...' button in the [[Hugin Camera and Lens tab]] tab.
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To load crop values just select one image in the 'Camera and Lens' tab and load the previously saved lens description file. That also sets the crop for all images in the project that have the same lens number.
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The lens description file is a plain text file with a .ini extension.
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[[Category:Software:Hugin]]
 
[[Category:Software:Hugin]]

Revision as of 18:25, 24 January 2013

Use the Crop tab to indicate the area of the panorama that should be used as output. This crop tab doesn't work on the individual images, but on the entire panorama.

Screenshot of the Crop tab; click for larger image


The "Autocrop" and "HDR Autocrop" buttons will adjust the crop rectangle so that it is entirely within the image area, i.e. there will be no 'black' borders in the final stitched image. It does this by maximising the area of the rectangle rather than the width or height. This is automatically done when running the Hugin Assistant tab.

To change the cropping at each edge, move the mouse towards that edge until a semi-transparant white box appears along it, then drag with the left mouse button until the edge is where you want it. The area outside the dragging rectangle represents the areas that will be cropped off the panorama. You can move two edges at once by moving the mouse towards the corner shared by the edges until both white boxes appear. If you wish to move the whole region at once, move the mouse into the middle so that all four edges have boxes along them and drag.

This Hugin Crop tab also has the option to display guides in the preview to help you crop the panorama until the composition applies to for example the "rule of thirds".

Note: cropping the panorama shouldn't be confused with a camera's Crop factor, which is something else entirely.

Note 2: This Hugin Crop tab is neither to crop individual images, like you would do for e.g. fisheye Projection images having a circular area in the middle with a useless black area outside or scanned images that might have edges that need to be cropped away.