Bạn có thể nhận được không gian màu đầu tiên thông qua CGImage.
@property(nonatomic, readonly) CGImageRef CGImage
CGColorSpaceRef CGImageGetColorSpace (
CGImageRef image
);
Và bỏ màu Không áp dụng chuyển đổi định dạng. Vì vậy, để có được những không gian màu của một hình ảnh, bạn muốn làm:
CGColorSpaceRef colorspace = CGImageGetColorSpace([myUIImage CGImage]);
Lưu ý: hãy chắc chắn để làm theo các get/tạo/quy tắc bản sao cho các đối tượng CG.
Màu chuyển đổi sang RGB8 (cũng có thể được áp dụng cho RGB16 hoặc RGB32, thay đổi các bit cho mỗi thành phần trong phương pháp newBitmapRGBA8ContextFromImage
):
// Create a bitmap
unsigned char *bitmap = [ImageHelper convertUIImageToBitmapRGBA8:image];
// Create a UIImage using the bitmap
UIImage *imageCopy = [ImageHelper convertBitmapRGBA8ToUIImage:bitmap withWidth:width withHeight:height];
// Display the image copy on the GUI
UIImageView *imageView = [[UIImageView alloc] initWithImage:imageCopy];
ImageHelper.h
#import <Foundation/Foundation.h>
@interface ImageHelper : NSObject {
}
/** Converts a UIImage to RGBA8 bitmap.
@param image - a UIImage to be converted
@return a RGBA8 bitmap, or NULL if any memory allocation issues. Cleanup memory with free() when done.
*/
+ (unsigned char *) convertUIImageToBitmapRGBA8:(UIImage *)image;
/** A helper routine used to convert a RGBA8 to UIImage
@return a new context that is owned by the caller
*/
+ (CGContextRef) newBitmapRGBA8ContextFromImage:(CGImageRef)image;
/** Converts a RGBA8 bitmap to a UIImage.
@param buffer - the RGBA8 unsigned char * bitmap
@param width - the number of pixels wide
@param height - the number of pixels tall
@return a UIImage that is autoreleased or nil if memory allocation issues
*/
+ (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *)buffer
withWidth:(int)width
withHeight:(int)height;
@end
ImageHelper.m
#import "ImageHelper.h"
@implementation ImageHelper
+ (unsigned char *) convertUIImageToBitmapRGBA8:(UIImage *) image {
CGImageRef imageRef = image.CGImage;
// Create a bitmap context to draw the uiimage into
CGContextRef context = [self newBitmapRGBA8ContextFromImage:imageRef];
if(!context) {
return NULL;
}
size_t width = CGImageGetWidth(imageRef);
size_t height = CGImageGetHeight(imageRef);
CGRect rect = CGRectMake(0, 0, width, height);
// Draw image into the context to get the raw image data
CGContextDrawImage(context, rect, imageRef);
// Get a pointer to the data
unsigned char *bitmapData = (unsigned char *)CGBitmapContextGetData(context);
// Copy the data and release the memory (return memory allocated with new)
size_t bytesPerRow = CGBitmapContextGetBytesPerRow(context);
size_t bufferLength = bytesPerRow * height;
unsigned char *newBitmap = NULL;
if(bitmapData) {
newBitmap = (unsigned char *)malloc(sizeof(unsigned char) * bytesPerRow * height);
if(newBitmap) { // Copy the data
for(int i = 0; i < bufferLength; ++i) {
newBitmap[i] = bitmapData[i];
}
}
free(bitmapData);
} else {
NSLog(@"Error getting bitmap pixel data\n");
}
CGContextRelease(context);
return newBitmap;
}
+ (CGContextRef) newBitmapRGBA8ContextFromImage:(CGImageRef) image {
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
uint32_t *bitmapData;
size_t bitsPerPixel = 32;
size_t bitsPerComponent = 8;
size_t bytesPerPixel = bitsPerPixel/bitsPerComponent;
size_t width = CGImageGetWidth(image);
size_t height = CGImageGetHeight(image);
size_t bytesPerRow = width * bytesPerPixel;
size_t bufferLength = bytesPerRow * height;
colorSpace = CGColorSpaceCreateDeviceRGB();
if(!colorSpace) {
NSLog(@"Error allocating color space RGB\n");
return NULL;
}
// Allocate memory for image data
bitmapData = (uint32_t *)malloc(bufferLength);
if(!bitmapData) {
NSLog(@"Error allocating memory for bitmap\n");
CGColorSpaceRelease(colorSpace);
return NULL;
}
//Create bitmap context
context = CGBitmapContextCreate(bitmapData,
width,
height,
bitsPerComponent,
bytesPerRow,
colorSpace,
kCGImageAlphaPremultipliedLast); // RGBA
if(!context) {
free(bitmapData);
NSLog(@"Bitmap context not created");
}
CGColorSpaceRelease(colorSpace);
return context;
}
+ (UIImage *) convertBitmapRGBA8ToUIImage:(unsigned char *) buffer
withWidth:(int) width
withHeight:(int) height {
size_t bufferLength = width * height * 4;
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, bufferLength, NULL);
size_t bitsPerComponent = 8;
size_t bitsPerPixel = 32;
size_t bytesPerRow = 4 * width;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
if(colorSpaceRef == NULL) {
NSLog(@"Error allocating color space");
CGDataProviderRelease(provider);
return nil;
}
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedLast;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
CGImageRef iref = CGImageCreate(width,
height,
bitsPerComponent,
bitsPerPixel,
bytesPerRow,
colorSpaceRef,
bitmapInfo,
provider, // data provider
NULL, // decode
YES, // should interpolate
renderingIntent);
uint32_t* pixels = (uint32_t*)malloc(bufferLength);
if(pixels == NULL) {
NSLog(@"Error: Memory not allocated for bitmap");
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(iref);
return nil;
}
CGContextRef context = CGBitmapContextCreate(pixels,
width,
height,
bitsPerComponent,
bytesPerRow,
colorSpaceRef,
bitmapInfo);
if(context == NULL) {
NSLog(@"Error context not created");
free(pixels);
}
UIImage *image = nil;
if(context) {
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, width, height), iref);
CGImageRef imageRef = CGBitmapContextCreateImage(context);
// Support both iPad 3.2 and iPhone 4 Retina displays with the correct scale
if([UIImage respondsToSelector:@selector(imageWithCGImage:scale:orientation:)]) {
float scale = [[UIScreen mainScreen] scale];
image = [UIImage imageWithCGImage:imageRef scale:scale orientation:UIImageOrientationUp];
} else {
image = [UIImage imageWithCGImage:imageRef];
}
CGImageRelease(imageRef);
CGContextRelease(context);
}
CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(iref);
CGDataProviderRelease(provider);
if(pixels) {
free(pixels);
}
return image;
}
@end
màu không thay đổi ,, chỉ xuất hiện thay đổi do màn hình hiển thị võng mạc của thiết bị. – aBilal17