ios Resizing images for thumbs - Blurry although high interpolation - iphone

I have written a category on UIImage to resize images like the iphone photos app.
Although the Interpolation is set to high, the image does not really look like the one in the photos app. Instead it looks unsharp or blurry.
Here is what I did:
- (UIImage *)resizeImageProportionallyIntoNewSize:(CGSize)newSize;
{
CGFloat scaleWidth = 1.0f;
CGFloat scaleHeight = 1.0f;
NSLog(#"Origin Size = %#", NSStringFromCGSize(self.size));
if (CGSizeEqualToSize(self.size, newSize) == NO) {
//calculate "the longer side"
if(self.size.width > self.size.height) {
scaleWidth = self.size.width / self.size.height;
} else {
scaleHeight = self.size.height / self.size.width;
}
}
// now draw the new image in a context with scaling proportionally
UIImage *sourceImage = self;
UIImage *newImage = nil;
//now we create a context in newSize and draw the image out of the bounds of the context to get
//an proportionally scaled image by cutting of the image overlay
if([[UIScreen mainScreen] scale] == 2.00) {
UIGraphicsBeginImageContextWithOptions(newSize, YES, 2.0);
}
UIGraphicsBeginImageContext(newSize);
// Set the quality level to use when rescaling
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
//Center image point so that on each egde is a little cutoff
CGRect thumbnailRect = CGRectZero;
thumbnailRect.size.width = (int) newSize.width * scaleWidth;
thumbnailRect.size.height = (int) newSize.height * scaleHeight;
thumbnailRect.origin.x = (int) (newSize.width - thumbnailRect.size.width) * 0.5;
thumbnailRect.origin.y = (int) (newSize.height - thumbnailRect.size.height) * 0.5;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(#"could not scale image");
return newImage ;
}
BTW: There is no difference on using high interpolation or not. Maybe I am doing something wrong.
Thanks in advance for your help!

The best way to make a thumbnail is to ask the system to do it for you, using the Image I/O Framework. The only trick is that since you're using a CGImage you must take account of the screen resolution:
CGImageSourceRef src = CGImageSourceCreateWith... // whatever
CGFloat scale = [UIScreen mainScreen].scale;
CGFloat w = // maximum size, multiplied by the scale
NSDictionary* d =
[NSDictionary dictionaryWithObjectsAndKeys:
(id)kCFBooleanTrue, kCGImageSourceShouldAllowFloat,
(id)kCFBooleanTrue, kCGImageSourceCreateThumbnailWithTransform,
(id)kCFBooleanTrue, kCGImageSourceCreateThumbnailFromImageAlways,
[NSNumber numberWithInt:(int)w], kCGImageSourceThumbnailMaxPixelSize,
nil];
CGImageRef imref =
CGImageSourceCreateThumbnailAtIndex(src, 0, (__bridge CFDictionaryRef)d);
UIImage* im =
[UIImage imageWithCGImage:imref scale:scale orientation:UIImageOrientationUp];
CFRelease(imref); CFRelease(src);

if it is unsharp / blurry, you should try to turn off anti-aliasing by:
CGContextSetShouldAntialias(context, NO);
hope this helps.

Related

Resize UIImage and change the size of UIImageView

I have this UIImageView and I have the values of its max height and max width. What I want to achieve is that I want to take the image (with any aspect ratio and any resolution) and I want it to fit in the borders, so the picture does not exceed them, but it can shrink them as it wants. (marked red in the picture):
Right now the image fits the necessary size properly, but I have 2 worries:
1. The UIImageView is not equal the size of the resized image, thus leaving red background (and I don't want that)
2. If the image is smaller that the height of my UIImageView it is not resized to be smaller, it stays the same height.
Here's my code and I know its wrong:
UIImage *actualImage = [attachmentsArray lastObject];
UIImageView *attachmentImageNew = [[UIImageView alloc] initWithFrame:CGRectMake(5.5, 6.5, 245, 134)];
attachmentImageNew.image = actualImage;
attachmentImageNew.backgroundColor = [UIColor redColor];
attachmentImageNew.contentMode = UIViewContentModeScaleAspectFit;
So how do I dynamically change the size not only of the UIImageView.image, but of the whole UIImageView, thus making its size totally adjustable to its content. Any help would be much appreciated, thanks!
When you get the width and height of a resized image Get width of a resized image after UIViewContentModeScaleAspectFit, you can resize your imageView:
imageView.frame = CGRectMake(0, 0, resizedWidth, resizedHeight);
imageView.center = imageView.superview.center;
I haven't checked if it works, but I think all should be OK
- (UIImage *)image:(UIImage*)originalImage scaledToSize:(CGSize)size
{
//avoid redundant drawing
if (CGSizeEqualToSize(originalImage.size, size))
{
return originalImage;
}
//create drawing context
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);
//draw
[originalImage drawInRect:CGRectMake(0.0f, 0.0f, size.width, size.height)];
//capture resultant image
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//return image
return image;
}
This is the Swift equivalent for Rajneesh071's answer, using extensions
UIImage {
func scaleToSize(aSize :CGSize) -> UIImage {
if (CGSizeEqualToSize(self.size, aSize)) {
return self
}
UIGraphicsBeginImageContextWithOptions(aSize, false, 0.0)
self.drawInRect(CGRectMake(0.0, 0.0, aSize.width, aSize.height))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
}
Usage:
let image = UIImage(named: "Icon")
item.icon = image?.scaleToSize(CGSize(width: 30.0, height: 30.0))
Use the category below and then apply border from Quartz into your image:
[yourimage.layer setBorderColor:[[UIColor whiteColor] CGColor]];
[yourimage.layer setBorderWidth:2];
The category:
UIImage+AutoScaleResize.h
#import <Foundation/Foundation.h>
#interface UIImage (AutoScaleResize)
- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize;
#end
UIImage+AutoScaleResize.m
#import "UIImage+AutoScaleResize.h"
#implementation UIImage (AutoScaleResize)
- (UIImage *)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
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;
// center the image
if (widthFactor > heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else
{
if (widthFactor < heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
}
UIGraphicsBeginImageContext(targetSize); // this will crop
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");
}
//pop the context to get back to the default
UIGraphicsEndImageContext();
return newImage;
}
#end
If you have the size of the image, why don't you set the frame.size of the image view to be of this size?
EDIT----
Ok, so seeing your comment I propose this:
UIImageView *imageView;
//so let's say you're image view size is set to the maximum size you want
CGFloat maxWidth = imageView.frame.size.width;
CGFloat maxHeight = imageView.frame.size.height;
CGFloat viewRatio = maxWidth / maxHeight;
CGFloat imageRatio = image.size.height / image.size.width;
if (imageRatio > viewRatio) {
CGFloat imageViewHeight = round(maxWidth * imageRatio);
imageView.frame = CGRectMake(0, ceil((self.bounds.size.height - imageViewHeight) / 2.f), maxWidth, imageViewHeight);
}
else if (imageRatio < viewRatio) {
CGFloat imageViewWidth = roundf(maxHeight / imageRatio);
imageView.frame = CGRectMake(ceil((maxWidth - imageViewWidth) / 2.f), 0, imageViewWidth, maxHeight);
} else {
//your image view is already at the good size
}
This code will resize your image view to its image ratio, and also position the image view to the same centre as your "default" position.
PS: I hope you're setting imageView.layer.shouldRasterise = YES
and imageView.layer.rasterizationScale = [UIScreen mainScreen].scale;
if you're using CALayer shadow effect ;) It will greatly improve the performance of your UI.
I think what you want is a different content mode. Try using UIViewContentModeScaleToFill. This will scale the content to fit the size of ur UIImageView by changing the aspect ratio of the content if necessary.
Have a look to the content mode section on the official doc to get a better idea of the different content mode available (it is illustrated with images).
if([[SDWebImageManager sharedManager] diskImageExistsForURL:[NSURL URLWithString:#"URL STRING1"]])
{
NSString *key = [[SDWebImageManager sharedManager] cacheKeyForURL:[NSURL URLWithString:#"URL STRING1"]];
UIImage *tempImage=[self imageWithImage:[[SDImageCache sharedImageCache] imageFromDiskCacheForKey:key] scaledToWidth:cell.imgview.bounds.size.width];
cell.imgview.image=tempImage;
}
else
{
[cell.imgview sd_setImageWithURL:[NSURL URLWithString:#"URL STRING1"] placeholderImage:nil completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL)
{
UIImage *tempImage=[self imageWithImage:image scaledToWidth:cell.imgview.bounds.size.width];
cell.imgview.image=tempImage;
// [tableView beginUpdates];
// [tableView endUpdates];
}];
}

iOS : Save image with custom resolution

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 .
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.
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;
}
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 :)
-(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.
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
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/
I think ALAssetRepresentation can help you.
CGSize sizePic = CGSizeMake(320, 460);
UIGraphicsBeginImageContext(sizePic);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *imagePic = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(imagePic, nil, nil, nil);
#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;
}

UIImageOrientation issue while upload on server

I don't know how this happens but when I take image from camera in portrait mode and upload to server it is displaying fine but when I take the same image from Photo Library and upload to server it is displaying in Landscape mode..
Don't know how this happens? and very stuck from last 5 hours..
I had gone through this and this but doesn't got success yet.
Any one help me about this problem?
Thanks in advance.
UPDATE
- (UIImage *)imageToFitSize:(CGSize)fitSize method:(MGImageResizingMethod)resizeMethod
{
float imageScaleFactor = 1.0;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
if ([self respondsToSelector:#selector(scale)]) {
imageScaleFactor = [self scale];
}
#endif
float sourceWidth = [self size].width * imageScaleFactor;
float sourceHeight = [self size].height * imageScaleFactor;
float targetWidth = fitSize.width;
float targetHeight = fitSize.height;
BOOL cropping = !(resizeMethod == MGImageResizeScale);
// Calculate aspect ratios
float sourceRatio = sourceWidth / sourceHeight;
float targetRatio = targetWidth / targetHeight;
// Determine what side of the source image to use for proportional scaling
BOOL scaleWidth = (sourceRatio <= targetRatio);
// Deal with the case of just scaling proportionally to fit, without cropping
scaleWidth = (cropping) ? scaleWidth : !scaleWidth;
// Proportionally scale source image
float scalingFactor, scaledWidth, scaledHeight;
if (scaleWidth) {
scalingFactor = 1.0 / sourceRatio;
scaledWidth = targetWidth;
scaledHeight = round(targetWidth * scalingFactor);
} else {
scalingFactor = sourceRatio;
scaledWidth = round(targetHeight * scalingFactor);
scaledHeight = targetHeight;
}
float scaleFactor = scaledHeight / sourceHeight;
// Calculate compositing rectangles
CGRect sourceRect, destRect;
if (cropping) {
destRect = CGRectMake(0, 0, targetWidth, targetHeight);
float destX, destY;
if (resizeMethod == MGImageResizeCrop) {
// Crop center
destX = round((scaledWidth - targetWidth) / 2.0);
destY = round((scaledHeight - targetHeight) / 2.0);
} else if (resizeMethod == MGImageResizeCropStart) {
// Crop top or left (prefer top)
if (scaleWidth) {
// Crop top
destX = 0.0;
destY = 0.0;
} else {
// Crop left
destX = 0.0;
destY = round((scaledHeight - targetHeight) / 2.0);
}
} else if (resizeMethod == MGImageResizeCropEnd) {
// Crop bottom or right
if (scaleWidth) {
// Crop bottom
destX = round((scaledWidth - targetWidth) / 2.0);
destY = round(scaledHeight - targetHeight);
} else {
// Crop right
destX = round(scaledWidth - targetWidth);
destY = round((scaledHeight - targetHeight) / 2.0);
}
}
sourceRect = CGRectMake(destX / scaleFactor, destY / scaleFactor,
targetWidth / scaleFactor, targetHeight / scaleFactor);
} else {
sourceRect = CGRectMake(0, 0, sourceWidth, sourceHeight);
destRect = CGRectMake(0, 0, scaledWidth, scaledHeight);
}
// Create appropriately modified image.
UIImage *image = nil;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0) {
UIGraphicsBeginImageContextWithOptions(destRect.size, NO, 0.0); // 0.0 for scale means "correct scale for device's main screen".
CGImageRef sourceImg;
if(resizeMethod == MGImageResizeCrop)
sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect); // cropping happens here.
else
sourceImg = CGImageRetain([self CGImage]); // scaling happens here.
image = [UIImage imageWithCGImage:sourceImg scale:0.0 orientation:self.imageOrientation]; // create cropped UIImage.
[image drawInRect:destRect]; // the actual scaling happens here, and orientation is taken care of automatically.
CGImageRelease(sourceImg);
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
#endif
if (!image) {
// Try older method.
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, fitSize.width, fitSize.height, 8, (fitSize.width * 4),
colorSpace, kCGImageAlphaPremultipliedLast);
CGImageRef sourceImg;
if(resizeMethod == MGImageResizeCrop)
sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect); // cropping happens here.
else
sourceImg = CGImageRetain([self CGImage]); // scaling happens here.
//CGImageRef sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect);
CGContextDrawImage(context, destRect, sourceImg);
CGImageRelease(sourceImg);
CGImageRef finalImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
image = [UIImage imageWithCGImage:finalImage];
CGImageRelease(finalImage);
}
return image;
}
Where MGImageResizingMethod is enum that I had defined and passing MGImageResizeScale as argument in function.
try it may be working. you have to set the condition according your image like
if(image == fromCamera){
[image fixOrientation];
}
else{
//please do not convert it to orientation
}
I suggest you to visit this two reference and you will get solution...
Camera image changes orientation
Image became horizontal after successfully uploaded on server using Http Post
Hope, this will help you..

How do you crop an image in iOS

I have a photo app where you can add stickers in one section. When you're finished I want to save the image. Here is the code that I have to do that.
if(UIGraphicsBeginImageContextWithOptions != NULL)
{
UIGraphicsBeginImageContextWithOptions(self.view.frame.size, YES, 2.5);
} else {
UIGraphicsBeginImageContext(self.view.frame.size);
}
CGContextRef contextNew=UIGraphicsGetCurrentContext();
[self.view.layer renderInContext:contextNew];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Now the image that gets saved is the full screen of the image, which is fine, but now I need to crop the image and I don't know how. You can see the image at the link below:
http://dl.dropbox.com/u/19130454/Photo%202012-04-09%201%2036%2018%20PM.png
I need to crop:
91px from the left and right
220px from the bottom
Any help would be greatly appreciated. If I haven't explained things clearly, please let me know and I'll do my best to re-explain.
How about something like this
CGRect clippedRect = CGRectMake(self.view.frame.origin.x+91, self.view.frame.origin.y, self.view.frame.size.width-91*2, self.view.frame.size.height-220);
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], clippedRect);
UIImage *newImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
Following code may help you.
You should get the correct cropFrame fist by below method
-(CGRect)cropRectForFrame:(CGRect)frame
{
// NSAssert(self.contentMode == UIViewContentModeScaleAspectFit, #"content mode must be aspect fit");
CGFloat widthScale = imageview.superview.bounds.size.width / imageview.image.size.width;
CGFloat heightScale = imageview.superview.bounds.size.height / imageview.image.size.height;
float x, y, w, h, offset;
if (widthScale<heightScale) {
offset = (imageview.superview.bounds.size.height - (imageview.image.size.height*widthScale))/2;
x = frame.origin.x / widthScale;
y = (frame.origin.y-offset) / widthScale;
w = frame.size.width / widthScale;
h = frame.size.height / widthScale;
} else {
offset = (imageview.superview.bounds.size.width - (imageview.image.size.width*heightScale))/2;
x = (frame.origin.x-offset) / heightScale;
y = frame.origin.y / heightScale;
w = frame.size.width / heightScale;
h = frame.size.height / heightScale;
}
return CGRectMake(x, y, w, h);
}
Then you need to call this method to get cropped image
- (UIImage *)imageByCropping:(UIImage *)image toRect:(CGRect)rect
{
// you need to update scaling factor value if deice is not retina display
UIGraphicsBeginImageContextWithOptions(rect.size,
/* your view opaque */ NO,
/* scaling factor */ 2.0);
// stick to methods on UIImage so that orientation etc. are automatically
// dealt with for us
[image drawAtPoint:CGPointMake(-rect.origin.x, -rect.origin.y)];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
- (UIImage*)imageByCropping:(CGRect)rect
{
//create a context to do our clipping in
UIGraphicsBeginImageContext(rect.size);
CGContextRef currentContext = UIGraphicsGetCurrentContext();
//create a rect with the size we want to crop the image to
//the X and Y here are zero so we start at the beginning of our
//newly created context
CGRect clippedRect = CGRectMake(0, 0, rect.size.width, rect.size.height);
CGContextClipToRect( currentContext, clippedRect);
//create a rect equivalent to the full size of the image
//offset the rect by the X and Y we want to start the crop
//from in order to cut off anything before them
CGRect drawRect = CGRectMake(rect.origin.x * -1,
rect.origin.y * -1,
self.size.width,
self.size.height);
//draw the image to our clipped context using our offset rect
// CGContextDrawImage(currentContext, drawRect, self.CGImage);
[self drawInRect:drawRect]; // This will fix getting inverted image from context.
//pull the image from our cropped context
UIImage *cropped = UIGraphicsGetImageFromCurrentImageContext();
//pop the context to get back to the default
UIGraphicsEndImageContext();
//Note: this is autoreleased
return cropped;
}
Refer the below link for crop image
https://github.com/myang-git/iOS-Image-Crop-View
** How to Use **
Very easy! It is created to be a drop-in component, so no static library, no extra dependencies. Just copy ImageCropView.h and ImageCropView.m to your project, and implement ImageCropViewControllerDelegate protocol.
Use it like UIImagePicker:
- (void)cropImage:(UIImage *)image{
ImageCropViewController *controller = [[ImageCropViewController alloc] initWithImage:image];
controller.delegate = self;
[[self navigationController] pushViewController:controller animated:YES];
}
- (void)ImageCropViewController:(ImageCropViewController *)controller didFinishCroppingImage:(UIImage *)croppedImage{
image = croppedImage;
imageView.image = croppedImage;
[[self navigationController] popViewControllerAnimated:YES];
}
- (void)ImageCropViewControllerDidCancel:(ImageCropViewController *)controller{
imageView.image = image;
[[self navigationController] popViewControllerAnimated:YES];
}

How to resize the image programmatically in objective-c in iphone

I have an application where I am displaying large images in a small space.
The images are quite large, but I am only displaying them in 100x100 pixel frames.
My app is responding slowly because of the size fo the images I am using.
To improve performance, how can I resize the images programmatically using Objective-C?
Please find the following code.
- (UIImage *)imageWithImage:(UIImage *)image convertToSize:(CGSize)size {
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *destImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return destImage;
}
This code is for just change image scale not for resizing. You have to set CGSize as your image width and hight so the image will not stretch and it arrange at the middle.
- (UIImage *)imageWithImage:(UIImage *)image scaledToFillSize:(CGSize)size
{
CGFloat scale = MAX(size.width/image.size.width, size.height/image.size.height);
CGFloat width = image.size.width * scale;
CGFloat height = image.size.height * scale;
CGRect imageRect = CGRectMake((size.width - width)/2.0f,
(size.height - height)/2.0f,
width,
height);
UIGraphicsBeginImageContextWithOptions(size, NO, 0);
[image drawInRect:imageRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
My favorite way to do this is with CGImageSourceCreateThumbnailAtIndex (in the ImageIO framework). The name is a bit misleading.
Here's an excerpt of some code from a recent app of mine.
CGFloat maxw = // whatever;
CGFloat maxh = // whatever;
CGImageSourceRef src = NULL;
if ([imageSource isKindOfClass:[NSURL class]])
src = CGImageSourceCreateWithURL((__bridge CFURLRef)imageSource, nil);
else if ([imageSource isKindOfClass:[NSData class]])
src = CGImageSourceCreateWithData((__bridge CFDataRef)imageSource, nil);
// if at double resolution, double the thumbnail size and use double-resolution image
CGFloat scale = 1;
if ([[UIScreen mainScreen] scale] > 1.0) {
scale = 2;
maxw *= 2;
maxh *= 2;
}
// load the image at the desired size
NSDictionary* d = #{
(id)kCGImageSourceShouldAllowFloat: (id)kCFBooleanTrue,
(id)kCGImageSourceCreateThumbnailWithTransform: (id)kCFBooleanTrue,
(id)kCGImageSourceCreateThumbnailFromImageAlways: (id)kCFBooleanTrue,
(id)kCGImageSourceThumbnailMaxPixelSize: #((int)(maxw > maxh ? maxw : maxh))
};
CGImageRef imref = CGImageSourceCreateThumbnailAtIndex(src, 0, (__bridge CFDictionaryRef)d);
if (NULL != src)
CFRelease(src);
UIImage* im = [UIImage imageWithCGImage:imref scale:scale orientation:UIImageOrientationUp];
if (NULL != imref)
CFRelease(imref);
If you are using a image on different sizes and resizing each time it will degrade your app performance. Solution is don't resize them just use button in place of imageview. and just set the image on button it will resize automatically and you will get great performance.
I was also resizing images while setting it on cell but my app got slow So I used Button in place of imageview (not resizing images programatically button is doing this job) and it is working perfectly fine.
-(UIImage *)scaleImage:(UIImage *)image toSize:. (CGSize)targetSize
{
//If scaleFactor is not touched, no scaling will occur
CGFloat scaleFactor = 1.0;
//Deciding which factor to use to scale the image (factor = targetSize / imageSize)
if (image.size.width > targetSize.width ||
image.size.height > targetSize.height || image.size.width == image.size.height)
if (!((scaleFactor = (targetSize.width /
image.size.width)) > (targetSize.height /
image.size.height))) //scale to fit width, or
scaleFactor = targetSize.height / image.size.height; // scale to fit heigth.
Since the code ran perfectly fine in iOS 4, for backwards compatibility I added a check for OS version and for anything below 5.0 the old code would work.
- (UIImage *)resizedImage:(CGSize)newSize interpolationQuality:(CGInterpolationQuality)quality {
BOOL drawTransposed;
CGAffineTransform transform = CGAffineTransformIdentity;
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 5.0) {
// Apprently in iOS 5 the image is already correctly rotated, so we don't need to rotate it manually
drawTransposed = NO;
} else {
switch (self.imageOrientation) {
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
drawTransposed = YES;
break;
default:
drawTransposed = NO;
}
transform = [self transformForOrientation:newSize];
}
return [self resizedImage:newSize
transform:transform
drawTransposed:drawTransposed
interpolationQuality:quality];
}
You can use this.
[m_Image.layer setMinificationFilter:kCAFilterTrilinear];
This thread is old, but it is what I pulled up when trying to solve this problem. Once the image is scaled it was not displaying well in my container even though I turned auto layout off. The easiest way for me to solve this for display in a table row, was to paint the image on a white background that had a fixed size.
Helper function
+(UIImage*)scaleMaintainAspectRatio:(UIImage*)sourceImage :(float)i_width :(float)i_height
{
float newHeight = 0.0;
float newWidth = 0.0;
float oldWidth = sourceImage.size.width;
float widthScaleFactor = i_width / oldWidth;
float oldHeight = sourceImage.size.height;
float heightScaleFactor = i_height / oldHeight;
if (heightScaleFactor > widthScaleFactor) {
newHeight = oldHeight * widthScaleFactor;
newWidth = sourceImage.size.width * widthScaleFactor;
} else {
newHeight = sourceImage.size.height * heightScaleFactor;
newWidth = oldWidth * heightScaleFactor;
}
// return image in white rect
float cxPad = i_width - newWidth;
float cyPad = i_height - newHeight;
if (cyPad > 0) {
cyPad = cyPad / 2.0;
}
if (cxPad > 0) {
cxPad = cxPad / 2.0;
}
CGSize size = CGSizeMake(i_width, i_height);
UIGraphicsBeginImageContextWithOptions(CGSizeMake(size.width, size.height), YES, 0.0);
[[UIColor whiteColor] setFill];
UIRectFill(CGRectMake(0, 0, size.width, size.height));
[sourceImage drawInRect:CGRectMake((int)cxPad, (int)cyPad, newWidth, newHeight)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
// will return scaled image at actual size, not in white rect
// UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
// [sourceImage drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
// UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// UIGraphicsEndImageContext();
// return newImage;
}
I called this like this from my table view cellForRowAtIndexPath
PFFile *childsPicture = [object objectForKey:#"picture"];
[childsPicture getDataInBackgroundWithBlock:^(NSData *imageData, NSError *error) {
if (!error) {
UIImage *largePicture = [UIImage imageWithData:imageData];
UIImage *scaledPicture = [Utility scaleMaintainAspectRatio:largePicture :70.0 :70.0 ];
PFImageView *thumbnailImageView = (PFImageView*)[cell viewWithTag:100];
thumbnailImageView.image = scaledPicture;
[self.tableView reloadData];
}
}];
Hello from the end of 2018.
Solved with next solution (you need only last line, first & second are just for explanation):
NSURL *url = [NSURL URLWithString:response.json[0][#"photo_50"]];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *image = [UIImage imageWithData:data scale:customScale];
'customScale' is scale which you want (>1 if image must be smaller, <1 if image must be bigger).
This c method will resize your image with cornerRadius "Without effecting image's quality" :
UIImage *Resize_Image(UIImage *iImage, CGFloat iSize, CGFloat icornerRadius) {
CGFloat scale = MAX(CGSizeMake(iSize ,iSize).width/iImage.size.width, CGSizeMake(iSize ,iSize).height/iImage.size.height);
CGFloat width = iImage.size.width * scale;
CGFloat height = iImage.size.height * scale;
CGRect imageRect = CGRectMake((CGSizeMake(iSize ,iSize).width - width)/2.0f,(CGSizeMake(iSize ,iSize).height - height)/2.0f,width,height);
UIGraphicsBeginImageContextWithOptions(CGSizeMake(iSize ,iSize), NO, 0);
[[UIBezierPath bezierPathWithRoundedRect:imageRect cornerRadius:icornerRadius] addClip];
[iImage drawInRect:imageRect];
UIImage *ResizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return ResizedImage;
}
This is how to use :
UIImage *ResizedImage = Resize_Image([UIImage imageNamed:#"image.png"], 64, 14.4);
I do not remember where i took the first 4 lines ..