[ros-users] problems with image_proc using a modified camera

James Bowman jamesb at willowgarage.com
Thu Apr 8 19:32:37 UTC 2010

Hi Dave,

you can actually use the slider in the  cameracalibration app to do this
border operation for you.  Tutorial:


I've just added a paragraph (copied from the corresponding StereoCalibration
tutorial) to make this clearer:

After a successful calibration, you can use the slider at the top of the
calibration window to change the size of the rectified image. A scale of 0.0
means that the image is sized so that all pixels in the rectified image are
valid. The rectified image has no border, but some pixels from the original
image are discarded. A scale of 1.0 means that all pixels in the original
image are visible, but the rectified image has black borders where there are
no input pixels in the original image.

On Wed, Apr 7, 2010 at 3:51 PM, David Feil-Seifer <
david.feilseifer at gmail.com> wrote:

> I am trying to use image_proc to rectify an image which is just a
> camera image that has a border added around. The purpose is to make a
> rectified image that includes all of the image (including what does
> not strictly fit into a square), not just the centermost part. To do
> this I made a new node image_letterboxer (included source) to add the
> border and to adjust the camera calibration cx and cy params to
> reflect the new center of the image. This has worked when not using
> image_proc to do the undistort.
> However, when I try to use this node with image_proc, it does not work
> at all. I dug a little into the source and found that the image
> transport is subscribing to the new image topics correctly, and that
> image transport is registering that subscription, but no callbacks are
> being called. My image_letterboxer node works well enough so that
> image_view can display the new image_raw topic with the letterboxed
> image, but image_proc does not work, though it does work on the camera
> itself.
> I assume that the problem is in the image_letterboxer node, but I
> cannot figure out what I did wrong. Is there some flaw in the way that
> I'm using image_transport to publish the images? Or is there something
> wrong with image_proc?
> Thanks in advance,
> -Dave
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> ros-users at code.ros.org
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