I am not sure whether I can improve image quality but following code displays very poor image quality in PDF. I know its standard code to generate images from view but is there anything I could do to specify image quality or improve it?
- (void)renderView:(UIView*)view {
UIGraphicsBeginImageContext(view.frame.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewAsImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[viewAsImage drawInRect:rect];
}
You probably need to create a graphics context with a scale of 2 (retina) instead of the default 1. To do so, use UIGraphicsBeginImageContextWithOptions(view.frame.size, YES, 0.0);. This will create an image context with an opaque target (you can set the second parameter to NO if you're rendering a transparent image) and with a scale factor of your device's main screen.
Double the size!
- (void)renderView:(UIView*)view {
CGSize newSize = view.frame.size;
newSize.width = newSize.width * [UIScreen mainScreen].nativeScale;
newSize.height = newSize.height * [UIScreen mainScreen].nativeScale;
UIGraphicsBeginImageContext(newSize);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewAsImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[viewAsImage drawInRect:rect];
}
Related
I am having problem with UIImage resizing, image masking is working fine but after applying mask UIImage is starched, the problem is with scaling as image is not scaled properly.
CCClippingNode *clippingNode = [[CCClippingNode alloc] initWithStencil:pMaskingFrame ];
pTobeMasked.scaleX = (float)pMaskingFrame.contentSize.width / (float)pTobeMasked.contentSize.width;
pTobeMasked.scaleY = (float)pMaskingFrame.contentSize.height / (float)pTobeMasked.contentSize.height;
clippingNode.alphaThreshold = 0;
[pContainerNode addChild:clippingNode];
pTobeMasked.position = ccp(pMaskingFrame.position.x, pMaskingFrame.position.y);
[clippingNode addChild:pTobeMasked];
One of my project I have used below function to resize an image;
/*
method parameters definition
image : original image to be resized
size : new size
*/
+ (UIImage*)resizeImage:(UIImage *)image size:(CGSize)size
{
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
//here is the scaled image which has been changed to the size specified
UIGraphicsEndImageContext();
return newImage;
}
This will work like a charm. It's similar to the already posted answer, but it has some more options:
+(UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize
{
//UIGraphicsBeginImageContext(newSize);
// In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
// Pass 1.0 to force exact pixel size.
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
My problem is when I'm scaling up my UIView's background image it gets anti-aligning and very blurry although the original image is in high resolution and very bright.
The process of scaling happens when I make an animation on the UIView to scale it. I'm scaling UIView using the transform property of UIView.
The code I'm using to make the UIImage fit into new scale is:
-(UIImage *)imageResize :(UIImage*)image withSize:(CGSize)size
{
CGSize newSize = self.bounds.size;
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
And I'm assigning the background color with this line:
self.backgroundColor = [UIColor colorWithPatternImage:[self imageResize:img withSize:(CGSize)size]];
I guess you should try to apply screen resolution in this line:
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
Should look like this
CGFloat screenScale = [[UIScreen mainScreen] scale];
UIGraphicsBeginImageContextWithOptions(newSize, NO, screenScale);
This question already has answers here:
How to easily resize/optimize an image size with iOS?
(18 answers)
How to compress/resize image on iOS before uploading to a server?
(13 answers)
Closed 9 years ago.
I am working on an app which has to load images taken from camera which is generally around 5-6MB , into tableview. I am loading the image asynchronously and caching it but i want to know that is there any way through which i can change this large size images to lower size?
try this simple way ... i found from this post What's the easiest way to resize/optimize an image size with the iPhone SDK?
+ (UIImage*)imageWithImage:(UIImage*)image
scaledToSize:(CGSize)newSize;
{
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Here i put logic of both Crop and resize image, use it as per your requirement.
For Get Cropped Image:
UIImage *croppedImg = nil;
CGRect cropRect = CGRectMake(AS YOu Need); // set frame as you need
croppedImg = [self croppIngimageByImageName:self.imageView.image toRect:cropRect];
The following method that return UIImage (as You want size of image)
- (UIImage *)croppIngimageByImageName:(UIImage *)imageToCrop toRect:(CGRect)rect
{
//CGRect CropRect = CGRectMake(rect.origin.x, rect.origin.y, rect.size.width, rect.size.height+15);
CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return cropped;
}
Here you get Croped Image that return by above method;
OR RESIZING
And also use following method with specific hight and width of image for Resizing:
+ (UIImage*)resizeImage:(UIImage*)image withWidth:(CGFloat)width withHeight:(CGFloat)height
{
CGSize newSize = CGSizeMake(width, height);
CGFloat widthRatio = newSize.width/image.size.width;
CGFloat heightRatio = newSize.height/image.size.height;
if(widthRatio > heightRatio)
{
newSize=CGSizeMake(image.size.width*heightRatio,image.size.height*heightRatio);
}
else
{
newSize=CGSizeMake(image.size.width*widthRatio,image.size.height*widthRatio);
}
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
This method return NewImage, with specific size that you want.
I'm trying to add a video player icon on top of a thumbnail of a video.
I get the image from the YouTube API, then crop it to be square, then resize it to be the proper size. I then add my player icon image on top of it.
The problem lies in the fact that the player icon is much smaller than it should be on the thumbnail (it's 28x28pt when on screen it's much smaller). See in the below image where I added it to the cell to show the size it should be, versus the thumbnail size:
I crop it to a square with this method:
/**
* Given a UIImage, return it with a square aspect ratio (via cropping, not smushing).
*/
- (UIImage *)createSquareVersionOfImage:(UIImage *)image {
CGFloat originalWidth = image.size.width;
CGFloat originalHeight = image.size.height;
float smallestDimension = fminf(originalWidth, originalHeight);
// Determine the offset needed to crop the center of the image out.
CGFloat xOffsetToBeCentered = (originalWidth - smallestDimension) / 2;
CGFloat yOffsetToBeCentered = (originalHeight - smallestDimension) / 2;
// Create the square, making sure the position and dimensions are set appropriately for retina displays.
CGRect square = CGRectMake(xOffsetToBeCentered * image.scale, yOffsetToBeCentered * image.scale, smallestDimension * image.scale, smallestDimension *image.scale);
CGImageRef squareImageRef = CGImageCreateWithImageInRect([image CGImage], square);
UIImage *squareImage = [UIImage imageWithCGImage:squareImageRef scale:image.scale orientation:image.imageOrientation];
CGImageRelease(squareImageRef);
return squareImage;
}
Resize it with this method:
/**
* Resize the given UIImage to a new size and return the newly resized image.
*/
- (UIImage *)resizeImage:(UIImage *)image toSize:(CGSize)newSize {
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
And add it on top of the other image with this method:
/**
* Adds a UIImage on top of another UIImage and returns the result. The top image is centered.
*/
- (UIImage *)addImage:(UIImage *)additionalImage toImage:(UIImage *)backgroundImage {
UIGraphicsBeginImageContext(backgroundImage.size);
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[additionalImage drawInRect:CGRectMake((backgroundImage.size.width - additionalImage.size.width) / 2, (backgroundImage.size.height - additionalImage.size.height) / 2, additionalImage.size.width, additionalImage.size.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
And this is how it is implemented:
UIImage *squareThumbnail = [self resizeImage:[self createSquareVersionOfImage:responseObject] toSize:CGSizeMake(110.0, 110.0)];
UIImage *playerIcon = [UIImage imageNamed:#"video-thumbnail-overlay"];
UIImage *squareThumbnailWithPlayerIcon = [self addImage:playerIcon toImage:squareThumbnail];
But in the end, the icon is always too small. The sizing things confuse me when working with images, as I'm used to it figuring out retina screen related things automatically, and for example in the above code block, I'm not sure why I set it to 110.0, 110.0 as it's a 55x55 UIImageView and I thought it scales automatically (but if I put it to 55 it's stretched terribly).
The reason you have to put 110 in your resizeImage call is because you are creating a CGGraphics context with a scale of 1.0. The graphics context for views in a view hierarchy on retina displays have a scale of 2.0 (provided you did nothing to scale anything else).
I believe that new UIImage that you create is now a "normal" image (Sorry I can't remember the technical term). It is not an #2x image. So its size that you will get when you ask for size will not scale for #2x.
Note this answer:
UIGraphicsGetImageFromCurrentImageContext retina resolutions?
I haven't tested this, but it should work. If it doesn't it should at least be more straightforward to debug.
//images should be passed in with their original scales
-(UIImage*)compositedImageWithSize:(CGSize)newSize bg:(UIImage*)backgroundImage fgImage:(UIImage*)foregroundImage{
//match the scale of screen.
CGFloat scale = [[UIScreen mainScreen] scale];
UIGraphicsBeginImageContextWithOptions(newSize, NO, scale);
//instead of resizing the image ahead of time, we just draw it into the context at the appropriate size. The context will clip the image.
CGRect aspectFillRect = CGRectZero;
if(newSize.width/newSize.height > backgroundImage.size.width/backgroundImage.size.height){
aspectFillRect.y = 0;
aspectFillRect.height = newSize.height;
CGFloat scaledWidth = (newSize.height / backgroundImage.size.height) * newSize.width;
aspectFillRect.x = (newSize.width - scaledWidth)/2.0;
aspectFillRect.width = scaledWidth;
}else{
aspectFillRect.x = 0;
aspectFillRect.width = newSize.width;
CGFloat scaledHeight = (newSize.width / backgroundImage.size.width) * newSize.height;
aspectFillRect.y = (newSize.height - scaledHeight)/2.0;
aspectFillRect.height = scaledHeight;
}
[backgroundImage drawInRect:aspectFillRect];
//pass in the 2x image for the fg image so it provides a better resolution
[foregroundImage drawInRect:CGRectMake((newSize.width - additionalImage.size.width) / 2, (newSize.height - additionalImage.size.height) / 2, additionalImage.size.width, additionalImage.size.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
You would skip all those methods you were calling before and do:
UIImage *playerIcon = [UIImage imageNamed:#"video-thumbnail-overlay"];
//pass in the non-retina scale of the image
UIImage *result = [self compositedImageWithSize:CGSizeMake(55.0, 55.0)
bg:responseObject
fg:playerIcon];
Hope this helps!
I think I may have an odd request, however hopefully someone can help. I am using the well known UIScrollView + UIImageView to zoom into and out of an image, as well as pan. This works fine and dandy, but the current project we have needs to be able to crop the image, but also include the black bars on the sides if the image is smaller than the crop rectangle. See the images below.
We wish to capture everything inside of the blue box, including the white (which will be black, since opaque is set to YES).
This works great for images that are completely zoomed out (The white is just the UIImageView's extra space).
However the problem arises when we try to zoom into the image, and capture only that portion, plus the empty space.
This results in the following image
The problem we are seeing is we need to be able to create an image that is exactly what is in the Crop Rect, regardless if there is part of the image there or not. The other problem is we wish to have the ability to dynamically change the output resolution. The aspect ratio is 16:9, and for this example kMaxWidth = 1136 and kMaxHeight = 639, however in the future we may want to request a larger or smaller 16:9 resolution.
Below is the function I have so far:
- (UIImage *)createCroppedImageFromImage:(UIImage *)image {
CGSize newRect = CGSizeMake(kMaxWidth, kMaxHeight);
UIGraphicsBeginImageContextWithOptions(newRect, YES, 0.0);
// 0 is the edge of the screen, to help with zooming
CGFloat xDisplacement = ((abs(0 - imageView.frame.origin.x) * kMaxWidth) / (self.cropSize.width / self.scrollView.zoomScale) / self.scrollView.zoomScale);
CGFloat yDisplacement = ((abs(self.cropImageView.frame.origin.y - imageView.frame.origin.y) * kMaxHeight) / (self.cropSize.height / self.scrollView.zoomScale) / self.scrollView.zoomScale);
CGFloat newImageWidth = (self.image.size.width * kMaxWidth) / (self.cropSize.width / self.scrollView.zoomScale);
CGFloat newImageHeight = (self.image.size.height * kMaxHeight) / (self.cropSize.height / self.scrollView.zoomScale);
[image drawInRect:CGRectMake(xDisplacement, 0, newImageWidth, newImageHeight)];
UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return croppedImage;
}
Any help would be greatly appreciated.
I ended up just taking a screenshot, and cropping that. It seems to work well enough.
- (UIImage *)cropImage {
CGRect cropRect = self.cropOverlay.cropRect;
UIGraphicsBeginImageContext(self.view.frame.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *fullScreenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef croppedImage = CGImageCreateWithImageInRect(fullScreenshot.CGImage, cropRect);
UIImage *crop = [[UIImage imageWithCGImage:croppedImage] resizedImage:self.outputSize interpolationQuality:kCGInterpolationHigh];
CGImageRelease(croppedImage);
return crop;
}
If using iOS 7, you would use drawViewHierarchyInRect:afterScreenUpdates:, instead of renderInContext:
I think the translated rect for the image view isn't calculated properly. Since UIImageView is the subview inside the UIScrollView, you should be able to calculate the visible rect by calling [scrollView convertRect:scrollView.bounds toView:imageView];. That will be the visible rect of your image view. All you need to now is crop it.
-(UIImage*)cropImage:(UIImage*)img inRect:(CGRect)rect{
CGImageRef cropped = CGImageCreateWithImageInRect(img.CGImage, rect);
UIImage *image = [UIImage imageWithCGImage:cropped];
CGImageRelease(cropped);
return image;
}
Edit: Yeah... I forgot to mention that cropping should be done in (0,1) coordinate space. I've modified the crop function for you, so it crops the image based on all parameters you provided, UIImageView inside UIScrollView and an image.
-(UIImage*)cropImage:(UIImage*)image inImageView:(UIImageView*)imageView scrollView:(UIScrollView*)scrollView{
// get visible rect from image scrollview
CGRect visibleRect = [scrollView convertRect:scrollView.bounds toView:imageView];
UIImage* rCroppedImage;
CALayer* maskLayer= [[CALayer alloc] init];
maskLayer.contents= (id)image.CGImage;
maskLayer.frame= CGRectMake(0, 0, visibleRect.size.width, visibleRect.size.height);
CGRect rect= CGRectMake(visibleRect.origin.x / image.size.width,
visibleRect.origin.y / image.size.height,
visibleRect.size.width / image.size.width,
visibleRect.size.height / image.size.height);
maskLayer.contentsRect= rect;
UIGraphicsBeginImageContext(visibleRect.size);
CGContextRef context= UIGraphicsGetCurrentContext();
[maskLayer renderInContext:context];
rCroppedImage= UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return rCroppedImage;
}