How can I load an image from photo library and show it in imageView?
How can I change image to black and white?
If you want to load an image from photo library, you have to use UIImagePickerController class. Refer this Link
To convert image form UIImagePickerController to black and white you can use this code:
UIImage *originalImage = [info objectForKey:UIImagePickerControllerOriginalImage]; // this image we get from UIImagePickerController
CGColorSpaceRef colorSapce = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(nil, originalImage.size.width, originalImage.size.height, 8, originalImage.size.width, colorSapce, kCGImageAlphaNone);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetShouldAntialias(context, NO);
CGContextDrawImage(context, CGRectMake(0, 0, originalImage.size.width, originalImage.size.height), [originalImage CGImage]);
CGImageRef bwImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSapce);
UIImage *resultImage = [UIImage imageWithCGImage:bwImage]; // This is result B/W image.
CGImageRelease(bwImage);
Related
Below is code for converting image to Black and white. it is working fine unless image with Transparency comes. That transparent area is converted to black. please help on this what is wrong here.
+ (UIImage *)getBlackAndWhiteVersionOfImage:(UIImage *)anImage
{
UIImage *newImage;
UIImage *imageToDisplay;
int orientation = anImage.imageOrientation;
if (anImage) {
CGColorSpaceRef colorSapce = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(nil, anImage.size.width * anImage.scale, anImage.size.height * anImage.scale, 8, anImage.size.width * anImage.scale, colorSapce, kCGImageAlphaNone);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetShouldAntialias(context, NO);
CGContextDrawImage(context, CGRectMake(0, 0, anImage.size.width, anImage.size.height), [anImage CGImage]);
CGImageRef bwImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSapce);
UIImage *resultImage = [UIImage imageWithCGImage:bwImage];
CGImageRelease(bwImage);
UIGraphicsBeginImageContextWithOptions(anImage.size, NO, anImage.scale);
[resultImage drawInRect:CGRectMake(0.0, 0.0, anImage.size.width, anImage.size.height)];
newImage = UIGraphicsGetImageFromCurrentImageContext();
imageToDisplay =
[UIImage imageWithCGImage:[newImage CGImage]
scale:1.0
orientation: orientation];
UIGraphicsEndImageContext();
}
return imageToDisplay;
}
I dont think gray colorspace has an alpha compononent
I got a UIImage from UIImagePickerController, and using the code from this site to resize the image
- (UIImage *)resizedImage:(CGSize)newSize
transform:(CGAffineTransform)transform
drawTransposed:(BOOL)transpose
interpolationQuality:(CGInterpolationQuality)quality {
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
CGRect transposedRect = CGRectMake(0, 0, newRect.size.height, newRect.size.width);
CGImageRef imageRef = self.CGImage;
// Build a context that's the same dimensions as the new size
CGContextRef bitmap = CGBitmapContextCreate(NULL,
newRect.size.width,
newRect.size.height,
CGImageGetBitsPerComponent(imageRef),
0,
CGImageGetColorSpace(imageRef),
CGImageGetBitmapInfo(imageRef));
// Rotate and/or flip the image if required by its orientation
CGContextConcatCTM(bitmap, transform);
// Set the quality level to use when rescaling
CGContextSetInterpolationQuality(bitmap, quality);
// Draw into the context; this scales the image
CGContextDrawImage(bitmap, transpose ? transposedRect : newRect, imageRef);
// Get the resized image from the context and a UIImage
CGImageRef newImageRef = CGBitmapContextCreateImage(bitmap);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
// Clean up
CGContextRelease(bitmap);
CGImageRelease(newImageRef);
return newImage;
}
UIImagePNGRepresentation() failed to return NSData on re-sized image, but UIImageJPEGRepresentation() succeed.
How do we know if a UIImage is presentable in PNG or JPEG? What missed in the above code that make the resized image can not be represented in PNG?
According to apple document: "This function may return nil if the image has no data or if the underlying CGImageRef contains data in an unsupported bitmap format."
What bitmap format supported by PNG presentation? How to make an UIImage PNG-supported format?
That was a mistake that in another part of the code the image was rescaled with the following
CGContextRef context = CGBitmapContextCreate(NULL,
size.width,
size.height,
8,
0,
CGImageGetColorSpace(source),
kCGImageAlphaNoneSkipFirst);
Changing kCGImageAlphaNoneSkipFirst to CGImageGetBitmapInfo(source) fixed the problem
go to following link...
How to check if downloaded PNG image is corrupt?
it may help you...
Let me know it is working or not...
Happy Coding!!!!
I am having and UIImageView and there is another canvas view over the UIImageView. I want to cut the UIImageView's image according to the canvas view's frame. But after crop the image is getting stretched and blur after crop. Below are my codes.
[UIImage *images = [self captureScreenInRect1:canvas.frame];
self.imgViewCurrent.contentMode = UIViewContentModeScaleToFill;
self.imgViewCurrent.image = images;
- (UIImage *)captureScreenInRect1:(CGRect)captureFrame {
CALayer *layer;
layer = self.view.layer;enter image description here
UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, 1.0);
CGContextClipToRect (UIGraphicsGetCurrentContext(),captureFrame);
[layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGImageRef imageRef = CGImageCreateWithImageInRect([screenImage CGImage], captureFrame);
UIImage *img = [UIImage imageWithCGImage:imageRef scale:0.0 orientation:UIImageOrientationUp];
CGImageRelease(imageRef);
return img;
}
change this line
self.imgViewCurrent.contentMode = UIViewContentModeScaleToFill;
to this line
self.imgViewCurrent.contentMode = UIViewContentModeScaleAspectFit
UIViewContentModeScaleToFill will basically stretches the image.
After cropping your image, you can resize your image with Custom Size. It may help you.
-(UIImage*) resizedImage:(UIImage *)inImage: (CGRect) thumbRect
{
CGImageRef imageRef = [inImage CGImage];
CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);
// There's a wierdness with kCGImageAlphaNone and CGBitmapContextCreate
// see Supported Pixel Formats in the Quartz 2D Programming Guide
// Creating a Bitmap Graphics Context section
// only RGB 8 bit images with alpha of kCGImageAlphaNoneSkipFirst, kCGImageAlphaNoneSkipLast, kCGImageAlphaPremultipliedFirst,
// and kCGImageAlphaPremultipliedLast, with a few other oddball image kinds are supported
// The images on input here are likely to be png or jpeg files
if (alphaInfo == kCGImageAlphaNone)
alphaInfo = kCGImageAlphaNoneSkipLast;
// Build a bitmap context that's the size of the thumbRect
CGContextRef bitmap = CGBitmapContextCreate(
NULL,
thumbRect.size.width, // width
thumbRect.size.height, // height
CGImageGetBitsPerComponent(imageRef), // really needs to always be 8
4 * thumbRect.size.width, // rowbytes
CGImageGetColorSpace(imageRef),
alphaInfo
);
// Draw into the context, this scales the image
CGContextDrawImage(bitmap, thumbRect, imageRef);
// Get an image from the context and a UIImage
CGImageRef ref = CGBitmapContextCreateImage(bitmap);
UIImage* result = [UIImage imageWithCGImage:ref];
CGContextRelease(bitmap); // ok if NULL
CGImageRelease(ref);
return result;
}
I was searching on the google if I get something for add effect to the Image like Black & White, Sepia, grayScale etc. I found a useful link for converting Image in Sepia but there is nothing for converting it in B&W or Grayscale.
Here is the link http://groups.google.com/group/iphonesdkdevelopment/browse_thread/thread/b987b02deec08b9f
After going through the code I come to know that we need to change RBG for that but How to get RBG for B&W and grayScale. What will be the RBG ratio for these kind of effects.
Any help will be appreciate.
Thanks In Advance
You can get a B&W Image by
-(UIImage *)convertOriginalImageToBWImage:(UIImage *)originalImage
{
UIImage *newImage;
CGColorSpaceRef colorSapce = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(nil, originalImage.size.width * originalImage.scale, originalImage.size.height * originalImage.scale, 8, originalImage.size.width * originalImage.scale, colorSapce, kCGImageAlphaNone);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetShouldAntialias(context, NO);
CGContextDrawImage(context, CGRectMake(0, 0, originalImage.size.width, originalImage.size.height), [originalImage CGImage]);
CGImageRef bwImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSapce);
UIImage *resultImage = [UIImage imageWithCGImage:bwImage];
CGImageRelease(bwImage);
UIGraphicsBeginImageContextWithOptions(originalImage.size, NO, originalImage.scale);
[resultImage drawInRect:CGRectMake(0.0, 0.0, originalImage.size.width, originalImage.size.height)];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
You need to do that is same way as given in the link(google groups).
Also, you can find the logic in this link to convert them into grayScale.
Hope this helps you.
I have another quartz 2d (iphone) question:
How to change all the colors of an ImageView to black and white and leave only red ???
DD
UIImage *originalImage = [info objectForKey:UIImagePickerControllerOriginalImage]; this image we get from UIImagePickerController
CGColorSpaceRef colorSapce = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(nil, originalImage.size.width, originalImage.size.height, 8, originalImage.size.width, colorSapce, kCGImageAlphaNone);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetShouldAntialias(context, NO);
CGContextDrawImage(context, CGRectMake(0, 0, originalImage.size.width, originalImage.size.height), [originalImage CGImage]);
CGImageRef bwImage = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSapce);
UIImage *resultImage = [UIImage imageWithCGImage:bwImage]; // This is result B/W image.
CGImageRelease(bwImage);
This is something that i found on other forums, AND IT SEEMS TO WORK!!!