我希望将 UIImage 转换为 8 位。我尝试这样做,但我不确定我是否做得正确,因为稍后当我尝试使用图像处理库 leptonica 时收到一条消息,指出它不是 8 位。谁能告诉我我是否正确执行此操作或如何执行此操作的代码?
Thanks!
CODE
CGImageRef myCGImage = image.CGImage;
CFDataRef data = CGDataProviderCopyData(CGImageGetDataProvider(myCGImage));
const UInt8 *imageData = CFDataGetBytePtr(data);
以下代码适用于没有 Alpha 通道的图像:
CGImageRef c = [[UIImage imageNamed:@"100_3077"] CGImage];
size_t bitsPerPixel = CGImageGetBitsPerPixel(c);
size_t bitsPerComponent = CGImageGetBitsPerComponent(c);
size_t width = CGImageGetWidth(c);
size_t height = CGImageGetHeight(c);
CGImageAlphaInfo a = CGImageGetAlphaInfo(c);
NSAssert(bitsPerPixel == 32 && bitsPerComponent == 8 && a == kCGImageAlphaNoneSkipLast, @"unsupported image type supplied");
CGContextRef targetImage = CGBitmapContextCreate(NULL, width, height, 8, 1 * CGImageGetWidth(c), CGColorSpaceCreateDeviceGray(), kCGImageAlphaNone);
UInt32 *sourceData = (UInt32*)[((__bridge_transfer NSData*) CGDataProviderCopyData(CGImageGetDataProvider(c))) bytes];
UInt32 *sourceDataPtr;
UInt8 *targetData = CGBitmapContextGetData(targetImage);
UInt8 r,g,b;
uint offset;
for (uint y = 0; y < height; y++)
{
for (uint x = 0; x < width; x++)
{
offset = y * width + x;
if (offset+2 < width * height)
{
sourceDataPtr = &sourceData[y * width + x];
r = sourceDataPtr[0+0];
g = sourceDataPtr[0+1];
b = sourceDataPtr[0+2];
targetData[y * width + x] = (r+g+b) / 3;
}
}
}
CGImageRef newImageRef = CGBitmapContextCreateImage(targetImage);
UIImage *newImage = [UIImage imageWithCGImage:newImageRef];
CGContextRelease(targetImage);
CGImageRelease(newImageRef);
With this code I converted an rgb image to an grayscale image:
希望这可以帮助
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