How to stop PHP iMagick auto-rotating images based on EXIF 'orientation' data

Question

Currently working with PHP and iMagick to develop a poster printing Web application.

This is the example image I am using to test upload/image editing features of th

Answer 1

Good start -- a few additions to make the function more robust. First, case 3 occurs when the image appears upside down. There's a GREAT illustration of the different orientation codes by Calvin Hass. It's possible that orientation information may appear at a different part of the exif_read_data array (depending on camera model, I think), so I've tried to take that into account in my example code.

Something like this:

public function fixOrientation() {

    $exif = exif_read_data($this->imgSrc);

    if( isset($exif['Orientation']) )
        $orientation = $exif['Orientation'];
    elseif( isset($exif['IFD0']['Orientation']) )
        $orientation = $exif['IFD0']['Orientation'];
    else
        return false;

    switch($orientation) {
        case 3: // rotate 180 degrees
            $this->image->rotateimage("#FFF", 180);
        break;

        case 6: // rotate 90 degrees CW
            $this->image->rotateimage("#FFF", 90);
        break;

        case 8: // rotate 90 degrees CCW
            $this->image->rotateimage("#FFF", -90);
        break;
    }
}

The transformation & save leaves you without the previous EXIF information, including Orientation. The lack of Orientation in the transformed image will prevent further processing from attempting to 'correct' things by rotating again. I do wish Imagick had support for ImageMagick's -auto-orient, but oh well.

Oh, also: the rotation is a lossy operation (unless you use jpegtran), so you should try to only do it in conjunction with a resize or other transformation.