ios - ImageMagick How to code to apply ShepardsDistortion on image - ios

Question

I am new to ImageMagick,and i want to develop an effect of ShepardsDistortion on source image. i gone through many posts and sites, but i didn't find way to implement "ShepardsDistortion" in iOS.
MagickWand *mw = NewMagickWand();
MagickSetFormat(mw, "png");
UIImage *sourceImage=[_sourceImgView image];
NSData *imgData=UIImagePNGRepresentation(sourceImage);
MagickReadImageBlob(mw, [imgData bytes], [imgData length]);
Image *image=GetImageFromMagickWand(mw);
DistortImage(image, ShepardsDistortion, , ,);
I done upto this, but i dont know what to pass as arg in DitortImage(). So if anyone knows then help me.
EDIT:
-(void)distortImage{
MagickWandGenesis();
MagickWand * wand;
MagickBooleanType status;
wand = NewMagickWand();
MagickSetFormat(wand, "png");
status = MagickReadImage(wand,"chess.png");
// Arguments for Shepards
double points[8];
points[0] = 250; // First X point (starting)
points[1] = 250; // First Y point (starting)
points[2] = 50; // First X point (ending)
points[3] = 150; // First Y point (ending)
points[4] = 500; // Second X point (starting)
points[5] = 380; // Second Y point (starting)
points[6] = 600; // Second X point (ending)
points[7] = 460; // Second Y point (ending)
MagickDistortImage(wand,ShepardsDistortion,8,points,MagickFalse);
NSString * tempFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:#"out.png"];
MagickWriteImage(wand,[tempFilePath cStringUsingEncoding:NSASCIIStringEncoding]);
UIImage * imgObj = [UIImage imageWithContentsOfFile:tempFilePath];
_resultImgView.image=imgObj;
//
// unsigned char * cBlob;
// size_t data_size;
// cBlob = MagickGetImageBlob(wand, &data_size);
// NSData * nsBlob = [NSData dataWithBytes:cBlob length:data_size];
// UIImage *uiImage = [UIImage imageWithData:nsBlob];
// _resultImgView.image=uiImage;
MagickWriteImage(wand,"out.png");
wand=DestroyMagickWand(wand);
MagickWandTerminus();
}

Answer 1

This might help:
MagickWandGenesis();
magick_wand = NewMagickWand();
double points[24];
points[0] = 250;
points[1] = 250;
points[2] = 50;
points[3] = 150;
points[4] = 0;
points[5] = 0;
points[6] = 0;
points[7] = 0;
points[8] = self.frame.width;
points[9] = 0;
points[10] = self.frame.width;
points[11] = 0;
points[12] = self.frame.width;
points[13] = self.frame.height;
points[14] = self.frame.width;
points[15] = self.frame.height;
points[16] = self.frame.width;
points[17] = self.frame.height;
points[18] = self.frame.width;
points[19] = self.frame.height;
points[20] = 0;
points[21] = self.frame.height;
points[22] = 0;
points[23] = self.frame.height;
NSData * dataObject = UIImagePNGRepresentation([UIImage imageNamed:#"Imagemagick-logo.png"]);//UIImageJPEGRepresentation([imageViewButton imageForState:UIControlStateNormal], 90);
MagickBooleanType status;
status = MagickReadImageBlob(magick_wand, [dataObject bytes], [dataObject length]);
if (status == MagickFalse) {
ThrowWandException(magick_wand);
}
// posterize the image, this filter uses a configuration file, that means that everything in IM should be working great
status = MagickDistortImage(magick_wand,ShepardsDistortion,24,points,MagickFalse);
//status = MagickOrderedPosterizeImage(magick_wand, "h8x8o");
if (status == MagickFalse) {
ThrowWandException(magick_wand);
}
size_t my_size;
unsigned char * my_image = MagickGetImageBlob(magick_wand, &my_size);
NSData * data = [[NSData alloc] initWithBytes:my_image length:my_size];
free(my_image);
magick_wand = DestroyMagickWand(magick_wand);
MagickWandTerminus();
UIImage * image = [[UIImage alloc] initWithData:data];
[data release];
[imageViewButton setImage:image forState:UIControlStateNormal];
[image release];

Answer 2

Arguments are passed to DistortImage as the start of a list of doubles, and size information about the list. Example:
size_t SizeOfPoints = 8;
double Points[SizeOfPoints];
DistortImage(image,
ShepardsDistoration,
SizeOfPoints,
Points,
MagickFalse,
NULL
);
In your example, you seem to be mixing MagickWand & MagickCore methods; which, seems unnecessary and confusing. I would keep this distortion simple, and only use MagickWand's MagickDistortImage method. Here's a example in c
int main(int argc. const char **argv)
{
MagickWandGenesis();
MagickWand * wand;
MagickBooleanType status;
wand = NewMagickWand();
status = MagickReadImage(wand,"logo:");
// Arguments for Shepards
double points[8];
// 250x250 -> 50x150
points[0] = 250; // First X point (starting)
points[1] = 250; // First Y point (starting)
points[2] = 50; // First X point (ending)
points[3] = 150; // First Y point (ending)
// 500x380 -> 600x460
points[4] = 500; // Second X point (starting)
points[5] = 380; // Second Y point (starting)
points[6] = 600; // Second X point (ending)
points[7] = 460; // Second Y point (ending)
MagickDistortImage(wand,ShepardsDistortion,8,points,MagickFalse);
MagickWriteImage(wand,"out.png");
wand=DestroyMagickWand(wand);
MagickWandTerminus();
return 0;
}
Resulting in a distorted translated image (details)
Edit
For iOS, you can use NSTemporaryDirectory (like in this answer), or create an image dynamically using NSData (like in this question).
Example with temporary path:
NSString * tempFilePath = [NSTemporaryDirectory()
stringByAppendingPathComponent:#"out.png"];
MagickWriteImage(self.wand,
[tempFilePath cStringUsingEncoding:NSASCIIStringEncoding]);
UIImage * imgObj = [UIImage imageWithContentsOfFile:tempFilePath];
And an example with NSData + blob
unsigned char * cBlob;
size_t data_size;
cBlob = MagickGetImageBlob(wand, &data_size);
NSData * nsBlob = [NSData dataWithBytes:cBlob length:data_size];
UIImage * uiImage = [UIImage imageWithData:nsBlob];