How to handle CT(Computed Tomography) grayscale binary data to RGB UIimage - ios

Question

Here is a binary CT grayscale data down the file/date_byte1
The aim is to change the window wide window to change the CT image
The two bytes in the data are 1 pixels, and the width and height are 512 pixels
How to transform the pixel array RGB array into a bitmap
- (void)viewDidLoad {
[super viewDidLoad];
NSData *data = [[NSData alloc]initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"data_byte1" ofType:#""]];
Byte *testByte = (Byte *)[data bytes];
self.imageView.image = [self imageFromGRAYBytes:testByte imageSize:CGSizeMake(512, 512)];
}
- (UIImage *)imageFromGRAYBytes:(unsigned char *)imageBytes imageSize:(CGSize)imageSize {
CGImageRef imageRef = [self imageRefFromGRAYBytes:imageBytes imageSize:imageSize];
UIImage *image = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return image;
}
- (CGImageRef)imageRefFromGRAYBytes:(unsigned char *)imageBytes imageSize:(CGSize)imageSize {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(imageBytes,
imageSize.width,
imageSize.height,
16,
imageSize.width * 2,
colorSpace,
kCGImageAlphaNone);
CGImageRef imageRef = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return imageRef;
}
I'm going through the following methodGet the picture
Obtained original diagram
But I want to change the display of the picture through this method
- (int)getPresentValueV:(int)v AndWidth:(int)w AndHeight:(int)h{
int minv = h - roundf(w/2);
if (v < minv) {
return 0;
}
int maxv = h + roundf(w/2);
if (v > maxv) {
return 255;
}
int pv = roundf(255*(v - minv)/w);
if (pv < 0 ){
return 0;
}
if( pv > 255 ){
return 255;
}
return pv;
}
This method changes the output of PV use w h, which is less than 255, The default value of w 1600 . The default value of h -400.Next based on PV as an array of RGB (PV, PV, PV) to create UIimage.
for (unsigned i = 0; i < data.length/2; i++) {
NSData *intData = [data subdataWithRange:NSMakeRange(i*2, 2)];
[arrray addObject:#([self getPresentValueV: *(int*)([intData bytes]) AndWidth:1600 AndHeight:-400])];
}
So I want to choose the different w h by the getPresentValueV method above, and get the PV to generate the RGB (PV, PV, PV) array to generate a new picture.
- (UIImage *)imageWithGrayArray:(NSArray *)array {
const int width = 512;
const int height = 512;
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
UInt32 * pixels = (UInt32 *)malloc(height * width * sizeof(UInt32));
memset(pixels, 0, height * width * sizeof(UInt32));
for (int i = 0; i < array.count;i++ ) {
NSArray *subArray = array[i];
for ( int j = 0 ; j < subArray.count; j++) {
*(pixels +i *width + j) = makeRGBAColor([subArray[j] integerValue],0, 0, 255);
}
}
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pixels,
width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
UIImage *image = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)];
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(pixels);
return image;
}
I generated a two-dimensional array to generate a new picture, but it was not the correct result.