UIImage strange scaling

Question

I have some file with size (1000x1000 for example).

I want to load it and make it smaller

UIImage *newImage = [UIImage imageWithCGImage:[UIImage imageWithContentsOfFile:filename].CGImage scale:(1.0f / scale) orientation:UIImageOrientationUp];
NSLog(newImage size: %f, %f", newImage.size.width, newImage.size.height);
// shows correct scaled size -> 50, 50

Then i want to save this scaled image

NSData* imageData = UIImageJPEGRepresentation(newImage, 1.0);
[imageData writeToFile:otherFileName atomically:NO];

I was confused to see that new image was saved with first start size(1000x1000).

How can it be possible and what to do with this?

It seems you need to know to how scale image. Possible duplicate http://stackoverflow.com/questions/6703502/how-to-resize-an-uiimage-while-maintaining-its-aspect-ratio — Mahmoud Fayez, Mar 07 '13 at 08:48
why dont you use `NSData* imageData = UIImageJPEGRepresentation(newImage, 1.0f / scale);` as you do in your first step? — pmk, Mar 07 '13 at 08:53

score 2 · Accepted Answer · answered Mar 07 '13 at 08:51

Just make one method:

-(UIImage *)scaleImage:(UIImage *)image toSize:(CGSize)newSize {

    float width = newSize.width;
    float height = newSize.height;

    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect: CGRectMake(0, 0, width, height)];

    UIImage *smallImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return smallImage;
}

And set your required size like this:

UIImage *resizedImg = [self scaleImage:[UIImage imageWithData:imageData] toSize:CGSizeMake(150.0f,150.0f)]; // i have taken 150 you can change value here

score 1 · Answer 2 · answered Mar 07 '13 at 08:49

you can create Image With smaller size witout scratch image Using Bellow Method:-

you can called bellow method like:-

newImage=[self scaleImage:newImage toSize:CGSizeMake(250, 250)];


- (UIImage*) scaleImage:(UIImage*)image toSize:(CGSize)newSize {
    CGSize scaledSize = newSize;
    float scaleFactor = 2.0;
    if( image.size.width > image.size.height ) {
        scaleFactor = image.size.width / image.size.height;
        scaledSize.width = newSize.width;
        scaledSize.height = newSize.height / scaleFactor;
    }
    else {
        scaleFactor = image.size.height / image.size.width;
        scaledSize.height = newSize.height;
        scaledSize.width = newSize.width / scaleFactor;
    }

    UIGraphicsBeginImageContextWithOptions( scaledSize, NO, 0.0 );
    CGRect scaledImageRect = CGRectMake( 0.0, 0.0, scaledSize.width, scaledSize.height );
    [image drawInRect:scaledImageRect];
    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return scaledImage;
}

UIImage strange scaling

2 Answers2