On MacOS, .heic image files can contain one light and one dark version. This can be seen for system wallpapers using open: for example
open /System/Library/Desktop\ Pictures/Dome.heic
The Preview app displays both versions. My goal is to be able to access them using Objective-C, as I would like to save both light and dark versions to .jpg format.
Following snippet succeeds in extracting the light version and saving it to disk:
NSString* wallpaper_path = /* insert source path here */;
NSString* converted_path_str = /* insert destination path here */;
NSImage* image = [[[NSImage alloc] initWithContentsOfFile:wallpaper_path] autorelease];
NSData* data = [image TIFFRepresentation];
NSBitmapImageRep* rep = [NSBitmapImageRep imageRepWithData:data];
NSDictionary* properties =[NSDictionary dictionaryWithObject:[NSNumber numberWithFloat:1.0] forKey:NSImageCompressionFactor];
data = [rep representationUsingType:NSJPEGFileType properties:properties];
[data writeToFile:converted_path_str atomically:NO];
However I cannot find how to access the dark version using NSImage, NSImageRep or NSBitmapImageRep.
As Preview succeeds in doing it, I think it's possible though. I just don't know how to do.
Related
I have read that you can change the meta data of an image to set the dpi to another value other than the default 72. I tried the solution in this question but had the same problem as the author of that question. The image metadata properties in the original image seems to take precedence over modifications.
I am using the ALAssetsLibrary to write an image to the photo library on my iPhone. I need to dpi to be 500 instead of the standard 72dpi. I know it is possible to change the properties by manipulating the bits directly (as shown here), but am hoping that iOS gives a better solution.
Thank you in advance for your help.
This piece of code for manipulating image metadata -if exists- and you can use this to change any values in image meta data. Please be aware changing DPI value in metadata does not actually process image and change DPI.
#import <ImageIO/ImageIO.h>
-(NSData *)changeMetaDataInImage
{
NSData *sourceImageData = [[NSData alloc] initWithContentsOfFile:#"~/Desktop/1.jpg"];
if (sourceImageData != nil)
{
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)sourceImageData, NULL);
NSDictionary *metadata = (__bridge_transfer NSDictionary *)CGImageSourceCopyPropertiesAtIndex(source, 0, NULL);
NSMutableDictionary *tempMetadata = [metadata mutableCopy];
[tempMetadata setObject:[NSNumber numberWithInt:300] forKey:#"DPIHeight"];
[tempMetadata setObject:[NSNumber numberWithInt:300] forKey:#"DPIWidth"];
NSMutableDictionary *EXIFDictionary = [[tempMetadata objectForKey:(NSString *)kCGImagePropertyTIFFDictionary] mutableCopy];
[EXIFDictionary setObject:[NSNumber numberWithInt:300] forKey:(NSString *)kCGImagePropertyTIFFXResolution];
[EXIFDictionary setObject:[NSNumber numberWithInt:300] forKey:(NSString *)kCGImagePropertyTIFFYResolution];
NSMutableDictionary *JFIFDictionary = [[NSMutableDictionary alloc] init];
[JFIFDictionary setObject:[NSNumber numberWithInt:300] forKey:(NSString *)kCGImagePropertyJFIFXDensity];
[JFIFDictionary setObject:[NSNumber numberWithInt:300] forKey:(NSString *)kCGImagePropertyJFIFYDensity];
[JFIFDictionary setObject:#"1" forKey:(NSString *)kCGImagePropertyJFIFVersion];
[tempMetadata setObject:EXIFDictionary forKey:(NSString *)kCGImagePropertyTIFFDictionary];
[tempMetadata setObject:JFIFDictionary forKey:(NSString *)kCGImagePropertyJFIFDictionary];
NSMutableData *destinationImageData = [NSMutableData data];
CFStringRef UTI = CGImageSourceGetType(source);
CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)destinationImageData, UTI, 1, NULL);
CGImageDestinationAddImageFromSource(destination, source,0, (__bridge CFDictionaryRef) tempMetadata);
CGImageDestinationFinalize(destination);
return destinationImageData;
}
}
While trying to employ this solution for exporting JPEGs, I found that Photoshop wouldn't honour the DPI as exported. It turns out that Photoshop actively ignores the JFIF header information (and, in fact, doesn't even export it itself when it writes out JPEGs).
I ditched the JFIF section entirely. Most modern image libraries look at the TIFF/EXIF data first, so including that (and only that) seems to work well. Your mileage may vary, so be sure to test as many export destinations as you can!
However, the TIFF data is missing the ResolutionUnit tag, without which Photoshop will ignore XResolution and YResolution. It can have three values:
1 = No absolute unit of measurement. Used for images that may have a non-square aspect ratio, but no meaningful absolute dimensions.
2 = Inch.
3 = Centimeter.
Setting ResolutionUnit to 2 is required for DPI (dots per inch), for example:
[EXIFDictionary setObject:#(2) forKey:(NSString *)kCGImagePropertyTIFFResolutionUnit];
Apparently with CGImages you can add kCGImagePropertyPNGXPixelsPerMeter and kCGImagePropertyPNGYPixelsPerMeter properties to the image and they will get added to the pHYs chunk of the png. But UIImageWriteToSavedPhotosAlbum doesn't directly accept a CGImage.
I've been trying to load the image as a UIImage, then create a CGImage from that, add the properties, and then create a new UIImage from that data and saving that to the photo album.
An image is getting written to the photo album, but without the PPM settings. I can verify this in the preview app on MacOS, or using ImageMagick's identify.
ObjC isn't my domain, so here's what I've cobbled together from similar stackoverflow questions.
UIImage *uiImage = [UIImage imageWithContentsOfFile:path];
NSDictionary* properties = [NSDictionary dictionaryWithObjectsAndKeys:
[NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:5905], (NSString *)kCGImagePropertyPNGXPixelsPerMeter, /* this doesn't work */
[NSNumber numberWithInt:5905], (NSString *)kCGImagePropertyPNGYPixelsPerMeter, /* this doesn't work */
#"This works when saved to disk.", (NSString *)kCGImagePropertyPNGDescription,
nil],(NSString*) kCGImagePropertyPNGDictionary,
nil];
NSMutableData* imageData = [NSMutableData data];
CGImageDestinationRef imageDest = CGImageDestinationCreateWithData((CFMutableDataRef) imageData, kUTTypePNG, 1, NULL);
CGImageDestinationAddImage(imageDest, uiImage.CGImage, (CFDictionaryRef) properties);
CGImageDestinationSetProperties(imageDest, (CFDictionaryRef) properties); /* I'm setting the properties twice because I was going crazy */
CGImageDestinationFinalize(imageDest);
UIImageWriteToSavedPhotosAlbum( [UIImage imageWithData:imageData], nil, NULL, NULL );
// This is a test to see if the data is getting stored at all.
CGImageDestinationRef diskDest = CGImageDestinationCreateWithURL(
(CFURLRef)[NSURL fileURLWithPath:[NSString stringWithFormat:#"%#.dpi.png",path]], kUTTypePNG, 1, NULL);
CGImageDestinationAddImage(diskDest, uiImage.CGImage, (CFDictionaryRef) properties);
CGImageDestinationSetProperties(diskDest, (CFDictionaryRef) properties);
CGImageDestinationFinalize(diskDest);
Updated: Revised and simplified the code a bit. Still saves image to photo album and disk, but the pixels per meter value is not saving. The description block gets saved to disk, but appears to get stripped when written to the photo album.
Update 2: By saving the file as a jpeg and adding TIFF X/Y Resolution tags to it I've been able to get the version saved to disk to store a PPI value other than 72. This information is still stripped off when saving to the photo album.
Comparing a photo taken via iOS Camera app, one taken via Instagram, and one saved by my code, I noticed that the Camera app version has a ton of TIFF/EXIF tags, and the Instagram and my one have the same limited set of tags. This leads me to the conclusion that iOS strips these tags intentionally. A definitive answer would help me sleep at night though.
The answer is don't use UIImageWriteToSavedPhotosAlbum.
There's an ALAssetsLibrary method
[writeImageDataToSavedPhotosAlbum: metadata: completionBlock:]
The metadata is a dictionary in the same format as the one passed to CGImageDestinationSetProperties. PNG and JFIF density settings may be broken, I'm using kCGImagePropertyTIFFXResolution.
I'm working on an application that needs to take a picture using UIImagePickerController, display a thumbnail of it in the app, and also submit that picture to a server using ASIFormDataRequest (from ASIHTTPRequest).
I want to use setFile:withFileName:andContentType:forKey: from ASIFormDataRequest since in my experience it's faster than trying to submit an image using UIImageJPEGRepresentation and submitting raw NSData. To that end I'm using CGImageDestination and creating an image destination with a url, saving that image to disk, and then uploading that file on disk.
In order to create the thumbnail I'm using CGImageSourceCreateThumbnailAtIndex (see docs) and creating an image source with the path of the file I just saved.
My problem is that no matter what options I pass into the image destination or the thumbnail creation call, my thumbnail always comes out rotated 90 degrees counterclockwise. The uploaded image is also rotated. I've tried explicitly setting the orientation in the options of the image using CGImageDestinationSetProperties but it doesn't seem to take. The only solution I've found is to rotate the image in memory, but I really want to avoid that since doing so doubles the time it takes for the thumbnail+saving operation to finish. Ideally I'd like to be able to rotate the image on disk.
Am I missing something in how I'm using CGImageDestination or CGImageSource? I'll post some code below.
Saving the image:
NSURL *filePath = [NSURL fileURLWithPath:self.imagePath];
CGImageRef imageRef = [self.image CGImage];
CGImageDestinationRef ref = CGImageDestinationCreateWithURL((CFURLRef)filePath, kUTTypeJPEG, 1, NULL);
CGImageDestinationAddImage(ref, imageRef, NULL);
NSDictionary *props = [[NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithFloat:1.0], kCGImageDestinationLossyCompressionQuality,
nil] retain];
//Note that setting kCGImagePropertyOrientation didn't work here for me
CGImageDestinationSetProperties(ref, (CFDictionaryRef) props);
CGImageDestinationFinalize(ref);
CFRelease(ref);
Generating the thumbnail
CGImageSourceRef imageSource = CGImageSourceCreateWithURL((CFURLRef)filePath, NULL);
if (!imageSource)
return;
CFDictionaryRef options = (CFDictionaryRef)[NSDictionary dictionaryWithObjectsAndKeys:
(id)kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailWithTransform,
(id)kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailFromImageIfAbsent,
(id)[NSNumber numberWithFloat:THUMBNAIL_SIDE_LENGTH], (id)kCGImageSourceThumbnailMaxPixelSize, nil];
CGImageRef imgRef = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, options);
UIImage *thumb = [UIImage imageWithCGImage:imgRef];
CGImageRelease(imgRef);
CFRelease(imageSource);
And then to upload the image I just use
[request setFile:path withFileName:fileName andContentType:contentType forKey:#"photo"];
where path is the path to the file saved with the code above.
As far as I know and after trying lots of different things, this cannot be done with current public APIs and has to be done in memory.
I am working on iphone app and i need to save image into .tiff format.
It is possible to save image into png format using UIImagePNGRepresentation method and JPEG format using UIImageJPEGRepresentation. But i need to save signature captured by imageview into tiff format.
I unable to use NSImage class so that i can call TIFFRepresentation method.
How can i do it.Send me suggestion...
Thanks in advance...
I don't know what you mean by "captured by imageview". The means to save as TIFF wasn't introduced until iOS 4. Here is example code to save an arbitrary file as a TIFF; you can do this with any file-format data, no matter how you obtained it. You need to link to ImageIO framework and do #import <ImageIO/ImageIO.h>:
NSURL* url = [[NSBundle mainBundle] URLForResource:#"colson" withExtension:#"jpg"];
CGImageSourceRef src = CGImageSourceCreateWithURL((CFURLRef)url, NULL);
NSFileManager* fm = [[NSFileManager alloc] init];
NSURL* suppurl = [fm URLForDirectory:NSApplicationSupportDirectory
inDomain:NSUserDomainMask
appropriateForURL:nil
create:YES error:NULL];
NSURL* tiff = [suppurl URLByAppendingPathComponent:#"mytiff.tiff"];
CGImageDestinationRef dest = CGImageDestinationCreateWithURL((CFURLRef)tiff,
(CFStringRef)#"public.tiff", 1, NULL);
CGImageDestinationAddImageFromSource(dest, src, 0, NULL);
bool ok = CGImageDestinationFinalize(dest);
NSLog(#"result %i", ok); // 1, all went well
// and don't forget memory management, release source and destination, NSFileManager
[fm release]; CFRelease(src); CFRelease(dest);
Hmm, I don't develop for the iPhone, so can't tell you if there's a magic API way of doing this, but many years ago I had to create TIFF images manually.
The TIFF format is a bit whacky if you're used to just using a framework's CreateThisStuffAsAnImage() methods, but you can get the spec here and create the file yourself:
http://partners.adobe.com/public/developer/tiff/index.html#spec
I am using the following code to save a frame of a movie to my desktop:
NSCIImageRep *imageRep = [NSCIImageRep imageRepWithCIImage:[CIImage imageWithCVImageBuffer:imageBuffer]];
NSImage *image = [[[NSImage alloc] initWithSize:[imageRep size]] autorelease];
[image addRepresentation:imageRep];
CVBufferRelease(imageBuffer);
NSArray *representations = [image representations];
NSData *bitmapData = [NSBitmapImageRep representationOfImageRepsInArray:representations usingType:NSJPEGFileType properties:nil];
[bitmapData writeToFile:#"/Users/ricky/Desktop/MyImage.jpeg" atomically:YES];
At the second last line of code, I receive the following messages in the console, with no result being saved to the desktop:
<Error>: CGImageDestinationFinalize image destination does not have enough images
CGImageDestinationFinalize failed for output type 'public.jpeg'
The NSImage is still an allocated object for the entire method call, so I'm not sure why I am receiving complaints about insufficient amount of images.
I'd appreciate any help.
Thanks in advance,
Ricky.
I think the source of the problem is that you're passing an array of NSCIImageRep objects to representationOfImageRepsInArray:usingType:properties:, which I believe expects an array of NSBitmapImageRep objects.
What you want to do is create an NSBitmapImageRep from your CIImage. Then you can use that to write to disk. That would be roughly:
CIImage *myImage = [CIImage imageWithCVImageBuffer:imageBuffer];
NSBitmapImageRep *bitmapRep = [[NSBitmapImageRep alloc] initWithCIImage:myImage];
NSData *jpegData [bitmapRep representationUsingType:NSJPEGFileType properties:nil];
[jpegData writeToFile:#"/Users/ricky/Desktop/MyImage.jpeg" atomically:YES];
Of course, you'd want to handle any error cases and probably pass a properties dictionary to fine-tune the JPEG creation.
I'm sorry i don't really know why your code doesn't work, but approaching it a different way (and i think more efficiently than your CVImageBuffer to CIImage to NSCIImageRep to NSImage to NSData, albeit at a slightly lower level):-
CVImageBuffer to CGImage
CGImage to jpg file
I don't have code ready made to do this but extracting the right stuff from those examples should be straight forward.