相機圖像改變方向

Question

我一直試圖將相機圖像從iPhone上傳到我的網絡服務器，但有些圖像是如何在病房后改變它的方向。 這只發生在相機圖像上，而不是從我的機器上傳到設備的簡單圖像。

以下是代碼：

    NSData *imgdataRepresentation = UIImageJPEGRepresentation(imgTemp, 0.5);


    ///////**********************************************
    // setting up the URL to post to
    NSString *addPhotoURL = [NSString stringWithFormat:@"%@%@%@",HTTP_HOST,ADD_PHOTO_URL,[userInfo.userDetail objectForKey:@"id"]];

    // setting up the request object now
    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
    [request setURL:[NSURL URLWithString:addPhotoURL]];
    [request setHTTPMethod:@"POST"];

    /*
     add some header info now
     we always need a boundary when we post a file
     also we need to set the content type

     You might want to generate a random boundary.. this is just the same
     as my output from wireshark on a valid html post
     */
    NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
    NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];
    [request addValue:contentType forHTTPHeaderField: @"Content-Type"];

    /*
     now lets create the body of the post
     */
    NSMutableData *body = [NSMutableData data];
    [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"Album\"; filename=\"ipodfile.jpg\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[NSData dataWithData:imgdataRepresentation ]];
    [body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    // setting the body of the post to the reqeust
    [request setHTTPBody:body];

    // now lets make the connection to the web
    NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
    NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];

Answer 1

無論手機如何保存，iPhone圖像始終以相同的方式存儲，但EXIF數據中設置了一個標記，指定圖像應該位於哪個方向。幾乎所有本機OSX應用程序（如iPhoto和Preview）都可以讀取此EXIF方向正確標記並自動旋轉圖像，但幾乎所有Windows應用程序和Web瀏覽器都不考慮方向EXIF標記。 在保存之前，您必須手動旋轉Web服務器上的圖像。 我不知道您使用哪種Web服務器技術，但執行此操作的C＃代碼是：

public static void FixOrientation(this Image image)
{
    // 0x0112 is the EXIF byte address for the orientation tag
    if (!image.PropertyIdList.Contains(0x0112))
    {
        return;
    }

    // get the first byte from the orientation tag and convert it to an integer
    var orientationNumber = image.GetPropertyItem(0x0112).Value[0];

    switch (orientationNumber)
    {
        // up is pointing to the right
        case 8:
            image.RotateFlip(RotateFlipType.Rotate270FlipNone);
            break;
        // up is pointing to the bottom (image is upside-down)
        case 3:
            image.RotateFlip(RotateFlipType.Rotate180FlipNone);
            break;
        // up is pointing to the left
        case 6:
            image.RotateFlip(RotateFlipType.Rotate90FlipNone);
            break;
        // up is pointing up (correct orientation)
        case 1:
            break;
    }
}

Answer 2

您可以使用imageOrientation方法獲取UIImage的圖像方向。 因此，例如，您想要保存從相機中拍攝的圖像：

UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
if (image) {
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
    [library writeImageToSavedPhotosAlbum:[image CGImage] 
                              orientation:[image imageOrientation]
                          completionBlock:^(NSURL *assetURL, NSError *error){ /* error handling */ }];
    [library autorelease];
}

然后當你想從庫中獲取UIImage時，可以通過執行以下操作來檢索方向：

UIImage *image = [UIImage imageWithCGImage:[[asset defaultRepresentation] fullResolutionImage] scale:1.0 orientation:[asset orientation]];