iOS : Save image with custom resolution - iphone

Question

Hi I am try to capture a view then save as an image into Photo Library , but I need create a custom resolution for captured image , here is my code but when app saves the images the resolution is low !
UIGraphicsBeginImageContextWithOptions(self.captureView.bounds.size, self.captureView.opaque, 0.0);
[self.captureView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * screenshot = UIGraphicsGetImageFromCurrentImageContext();
CGRect cropRect = CGRectMake(0 ,0 ,1435 ,1435);
CGImageRef imageRef = CGImageCreateWithImageInRect([screenshot CGImage], cropRect);
CGImageRelease(imageRef);
UIImageWriteToSavedPhotosAlbum(screenshot , nil, nil, nil);
UIGraphicsEndImageContext();
but the resolution in iPhone is : 320 x 320 and retina is : 640 x 640
I would be grateful if you help me to fix this issue .

Answer 1

Your code is pretty close. What you need to do is re-render the screenshot at the custom resolution. I modified your code to do this:
UIView* captureView = self.view;
/* Capture the screen shoot at native resolution */
UIGraphicsBeginImageContextWithOptions(captureView.bounds.size, captureView.opaque, 0.0);
[captureView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
/* Render the screen shot at custom resolution */
CGRect cropRect = CGRectMake(0 ,0 ,1435 ,1435);
UIGraphicsBeginImageContextWithOptions(cropRect.size, captureView.opaque, 1.0f);
[screenshot drawInRect:cropRect];
UIImage * customScreenShot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
/* Save to the photo album */
UIImageWriteToSavedPhotosAlbum(customScreenShot , nil, nil, nil);
Note that if capture view is not square then the image will be distorted. The saved image will always be square and 1435x1435 pixels.

Answer 2

have a look at this answer. The code includes rotation but nonetheless the questioner asked the same question: "How to get a […] image from an UIImageView at its full resolution?"
copied content (in case of deletion or whatever):
- (UIImage *)capturedView
{
float imageScale = sqrtf(powf(self.captureView.transform.a, 2.f) + powf(self.captureView.transform.c, 2.f));
CGFloat widthScale = self.captureView.bounds.size.width / self.captureView.image.size.width;
CGFloat heightScale = self.captureView.bounds.size.height / self.captureView.image.size.height;
float contentScale = MIN(widthScale, heightScale);
float effectiveScale = imageScale * contentScale;
CGSize captureSize = CGSizeMake(enclosingView.bounds.size.width / effectiveScale, enclosingView.bounds.size.height / effectiveScale);
NSLog(#"effectiveScale = %0.2f, captureSize = %#", effectiveScale, NSStringFromCGSize(captureSize));
UIGraphicsBeginImageContextWithOptions(captureSize, YES, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextScaleCTM(context, 1/effectiveScale, 1/effectiveScale);
[enclosingView.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}

Answer 3

First get your image in UIImage object. Create your size what ever you want and use following..
UIImage *image = // you image;
CGSize size;
if ([[UIScreen mainScreen] respondsToSelector:#selector(displayLinkWithTarget:selector:)] &&
([UIScreen mainScreen].scale == 2.0)) {
// RETINA DISPLAY
size = CGSizeMake(640, 640);
}
else {
// Non Ratina device
size = CGSizeMake(320, 320);
}
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Now you will get destImage with new resolution.
Hope this is what you are looking for :)

Answer 4

-(UIImage*)processImageRect:(UIImage*)image:(CGSize)sizeToForm {
// Draw image1
UIGraphicsBeginImageContext(CGSizeMake(sizeToForm.width, sizeToForm.height));
[image drawInRect:CGRectMake(0.0, 0.0, sizeToForm.width, sizeToForm.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
return resultingImage;
}
Go with this may solve your issue.

Answer 5

You can use that :
UIImageExtras.h
#interface UIImage (Extras)
-(UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;
#end
UIImageExtras.m
#import "UIImageExtras.h"
#implementation UIImage (Extras)
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
//Image de base
UIImage *sourceImage = self;
//Image redimenssionnée
UIImage *newImage = nil;
//Taille de l'image de base
CGSize imageSize = sourceImage.size;
//Longueur et largeur
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
//Dimension désirée
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
//Echelle...
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
//Si taille des image est différentes on redimensionne de facon proportionnelle
if (CGSizeEqualToSize(imageSize, targetSize) == NO)
{
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor > heightFactor)
scaleFactor = widthFactor; // scale to fit height
else
scaleFactor = heightFactor; // scale to fit width
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
//Centre l'image
if (widthFactor > heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else if (widthFactor < heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
if(newImage == nil)
NSLog(#"could not scale image");
UIGraphicsEndImageContext();
return newImage;
}
#end

Answer 6

This worked for me. I tried with image that i got from Facebook SDK
http://pulkitgoyal.in/resizing-high-resolution-images-on-ios-without-memory-issues/

Answer 7

I think ALAssetRepresentation can help you.

Answer 8

CGSize sizePic = CGSizeMake(320, 460);
UIGraphicsBeginImageContext(sizePic);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *imagePic = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(imagePic, nil, nil, nil);

Answer 9

#import <ImageIO/ImageIO.h>
#import <MobileCoreServices/MobileCoreServices.h>
+ (UIImage *)resizeImage:(UIImage *)image toResolution:(int)resolution {
NSData *imageData = UIImagePNGRepresentation(image);
CGImageSourceRef src = CGImageSourceCreateWithData((__bridge CFDataRef)imageData, NULL);
CFDictionaryRef options = (__bridge CFDictionaryRef) #{
(id) kCGImageSourceCreateThumbnailWithTransform : #YES,
(id) kCGImageSourceCreateThumbnailFromImageAlways : #YES,
(id) kCGImageSourceThumbnailMaxPixelSize : #(resolution)
};
CGImageRef thumbnail = CGImageSourceCreateThumbnailAtIndex(src, 0, options);
CFRelease(src);
UIImage *img = [[UIImage alloc]initWithCGImage:thumbnail];
return img;
}