I am making a simple camera app where a user takes an image and then emails it. I have one problem: once the user takes an image (which always works), if it is portrait, the MFMailComposer auto-rotates it to landscape incorrectly, making everything sideways. How can I stop this behavior?
This occurs because PNGs do not store orientation information. Attach the photo to the email as a JPG instead and it will be oriented correctly!
Use this code to attach your image instead:
let data:NSData = UIImageJPEGRepresentation(image, 0.9)! // 0.9 is compression value: 0.0 is most compressed/lowest quality and 1.0 is least compressed/highest quality
mailcomposer.addAttachmentData(data, mimeType: "image/jpg", fileName: "image.jpg")
Source + more info: https://stackoverflow.com/a/34796890/5700898
Related
As storing pictures is going to be one of the more expensive features of Firebase my app will be using I want to make sure I'm doing it efficiently.
The steps I'm taking are the following:
Resize picture the user wants to upload to have width of 500 points (A point represents a pixel on non-retina screens and two pixels on retina screens)
Upload the data for the specified image in PNG format to Firebase storage
Here's my actual code:
let storageRef = FIRStorage.storage().reference().child("\(name).png")
if let uploadData = UIImagePNGRepresentation(profImage.resizeImage(targetSize: CGSize(width: 500, height: Int(500*(profImage.size.height/profImage.size.width))))) {
storageRef.put(uploadData, metadata: nil, completion: nil)
}
The photos are going to be a little less than the width of an iPhone screen when displayed to the user. Is the way I'm storing them efficient or is there a better way to format them?
**Edit: After a bit more research I've found out that JPGs are more efficient than PNG so I'll be switching to that since transparency isn't important for me. See my answer for example.
I've changed the image format from png to jpeg and found it saves a lot of space. Here's a picture of my storage for comparisons:
My code went from using UIImagePNGRepresentation to UIImageJPEGRepresentation with a compression factor of 1. I'm sure if I reduce the compression factor it'll save even more space.
I am creating a feature where a user can record a video of themselves, and superimposed on this video is a view that displays an image and some text. When they are done recording, I am using AVFoundation's composition classes to composite the video and the view (as an image) into one video file, and output this in the next scene in a custom video player. The problem is that while the view's resolution is crystal clear in the record scene, after the composition (and after the AVExportSession completes) the resulting video's overlayed view quality is not clsoe to the actual view quality. I am converting the view to an image, and then setting the contents of an overlay layer as this image's CGImage, which, as I have checked, still has the same quality as the original view. The problem occurs when I apply the composition, and the image becomes blurry. Does anyone have any idea why this might be happening?
If you need to see the code, please feel free to ask! I can also provide screenshots.
Thank you!
It could happen when initiating your UIImage, iOS automatically pick #2x or #3x image source for you corresponding to your device.
Let say you get image size using size property like image.size, it gives you #1x size, and you might reduce your image size from #2x or #3x to #1x, you get a bad quality image output, because JPEG or PNG resize algorithms.
In an app I'm developing, the customer enters in some personal information and signs a box on the screen. I then programmatically screenshot the the full view and convert it to base64.
This is working fine, however, due to the size of the image it takes approximately 15 seconds to convert it to base64 and send it to an API server. The image size at full quality is the same size as the iPad Air resolution (1536x2048).
Once saved on the server as a PNG, the image weighs in at around 410kb.
I want to resize the image capture down to 768x1024 (half of what it is) without losing clarity. I think this will save both time and storage space.
I'm currently taking the "screenshot" using the following function:
func screenCaptureAndGo() {
//Create the UIImage
UIGraphicsBeginImageContextWithOptions(view.frame.size, view.opaque, 0.0)
view.layer.renderInContext(UIGraphicsGetCurrentContext())
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
imageData = UIImagePNGRepresentation(image)
imageDataString = imageData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding64CharacterLineLength)
}
I left out the API server stuff as it's not really relevant.
I ended up just using the Scale property. It didn't work the first time, which is why I didn't think to use it again, but after toying with it I got it to work.
I'm using 0.7 as the scale amount, and the images now clock in at 100kb, and it takes 4 seconds to convert and send the base64 string.
In my web app (runs in native Safari not UIWebView) I am using canvas to basically allow to draw an image. The user should then be able to save this image to his computer, however it's very important that this process is lossless. That's why I am using the PNG file format.
All this works perfectly on desktop, and in theory it should also work on iOS because by tap and holding the resulting image can be saved to the camera roll. The problem occurs if the image is later imported into the app again. On inspection of the uploaded image type you can see that the image is now in the JPG file format and no longer a pixel perfect representation of the drawing the user made.
Is that a general issue with the camera roll on iOS? Is there any workaround?
YES, The default file format is JPG while saving image to camera roll. You can save a image in PNG format in a native app by writing some code. But in Safari, there may no be possible to save as PNG format.
I'm using UIImagePickerController to fetch images from the user's photo library and/or taken with the camera. Works great.
I'm noticing that fetched images are often (always?) coming back with their imageOrientation set to UIImageOrientationRight. But the image was captured with the device in portrait orientation. Why is this? This is an iPhone4S, iOS6, using the rear camera - so the resolution is 8MP.
In the simulator, grabbing photos from the photo library, images come back UIImageOrientationUp.
When I display the image in a UIImageView the orientation looks correct (portrait/up). But when I go to crop the image the coordinate system isn't what I would expect. 0,0 is in the upper-right of the image, which I guess makes sense when it reports UIImageOrientationRight.
I'm looking for an explanation of what's going on and the correct approach to dealing with the odd coordinate system.
EDIT: it sure appears to me that, on iPhone4S at least, the camera always takes UIImageOrientationRight/"landscape" images, and that UIImageView is respecting the imageOrientation on display. However, if I save the image using UIImagePNGRepresentation the orientation is not preserved (I think I read about this somewhere.)
It has to do with the orientation the phone was in when the image was taken. The phone doesn't rotate the image data from the camera sensor to make up in the image be up but instead sets the imageOrientation and then UIImage will take care of rendering things the right way.
When you try and crop, you typically change the image to be a CGImage and that loses the orientation information so suddenly you get the image with a strange orientation.
There are several categories on UIImage that you can get that will perform image cropping while taking imageOrientation into account.
Have a look at link or link