Xamarin.iOS capture photo in 72 dpi

Question

photoOutput = new AVCapturePhotoOutput();
if (CaptureSession.CanAddOutput(photoOutput))
{
        CaptureSession.AddOutput(photoOutput);
        photoOutput.IsHighResolutionCaptureEnabled = true;
}

TakePhoto button:

void TakePhoto()
{
        AVCapturePhotoSettings settings = GetCurrentPhotoSettings();
        photoOutput.CapturePhoto(settings, this);
}

AVCapturePhotoSettings GetCurrentPhotoSettings()
{
        AVCapturePhotoSettings photoSettings = AVCapturePhotoSettings.Create();

        var previewPixelType = photoSettings.AvailablePreviewPhotoPixelFormatTypes.First();

        var keys = new[]
        {
                new NSString(CVPixelBuffer.PixelFormatTypeKey),
                new NSString(CVPixelBuffer.WidthKey),
                new NSString(CVPixelBuffer.HeightKey),
        };

        var objects = new NSObject[]
        {
                previewPixelType,
                new NSNumber(160),
                new NSNumber(160)
        };

        var dictionary = new NSDictionary<NSString, NSObject>(keys, objects);
        photoSettings.PreviewPhotoFormat = dictionary;

        photoSettings.IsHighResolutionPhotoEnabled = true;
        return photoSettings;
}

[Export("captureOutput:didFinishProcessingPhotoSampleBuffer:previewPhotoSampleBuffer:resolvedSettings:bracketSettings:error:")]
void DidFinishProcessingPhoto(AVCapturePhotoOutput captureOutput,CMSampleBuffer photoSampleBuffer,CMSampleBuffer previewPhotoSampleBuffer,AVCaptureResolvedPhotoSettings resolvedSettings, AVCaptureBracketedStillImageSettings bracketSettings,NSError error)
    {
            if (photoSampleBuffer == null)
            {
                    Console.WriteLine($"Error occurred while capturing photo: {error}");
                    return;
            }

            NSData imageData = AVCapturePhotoOutput.GetJpegPhotoDataRepresentation(photoSampleBuffer, previewPhotoSampleBuffer);
    
            UIImage imageInfo = new UIImage(imageData);
                
            (Element as CameraView).SetPhotoResult(imageInfo.AsJPEG().ToArray());
    }

As a result of executing this code, I get an array of bytes of the image that I save using the function:

void SaveImageTest(string filename, byte[] arr)
    {
            UIImage img = new UIImage(NSData.FromArray(arr));
            var jpeg = img.AsJPEG();
                
            NSError error;
            jpeg.Save(filename, false, out error);
    }

Uploading an image to the server, I get 96 DPI in image details. image details

I would like to create 72 DPI images.,

I did not find an intelligible solution, maybe swift is not able to create such images and you probably know Xamarin libraries for image transformation

You could try the way in the link below to set with the DPI you want. https://stackoverflow.com/questions/43974553/how-to-reduce-size-of-the-picture-taken-by-camera-in-iphone-7 — Wendy Zang - MSFT, Mar 29 '21 at 05:32

score 0 · Answer 1 · answered Apr 01 '21 at 06:09

We could resize the image with the following code

/*
   sourceImage:the iamge that you download
   newSize the size you want ( for example 72*72)
*/
public UIImage ScalingImageToSize(UIImage sourceImage,CGSize newSize)
{


   UIGraphics.BeginImageContextWithOptions(newSize, false, UIScreen.MainScreen.Scale);
   sourceImage.Draw(new CGRect(0, 0, newSize.Width, newSize.Height));

   UIImage newImage = UIGraphics.GetImageFromCurrentImageContext();

   UIGraphics.EndImageContext();

   return newImage;

  }

Xamarin.iOS capture photo in 72 dpi

1 Answers1