[알고리즘] C# PHP Photo Rotate 정보 알기

PHP

질문: How to detect shot angle of photo, and auto rotate for website display like desktop apps do on viewing?

답변: In order to do that, you must read the EXIF information out of the JPEG file. You can either do that with exif PHP extension or with PEL.

Basically, you have to read the Orientation flag in the file. Here is an example using the exifPHP extension and WideImage for image manipulation.

<?php
$exif = exif_read_data($filename);
$ort = $exif['Orientation'];

$image = WideImage::load($filename);

// GD doesn't support EXIF, so all information is removed.
$image->exifOrient($ort)->saveToFile($filename);

class WideImage_Operation_ExifOrient
{
  /**
   * Rotates and mirrors and image properly based on current orientation value
   *
   * @param WideImage_Image $img
   * @param int $orientation
   * @return WideImage_Image
   */
  function execute($img, $orientation)
  {
    switch ($orientation) {
      case 2:
        return $img->mirror();
        break;

      case 3:
        return $img->rotate(180);
        break;

      case 4:
        return $img->rotate(180)->mirror();
        break;

      case 5:
        return $img->rotate(90)->mirror();
        break;

      case 6:
        return $img->rotate(90);
        break;

      case 7:
        return $img->rotate(-90)->mirror();
        break;

      case 8:
        return $img->rotate(-90);
        break;

      default: return $img->copy();
    }
  } 

}

출처: http://stackoverflow.com/questions/3657023/how-to-detect-shot-angle-of-photo-and-auto-rotate-for-website-display-like-desk

C# 관련

When processing photos, sometimes you want to re-orient the photo according the orientation recorded by the camera (such as the iPhone’s accelerometer) and stored in the EXIF meta data.  It’s easy to do:

// Rotate the image according to EXIF data

var bmp = new Bitmap(pathToImageFile);
var exif = new EXIFextractor(ref bmp, "n"); // get source from http://www.codeproject.com/KB/graphics/exifextractor.aspx?fid=207371
 
if (exif["Orientation"] != null)
{
RotateFlipType flip = OrientationToFlipType(exif["Orientation"].ToString());
 
if (flip != RotateFlipType.RotateNoneFlipNone) // don't flip of orientation is correct
{
bmp.RotateFlip(flip);
exif.setTag(0x112, "1"); // Optional: reset orientation tag
bmp.Save(pathToImageFile, ImageFormat.Jpeg);
}
 
// Match the orientation code to the correct rotation:
 
private static RotateFlipType OrientationToFlipType(string orientation)
{
switch (int.Parse(orientation))
{
case 1:
return RotateFlipType.RotateNoneFlipNone;
break;
case 2:
return RotateFlipType.RotateNoneFlipX;
break;
case 3:
return RotateFlipType.Rotate180FlipNone;
break;
case 4:
return RotateFlipType.Rotate180FlipX;
break;
case 5:
return RotateFlipType.Rotate90FlipX;
break;
case 6:
return RotateFlipType.Rotate90FlipNone;
break;
case 7:
return RotateFlipType.Rotate270FlipX;
break;
case 8:
return RotateFlipType.Rotate270FlipNone;
break;
default:
return RotateFlipType.RotateNoneFlipNone;
}
}

출처: http://automagical.rationalmind.net/2009/08/25/correct-photo-orientation-using-exif/