Detect EXIF Orientation and Rotate Image using ImageMagick - php

Question

Canon DSLRs appear to save photos in landscape orientation and uses exif::orientation to do the rotation.
Question: How can imagemagick be used to re-save the image into the intended orientation using the exif orientation data such that it no longer requires the exif data to display in the correct orientation?

Answer 1

Use the auto-orient option of ImageMagick's convert to do this.
convert your-image.jpg -auto-orient output.jpg
Or use mogrifyto do it in place
mogrify -auto-orient your-image.jpg

Answer 2

The PHP Imagick way would be to test the image orientation and rotate/flip the image accordingly:
function autorotate(Imagick $image)
{
switch ($image->getImageOrientation()) {
case Imagick::ORIENTATION_TOPLEFT:
break;
case Imagick::ORIENTATION_TOPRIGHT:
$image->flopImage();
break;
case Imagick::ORIENTATION_BOTTOMRIGHT:
$image->rotateImage("#000", 180);
break;
case Imagick::ORIENTATION_BOTTOMLEFT:
$image->flopImage();
$image->rotateImage("#000", 180);
break;
case Imagick::ORIENTATION_LEFTTOP:
$image->flopImage();
$image->rotateImage("#000", -90);
break;
case Imagick::ORIENTATION_RIGHTTOP:
$image->rotateImage("#000", 90);
break;
case Imagick::ORIENTATION_RIGHTBOTTOM:
$image->flopImage();
$image->rotateImage("#000", 90);
break;
case Imagick::ORIENTATION_LEFTBOTTOM:
$image->rotateImage("#000", -90);
break;
default: // Invalid orientation
break;
}
$image->setImageOrientation(Imagick::ORIENTATION_TOPLEFT);
}
The function might be used like this:
$img = new Imagick('/path/to/file');
autorotate($img);
$img->stripImage(); // if you want to get rid of all EXIF data
$img->writeImage();