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iosobjective-cimagesnapchat

Objective-C How does snapchat make the text on top of an image/video so sharp and not pixelated?

In my app, it allows users to place text on top of images like snapchat, then they are allowed to save the image to their device. I simply add the text view on top of the image and take a picture of the image using the code:

UIGraphicsBeginImageContext(imageView.layer.bounds.size);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage* savedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

But when I compare the text on my image, to the text from a snapchat image...it is significantly different. Snapchat's word text on top of image is significantly sharper then mine. Mine looks very pixelated. Also I am not compressing the image at all, just saving the image as is using ALAssetLibrary.

Thank You

Solution

  • When you use UIGraphicsBeginImageContext, it defaults to a 1x scale (i.e. non-retina resolution). You probably want:

    UIGraphicsBeginImageContextWithOptions(imageView.layer.bounds.size, YES, 0);

    Which will use the same scale as the screen (probably 2x). The final parameter is the scale of the resulting image; 0 means "whatever the screen is".