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Cropping a UIImage
I saw many tutorials about cropping images and am trying my luck but with no success.
I need to crop the image from AVFoundation. Since when the image is being taken from the camera it is rotated left from Portrait mode, I also need to rotate it right and my x and y are opposite. The problem is that if I send the frame of the image where I would it to reside, it seems to me that there is no correlation in the size of the image and the rectangle.
The code is:
#property (weak, nonatomic) IBOutlet UIView *videoPreviewView;
...
...
int width = videoPreviewView.frame.size.width;
int height = videoPreviewView.frame.size.height;
int x = videoPreviewView.frame.origin.x;
int y = videoPreviewView.frame.origin.y;
CGRect croprect = CGRectMake(y, x,height,width);
// Draw new image in current graphics context
CGImageRef imageRef = CGImageCreateWithImageInRect([sourceImage CGImage], croprect);
// Create new cropped UIImage
UIImage *resultImage = [UIImage imageWithCGImage:imageRef scale:[sourceImage scale] orientation:UIImageOrientationRight];
When I print the size of the frame I get:
(4.5,69.5,310,310)
and the image size is:
(720,1280)
How can I perform cropping in any image resolution?
I tried multiplying the values with image.scale - however, the value is 1.00
Try this one.This will definitely help you out. https://github.com/barrettj/BJImageCropper
To resize image, Try this
UIImage *image = [UIImage imageNamed:#"image.png"];
CGSize itemSize = CGSizeMake((your Width), (your Height));
UIGraphicsBeginImageContext(itemSize);
CGRect imageRect = CGRectMake(0.0, 0.0, itemSize.width, itemSize.height);
[image drawInRect:imageRect];
UIImage * yourCroppedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
To Crop,
// Create new image context
UIGraphicsBeginImageContext(SIZE);
// Create CGRect for image
CGRect newRect = CGRectMake(x, y,SIZE.width,SIZE.height);
// Draw the image into the rect
[ORIGINALIMAGE drawInRect:newRect];
// Saving the image, ending image context
UIImage * newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Related
I want to crop Image according to red View . There are some points to keep in mind.
1.Image can be scrolled and Zoomed.
2.Red ImageView is created Dynamically according to Image
UIImage* whole = [UIImage imageNamed:#"9.png"]; //I uses this image
CGImageRef cgImg = CGImageCreateWithImageInRect(whole.CGImage, CGRectMake(x, y, incX, incY));
UIImage* part = [UIImage imageWithCGImage:cgImg];
I just want to know How to find the Values of
x, y, incX, incY
Thanks...
Scenario 1: Normal (Not Scrolled)
Expected Result (Ignore Black Border On Top and Bottom)
Scenario 2:Scrolled
Expected Result (Ignore Black Border On Top and Bottom)
Scenario 3: Zoomed
And same Expected Result for the Zoomed One.
In all cases I want the respective Images Inside the Red Rectangle.
For all These I am Using this Code...
-(void)cropClicked:(UIButton*)sender
{
float zoomScale = 1.0 / [mainScrollView zoomScale];
CGRect rect;
rect.size.width = [redImageView bounds].size.width * zoomScale ;
rect.size.height = [redImageView bounds].size.height * zoomScale ;
rect.origin.x = ([mainScrollView bounds].origin.x + redImageView.frame.origin.x );
rect.origin.y = ([mainScrollView bounds].origin.y + redImageView.frame.origin.y );
CGImageRef cr = CGImageCreateWithImageInRect([[mainImageView image] CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:cr];
mainImageView.image=cropped;
UIImageWriteToSavedPhotosAlbum(cropped, nil, nil, nil);
CGImageRelease(cr);
}
Well, as #HDdeveloper rightly said, you can use CGImageCreateWithImageInRect. This take 2 params, the first is the whole image, the second is the frame that you want to crop (so probably the frame of your red imageView).
The problem is that if you're targeting for both retina/non retina; if your whole image is an image #2x and you want to crop the image with the red imageview frame you have to double your frame to get the right screenshot.
So you can try with this method:
//Define the screen type:
#define isRetinaDisplay [[UIScreen mainScreen] respondsToSelector:#selector(displayLinkWithTarget:selector:)] && ([UIScreen mainScreen].scale == 2.0)
- (UIImage*)cropInnerImage:(CGRect)rect {
//Take a screenshot of the whole image
UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, 0.0);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage* ret = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGRect rct;
//Double the frame if you're in retina display
if (isRetinaDisplay) {
rct=CGRectMake(rect.frame.origin.x*2, rect.frame.origin.y*2, rect.size.width*2, rect.size.height*2);
} else {
rct=rect;
}
//Crop the image from the screenshot
CGImageRef imageRef = CGImageCreateWithImageInRect([ret CGImage], rct);
UIImage *result = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
//Save and open the result images with Preview.app
[UIImagePNGRepresentation(result) writeToFile: #"/tmp/testCrop.png" atomically: YES];
system("open /tmp/testCrop.png");
[UIImagePNGRepresentation(ret) writeToFile: #"/tmp/testRet.png" atomically: YES];
system("open /tmp/testRet.png");
//
return result;
}
Where the rect parameter must be your red image frame, and self.view.frame must be the equal to the wholeImageView.frame. You can skip the last 4 lines, these are just to see in your Mac what you're cropping.
PS: i use this method to crop an image and set it as background of UIView, this is the reason i have to double the frame.
You can use CGImageRef
pass your rect in the whole image. Then call this on button click
UIImage* whole = [UIImage imageNamed:#"9.png"]; //I uses this image
CGImageRef cgImg = CGImageCreateWithImageInRect(whole.CGImage, CGRectMake(x, y, incX, incY));
UIImage* part = [UIImage imageWithCGImage:cgImg];
I have a large sized image (2048*2048px), this image is shown as 320*320 on iPhone screen. I want to do this:
In my APP, user can open large sized image(e.g. 2048*2048), the image is shown as 320*320 on iPhone screen, and there is rectangle over the image, user can move the rectangle anywhere within image on iPhone screen, e.g. rectangle(100, 100, 300, 200), then I want to clip the original sized image within the rectangle area in scale.
I tried many ways,
UIImageView *originalImageView = [[UIImage View alloc] initWithImage:originalImage]];
CGRect rect = CGRectMake(100, 100, 300, 200);
UIImage *cropImage = [UIImage imageWithCGImage:CGImageCreateWithImageInRect([originalImageView.image CGImage], rect)];
But I got the cropImage is just 300*200 sized image, not scale properly.
How about doing this, it will preserve the original image quality
CGSize bounds = CGSizeMake(320,320) // Considering image is shown in 320*320
CGRect rect = CGRectMake(100, 100, 220, 200); //rectangle area to be cropped
float widthFactor = rect.size.width * (originalImage.size.width/bounds.size.width);
float heightFactor = rect.size.height * (originalImage.size.height/bounds.size.height);
float factorX = rect.origin.x * (originalImage.size.width/bounds.size.width);
float factorY = rect.origin.y * (originalImage.size.height/bounds.size.height);
CGRect factoredRect = CGRectMake(factorX,factorY,widthFactor,heightFactor);
UIImage *cropImage = [UIImage imageWithCGImage:CGImageCreateWithImageInRect([originalImage CGImage], factoredRect)];
And most importantly if you want to crop image that imagePickerController returns, then this can be done by built in function as below,
imagePickerController.allowsEditing = YES;
Firstly resize image with size 320*320 using this method:
+(UIImage *)resizeImage:(UIImage *)image width:(float)width height:(float)height
{
CGSize newSize;
newSize.width = width;
newSize.height = height
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
Now set resized image in imageView
UIImage *resizeImage = [YourControllerName resizeImage:originalImage width:320 height:320];
UIImageView *originalImageView = [[UIImage View alloc] initWithImage:resizeImage]];
You can now crop
CGRect rect = CGRectMake(100, 100, 300, 200);
UIImage *cropImage = [UIImage imageWithCGImage:CGImageCreateWithImageInRect([originalImageView.image CGImage], rect)];
Why not calculate the scale factor (e.g. originalImageWidth/smallImageWidth)?
If the rectangle is (100,100,300,200) in your small image, you should clip your lage image at size (100*factor,100*factor,300*factor,200*factor).
I make a picture with phone (640*480) and put it inside uiimageview (300*300) with scale to fill options set.
I need to send the same image that is displayed inside uiimageview (300*300, croped, resized) to server....
How can i get it?
There is a quick a dirty way to do this, by rendering the UIImageView layer to a graphics context.
UIGraphicsBeginImageContext(self.bounds.size);
[self.imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
you will need to import <QuartzCore/QuartzCore.h> for this.
The other way would be to do the calculations for AspectFill your self.
CGSize finalImageSize = CGSizeMake(300,300);
CGImageRef sourceImageRef = yourImage.CGImage;
CGFloat horizontalRatio = finalImageSize.width / CGImageGetWidth(sourceImageRef);
CGFloat verticalRatio = finalImageSize.height / CGImageGetHeight(sourceImageRef);
CGFloat ratio = MAX(horizontalRatio, verticalRatio); //AspectFill
CGSize aspectFillSize = CGSizeMake(CGImageGetWidth(sourceImageRef) * ratio, CGImageGetHeight(sourceImageRef) * ratio);
CGContextRef context = CGBitmapContextCreate(NULL,
finalImageSize.width,
finalImageSize.height,
CGImageGetBitsPerComponent(sourceImageRef),
0,
CGImageGetColorSpace(sourceImageRef),
CGImageGetBitmapInfo(sourceImageRef));
//Draw our image centered vertically and horizontally in our context.
CGContextDrawImage(context,
CGRectMake((finalImageSize.width-aspectFillSize.width)/2,
(finalImageSize.height-aspectFillSize.height)/2,
aspectFillSize.width,
aspectFillSize.height),
sourceImageRef);
//Start cleaning up..
CGImageRelease(sourceImageRef);
CGImageRef finalImageRef = CGBitmapContextCreateImage(context);
UIImage *finalImage = [UIImage imageWithCGImage:finalImageRef];
CGContextRelease(context);
CGImageRelease(finalImageRef);
return finalImage;
From the documentation:
UIViewContentModeScaleToFill
Scales the content to fit the size of itself by changing the aspect
ratio of the content if necessary.
You can do the maths. Or if you are feeling particularly lazy, there is this hack way.
I am capturing CGRect with following code. But the resulting image is not the image what i want. Image has some transparent background. What to do for removing transparent background as suggesting the picture.
- (UIImage *)captureScreenInRect:(CGRect)captureFrame {
CALayer *layer;
layer = imageScrollview.layer;
UIGraphicsBeginImageContext(imageScrollview.bounds.size);
CGContextClipToRect (UIGraphicsGetCurrentContext(),captureFrame);
\[layer renderInContext:UIGraphicsGetCurrentContext()\];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return screenImage;
}
Translate your context so that its origin matches your captureFrame:
UIGraphicsBeginImageContext(imageScrollview.bounds.size);
CGContextRef c = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(c, -captureFrame.origin.x, -captureFrame.origin.y);
[imageScrollView.layer renderInContext:c];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
(written from memory, untested)
Additionally clipping the context is not necessary as the image is already clipped by the image context's bounds.
Try this one
CGRect cropRect = CGRectMake(imageScrollview.frame.origin.x+15, imageScrollview.frame.origin.y+15, WIDTH, HEIGHT);
I created a masked image using a function form an iphone blog:
UIImage *imgToSave = [self maskImage:[UIImage imageNamed:#"pic.jpg"] withMask:[UIImage imageNamed:#"sd-face-mask.png"]];
Looks good in a UIImageView
UIImageView *imgView = [[UIImageView alloc] initWithImage:imgToSave];
imgView.center = CGPointMake(160.0f, 140.0f);
[self.view addSubview:imgView];
UIImagePNGRepresentation to save to disk:
[UIImagePNGRepresentation(imgToSave) writeToFile:[self findUniqueSavePath] atomically:YES];
UIImagePNGRepresentation returns NSData of an image that looks different.
The output is inverse image mask.
The area that was cut out in the app is now visible in the file.
The area that was visible in the app is now removed. Visibility is opposite.
My mask is designed to remove everything but the face area in the picture. The UIImage looks right in the app but after I save it on disk, the file looks opposite. The face is removed but everything else this there.
Please let me know if you can help!
In quartz you cam mask either by an image mask (black let through and white blocks), or a normal image (white let through and black blocks) which is the opposite. It seems for some reason saving is treating the image mask as a normal image to mask with. One thought is to render to a bitmap context and then create an image to be saved from that.
I had the exact same issue, when I saved the file it was one way, but the image returned in memory was the exact opposite.
The culprit & the solution was UIImagePNGRepresentation(). It fixes the in-app image before saving it to disk, so I just inserted that function as the last step in creating the masked image and returning that.
This may not be the most elegant solution, but it works. I copied some code from my app and condensed it, not sure if this code below works as is, but if not, its close... maybe just some typos.
Enjoy. :)
// MyImageHelperObj.h
#interface MyImageHelperObj : NSObject
+ (UIImage *) createGrayScaleImage:(UIImage*)originalImage;
+ (UIImage *) createMaskedImageWithSize:(CGSize)newSize sourceImage:(UIImage *)sourceImage maskImage:(UIImage *)maskImage;
#end
// MyImageHelperObj.m
#import <QuartzCore/QuartzCore.h>
#import "MyImageHelperObj.h"
#implementation MyImageHelperObj
+ (UIImage *) createMaskedImageWithSize:(CGSize)newSize sourceImage:(UIImage *)sourceImage maskImage:(UIImage *)maskImage;
{
// create image size rect
CGRect newRect = CGRectZero;
newRect.size = newSize;
// draw source image
UIGraphicsBeginImageContextWithOptions(newRect.size, NO, 0.0f);
[sourceImage drawInRect:newRect];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// draw mask image
[maskImage drawInRect:newRect blendMode:kCGBlendModeNormal alpha:1.0f];
maskImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// create grayscale version of mask image to make the "image mask"
UIImage *grayScaleMaskImage = [MyImageHelperObj createGrayScaleImage:maskImage];
CGFloat width = CGImageGetWidth(grayScaleMaskImage.CGImage);
CGFloat height = CGImageGetHeight(grayScaleMaskImage.CGImage);
CGFloat bitsPerPixel = CGImageGetBitsPerPixel(grayScaleMaskImage.CGImage);
CGFloat bytesPerRow = CGImageGetBytesPerRow(grayScaleMaskImage.CGImage);
CGDataProviderRef providerRef = CGImageGetDataProvider(grayScaleMaskImage.CGImage);
CGImageRef imageMask = CGImageMaskCreate(width, height, 8, bitsPerPixel, bytesPerRow, providerRef, NULL, false);
CGImageRef maskedImage = CGImageCreateWithMask(newImage.CGImage, imageMask);
CGImageRelease(imageMask);
newImage = [UIImage imageWithCGImage:maskedImage];
CGImageRelease(maskedImage);
return [UIImage imageWithData:UIImagePNGRepresentation(newImage)];
}
+ (UIImage *) createGrayScaleImage:(UIImage*)originalImage;
{
//create gray device colorspace.
CGColorSpaceRef space = CGColorSpaceCreateDeviceGray();
//create 8-bit bimap context without alpha channel.
CGContextRef bitmapContext = CGBitmapContextCreate(NULL, originalImage.size.width, originalImage.size.height, 8, 0, space, kCGImageAlphaNone);
CGColorSpaceRelease(space);
//Draw image.
CGRect bounds = CGRectMake(0.0, 0.0, originalImage.size.width, originalImage.size.height);
CGContextDrawImage(bitmapContext, bounds, originalImage.CGImage);
//Get image from bimap context.
CGImageRef grayScaleImage = CGBitmapContextCreateImage(bitmapContext);
CGContextRelease(bitmapContext);
//image is inverted. UIImage inverts orientation while converting CGImage to UIImage.
UIImage* image = [UIImage imageWithCGImage:grayScaleImage];
CGImageRelease(grayScaleImage);
return image;
}
#end