Im using the following code to crop my UIImage:
-(UIImage*)cropWithRect:(CGRect)rect
{
if(self.scale > 1.0f){
rect = CGRectMake(rect.origin.x * self.scale,
rect.origin.y * self.scale,
rect.size.width * self.scale,
rect.size.height * self.scale);
}
CGImageRef imageRef = (CGImageCreateWithImageInRect(self.CGImage, rect));
return [UIImage imageWithCGImage:imageRef scale:self.scale orientation:self.imageOrientation];
}
But this gives me an output image which has wrong pixel colors which is noticeable when zoomed in. For instance, white input pixel sometimes becomes off-white (not always - only when the white pixels are close to other pixels of dark colors).
Can I get better results or is there another way to produce better cropped images?
Thanks.
May be this will help you FXImageView
Step 1: select Image
Step 2: Crop Image
Step 3: Result Image
Related
I am trying to resize an image using UIGraphics. The image is one taken with the camera, and I am using this code:
CGSize origImageSize = photograph.size;
//this saves as 140*140 for retina
CGRect newRect = CGRectMake(0, 0, 70, 70);
//scaling ratio
float ratio = MAX(newRect.size.width/origImageSize.width, newRect.size.height/origImageSize.height);
UIGraphicsBeginImageContextWithOptions(newRect.size, NO, 0.0);
CGRect projectRect;
projectRect.size.width= ratio*origImageSize.width;
projectRect.size.height=ratio*origImageSize.height;
//center the image
projectRect.origin.x= ((newRect.size.width-projectRect.size.width)/2);
projectRect.origin.y=((newRect.size.height-projectRect.size.height)/2);
[photograph drawInRect:projectRect];
//get the image from the image context
UIImage *smallImage = UIGraphicsGetImageFromCurrentImageContext();
For some reason the final photo isn't as sharp, it's slightly blurry. Am I doing anything wrong here? Any pointers would be really appreciated. thanks
I assume you calculate rectangle properly. Then make sure you use integral rectangle. Non-integral values may cause sub pixel rendering.
Run your projectRect through CGRectIntegral to get integral rectangle, then use it to render your image.
projectRect = CGRectIntegral(projectRect);
I want to crop selected image from a gallery (Programmatically). I have done a lot of research and got the [tutor](http://iosdevelopertips.com/graphics/how-to-crop-an-image.html) gone through this.still getting confuse whether cropping of image can be done by using UIImagePickerController or UIImageView.I'm not getting from where to start or how to start?. please suggest me the right way any one.
Answer : CGImage Reference
1) Create a rectangle that represents a cropped image from the middle of the existing image :
CGRect rect = CGRectMake(size.width / 4, size.height / 4 ,
(size.width / 2), (size.height / 2));
2) Create bitmap image from original image data, using rectangle to specify desired crop area :
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], rect);
UIImage *img = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
3) Create and show the new image from bitmap data :
imageView = [[UIImageView alloc] initWithImage:img];
Useful Links :
1) Working with UIGestureRecognizers.
2) Cropping and Resizing Images from Camera in iOS and Objective-C.
GoodLuck !!!
I have a UIImage that is reading from a transparent PNG (500px by 500px). Somewhere in the image, there is a picture that I want to crop out and save as a separate UIImage. I also want to store the X and Y coordinates based on how many transparent pixels there were on the left and top of the newly cropped rectangle.
I was able to crop an image with this code:
- (UIImage *)cropImage:(UIImage *)image atRect:(CGRect)rect
{
double scale = image.scale;
CGRect scaledRect = CGRectMake(rect.origin.x*scale,rect.origin.y*scale,rect.size.width*scale,rect.size.height*scale);
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], scaledRect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef scale:scale orientation:image.imageOrientation];
CGImageRelease(imageRef);
return cropped;
}
Which actually cuts off the transparent pixels on the top and left :S (this would be great if I was able to crop the pixels on right and bottom too!). It then resizes the rest of the image to the rectangle I specified. Unfortunately though I need to cut a picture that is in the middle of the image and I need the size to be able to be dynamic.
Been struggling with this for several hours now. Any ideas?
To crop an image, draw it into a smaller graphics context.
For example, let's say you have a 600x600 image. And let's say that you want to crop 200 pixels off all four sides. That leaves a 200x200 rectangle.
So you would make a 200x200 graphics context, using UIGraphicsBeginImageContextWithOptions. Then you would draw the image into it using drawAtPoint:, drawing at the point (-200,-200). If you think about it, you will see that that offset causes just the 200x200 from the middle of the original to be drawn into the actual bounds of the context. Thus you have cropped the image by 200 pixels on all four sides, which is what we wanted to do.
Thus here is a generalized version, assuming that we know the amount to crop from the left, right, top, and bottom:
UIImage* original = [UIImage imageNamed:#"original.png"];
CGSize sz = [original size];
CGFloat cropLeft = ...;
CGFloat cropRight = ...;
CGFloat cropTop = ...;
CGFloat cropBottom = ...;
UIGraphicsBeginImageContextWithOptions(
CGSizeMake(sz.width - cropLeft - cropRight, sz.height - cropTop - cropBottom),
NO, 0);
[original drawAtPoint:CGPointMake(-cropLeft, -cropTop)];
UIImage* cropped = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
After that, cropped is your cropped image.
I have a pdf generation project, it consist of some texts and an image which is already stored in db, i want to preview and mail the pdf generated, everything is ok when there is only text data.
Problem arises if there is image in our data. The mail receives
the pdf of size 10MB or above even if it have image of size 1MB or below.It is working fine in simulator.My code to draw image is shown below:
UIImage *plotImage=[[UIImage alloc]initWithContentsOfFile:[localPictureArray objectAtIndex:i]];
CGSize imageSize=plotImage.size;
CGFloat scaleFactor = 1.0;
if (imageSize.height>(maxHeight-currentPageY) || imageSize.width>maxWidth )
{
UIGraphicsBeginPDFPageWithInfo(CGRectMake(0, 0, kDefaultPageWidth, kDefaultPageHeight), nil);
currentPageY = kMargin;
if (!((scaleFactor = (maxWidth / imageSize.width)) > ((maxHeight-currentPageY) / imageSize.height)))
{
scaleFactor = (maxHeight-currentPageY) /imageSize.height;
// scale to fit heigth.
}
CGRect rect = CGRectMake(kMargin,currentPageY,
imageSize.width * scaleFactor, imageSize.height * scaleFactor);
//Draw the image into the rect
[plotImage drawInRect:rect];
}
else
{
plotImage drawInRect:normal size)];//Normal size we need
NSLog(#"%#",NSStringFromCGSize(plotImage.size));
}
Since iam a starter iam struggling to solve it.
I struggled a lot.. at last when wrote image in jpeg format to pdf page using below code, size got reduced ten times!! Don't know it is the right method...
UIImage *lowResImage = [UIImage imageWithData:UIImageJPEGRepresentation(plotImage, 0.02)];
Instead of resizing the rect in the context, You need to change the CTM (Current Transform Matrix).
CGContextSaveGState(theContext);
CGContextScaleCTM(theContext, scaleFactor, scaleFactor);
... Drawing commands here ...
CGContextRestoreGState(theContext);
(http://macdevcenter.com/pub/a/mac/2004/11/02/quartz.html)
I want to crop an ellipse from an image in ios. Using core image framework, I know know to crop a reactangular region.
Using core graphics, I am able to clip the elliptical region. But, the size of the cropped image is same as the size of the original image as I am applying mask to area outside the ellipse.
So, the goal is to crop the elliptical region from an image and size of cropped image won't exceed the rectangular bounds of that image.
Any help would be greatly appreciated. Thanks in advance.
You have to create a context in the correct size, try the following code:
- (UIImage *)cropImage:(UIImage *)input inElipse:(CGRect)rect {
CGRect drawArea = CGRectMake(-rect.origin.x, -rect.origin.y, input.size.width, input.size.height);
UIGraphicsBeginImageContext(rect.size);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextAddEllipseInRect(ctx, CGRectMake(0, 0, rect.size.width, rect.size.height));
CGContextClip(ctx);
[input drawInRect:drawArea];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Maybe you have to adjust the drawArea to your needs as i did not test it.