I'm using the Xam.Plugin.Media in my Forms app to take pictures.
I take the Image stream (GetStream) and convert to a byte[] and store in my DB.
I then use that as the image source.
On Android and UWP, its working fine.
On iOS, if the picture is taken in portrait mode, the image once, selected is always rotated 90 deg.
I will later, upload this to a server and that image could be used on a different device.
For this, I also tried the GetStreamWithImageRotatedForExternalStorage but in this case, I cant see the image at all.
There are bytes in the stream (I DisplayAlert the length) but the image does not display.
Any idea what I might be doing wrong?
My code:-
private async Task TakePicture(WineDetails details)
{
await CrossMedia.Current.Initialize();
if (CrossMedia.Current.IsCameraAvailable && CrossMedia.Current.IsTakePhotoSupported)
{
var file = await CrossMedia.Current.TakePhotoAsync(new Plugin.Media.Abstractions.StoreCameraMediaOptions
{
AllowCropping = true,
PhotoSize = Plugin.Media.Abstractions.PhotoSize.Medium,
SaveToAlbum = false,
RotateImage = true
});
if (file == null)
return;
using (var ms = new MemoryStream())
{
var stream = file.GetStreamWithImageRotatedForExternalStorage();
stream.CopyTo(ms);
details.LabelImage = ms.ToArray();
details.NotifyChange("ImageSource");
}
}
}
The image is updated in the page via the NotifyChange and looks like this:-
ImageSource.FromStream(() => new MemoryStream(this.LabelImage))
This works fine in all cases on Android and UWP, works on iOS using GetStream (except the image is incorrectly rotated) but does not work using GetStreamWithImageRotatedForExternalStorage on iOS.
Anyone else using this plugin?
Any idea why GetStream returns a rotated image?
Any idea why GetStreamWithImageRotatedForExternalStorage is not working?
Thanks
Update:-
Changed SaveToAlbum = true and when I open the gallery, the image is rotated 90 deg.
Have RotateImage = true which could cause the issue? I'll try setting it to false.
I still can't set the image source to the byte array of the image using GetStreamWithImageRotatedForExternalStorage.
using (var ms = new MemoryStream())
{
file.GetStreamWithImageRotatedForExternalStorage().CopyTo(ms);
details.LabelImage = ms.ToArray();
}
using the byte array for an image
return ImageSource.FromStream(() => new MemoryStream(this.LabelImage));
This does not work for me, GetStream works ok.
Update:-
Ok so, RotateImage = false + GetStreamWithImageRotatedForExternalStorage allows me to display the image but its still incorrectly rotated in my app and the gallery.
I'm using this plugin, which is similar (if not the same thing - I know James Montemagno has recently packaged/bundled his work with Xamarin).
If you check the issues board there, you'll see there are quite a few people that have similar troubles (image rotation on iOS). Almost every 'solution' mentions using GetStreamWithImageRotatedForExternalStorage.
My issue was similar - I was unable to take a photo on iOS in portrait mode, without other (non-ios Devices) rotating the image. I have tried for weeks to solve this issue, but support on the plugin seems to be quite limited.
Ultimately I had to solve this with a huge workaround - using a custom renderer extending from FFImageLoading to display our images and MetadataExtractor. We were then able to extract the EXIF data from the stream and apply a rotation transformation to the FFImageLoding image control.
The rotation information was stored in a sort of weird way, as a string. This is the method I'm using to extract the rotation information, and return the amount it needs to be rotated as an int. Note that for me, iOS was able to display the image correctly still, so it's only returned a rotation change for Android devices.
public static int GetImageRotationCorrection(byte[] image)
{
try
{
var directories = ImageMetadataReader.ReadMetadata(new MemoryStream(image));
if (Device.Android == "Android")
{
foreach (var directory in directories)
{
foreach (var tag in directory.Tags)
{
if (tag.Name == "Orientation")
{
if (tag.Description == "Top, left side(Horizontal / normal)")
return 0;
else if (tag.Description == "Left side, bottom (Rotate 270 CW)")
return 270;
else if (tag.Description == "Right side, top (Rotate 90 CW")
return 90;
}
}
}
}
return 0;
}
catch (Exception ex)
{
return 0;
}
}
Note that there is also a custom renderer for the image for FFImage Loading.
public class RotatedImage : CachedImage
{
public static BindableProperty MyRotationProperty = BindableProperty.Create(nameof(MyRotation), typeof(int), typeof(RotatedImage), 0, propertyChanged: UpdateRotation);
public int MyRotation
{
get { return (int)GetValue(MyRotationProperty); }
set { SetValue(MyRotationProperty, value); }
}
private static void UpdateRotation(BindableObject bindable, object oldRotation, object newRotation)
{
var _oldRotation = (int)oldRotation;
var _newRotation = (int)newRotation;
if (!_oldRotation.Equals(_newRotation))
{
var view = (RotatedImage)bindable;
var transformations = new System.Collections.Generic.List<ITransformation>() {
new RotateTransformation(_newRotation)
};
view.Transformations = transformations;
}
}
}
So, in my XAML - I had declared a RotatedImage instead of the standard Image. With the custom renderer, I'm able to do this and have the image display rotated the correct amount.
image.MyRotation = GetImageRotationCorrection(imageAsBytes)
It's a totally unnecessary workaround - but these are the lengths that I had to go to to get around this issue.
I'll definitely be following along with this question, there might be someone in the community who could help us both!
The SaveMetaData flag is causing the rotation issue.
Setting it to false (default is true) now displays the photo correctly.
One side effect of that, the image no longer appears in the gallery if SaveToAlbum=true.
Still can't use an image take when using GetStreamWithImageRotatedForExternalStorage, even using FFImageLoading.
I found that while using Xam.Plugin.Media v5.0.1 (https://github.com/jamesmontemagno/MediaPlugin), the combination of three different inputs produced different results on Android vs. iOS:
StoreCameraMediaOptions.SaveMetaData
StoreCameraMediaOptions.RotateImage
Using MediaFile.GetStream() vs. MediaFile.GetStreamWithImageRotatedForExternalStorage()
On Android, SaveMetaData = false, RotateImage = true, and using MediaFile.GetStreamWithImageRotatedForExternalStorage() worked for me whether I was saving the result stream externally or processing the result stream locally for display.
On iOS, the combination of RotateImage = true and StreamRotated = true would result in a NullReferenceException coming out of the plugin library. Using MediaFile.GetStreamWithImageRotatedForExternalStorage() appeared to have no impact on behaivor.
--
Before going further, it's important to understand that image orientation in the JPEG format (which Xam.Plugin.Media seems to use) isn't as straightforward as you might think. Rather than rotating the raw image bytes 90 or 180 or 270 degrees, JPEG orientation can be set through embedded EXIF metadata. Orientation issues will happen with JPEGs either if EXIF data is stripped or if downstream consumers don't handle the EXIF data properly.
The approach I landed on was to normalize JPEG image orientation at the point the image is captured without relying on EXIF metadata. This way, downstream consumers shouldn't need to be relied on to properly inspect and handle EXIF orientation metadata.
The basic solution is:
Scan a JPEG for EXIF orientation metadata
Transform the JPEG to rotate/flip as needed
Set the result JPEG's orientation metadata to default
--
Code example compatible with Xamarin, using ExifLib.Standard (1.7.0) and SixLabors.ImageSharp (1.0.4) NuGet packages. Based on (Problem reading JPEG Metadata (Orientation))
using System;
using System.IO;
using ExifLib;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Formats.Jpeg;
using SixLabors.ImageSharp.Metadata.Profiles.Exif;
using SixLabors.ImageSharp.Processing;
namespace Your.Namespace
{
public static class ImageOrientationUtility
{
public static Stream NormalizeOrientation(Func<Stream> inputStreamFunc)
{
using Stream exifStream = inputStreamFunc();
using var exifReader = new ExifReader(exifStream);
bool orientationTagExists = exifReader.GetTagValue(ExifTags.Orientation, out ushort orientationTagValue);
if (!orientationTagExists)
// You may wish to do something less aggressive than throw an exception in this case.
throw new InvalidOperationException("Input stream does not contain an orientation EXIF tag.");
using Stream processStream = inputStreamFunc();
using Image image = Image.Load(processStream);
switch (orientationTagValue)
{
case 1:
// No rotation required.
break;
case 2:
image.Mutate(x => x.RotateFlip(RotateMode.None, FlipMode.Horizontal));
break;
case 3:
image.Mutate(x => x.RotateFlip(RotateMode.Rotate180, FlipMode.None));
break;
case 4:
image.Mutate(x => x.RotateFlip(RotateMode.Rotate180, FlipMode.Horizontal));
break;
case 5:
image.Mutate(x => x.RotateFlip(RotateMode.Rotate90, FlipMode.Horizontal));
break;
case 6:
image.Mutate(x => x.RotateFlip(RotateMode.Rotate90, FlipMode.None));
break;
case 7:
image.Mutate(x => x.RotateFlip(RotateMode.Rotate270, FlipMode.Horizontal));
break;
case 8:
image.Mutate(x => x.RotateFlip(RotateMode.Rotate270, FlipMode.None));
break;
}
image.Metadata.ExifProfile.SetValue(ExifTag.Orientation, (ushort)1);
var outStream = new MemoryStream();
image.Save(outStream, new JpegEncoder{Quality = 100});
outStream.Position = 0;
return outStream;
}
}
}
And to use in conjunction with Xam.Plugin.Media:
MediaFile photo = await CrossMedia.Current.TakePhotoAsync(options);
await using Stream stream = ImageOrientationUtility.NormalizeOrientation(photo.GetStream);
I am working in xamarin.ios. I am capturing a picture with help of camera and trying to upload it on server. But when I am trying to upload it on server I am getting "TargetInvocationException". But when I am running same code on Ipad everything is working fine.
Following is the code :
Camera.TakePicture(this, (obj) =>
{
var photo = obj.ValueForKey(new NSString("UIImagePickerControllerOriginalImage")) as UIImage;
Byte[] myByteArray;
using (NSData imageData = photo.AsJPEG(0.0f))
{
//myByteArray = imageData.ToArray();
myByteArray = new Byte[imageData.Length];
System.Runtime.InteropServices.Marshal.Copy(imageData.Bytes, myByteArray, 0, Convert.ToInt32(imageData.Length));
}
ImageLoaderPopup imageLoader = new ImageLoaderPopup(this, selectedWorkOrder, myByteArray, title);
imageLoader.PopUp(true, delegate { });
});
Does anyone know why I am facing this problem? What am I doing wrong?
You might be having problem with the size of the image returned by the Picker. Images taken with the iPhone 7 are huge in size.
You just need to scale down the original image before uploading it using the Scale method and setting the size you find acceptable.
var smallImage = image.Scale(new CGSize(1280, 720)); //Or the size you need.
UPDATE
All you need is the Scale method mentioned above.
The big advantage of Xamarin being Open Source is that you can look at the internals any time you have a doubt.
https://github.com/xamarin/xamarin-macios/blob/master/src/UIKit/UIImage.cs#L66
I am using tesseract on my iOS device and it was working properly until recently it started to crash on me. I have been testing with the same image over and over again and prior to now I had it working about 75 times consecutively. The only thing I can think of is that I deleted the app from my iOS device and then ran it again through Xcode.
I am far from an expert on tesseract and I could really use some advice on what to do next, it would truly be a disappointment for all the hours I put in to go to waste because I cannot read the image anymore. Thank you
This is the crash error it appears to happen when the tesseract file in this method
- (BOOL)recognize
{
int returnCode = _tesseract->Recognize(NULL);// here is where the arrow points on the crash
return (returnCode == 0) ? YES : NO;
}
This is an old question from Alex G and I don't see any answer.
Does anyone find the root cause and solution? Please advice. Many thanks.
I hope you are using AVCaptureSession to take continuously photo and passing to tesseract after some image processing.
So before passing UIImage to tesseract for recognising you should check with this:
CGSize size = [image size];//your image
int width = size.width;
int height = size.height;
if (width < 100 || height < 50) {//UIImage must contain some some size
//Consider as invalid image
return;
}
//This condition is not mandatory.
uint32_t* _pixels = (uint32_t *) malloc(width * height * sizeof(uint32_t));
if (!_pixels) {
return;
//Consider as invalid image
}
I have implemented Uploadify in my ASP.NET MVC 3 application to upload images, but I now want to resize the images that I upload. I am not sure on what next to do in order to start resizing. I think there might be various ways to perform this resize, but I have not been able to find any example of this as yet. Can anyone suggest some way of doing this? Thanx
Here's a function you can use on the server side. I use it to process my images after uploadify is done.
private static Image ResizeImage(Image imgToResize, Size size)
{
int sourceWidth = imgToResize.Width;
int sourceHeight = imgToResize.Height;
float nPercent = 0;
float nPercentW = 0;
float nPercentH = 0;
nPercentW = ((float)size.Width / (float)sourceWidth);
nPercentH = ((float)size.Height / (float)sourceHeight);
if (nPercentH < nPercentW)
nPercent = nPercentH;
else
nPercent = nPercentW;
int destWidth = (int)(sourceWidth * nPercent);
int destHeight = (int)(sourceHeight * nPercent);
Bitmap b = new Bitmap(destWidth, destHeight);
Graphics g = Graphics.FromImage((Image)b);
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.DrawImage(imgToResize, 0, 0, destWidth, destHeight);
g.Dispose();
return (Image)b;
}
Here's how I use it:
int length = (int)stream.Length;
byte[] tempImage = new byte[length];
stream.Read(tempImage, 0, length);
var image = new Bitmap(stream);
var resizedImage = ResizeImage(image, new Size(300, 300));
Holler if you need help getting it running.
You have 3 ways:
Use GDI+ library (example of code - C# GDI+ Image Resize Function)
3-rd part components (i use ImageMagick - my solution: Generating image thumbnails in ASP.NET?)
Resize images on user side (some uploaders can do this)
I use AS3 in Flex 3 to create new image and seem unable to get the exact size of the original image. percentHeight & percentWidth to 100 can do the job, but limitation in ObjectHandlers require me to set the image scale in pixel.
Any solution?
Note: this is also applicable for displaying Image original dimension without ObjectHandler control, just remove those lines that are not applicable.
After struggle hours for solution, I found my own answer thru in actionscript forum, in fact, only one solution, I surprise there was no such topic elsewhere.
private function init():void {
var image:Image = new Image();
image.source = "http://www.colorjack.com/software/media/circle.png";
image.addEventListener(Event.COMPLETE, imageLoaded);
/* wait for completion as Image control is asynchronous,
* which mean ObjectHandler will attempt to load asap
* and you are not able to get the correct dimension for scaling.
* EventListener fixed that.
*/
this.addChild(image);
//whenever you scale ObjectHandler control, the image is always fit by 100%
image.percentHeight = 100;
image.percentWidth = 100;
}
private function imageLoaded(e:Event):void{
var img:Image = e.target as Image;
trace("Height ", img.contentHeight);
trace("Width ", img.contentWidth);
var oh:ObjectHandles = new ObjectHandles();
oh.x = 200;
oh.y = 200;
oh.height = img.contentHeight;
oh.width = img.contentWidth;
oh.allowRotate = true;
oh.autoBringForward = true;
oh.addChild(img);
genericExamples.addChild(oh);
}