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.
Related
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!!!!
When I combine two UIImage's (using drawinrect:) they are both the same alpha even though one is supposed to be less than 1.0. How can I change the alpha of specifically a UIImage?
You can't change the alpha of a UIImage. You could draw it with alpha to a new context and get a new image from that. Or you could extract the CGImage, then extract the data, then adjust the alpha bytes, then create a new CGImage from the data and a new UIImage from the CGImage.
But in this case, just use drawInRect:blendMode:alpha: instead of drawInRect:.
If the UIImage is being displayed inside a UIImageView you can set the alpha property on the UIImageView.
Here is UIImage Category.
usage >>
UIImage * imgNew = [imgOld cloneWithAlpha:.3];
code >>
- (UIImage *)cloneWithAlpha:(CGFloat) alpha {
UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0f);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGRect area = CGRectMake(0, 0, self.size.width, self.size.height);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -area.size.height);
CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
CGContextSetAlpha(ctx, alpha);
CGContextDrawImage(ctx, area, self.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
ref >> How to set the opacity/alpha of a UIImage?
Wondering if there is a way to isolate a single color in an image either using masks or perhaps even a custom color space. I'm ultimately looking for a fast way to isolate 14 colors out of an image - figured if there was a masking method it might may be faster than walking through the pixels.
Any help is appreciated!
You could use a custom color space (documentation here) and then substitute it for "CGColorSpaceCreateDeviceGray()" in the following code:
- (UIImage *)convertImageToGrayScale:(UIImage *)image
{
// Create image rectangle with current image width/height
CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);
// Grayscale color space
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); // <- SUBSTITUTE HERE
// Create bitmap content with current image size and grayscale colorspace
CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);
// Draw image into current context, with specified rectangle
// using previously defined context (with grayscale colorspace)
CGContextDrawImage(context, imageRect, [image CGImage]);
// Create bitmap image info from pixel data in current context
CGImageRef imageRef = CGBitmapContextCreateImage(context);
// Create a new UIImage object
UIImage *newImage = [UIImage imageWithCGImage:imageRef];
// Release colorspace, context and bitmap information
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
CFRelease(imageRef);
// Return the new grayscale image
return newImage;
}
This code is from this blog which is worth a look at for removing colors from images.
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!!!
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);