ImageMagick rotate bug?

[Vigour]

Hi!

I am using ImageMagick on my Mac Mini webserver to rotate images. I just discovered something very strange. If I scan my pictures (tif format) with my Epson scanner and rotate my images everything works ok. But today I took some photos (jpg format) with my Nikon D3000 and tried to rotate them. If I rotate the image left it rotates right. If I rotate left one more time it rotates back (left). So it seems that it rotates left, right, left, right and so on. What is going on here?

[fmw42]

Possibly there is some profile or EXIF data that is telling it what orientation it has. You can remove all that info with -strip. See if that helps.

Otherwise, post a link to your image, so others can examine it.

Also please show your exact command line.

Also please identify what version of IM you are using. That is always a good idea when posting. If your IM is very old, then you might upgrade that and possibly libjpg

[Vigour]

I remember that when I took this photo I rotated the camera 90 degrees.

I have tried -strip without any success (not sure if I used -strip in the right way).

The link to my image is:

http://www.thrutherockies.com/DSC_0419.JPG

This is the PHP script that tries to rotate it 90 degrees left.

$exec = "/usr/local/bin/convert '$input' -rotate 270 '$output'";

PHP version is 5.3.3

ImageMagick version is 6.6.5-3

I also discovered that when I use -negate it sets the image to grayscale (that is what I want) but also mirror the image at the same time.

$exec = "/usr/local/bin/convert '$input' -negate '$output'";

[Vigour]

Good news. I used -auto-orient and that seems to fix the problem.

[anthony]

Just a warning don't save back to JPG! unless that is your final image. (and keep the original)

JPEG is a lossy file format, and any read and write will degrade the image slightly. The more you read-write the more that file format degrades.

There is a method of non-lossy JPEG rotates (not Image magick) that you can use, but -auto-orient is find if you also plan to use imagemagick to process the image in other ways.

See IM Examples, Photo Handling, for more details...
http://www.imagemagick.org/Usage/photos/