I have an application in which I am scanning text from a picture. I am using OCR. Now the problem is my source image size is 3024*3024. I have copied the image into iPhone 6 Simulator in Xcode. Now when I uploaded the image using uiimagepicker controller the image was resized to 748*748 and its quality is not same.
When I tried to increase image size the image's quality is not the same.
What I need is image in its actual size and quality/resolution should not change.
try this code to resize image
- (UIImage*)imageWithImage:(UIImage*)img scaledToSize:(CGSize)newSize;{
UIGraphicsBeginImageContext( newSize );
[img drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImg;
}
and For the compression of images
NSData *dataForJPEGFile = UIImageJPEGRepresentation(theImage, 0.6);
Thanks
Did you set the qualityType property of your UIImagePickerController to UIImagePickerControllerQualityTypeHigh? The default is medium.
Related
I have an UIView with UIImageViews and UILabels, which I have to capture into image and then export to photo gallery. The image has a fixed size in pixels and must have alpha channel, because UIView background color is clear.
Now I use UIGraphicsBeginImageContextWithOptions with renderInContext or drawViewHierarchyInRect, then I resize image to a given size and save it with UIImagePNGRepresentation. It works - I get an UIImage of the exact pixel size I need, with alpha channel, saved in gallery.
UIGraphicsBeginImageContextWithOptions(_templateView.bounds.size, NO, 0.0);
[_templateView drawViewHierarchyInRect:_templateView.bounds afterScreenUpdates:NO];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsBeginImageContext(CGSizeMake(1080.0f, 1080.0f));
[img drawInRect:CGRectMake(0, 0, 1080.0f, 1080.0f)];
img = UIGraphicsGetImageFromCurrentImageContext();
NSData *pngImageData = UIImagePNGRepresentation(img);
The problem is the size of the result image. It is a way larger than expected. When I add only one UIImageView (filling parent UIView) with the image of 1.2Mb. it's capture results in 1.65Mb.. It is crucial because I have a limit size for an image. How can I reduce it's size? Is is possible to reduce quality of such an image with alpha channel?
I tried resize it to 50% and then again to 100% but it results even in largest size.
I'm using UIImagePNGRepresentation to save an image. The result image is of size 30+ KB and this is BIG in my case.
I tried using UIImageJPEGRepresentation and it allows to compress image, so image saves in < 5KB size, which is great, but saving it in JPEG gives it white background, which i don't want (my image is circular, so I need to save it with transparent background).
How can I compress image size, using UIImagePNGRepresentation?
PNG uses lossless compression, that's why UIImagePNGRepresentation does not accept compressionQuality parameter like UIImageJPEGRepresentation does. You might get a bit smaller PNG file with different tools, but nothing like with JPEG.
May be this will help you out:
- (void)resizeImage:(UIImage*)image{
NSData *finalData = nil;
NSData *unscaledData = UIImagePNGRepresentation(image);
if (unscaledData.length > 5000.0f ) {
//if image size is greater than 5KB dividing its height and width maintaining proportions
UIImage *scaledImage = [self imageWithImage:image andWidth:image.size.width/2 andHeight:image.size.height/2];
finalData = UIImagePNGRepresentation(scaledImage);
if (finalData.length > 5000.0f ) {
[self resizeImage:scaledImage];
}
//scaled image will be your final image
}
}
Resizing image
- (UIImage*)imageWithImage:(UIImage*)image andWidth:(CGFloat)width andHeight:(CGFloat)height
{
UIGraphicsBeginImageContext( CGSizeMake(width, height));
[image drawInRect:CGRectMake(0,0,width,height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext() ;
return newImage;
}
I'm trying to resize the UIImage
Before the UIImage:
After this code and UIImage:
UIGraphicsBeginImageContext (CGPointMake(155,139));
[currentImageView.image drawInRect:CGRectMake(0,0,155,139)];
currentImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog(#"get size : %#",NSStringFromCGSize(currentImageView.image.size));
NSLog: get size : {155,139}
Last, I try to restore the size by this code. but its blurry.
UIGraphicsBeginImageContext (OriginalSize);
[currentImageView.image drawInRect:CGRectMake(0,0,OriginalSize.width,OriginalSize.height)];
currentImageView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog(#"get size : %#",NSStringFromCGSize(cnurrentImageView.image.size));
NSLog: get size : {1024,352}
What happened?
Have any suggestions and advice?
You are making two mistakes,
1.Reducing the image size and setting it to a larger size imageView,
this can be fixed with the code,
imageView.contentMode = UIViewContentModeScaleAspectFit;
2.You have resize the original image to a smaller size, then
resizing the smaller image to original size, this will stretch the
image.
FOR 1 : first step,
You can use this code so that the image quality doesn't loose:
Instead of
UIGraphicsBeginImageContext
Use
UIGraphicsBeginImageContextWithOptions(currentImageView.frame.size, NO, 0);
as the size you want is smaller and the imageview is larger so you also need to set
YourimageView.contentMode = UIViewContentModeScaleAspectFit;
For Second Step :
Use original image to resize it.
Image Size captured using Camera return's image of size 720*960.
The captured Image is displayed in a UIImageView of 320*436, like this.
UIImageView *imgView=[[UIImageView alloc] initWithFrame:CGRectMake(0.0,0.0,320.0,436.0)];
imgView.image=img;//Image received from camera.
[self.view addSubView:imgView];
This, works fine image 720*960 is scaled to 320*436 and displayed.
Now, from here actual problem starts. I have another image of size 72*72. This image is overlapped with the image received from camera at some arbitrary coordinates.
CGRectMake(0.0,0.0,72.0,72.0);
I am not able to find a better way to handle scaling and applying a overlay of another Image, at the same time maintain its quality.
The image needs to be send to a server.
Use the following code to scale images:
-(UIImage*) imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize
{
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I am displaying an image in tableview cell (Image name saved in a plist). Before setting it to the cell, I am resizing the image to
imageSize = CGSizeMake(32, 32);
But, after resizing the image, quality is also getting degraded in retina display.
I have both the images added to the project (i.e. 1x and #2x).
This is how I am reducing the image size to 32x32.
+ (UIImage *)scale:(UIImage *)image toSize:(CGSize)size
{
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return scaledImage;
}
Any pointers on this is very much appreciated.
Thanks
try this : instead of UIGraphicsBeginImageContext(size);use UIGraphicsBeginImageContextWithOptions(size,NO,0.0);
from what i understand what you're doing there is resizing the image to 32x32 (in points) no matter what the resolution. the UIGraphicsBeginImageContextWithOptions scales the image to the scale of the device's screen..so you have the image resized to 32x32 points but the resolution is kept for retina display
(note that this is what i understood from apple's uikit reference..it may not be so..but it should)
read here