[英]iPhone : How to get colour of each pixel of an image?
我想獲取圖像所有像素的顏色。 詳細地說,我有一個名為“ SampleImage”的圖像,具有400 x 400像素。基本上,我想從“ SampleImage”創建一個網格,該網格將具有400 x 400的正方形,每個正方形填充有對應於“ SampleImage”中特定像素的顏色。
我知道這有點抽象,但是我是iOS的新手,也不知道從哪里開始。 提前致謝!
使用此方法:這是更有效的解決方案:
// UIView+ColorOfPoint.h
@interface UIView (ColorOfPoint)
- (UIColor *) colorOfPoint:(CGPoint)point;
@end
// UIView+ColorOfPoint.m
#import "UIView+ColorOfPoint.h"
#import <QuartzCore/QuartzCore.h>
@implementation UIView (ColorOfPoint)
- (UIColor *) colorOfPoint:(CGPoint)point
{
unsigned char pixel[4] = {0};
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, kCGImageAlphaPremultipliedLast);
CGContextTranslateCTM(context, -point.x, -point.y);
[self.layer renderInContext:context];
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
//NSLog(@"pixel: %d %d %d %d", pixel[0], pixel[1], pixel[2], pixel[3]);
UIColor *color = [UIColor colorWithRed:pixel[0]/255.0 green:pixel[1]/255.0 blue:pixel[2]/255.0 alpha:pixel[3]/255.0];
return color;
}
@end
希望對您有幫助。
這段代碼對我來說是完美的-
- (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)xx andY:(int)yy count:(int)count{
NSMutableArray *result = [NSMutableArray arrayWithCapacity:count];
// First get the image into your data buffer
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = (unsigned char*) calloc(height * width * 4, sizeof(unsigned char));
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRelease(context);
// Now your rawData contains the image data in the RGBA8888 pixel format.
int byteIndex = (bytesPerRow * yy) + xx * bytesPerPixel;
for (int ii = 0 ; ii < count ; ++ii)
{
CGFloat red = (rawData[byteIndex] * 1.0) / 255.0;
CGFloat green = (rawData[byteIndex + 1] * 1.0) / 255.0;
CGFloat blue = (rawData[byteIndex + 2] * 1.0) / 255.0;
CGFloat alpha = (rawData[byteIndex + 3] * 1.0) / 255.0;
byteIndex += 4;
UIColor *acolor = [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
[result addObject:acolor];
}
free(rawData);
return result;
}
如果您是新手,則應該考慮先做些簡單的事情。 無論如何,您需要做的是通過CGBitmapContextCreate
設置CGContextRef
, CGBitmapContextCreate
包含足夠的數據來保存圖像。 創建它之后,您需要通過CGDrawImage
將圖像渲染到其中。 之后,您將有一個指向圖像中每個像素的指針。 該代碼與Nishant的答案類似,但是您將使用400x400而不是1x1一次獲取所有像素。
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