how to do image recognition in iphone apps [duplicate] - objective-c

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Closed 10 years ago.
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An iPhone library for shape recognition via the camera
I am iPhone mobile apps developer and am looking for image recognition libraries to integrate in one of my App which should work like google's goggle functionality .
I saw https://www.iqengines.com/ and downlaoded its ios sdk and it worked well . But its not free version . I am searching for open source sdk .
also how opencv useful in accomplishing this ? beacuse some of the sources redirecting to openCV .
Please let me know if any one come across this .
Thanks

Answer 1

Yes, OpenCV works on iOS and will provide you with a good library of tools to use. You can either build your own .framework (a bit tiresome) or download one of the internet.
To build one, refer to this OpenCV guide
If you want to download a pre-built framework, head over there
After that, you should be able to build computer vision software on iOS, be careful though, image processing can take a lot of power and memory.
OpenCV has its own C++ classes for images, you will probably need to convert them back and forth to UIImage for input and displaying
I leave here this piece of code I use for NSImage, you should find enough for you to change a bit the code for UIImage
//
// NSImage+OpenCV.h
//
#import <AppKit/AppKit.h>
#interface NSImage (NSImage_OpenCV) {
}
+(NSImage*)imageWithCVMat:(const cv::Mat&)cvMat;
-(id)initWithCVMat:(const cv::Mat&)cvMat;
#property(nonatomic, readonly) cv::Mat CVMat;
#property(nonatomic, readonly) cv::Mat CVGrayscaleMat;
#end
And
//
// NSImage+OpenCV.mm
//
#import "NSImage+OpenCV.h"
static void ProviderReleaseDataNOP(void *info, const void *data, size_t size)
{
return;
}
#implementation NSImage (NSImage_OpenCV)
-(CGImageRef)CGImage
{
CGContextRef bitmapCtx = CGBitmapContextCreate(NULL/*data - pass NULL to let CG allocate the memory*/,
[self size].width,
[self size].height,
8 /*bitsPerComponent*/,
0 /*bytesPerRow - CG will calculate it for you if it's allocating the data. This might get padded out a bit for better alignment*/,
[[NSColorSpace genericRGBColorSpace] CGColorSpace],
kCGBitmapByteOrder32Host|kCGImageAlphaPremultipliedFirst);
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithGraphicsPort:bitmapCtx flipped:NO]];
[self drawInRect:NSMakeRect(0,0, [self size].width, [self size].height) fromRect:NSZeroRect operation:NSCompositeCopy fraction:1.0];
[NSGraphicsContext restoreGraphicsState];
CGImageRef cgImage = CGBitmapContextCreateImage(bitmapCtx);
CGContextRelease(bitmapCtx);
return cgImage;
}
-(cv::Mat)CVMat
{
CGImageRef imageRef = [self CGImage];
CGColorSpaceRef colorSpace = CGImageGetColorSpace(imageRef);
CGFloat cols = self.size.width;
CGFloat rows = self.size.height;
cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to backing data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNoneSkipLast |
kCGBitmapByteOrderDefault); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), imageRef);
CGContextRelease(contextRef);
CGImageRelease(imageRef);
return cvMat;
}
-(cv::Mat)CVGrayscaleMat
{
CGImageRef imageRef = [self CGImage];
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
CGFloat cols = self.size.width;
CGFloat rows = self.size.height;
cv::Mat cvMat = cv::Mat(rows, cols, CV_8UC1); // 8 bits per component, 1 channel
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to backing data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNone |
kCGBitmapByteOrderDefault); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), imageRef);
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpace);
CGImageRelease(imageRef);
return cvMat;
}
+ (NSImage *)imageWithCVMat:(const cv::Mat&)cvMat
{
return [[[NSImage alloc] initWithCVMat:cvMat] autorelease];
}
- (id)initWithCVMat:(const cv::Mat&)cvMat
{
NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize() * cvMat.total()];
CGColorSpaceRef colorSpace;
if (cvMat.elemSize() == 1)
{
colorSpace = CGColorSpaceCreateDeviceGray();
}
else
{
colorSpace = CGColorSpaceCreateDeviceRGB();
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
CGImageRef imageRef = CGImageCreate(cvMat.cols, // Width
cvMat.rows, // Height
8, // Bits per component
8 * cvMat.elemSize(), // Bits per pixel
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNone | kCGBitmapByteOrderDefault, // Bitmap info flags
provider, // CGDataProviderRef
NULL, // Decode
false, // Should interpolate
kCGRenderingIntentDefault); // Intent
NSBitmapImageRep *bitmapRep = [[NSBitmapImageRep alloc] initWithCGImage:imageRef];
NSImage *image = [[NSImage alloc] init];
[image addRepresentation:bitmapRep];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return image;
}
#end
(source)