Rotation adds border at bottom of image

[Paul_N]

Here's something I just discovered. I have an image that has been resized and formatted with a legacy programed called "PhotoBatch". When I use BBPro to rotate that processed image I get a black border at the bottom of the image. But I don't get the the border when I rotate the original camera produced image.

Here's the problem image...

http://www.solvara.com/sets/091018-02-2192.jpg

And here's the image after rotation by BBPro...

http://www.solvara.com/sets/091018-02-2192r.jpg

Any thoughts?

[DavidB]

The following quote from BB Pro Help is informative, and I think it answers your question.


BreezeBrowser Pro has two methods of rotating JPEG images both of which are lossless and don't affect the image quality:

1) rearranging image data to rotate the image

2) editing the EXIF orientation variable stored in the shooting data

The first method is not as fast as the second method and can result in small strips of the image being wrapped around if the image size is not an exact multiple of the JPEG tile size (this isn't a problem with unedited images straight from a digital camera). The second method is very fast but not many applications read this value resulting in the image being displayed in its original unrotated orientation. At the time of writing Windows Explorer, Internet Explorer, Photoshop, Photoshop Elements and Paint Shop Pro all ignore the EXIF orientation.

David

[Chris Breeze]

This is almost certainly the problem. Please also see this FAQ: http://www.breezesys.com/BreezeBrowser/support.htm#BBP9

[DavidB]

As a follow-on to the above, I have always assumed that if the "Use EXIF orientation ..." box on the Image display tab of Preferences is ticked, Method 2 (see above) will be used to rotate images; otherwise Method 1 will be used. Is this correct? I don't think that Help says this explicitly.

The reason I am unsure about this is that I don't often need to use BB Pro to rotate images; I use EXIF rotation in the camera, and most other rotations are done in editing programs which seem to be compatible with BB Pro in this respect.

David

[Chris Breeze]

If "Use EXIF orientation ..." box on the Image display tab of Preferences is ticked and the image contains EXIF data with the EXIF orientation tag BBPro will rotate the image using the EXIF orientation tag. If the option is not selected or the image doesn't contain the EXIF orientation tag BBPro rotates the image by reading the image data, rotating as required and then rewriting. Rotation of JPEGs is lossless (it basically rearranges the tiles) but if the image size isn't a whole number of tiles you may get a small strip of the image wrapped around. Normally this isn't a problem because JPEGs from digital cameras are always a whole number of tiles in size and if they are later cropped in an image editor they are also rotated at that stage and don't need to be rotated later in BBPro.

[DavidB]

Thanks, Chris. That's a very useful summary, and a very good post to link to when questions about rotation crop up again.

David